Water Journal March 2005

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AUSTRALIAN WATER ASSOCIATION ABN 78 096 035 773

OPINION Sharing is the Name of the Game; Developing Strategies; My Point of View, T Kelly ASSOCIATION ACTIVITIES 8 WaterAid Australia Update; To All Australian Water Association Members PROFESSIONAL DEVELOPMENT l 0 Details of courses, classes and other upcoming water events CROSSCURRENT 12 Industry news FEATURES 18 Community-Based Social Marketing CONFERENCE REPORTS 24 4th National Waterwatch Conference; AWA Specialty Conference - Membranes & Desalination Water efficient showerheads Page 74

GOVERNANCE 28

THE ROLE OF WATER AUTHORITIES IN PROVISION OF INDEPENDENT ADVICE Independent water companies or government advisors?

T Mollenkopf

32

CHALLENGES IN SUSTAINABILITY Encouraging sustainable solutions F Pammi nger, K Gan

DEMAND MANAGEMENT 34 [ml INTEGRATED WATER CYCLE MANAGEMENT: ANALYSIS OF RESOURCE SECURITY

Methods for evaluating water cycle scenarios P J Coombes 46

DIY: $1000 PER HOUSE SAVES 90% OF MAINS WATER

A pragmatic house-scale benefit-cost evaluation R G Shaw

Excessive biological foam at Bendigo WRP - Page 1 17

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~ PRICING OF DRINKING WATER VS RECYCLED WATER: FAIRNESS AND SATISFACTION

A further survey of Mawson Lakes residents A Hurlimann , J McKay, G Geursen 68

[ii REDUCING DOMESTIC WATER USE: LESSONS FROM MARKETING AND ECONOMICS Comments from two other disciplines M W allace, G Barrett

74

SHOWERHEAD RETROFIT SCHEMES: A SOCIAL MARKETING PERSPECTIVE

Comparing four systems for encouraging replacements K Stinchcombe, K W ildman , M W il tshire

WATER QUALITY 84 [jl THE Ps AND Qs OF RISK ASSESSMENT Astraightforward explanation of the concepts D Deere, A Davison

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30 ML/d ultra-filtration plant Page 120

DETERMINING BENEFITS OF A REGULATORY FRAMEWORK FOR DRINKING WATER QUALITY

Assessing the costs /benefits of water quality legislation R Deighto n-Sm ith , B Labza

OUR COVER: Yarra Valley Water has a firm commitment to sustainability, as outlined by Tony Kelly (page 6). One project is a long-term partnership with CERES Environmental Park, in Brunswick, Victoria, where a number ofinnovative recycling systems are being trialled.

Visit www.ceres.org.au

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104 ~ CUSTOMERS HELP ASSESS OPTIONS FOR TASTE CONTROL

Four treatment modifications tasted by a small panel P Mosse, J Busch 110 aj DETERMINING ALKALINITY CONSUMPTION BY COAGULANTS

A simple test method P Gebbie, R J Turney

WASTEWATER 117

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SURFACTANT FOAMING AT THE BENDIGO WATER RECLAMATION PLANT

Atrade waste tracked down H Hall

120 AUSTRALIA'S LARGEST ULTRA-FILTRATION RECLAIMED WATER PLANT

Pathogen removal by UF and chloramine

Cross section of the Biolytix Waste Treatment System · Page 128

A Davey, P Mill er, F Knops

125 DECENTRALISED VS CENTRALISED SEWERAGE

On-site treatment: Why is Australia behind America?

D Cameron

128 BIOL YTIX™ • A LOW COST, HIGH PERFORMANCE SEWERAGE ALTERNATIVE

The Biolytix system explained D Camero n

ODOUR CONTROL 130 ~ PRODUCTION OF H2S IN SMALL DIAMETER RISING MAINS

Sulfide generation in small diameter rising mains is not linear with length B Hu tchinson, G Hamilto n

135 ACTIVATED SLUDGE DIFFUSION FOR ODOUR CONTROL

H2S removal by activated sludge V Barbosa, R M Scuetz

Vietnamese canal water being treated - Page 14 1

139 MICROBIAL CONTROL REDUCES SULFIDE

Anew product undergoes trials R Cha ndler

OVERSEAS PROJECTS 141 WATER SUPPLY AND SANITATION IN A VIETNAMESE VILLAGE

Visit the

Trials of domestic water treatment

Australian Water Association

T Wrigley

HOME PAGE

and access news, calendars, bookshop and aver I 00 pages al information at

WATER BUSINESS

http:/ /www.awa.asn.au

146 NEW PRODUCTS AND BUSINESS INFORMATION

A BETTER TOMORROW made possible Melbourne

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MARCH 2005 3

from the president

DEVELOPING STRATEGIES le is worth reporting on our lase Board Meeti ng and che inaugural meeting of the Strategic Advisory Council (SAC - excuse the acronym).

T he SAC includes rwo represen cacives from each Branch with their role concentrating on electing the Board and guiding policy and direction for AWA. My congrawlacions to the SAC for the professional procedures on electing che new Board and on che positive contribution chat was made to establishi ng priority actions for rhe Association for che next twelve months. Admi tted ly there was lim ited time to delve into much derail bur char wi ll follow at lacer meetings.

Ir should be noted char the SAC has different responsibil ities to the Board, and meets twice per year. The Board will be meeting at lease six times per year. My thanks to outgoing Board members, many of whom will sti ll be active in AWA management through representation on the SAC and a number of whom may nominate fo r che Board down the crack.

My congratulations co all representatives on che new Board as well.

One of the most exciting ini tiatives chat came out of the SAC meeting was a commitment to life our game in

che Association and in the participation in our activities in general. We were very pleased chat four young members from che Victorian Branch (the SAC meeting was held in Melbourne) could attend che SAC meeting and presen t some views on what AWA was doing well and what ocher things AWA could be doi ng to foster young and new membersh ip. Many ideas were fort hcoming bur the outcome was rhe formation of a committee involving young member representatives from each Branch. This comm ittee will review che outputs from the Melbourne meeting and look at initiatives chat might move us forward. They are to report back to che next Board meeting at Ozwacer in May.

There have been some interesting developments with young members over the last year but we would like to more actively engage their involvement in the running of the Association and in the participation in our activities in general.

to operators th roughout the country through state based operators conferences, newsletters and journals.

Worki ng with AWA support, the WIOA will be provid ing services in most, if not all, states within the next few years. AWA will be represented on the WIOA Board to help guide the nationalisation process and to ensure fu ll co-ordination with AWA accivicies. We are hopeful chat WSM will also join AWA down the track in being a supporting partner fo r rhe venture. My thanks co Ron Bergemeier and George Wall from WJOA for their perseverance and resolve in working with the AWA to reach chis point. My thanks also to Barry Norman, Peter Do nlan, Chris Davis and Ian Jarman for their inputs to arriving at a workable model for raking the concept forward.

When looking through the Board papers for the last Board meeti ng I noted an item regarding the launchi ng of the new web sire. Many people may have visited ou r web site over the lase yea r or so may have noted that there were some deficiencies. The reason fo r this was char our energies have been focused on getting the new system up and running.

Some two years ago AWA agreed to invest a considerable sum of money in the upgrading

water FUTURE MAJOR FEATURES MAY - C RC Fres hwa ter E cology, Membra ne Tec hn o lo gy

regard co young and new members. There have been some interesting developments with young members over the lase year but we would like to more actively engage their involvement in the running of

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Another pleasi ng output from our Board meeting in Melbourne was the approval to support the nationalisation of the Water Industry Operators Association (WIOA). The aim is to provide an improved service

JUNE ¡ Ozwater Conference Report

AUGUST

Asse t s, Govern an ce & Ec onomi cs, ASR, Pumping & Pipelines

of the IT sys tem and web site. fnformarion is one of the most important parrs of our busi ness and ir was appreciated char we needed to invest in upgrading our information systems accordingly. T here has been a loc of work done over the lase two years and our new web sire sho uld be operational by the rime chis reaches your desks.

Once this happens we will be able to concentrate on the next phase which is im proving the info rmation char is accessible on the web site. We already have a wo rking parry looking at rhe developmenc of a web based lib rary system for technical papers and the like. There may be other opportunities as well.

Rod Lehmann

water

Contributions Wanted Water journal welcomes the submission of papers equivalent to 3,000-4,000 words (allowing for graphics) relating to all areas of the warer cycle and water business to be published in the journal. Topical stories of up to 2,000 words may also be accepted.

All submissions of papers intended for rhe main'body of the journal should be emailed ro the Technical Editor, bswinton@bigpond.ner.au.

Shorter news irems should be emailed to news@awa.asn .au. A submitted paper will be tabled at a monthly Journal Committee meeting where, if appropriate, it will be assigned to referees. Their comments will be passed back to rhe principal author.

If accepted and after any comments have been dealt with, the final paper can be emailed with rhe text in MS Word bur with high resolution graphics (300 dpi riff, jpg or eps files - Zip disks or CD-ROMs can be accepted) as separate files, or hard copy phoros and graphics suitable fo r scanning by the publisher can be mailed ro 23 Blaxland Rd, Wentworth Falls, NSW 2782.

conferences Tampa Bay Water awarded rhe contract to S&W Water, a Stone and Webster - Poseidon Resources JVC Construction began in August 2001 and the first 20,000m3 of water was produced in March 2003.

However, since th en, the plane has run sporadically, producing far shore of its intended output.

T hree of rhe companies involved in the project have filed fo r bankruptcy and on 2 December 2003 the dispute over co ntrol and ownership went before a Federal Judge.

T he project invo lved rhe plane itself, a seawater in take, concentrate discharge system, various chemical storage and dosing facil ities and 24km (1 5 miles) of product water transmission mai n.

The Problems In 2000, Stone & Webster declared bankruptcy, leaving S&W W ater without an

engineering and construction partner. Lacer char year, with perfo rmance deadlines looming, Poseidon reamed up with Covanra Energy. A year on, the replacement went the same way as its predecesso r. A new company was created to comp lete rhe plane, Cova nta T ampa Consrrucrion.

W hen, in early 2002, it became clear char Poseidon and Covanra had been unsuccessfu l in securing long-term financing, Tampa Bay Water decided to buy our Poseidon's interest in the project and push fo rward.

T his allowed chem to save $ 1 mill ion a year in financing charges, while retaining Covanra to finish rhe job.

Several deadlines were missed in 2003. A crucial two-week performance rest in May revealed 31 deficiencies in rhe plan e, including excessive membrane silting. Th e

problems ranged from failures of the contractor to adhere to rhe specifications (inferior cartridge filters, pipe materials, leaky connections, non installation of an on-li ne mixer for dispersing chemicals) co sloppy engineering practice (disposal of metal shavings which damage membranes, and polystyrene food conta iners in the fi lter media). Pre-treatment performance was found to be inco nsistent in terms of SDI and turb idity. Cartridge fi lters expired well befo re normal life. ln September, Asian green mussels were fo und to be clogging rhe filters and yet another default on the contract followed. In October, with the plant still unable to pass the l 4day performance rest required for fi nal accepta nce, Covanta Tampa Construction followed its parent company into bankru ptcy. T he ensuing dispute with Tampa Bay

led to December's co urt heari ng.

T he judge ordered both sides into mediation, setting a 15 January 2004 deadlin e fo r Covanra to cure the plane shortcomings with a pre-trial heari ng for February. Since char rime, an interi m operator has been appointed to br ing the plant finally on line, a process which is ongoing.

Ir was clear from Vourchkov's presentation and subsequent discussio n char rhe problems with rhe Tampa Bay plane did nor lie with rhe technology. Lessons were learned and rhe parti es involved resolved to ensure ch ar similar mistakes did nor recur.

Un fo rtunately, rhe b ad publicity generated together with ill-in fo rmed media has sall ied seawater desa lination with a reputation fo r being unreliable, costly and prone co problems.

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MARCH 2005 27

THE ROLE OF WATER AUTHORITIES IN PROVISION OF INDEPENDENT ADVICE T Mollenkopf Introduction by Dr Nora Scheinkestel, Chairman, South East Water "Many years ago, in a speech to the water industry, I suggested that a decided asset, if not a pre-requisite, for directors of Governmentowned water businesses was having a split personality. The role requires directors to wear multiple hats and juggle competing agendas and, I think, in the years since I gave that speech, the need to play different roles, see things from multiple angles and play devils' advocate, sometimes apparently against one's own interest, has only increased!

As directors ofcompanies, we are bound by the full panoply ofdirectors' duties, bound to act in the best interests ofthe company. Whilst this is generally understood to mean primarily shareholders and our companies are government owned, one can envision a situation where a short term political goal may not be in the long term interest of the company. Further, in this circumstance, should the 'company' and its 'shareholders' be strictly interpreted as government of the day, the company as a sustainable entity going forward or the wider community?

There are, ofcourse, always choices. A director who ultimately felt that implementation ofgovernment policy was not in the interests of the 'company' could resign. A government, faced with a recalcitrant board or director, could heed their advice or sack them. However, the best option must surely be to work together to ensure that government policy is developed in a way which benefits the wider community and ensures the sustainability of the entities providing this essential service. We, within the water sector, have an obligation to ensure that government policy is informed by the best skills and knowledge we have to offer.

The article by Tom Mollenkopf, General Manager, Corporate Strategy at South East Water, develops this proposition and shows how, while many of us in the industry fiercely defend the benefits ofcorporatisation, we also, in many ways, adhere to one of the most traditional ofpublic service conventions - the obligation to give the government of the day fearless and impartial advice. This may not guarantee that we will always like the result and maybe the stark choices referred to above still have to be addressed but we will know that we have done our best to discharge this important obligation" Dr Scheinkestel h as h ad a major involvemen t with the regulated utility sector having served as both chairman and director of a number of utilities across the gas, water and electricity sectors. She is also an Associate Professor at the Melbourne Business School at Melbourne University.

A Duty?

Clear and accountable governance arrangements are essential fo r the effective delivery of water, sewerage and recycled water services. Currently, the prevalent contemporary governance model involves: 1. The Government developing and setting industry policy; 2. An independent regulator/s developing and enforcing the standards applying to an industry; and 3. Businesses delivering services withi n rhe policy framework set by Government, and to standards required by the independent regularo r/s.

Historically, the governance arrangements in the water industry have been d iffe rent to rhe current model, in char many water industry participants undertook the dual roles of service p rovider and industry regulator. In some cases, the water authority also sat with, or close to, the governmem department which set policy. In Victoria, the separation of roles has been explicitly achieved through the disaggregation o f larger utili ties, corporatisation and the recent creation of independent economic and technical regulators.

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I am a firm advocate of the benefi t of the separation of the roles of policy setting, service delivery and regulation. The metropolitan Melbou rne experience has shown a consistent trend of imp roved performance across a suite of indicators economic, social and environmental since the structural reforms of 1995 . Ir is worth noting that the qualiry and responsiveness of management chat has flowed from independent Boards of corporatised emities can comfortably be achieved with fu ll government ownership. But this is a subject fo r further exploration at another time.

W hat I would like to suggest however, is that notwithstanding the separation of roles, water businesses have a unique capacity - indeed a duty - to comribute to the developmem of governmem policy and to proactively offer approaches and solutions to the increasing challenges confronting our industry.

A Challenging and Dynamic Sector a Need for Input The challenges and opportunities confro nting the water sector are well recognised - and numerous.

Nationally we have suffered from several years of drough t now. This is not a short-

term issue as we may have thought in previous droughts. It is compounded by the potential long-term impacts of climate change resulting in changed usage patterns and reduced water yields. We can add to this the need to address the requirements for environmemal flows on currently stressed rivers while meeting increasing demands for water from a growing population.

Whilst a sustainable water strategy may be the major and very visible challenge it is nor the o nly one. Consider for example questions of public health, securiry of infrastructure and risk management, ageing assets and competing demands for invesnnem, environmental standards fo r sewage treatment and customer and community expectations.

With the b readth of issues confronting our sector, the insight, ideas and intellect residing in our water companies will be essential to finding sustainable and innovative solutions.

A Role to Play Whilst water businesses are often independem companies or stamtory corporations, they commonly have explicit

governance or implicit requirements to consider matters beyo nd purely normal 'commercial' operations. In the case of South East Water, its constitution provides that its pri ncipal objectives are twofold: "(a) [to operate] as efficiently as possible consistent with prudent commercial practice; and (b) maximising ics contribution to che economy and well being of the State of Victoria."

T he organisation also has a number of other obligations in addition to th ose associated with rhe principal obj ectives.

Specific examples in cl ude: • Contribu ting to the Government's 20% recycled water target for the metropolitan Melbourne area; • Reducing per capita co nsumption by 15% by 2010; • Impl ementing a backlog sewerage program; and • Administering a number of Community Service O bligations.

In addition, South East Water abides by che ethos of Corporate Social Responsibility when operating its business.

T his notio n is not unique to State O wned Corporations - indeed its roots are firm ly in the private sector around the world.

Corporate Social Responsibility reflects the philosophy that companies have obligations that extend beyond shareholders. It requires chat companies have regard to cheir broader co mmunities and the enviro nment. Ic invokes companies co co nsider their role on che broader societal stage bo th in the way they conduce themselves eth ically and che positive contributions chat can be made in che co mmunities in which they operate or the areas upon which they impact.

Given these obligations, the water businesses are significantly affected by, and often an instrument of, Government policy. T herefore, ir is in the water industry's interests to see that the best tech nical, policy and regulatory skills are uti lised by Govern ment to develop water industry policies. le is also che industry's du ty co make that co ntribu tion .

The Capacity to Contribute T he water industry is home to an enormously talented pool of peo ple. T heir skills traverse more than just design and construction or implementing systems.

T hey have often moved between co nsultin g firms, the water seccor and government or regulacory agencies such that they have seen the water industry from all sides.

W hilst most businesses operate within a defined geographic area in the p r ovision of co re services, we do so with natio nal and in ternacional connections and experience.

By way of example, South East Water's people have played key roles in a reas as diverse as che groundbreaking M elbourn e water filter study, sharing leading Asset Management practices with US W ater Authorities, national water quality guidelines or proprietary field m anagement systems. We routinely engage with water businesses, government agencies and regulacors from around the world. And we actively grow and share intellectu al capital through state, national and global water associations and related networks .

••• ••• Australian

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Centre

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MARCH 2005

29

governance A water business also has rhe practical experience, rogerher with its closeness to customers to give ir rhe insight necessary to identify needs and expectations of irs community and the opportunities for longterm policy development. T his derai led appreciation comes from hundreds of thousands of customer co ntacts in a year, active community engagement on current issues and specific proposals, regular customer surveys and other feed back instruments and community committees.

Our people are at the coalface where rhe problems may present and rhe solutions will be found. They have rhe most powerfu l incentive to find both the immediate operational solution and rhe long-term fix for rhe root cause. Ar South East Water we operate on many levels to tackle our business' challenges looking from continuous improvement to innovative breakthroughs. Inevitably the advances we seek to deliver whether in customer service, operational or environmental performance or improved shareholder rerurns, will be constrained or enabled by the surrounding regulatory and policy framework.

Given the capabi lities and interest of water businesses, they must proactively co ntribute to government policy development and rhe associated policy debate. More specifically they should be a source of independent advice to policy advisors, particularly concerning rhe practical impacts and imp lementation issues associated with proposed policies.

T here are many recent examples where the water industry has led the way in providing the foundations fo r government policy. T his includes key aspects of Water Conservation Policy (eg product rebates, alternative water sou rce promotion and seed fun ding for cooperative ventures with industry and rhe community); Tradeable Water Entitlements; and Tariff Structures.

The larrer is a case in point: South East Water, along with rhe other rwo metropolitan Melbourne Retailers, was extensively involved in rhe development of the Victorian Government's newly implemented rhree-rier increasing block tariff. T his important conservation initiative had its genesis in research work commissioned by the water industry. It involved developing an understanding of the benefits of pricing fo r conservation, understanding the likely customer responses, considering the likely stakeholder issues and practical implementation challenges. The concept was rested with Government who then sought furth er input as part of rhe fo rmal policy adoption process. This involved the three Retailers worki ng closely with Government to attain

30 MARCH 2005

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an outcome rhar was practical and acceptable to the broad customer base. In particular, we were able to provide detailed customer impact analyses to Government, which helped shape rhe fi nal prices and customer hardship arrangements.

Currently there is an important role for water businesses to play in critical areas such as Water Recycling and the role of Ocean Outfalls in the sewage treatment and disposal cycle.

Recycling is seen by many as a panacea fo r rhe twin challenges of supplementing scarce potable water supplies and reducing discharge of treated effl uent to the environment. There are however, complex health, social, environmental and economic matters that need to be understood and managed, particularly as we move to extend recycling. The metropolitan water companies have much to contribute to this debate. South East Water, for example, already has substantial experience in recycling, achieving around 20% reuse from its own Treatment Plants as well as retailing rreared effluent so urced from irs wholesaler Melbourne Water. Ir is therefo re well placed to provide scientific, technical and operational analysis and advice, customer and community insights and eco nomic assessme'n ts that will be integral ro rhe successful and sustainable extension of recycling into more domestic and industrial settings. Environmental and Health standards must be serried quickly on rhe basis of a balance of sound science, available and cost effective technologies and informed co mmunity expectatio ns. The business case fo r recycl ing projects will also need to recognise that many schemes will nor be justifiable at present on economic grounds alone. Yer there are perceived environmental and social benefits to be achieved and so, on a Triple Bottom Line basis, rhe schemes may be warranted.

Finding the right tools to assess and implement additional recycling is a key opporruniry for water businesses.

Ocean outfalls have attracted increasing attention over recent years. Around Australia there are some 140 outfalls discharging treated effluent of various standards. Lobbying fro m interest groups such as the C lean Ocean Foundation has resulted in a number of political parries (both in government and in opposition) adopting policies to 'close' ocean outfalls.

Ar this stage however there are still many practical and scientific questions rhar need to be resolved before it can be determined if th is is the optimal approach .

The outfall at Boags Rocks on the Mornington Peninsula discharges around 420ML per day of secondary rreared

effluent onto rhe Bass Strait shoreli ne.

Work done by South East Water indicates rhar a local recycling scheme to utilise all rhis water would require irrigation of about 700 km 2 of land and a 100GL storage reservoir for winter Aows when irrigation does nor occur. Each of these requirements raises significant concerns about the practicability of 'closing' the outfall. The cost may also be difficult to justify because environmental studies have indicated that the main effects are in the immediate vicinity of the present shoreline discharge and health stud ies have concluded rhar there is no risk to swimmers ar nearby beaches. This latter fin ding is nor supported by local interest groups who maintain rhar there is a high incidence of illness amongst sw11nmers.

If as a community, we are to pursue a policy of closing outfalls, ir needs to be done wirh a fou ndation of well-documented costs and benefits. It is the community as a whole that will pay for any works necessary to close outfalls, an allocation of potentially billions of dollars of scarce resources. We must be certain that we are directing those reso urces to the area of greatest need .

Conclusion Whilst Government is rhe fi nal arbiter of community expectations, and hence has the final say in policy development, it does require rhe best technical, policy and regulatory skills and ideas to develop industry poli cy.

I believe rhar water businesses have a unique capacity, in fact duty, to make greater co ntributions, and in many cases lead, government policy development. In addition , water businesses should provide independent technical, policy and regulatory advice to the policy development process.

The Author Tom Mollenkopf is the General Manager, Corporate Strategy, ar South East Water Limited in Melbourne. He joined the company soo n after its establishment in 1995 and has held various positions including Company Secretary and, more recently, General Counsel and General Manager, Corporate and Finance. Tom has served on many industry bodies including the Research Comm ittee of the Water Services Association of Australia and as Chairman of the Water Industry Superannuation Fund. H e is also on rhe Board of Corporate Social Respo nsibility Australia. Email Tom.Mollenkopf@sewl.com.au

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governance

CHALLENGES IN SUSTAINABILITY F Pamminger, K Gan Have you ever heard anyone argue that we should not strive for a sustainable water ind ustry? We haven't. Having never heard anyone disagree, why is sustainability so difficult to translate into a program of practical actions/ And it gets even worse when you hear some people argue that all that has changed under the auspices of sustainability is that annual reports have got thicker and that marketing spin is exceeding sustainable improvements. So it is easy to see why some peop le get frustrated with any talk about sustainability and consequently devalue the notion itself. Given all this complexity, and assuming that we want a sustainable water industry, what should we be doing to improve the existing situatio n?

The inherent problem is trying to get agreement with d ifferent people in a con cept that is large, complex and multi-layered. We have difficulty visualising where to start, how we should work w ith others, and conceptually seeing how it all fits together. It is something similar to trying to describe the concept of a large intricate building like a cathedral just using words. Talk to di fferent people and they are likely to have different images of what the end p roduct will look like. Then imagine that we had to rely on the contributions of a large range of individuals to p roduce the end product. We imagine that chis would be cumbersome, if not

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comical. If we were co gee an outcome, and we are not su re that we would, it is hardly likely to b e a fin e piece of art.

When one is dealing with a host of abstract concepts that must finally mesh together into a u nified whole, into a sort of cathedral of ideas, eg sustainability, we n eed as much co-operative action as possible for it to get implemented. So how do we move it from the id ea stage to the action phase?

We n eed to be clear of all the d ifferent people and their views.

With respect to the water industry, we see three different groups .

There is the policy maker/ regulator, water company and consumer.

We must recognise each of these will have d ifferent world views by the very nature of the structural positio n they are in, independent of who is in that position. Think of what you would do in any of those respective positions. If we use the decision to buy a rainwater tank for example, working in the water industry, we in M elbourne may come to the co nclusion chat it is not economical. Working as a policy maker/regulator however, we conclude chat reticulated water is better. While as a consumer we probably don 't consider any of chose perspectives, and just th ink it is a great environmentally friendly way to save water. Who considers the cost benefit or relative health aspect when buying a fridge? G iven the divergence of opin ions, how can we forge a path fo rward if we all have differen t perspectives?

T o answer that question let us look at why each of these different groups, or arguably any person operating in any of these situatio nal positions, has such differi ng views . As a policy maker/regulator our primary responsibility is ensuring the collective protection of society. We could cal l chat governance. In chat role we wane to make sure chat che health of ch e community is maintained. In a water company, our primary focus is co ensure chat th e service as specified by the health experts is delivered in the most economical way. To deliver chis we focus on quantifiable data. While as a customer, o ur p rimary focus is o n meeting our wants and needs, which is based on value judgements. And each of these differing views is brought together when we consider a choice such as a rainwater tank.

Figure 1 shows the differing views that each o f the three groups has. This highlights the complexity of the inter-relationship. We would argue, great to look at and ponder, but from our perspective unsolvable in the context of there being only one answer. They are all linked together and, depending on what perspective that you experience it, they are all correct.

Increasing the area ofshared understanding betllleen policy makenl regulato1·s, wate1' companies and customers.

We have taken the rainwater tank as a simple example of how complex the interaction can become. Let us look at what happens when we consider third p ipes for example, which is a more complex sustainable consideration. The government may mandate the installation of a domestic third pipe system leading the developer, who may find it too expensive, to demand a more generous pricing model from the water company. The water company may consider

32 MARCH 2005

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governance ir inappropriate that they should have to ca rry the increased operating expenditure leading to a stalemate of inaction. Add the regulations by the EPA prohib iti ng certai n uses of recycled water because of perceived health risks and sustai nability minded consumers may co nsider this an unnecessary hi ndrance, addi ng another level of co mplexity for the water company who is trying to walk a tightrope between the two .

people, rhe better rhar information , the better the collective decisio n rhar will be made. Just like che economic marker model, this operates best with correctly informed people, together with transparent coses. So, too, we will make more sustainable decisions with the appropriate informat ion .

In sum mary, we co nsider that the most effective way to encourage susta inable solutions is to disseminate as much information as possible to all parties. T hat is our challenge.

Addressing the challenges in sustainability comes down The Authors to exploring increasing rh e area of sha red understanding Francis Pamminger is between policy the Strategic Water Figure 1. Different interacting factors in a sustainable decision Resources Planner at Yarra making process. makers/regulato rs, water Valley Water. Email: companies and customers. fpammin g@yvw.com.au; We argue that all of these pertaining to th e individual srakeholder's Dr Kein Gan is the Supply-Dem and groups make their decisions by considering interests and needs, bur also those relevant the information avai lable to them. This Manager at Yarra Valley Water. to other stakeholde rs as well. So the more includes not just information directly Emai l: kgan@yvw.com .au. information that is made avai lable to all

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MARC H 2005

33

demand management

rim

INTEGRATED WATER CYCLE MANAGEMENT: ANALYSIS OF RESOURCE SECURITY P J Coombes Abstract This paper sum marises a systems analysis of the impact of In tegrated Water Cycle Management approaches on the security of regional water supplies.

The synergistic impacts of supply and demand management approaches on the security of regional water supply systems can be accurately evaluated using a combi nation of non-parametric regional demand methods: the PURRS lot scale water balance simulator and th e WATHNET network linear headworks model.

The systems methodo logies described in this paper have wid espread application .

A case study analyses regio nal water security in the Greater Figure 1. Sydney he adworks system.

Syd ney region to demo nstrate the capability of the methodologies. water from the water supply catchments The use of different pump marks fo r (see Figure 1) to SWC. extractions from the Shoalhaven River, Si nce che 1960s Sydney's water various freq uencies of water restrictio ns, consumption increased dramatically due to rai nwater tanks and demand management growth in population, prosperity and measures has been investigated. An increase su bsequent u rban develop ment. Th e in acceptable freq uency o f water restriction increased consu m ption was d riven by use of to 5% and a pump mark of 70% will defer water consuming domestic appliances and a the requirement to augment the water water inefficient heavy industry. Water supply headworks system by 26 years. The demand decreased fo llowing the 1978 use of demand managemen t measures alone 1983 drought and during economic will not defer augmentation whilst recession that led to rescruccure of heavy installation o f 5 kL rainwater ranks for hot industry. During the lace 1980s and early water, toilet, laundry and outdoor uses can defer augmentation beyond 2090 . A Pa reto diagram is employed to examine con flicting The impact of various environmental and economic objectives .

Introduction About 4 millio n people currenrly occupy the Greater Syd ney region chat extends fro m the Hawkesbury River in rhe north to Gerroa in rhe sou th and from Mt. Victoria in the west to the east coast. Sydney Water Corporation (SWC) is responsible fo r the provision of reliable water supply to people living in the Syd ney region and for managing water demand. T he Sydney Catchment Auth ority (SCA) supply bulk

34 MARCH 2005

water

water demand has increased by over I 1.5% since 1995 . le is an operating license requ irement chat SWC red uce per cap ita water demand by 35% over 1991 water demand in order to avoid construction o f the Welcome Reef Dam on the Shoal haven River. Note chat the triggers to augment a regional water supply system are an u naccep table change of water restrictions and risk of fa iling to su pply water. A Lease Cost Planni ng (LCP) model was developed to rank various demand management strategies on a unique cost effectiveness basis. Usi ng the Lease Cost Planni ng Mod el as a guide SWC began to implement a demand management strategy using a li mited range of demand side options in 1999. No netheless water demand increased by 5 .4% since 1999 in response to populatio n growth .

Reviews of che Demand Management Strategy found that a wider range of demand and supply management options was required to avoid augmentation of th e water supply headworks system. Selection of demand and supply management methods should also co nsider the long term system impacts on the environment, the water supply headworks system and the commun ity.

demand and supply management options is analysed. House water tanks can defer supply extension.

1990s pu blic education programs and pricing policies also assisted in management of water demand. Deen [2000] reported char the introduction of user pays pricing for water, accompanying media campaigns and water restrictions during the 19921998 drought redu ced water demand by 10% - 15% during the mid 1990s. Sydney's

Rainwater collected from roofs and stored in tanks to supplement mains water supplies for domestic consu mption has been shown to significan tly reduce household mains water use. Importanrly Coombes et al. [200 0] and Spin ks et al. [2003] found char the q uality of water supp ly from rainwater tanks was acceptable for hoc

refereed paper

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demand management water, toilet and outdoor uses. Coombes et al. [2002] fou nd chat the use of rainwater tanks will defer rhe requirement to augment che Lower Hunter and Central Coast water supply headworks systems by 28- 100 years. Many authors including White et al. [ 1998] claim char rhe use of dual flush toilers, and AAA raced shower roses and washing machines will significantly reduce domestic mains water demand.

T his study examines the economic, environmental and water supply systems impact of the use of demand management measures and rainwater tanks in rhe regional water supply system; namely rhe Greater Sydney region. The non-parametric regional demand model developed by Coombes et al. [2002] and rhe network linear program for headworks simulation WATHNET by Kuczera [1992] was used co analyse water demand, screamflows and headworks security. The Pareto analysis presented by Kuczera and Coombes (200 I] is used to compare the environmental and economic performance of different scenarios. A more complete description of this study is provided by Coombes et al.

(2003].

The Headworks System

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36 MARCH 2005

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30

40

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60

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80

90

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Streamflow percentiles Figure 2. Impact of pump marks on the Shoalhaven River in the year 2020.

supplied with water from che Wingecarribee Reservoir.

Simulation of Headworks System Performance Perfo rmance of che water supply headworks system and impact of urban water demand on screarnflow in the water supply catchment was si mulated using the WATH NET network li near program for headworks simulation by Kuczera [1992] .

The screarnflow records and climate data (rain depth, rain days and daily maximum temperature) from che period 1909 co 2000 were used in chis study. To preserve rhe climatic correlation between the urban and • water supply catchments 2000 replicates of srrearnflow and climatic variables in both catchments were simultaneously generated for che period 200 I ro 2090. l e is important to highlight the significance of using replicates of streamflow and cli matic variables in preference to the use of a single historical sequence of information. The use of a single historical sequence to evaluate rhe security of a regional water supply can only provide understanding of rhe water system's response ro a si ngle given sequence of

Water is currently supp lied co the Sydney region from the Warragamba, Upper Nepean, Shoalhaven and Woronora ri ver catchments char have a com bined area of 16,850 km 2 (Figure 1). Srreamflow from che W arragamba catchment is captured in Warragarnba Reservoir char has a storage capacity of 1890 gigalirres (GL). Water from the Cataract, Cordeaux, Avon and Nepean Darns located in the Upper Nepean catchment is conveyed via a system of pipes, natural river channels, weirs, tunnels and aqueducts to Prospect Reservoir whilst also supplying various communi ties along che routes. The Sou ch Coast region is supplied with water from che Avon and Cordeaux Dams and Nepean Darn via the Nepean-Avon tunnel.

Scream flow from che Shoalhaven catchment is captured in Lake Yarrunga and Tallowa darn where water is raised 6 l 2 metres co Table l. Water restriction criteria Wingecarribee Reservoir via demand.

Fitzroy Falls Reservoir when rhe water storage volume in 60 Storage less than (%) Warragarnba Darn is less than 33 Reduction in demand (%) 65%. Water from che Wingecarribee Reservoir is Table 2. Water restriction criteria distributed co Nepean darn and Lake Burragorang via the W ingecarribee and Wollond illy Rivers. The townships of Mirragong and Bowral are also

20

cl imatic events. In contrast, the use of replicates will allow a reliable understanding of system responses to a range of different climate sequences chat may occur in the future and allow evaluation of rhe systems failure probabilities.

Headworks System Reliability In chis study reliability is defi ned as che probability char water restri ctions will not be imposed in a particular year. Restrictions on urban water demand are triggered when storage levels in Warragarnba Dam and Avon Darn fall below 60%. T he repo rted effectiveness of water restrictions in the Syd ney region duri ng the 1992-1998 drought by Deen (2000] was used co develop resrricrion criceria and subsequent demand reductions for domestic outdoor demand. Water restrictions were only applied co domestic outdoor demand and non-domestic demand (Tables l and 2) .

T he trigger co augment Sydney's water supply system with the construction of che Welcome Reef Dam was an unacceptable chance of water restrictions and risk of failing co supply water.

Water Demand for domestic outdoor

55

50

40

57

75

100

for non-do mestic

dema nd .

Storage less than (%)

50

40

Reduction in demand (%)

5

10

30 15

20 20

The Sydney region was divided into ten water supply zones with different climatic conditions (monthly rain depth , temperature and rain days) chat coincided with trunk distribution system monitoring data provided by the SCA. These zones include: Prospect Ease, Prospect So uth, Prospect North, Blue Mountains, Orchard Hills, Avon, Nepean, Macarthur, Warragamba and

refereed paper

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demand management Woronora. The North Richmond zone was not included in the study.

Monthly daily average domestic water demand for d ifferent dwelling rypes within the various demand zones was estimated using climate data from the NSW office of the Bureau o f M eteorology, socio-economic data from the Australian Bureau of Statistics and the methods developed by Coombes et al. (2002].

Daily water balance results for households was derived using the PURRS (probabilistic urban rainwater and wastewater reuse simulator) allotment water balance model and historical climate data was compiled into resource fi les.

Resource fi les were also created for households with demand management measures and rainwater tanks.

water restrictions.

Pump mark

65% 70% 80% 90%

1%

3%

5%

10%

2003 2004 2004 2008

2006 2008 2028 2030

2020 2029 2043 2044

2046 2054 2073 2073

Adoption of a 70 % pump mark and acceptance of a 5% frequency of water restrictions will defer augmentation of the headworks system by 26 years with increases in annual pumping costs of $0.7M to $1 M, greenhouse gas emissions increase of 40% and the smallest additional reduction in streamflow in Shoalhaven River.

emissions from pump marks in 2020.

Pump mark

Cost ISM)

CO 2 ITonnes)

CO2 increase 1%)

65% 70% 80% 90%

1.8 - 2.4 2.5 - 3.4 5.5 - 7.4 6.8 - 9.3

40,790 56,700 124,000 154,780

39 204 280

Importantly, the use of climate replicates and the non-parametric methods ensures that water demands are temporally and spatially consistent with the rai nfall and stream flows in the water supply catchments. Population data used in this study was provided by the Australian Bureau of Statistics, Planning NSW and SCA.

Pump Marks and Frequency of Water Restrictions The performance of the water supply headworks system was evaluated using 2000 replicates of streamflow and water demands in the WATHNET program. Variation in the Shoalhaven pump marks and frequency of water restrictions were consid ered. The pump mark in the base system is considered to be 65% which means when storage levels in Avon and Warragamba Dams fall below 65% pumping from the Shoalhaven River is commenced. Performa nce o f the headworks system subject to variation in pump marks and frequency of restrictions is shown in Table 3.

Table 3 shows that increased pump marks and frequency of water restrictions delays the requirement for augmentatio n by up to 66 years. At the currently accepted frequ ency of water restrictions of 3% increasing pump marks can delay augmentation of the water supply headworks system by 24 years. At a pump

water

Augmentation year by frequency of restrictions

Table 4. A nnual energy costs a nd greenhouse gas

The method of non-parametric aggregation created by Coombes et al.

(2002] was used to generate month ly domestic water use for each dwelling rype in each climate zone using the historical resource files and the climate replicates generated for the headworks simulation.

38 MARCH 2005

to $6.9M and greenhouse gas emissions by 39% to 280% in the year 2020. T he cost to pump water from the Shoalhaven River to Wingecarribee Reservoir was estimated to range fro m $62/ML to $84/ML with energy consumption of 1624 kWh/ML. About 0.89 kg of greenhouse gases (CO2) is generated for each kWh of electricity co nsu mptio n.

Table 3. Va riation in pump marks and frequency of

mark of 65% increasing the frequency of water restrictions can defer the requirement to augment the water supply headworks system by up to 40 years. The impact of variation in pump marks on streamflow in the Shoalhaven River in January 20 20 with acceptance of a 3% chance of water restrictio ns is shown in Figure 2.

Figure 2 shows the cumulative percentiles of streamfl ows that exceed a given value as a proportion o f natural flows. Water extractio ns from the Shoalhaven River in response to pump marks ranging from 65% to 90% result in very significant reductions in streamflow. Increasing pump marks to 80% and 90% will result in up to 85% depletion of medium range streamflow.

Increasing the pump marks will also increase energy consumption, costs and greenhouse gas emissions (Tab le 4).

Table 4 shows that higher pump marks will increase annual energy costs by $0.7M

;

925

The Impact of Demand and Supply Management Measures T he impact of various demand and supply management measures on mains water demand in the Sydney region was d etermined using the regional demand method. A limited selection of approaches was evaluated including 1% and 2% per an num installation of AAA rated shower roses (AAA_ l %, AAA_2%), d emand management measures includ ing 6/3 litre fl ush toilets, AAA rated shower roses and washing machines (DM_l %, DM_2 %), 5 kL rainwater tanks with mains water trickle top up for domestic toilet and outdoor d emand (T_TO_ l o/o, T _TO_2%) and 5 kL rainwater tanks with mains water trickle top up for domestic hot water, toilet, laundry and o utdoor demand (T_HTLO_ l %, T_HTLO_2%).

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refereed paper

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demand management Using the WATHNET program che impact of demand headworks system. and supply management scenarios on the reliab ility of the water Augmentation year by frequency of restrictions Scenario supply headworks system was 5% 10% 1% 3% evaluated. The impact of the 2020 2046 2006 Bose 2003 different scenarios on 2050 AAA_1% 2025 2003 2006 augmentation timing is shown in· 2050 AAA_2% 2003 2006 2025 Table 5.

2050 DM_1% 2006 2025 Table 5 shows chat under 2003 reliability criteria of 3% (similar 2061 DM_2% 2006 2029 2003 to current criteria) only che T_T0_1% 2003 2006 2026 2051 scenarios T _ HTLO _l %, T_T0_2% 2006 2028 2051 2003 T _HTLO_2%, T _0.5%DM_l % T_HTLO_1% 2027 >2090 >2090 2003 and T _l %D M_l % chat include 5 >2090 >2090 T_HTLO_2% 2077 2003 kL rainwater tanks used to sup ply 2084 2030 T_0.25% DM_1% 2003 2006 hoc water, toilet, laundry and >2090 2003 2007 2043 T_0. 5% DM_1% outdoor uses defer augmentation.

Figure 3 shows chat a 2% per The T_HTLO_2% and >2090 T_1% DM_1% 2003 2090 >2090 annum inscallacion of AAA raced T _I %_DM_l % scenarios result shower roses (AAA_2%), demand in long term deferral of reductions in regional water demand . management measures (DM_2%) and 5 kL augmentation by 71 to 84 years. Note chat Comb inations of demand management rainwater tanks for toilet and outdoor uses the scenarios with AAA raced shower roses measures and 5 kL rainwater tanks used to (T_TO_2%) will have a moderate impact and demand management measures will not supply domestic hoc water, toilet, laundry on regional water demand. The I % and 2% defer the requirement to augment the water and outdoor uses, especially che installation per annum of 5 kL rainwater supply h eadworks system subj ect co current reliability criteria. Similar resulrs apply co T _I % DM_l % scenario, also produce tanks for hoc water, toilet, laundry and che scenarios with 5 kL rainwater tanks co considerable reductions in regional mains outdoor uses (T_HTLO_ 1%, supply coi lec and outdoor uses. water demand.

T _HTLO_2%) produces substantial Combinations of measures were also considered including I % per annum installation of demand management measures in combination with 0.25%, 0.5% and I % per annum uptake of 5 kL rainwater tanks with mains water trickle top up for hoc water, toilet, laund ry and outdoor uses (T_0.25%DM_I %, T _ 0.5 %DM_l %, T_l%_DM_l %) . A pump mark of 65% was used. Regional average annual water demand from some of these scenarios is shown in Figure 3.

Table 5. A ugmentatio n requirement for the water supply

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refereed paper

Interestingly, accep tance o f a 5% chance of water restrictions produces the greatest deferral of augmentatio n riming (5 to 8 years) fo r scen arios with demand managemen t o r rainwater tanks fo r toiler and o utd oor uses. Fo r these scenarios a I 0% reliability criteria dimi nishes the relative im pact on augm entation riming.

T he scenarios wi th 5 kL rainwater tanks fo r hoc water, toiler, laundry and o utdoo r supply and/or d emand management measures provide greater d efer ment of augm entatio n with increases in freq uencies of water restrictions fro m 3% to 5% or 10% . Note chat a co mbination of a 5% reliab ility criteria and scenarios T_H T LO_ I %, T _ HT LO_2% and T _l % O M_ I% defer the requirem ent to augment the water su pply headwo rks system beyo nd the 90 year planning ho rizo n.

Installation costs fo r 3A raced washing m achi nes and 6 /3 litre toilers were $800 and $85 per d evice respectively. The washing machi nes were estimated to have a ten year design li fe. T he dem and man agem ent scenarios were expected to produce water distribu tion in frastructu re installatio n savings of $ 54 .40 per dwelling respecti vely. T he installation of rai nwa ter tan ks was estimated to cost $2, 500 each providi ng sto rmwacer and water d istribu tion infrastructure savings o f $ 1,300 per dwell ing. The rank has a des ign life of 50 years with a re placement cost of $800 and the pump has a des ign life of 10 years with a replacem ent cost of $350. Augmen tation of the water su pply headworks system by the constructio n of the Welcome Reef D am was expected to cos t $226M (based o n N SW Treasury esti mates fro m 2003 , no te chat the cu rrent estimated cost is over $2 billio n).

Economic Impacts

A 5% fre quency of water restrictions was accepted fo r the economic analysis.

The presen t benefits of the demand managem en t scenarios ranged from $527 M to $ 144.9 and co st o f water sup ply fro m rai nwater ranks varied from $98 5M to $774M.

T he inves tment model d eveloped by Coombes et al. [2002] compares eco no mi c benefits accru ing to the co mmuni ty fro m a tradi tional Base scenario to alternative scenarios that include installation o f rainwater ran ks and d emand management m easures. The Base scenario co nsiders the status quo: provision of tradition al sto rm water systems to areas u nd ergoing u rbanisation and p rovision of add itional mai ns water supp ly by fu rther regulation of river systems.

C osts and benefits fo r the p rovisio n of mains water and the d isposal of stormwacer considered com mo n to the base and alternat ive scenari os were no t included in th e analysis. The coses and benefits chat differ fro m the base scenario are co nsid ered in analysis of the alternative scenarios. In the alternative investment scenario a household can pu rchase water fro m a water utility, use ra inwater ranks fo r water supply and install d em and m anagem en t measures to reduce water use. The comm u nity pays the cost of installing, operati ng, m aintain ing and replacing rainwater tank and demand managem ent systems whilst gaining b en efits from red uctions in m ains water use and the requirement for water cycle infrastructure. T he reduced req uirement fo r infras tructure results in d ecreased depreciation and mainten ance costs.

Installation of 3A rared shower roses was estimated to reduce water distribu tion infrastructure installation costs by $2 1. 1 per device ar an installation cost o f $80 each. 3A raced shower roses have an estim ated 10 year life with a replacem en t cost of $45 p er device.

refereed paper

Environmental Impact T he impact of demand and sup ply m anageme nt m easures o n the enviro nmental health of the Sydney region in the year 20 20 was considered in terms of scream flow in the Shoal haven River, stormwater runoff in urban areas, the vo lume of sewage generated and green house gas em iss io ns. A 5% frequency of water res trictions was accepted fo r the enviro nmental analys is.

Streamflow in the Shoalhaven River I ncreasing water urban d emand s o r the constructio n of W elcome Reef Dam has the potential to furth er degrade che Shoalhaven Ri ver system . Although the m o nthly rime seep used in the streamflow analys is in chis study is unsatisfactory fro m an ecological persp ective the ch anges in srream fl ow in response to urban water dem and will provide an indicator of river health. The greatest red uction in screamflo w fo r January 2020 fro m each scenario was calcu lated as a percentage of natural screamflow. T hese percentages from each scenario were used to develo p an environmen tal flow score chat ranged from 75% to 80% .

Frequent Stormwater Discharges T he use of rainwater tanks can result in substantial reductions in stormwacer runoff. A stormwacer d ischarge score was developed chat d eterm ined the percentage

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41

demand management reduction in 3 month ARI stormwacer discharges in the Sydney region resulting from installation of rainwater tan ks. Values for the stormwacer discharge score ranged from 14% to 30%.

The Volume of Sewage Discharges Installation of demand management measures such as 6/3 flush toilets, 3A raced shower roses and wash ing machines will reduce the magnitude of indoor water use.

T he water savings become a reduction in the volume of sewage discharges rhat will reduce impacts on the environment. The sewage score represents the reduction in sewage discharges in che Sydney regio n that result from demand management measures.

Values for the sewage score range from 1.28% to 6.6%.

Greenhouse Gas Emissions Changes in energy usage resulting from reduced pumping from the Shoalhaven River, in rainwater tank systems (small pumps chat use less energy than delivering water via the mains distribution system) and in the sewage and water rericulaced systems and reduced water heating in hoc water systems will reduce greenhouse gas emissions. The greenhouse gas score determines the percentage reduction in green h ouse gas emissions in comparison to emission from the Base water supply scenario. Val ues fo r the score range from 0.02% ro 133% fo r the T _TO_ l % and AAA_2% scenarios respectively. Use of 3A raced shower roses ach ieved a considerable energy saving. N o re chat 3A rared shower roses generate additional energy savings derived from hearing less water.

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500

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Present value ($M) Figure 4. Pareto Diagra m of a lternative sol ution s.

The Pareto Frontier The results from the environmental impact scores were combined with equal weight with the exception of the greenhouse gas score which was given an arbitrary weight of 0.01 in recognition of the relative significance of th e ocher environmental scores to form an environmental criterion. The economic results reported as rhe present value of alternative solutions were combined with rhe environmental criteria in the Pareto Diagram shown in Figure 4 .

The Pareto Diagram provides a method of comparing confli cting environmental and economic objectives. Inferior solutio ns

are chose chat have lower economic values and environmental scores than ocher solutions.

Figure 4 shows chat th e scenario with 2% per annum installation of rainwater tanks for hoc water, toilet, laundry and outdoor uses is a Pareto optimum solution and the disturbing realisation chat rhe cu rrenrly prefer red water industry solutions are far from opti mum. Although chis study has not analysed enough scenarios to accurately locate rhe Pareto Optimum a number of observations can be made. It is clear chat scenarios with 5 kL rainwater tanks for supply of hot water, toilet, laundry and outdoor uses (T_HTLO_!O/o; T _ HTLO_ 2%) are close to Pareto

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42 MARCH 200s

water

refereed paper

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Optimum solutions. Similarly scenarios th at combine demand management measures and 5 kL rainwater tanks fo r hot water, toilet, laundry and outdoor uses approach the Pareto Optimum.

Figure 4 a lso shows that scenarios with 5 kL rainwater tanks for supply of toilet and outdoor uses o r AAA rated shower roses or demand management measures alone are infer ior solutions and should therefore be discarded.

Conclusions The most significant contribution of this paper is an explanation of systems methodologies to evaluate the performance of integrated water cycle-management scenarios. These methodologies and models have generic application to evaluation of regional water security at a ny location.

Although the systems methodologies have been used in the analysis that evaluated a limited range of water managem ent scenarios, the results are instructive.

Acceptance of a greater frequency of water restrictions will defer the requirement to augmen t the water supply head works system by up to 43 years.

Increasing the pu mp mark for water extractions from the Shoalhaven River with current freque ncy of restrictions will defer augmentation by up to 24 years with substantial impact on the Shoalhaven River. A pump mark of 70% with acceptance of a 5% chance of water restrictions will defer augmentation by 23 years .

Use of demand management m easures o r 5 kL rainwater tanks for toilet and outdoor uses, and retention of the 3% chance of water restriction rules will not result in deferment of Welcome Reef Dam. However the installation of 5 kL rainwater tanks fo r hot water, toilet, lau ndry and o utdoor uses with or withom demand management measures at rates of 1% and 2% per annum will defer augmentation by 21 to 84 yea rs. If the acceptab le chance of water restrictions is increased to 5% these scenarios will defer the requirement to construct Welcome Reef Dam beyond 2090. The present value of scenarios with demand management measures ranged from -$527M to $133.3M a nd with rainwater tanks varied from -$985M to $774M. The results of this study indicate that the urban water industry is operating in a constrained solution space resulting in subo ptima l solutions. This observation is particularly relevant given chat the water industry claim that rainwater tanks are inferior solutions in comparison to demand management measures. Installation of

demand management measures alone will have minimal impact on the requirement to augment Sydney's water supply headworks system. The a doption of a wide range of supply and demand management measures, including recycling of wastewater, will have a significa n t impact on the security of Sydney's water sup ply.

Importantly, the use of methods outlined in chis paper wi ll a llow improved understanding of the syn ergistic and systems benefits of a wide range o f water management ap proaches .

The Author Dr Peter Coombes is Conjoint Senior Fellow in Integrated Water Cycle Management, School of Environmen tal and Life Sciences, Un iversity of Newcastle.

Email P.Coombes@newcastle.edu.au. He is also the managing d irector of the consulting company U rban Water Cycle Solutions. Dr Coombes has a PhD in water systems engineering and microbiology, degrees in Civil Engineering and Surveying, and an Associate Diploma in E ngineering.

References Coombes P.J., G . Kuczera, J.D. Kalma and J.R. Argue. An evaluarion of rhe benefirs of source control measures ar rhe regional scale.

Urban Water. 4(4). London, UK. 2002.

Coombes P. J., G Kuczera, J.D. Kalma and R.H. Dunsran ., Rainwarer qualiry from roofs, ranks and hor warer sysrems at Figrree P lace, 3rd International Hydrology and Water Resource Symposium, 1042-1047, Perch, Australia. 2000.

Coombes P.J. , L Holz and G. Kuczera. T he Impact of Supply and Demand Approaches on the Security of Sydney's Water Supply.

The Insriturion of Engineers, Aust ralia. 28th International Hydrology and Water Resources Symposium, Wollongong, 2003 Deen A. R. Drought assessment and management in Sydney during 1992 - 1998.

10t h World Water Conference. IWA. Melbourne. 2000.

Kuczera, G. Water supply headworks simulation using network linear programming. Advances in Engineering Software. Vol. 14. 55-60. 1992.

Kuczera G . and P.J. Coombes. A sysrems perspective of rhe urban warer cycle: new insights, new opportunities. Srormwarer Industry Association Regional Conference.

Pore Stephens. NSW. 2001.

Spinks A., R. H. Dunstan, P.J. Coombes and G .

Kuczera. Thermal Destruction Analyses of Water Related Bacteria in a Rainwater Medium at Domestic Hor Water Sysrem Temperarures. 28th l nrernarional H ydrology and Water Resources Symposium. Wollongong. 2003.

White S., G . Milne and K. Banfield. Sydney Water least cost planning study: phase 1 report. Inst itute of Sustainable Futures.

Universiry of Technology. Sydney. 1998.

refereed paper

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DIV: $1000 PER HOUSE SAVES 90o/o OF MAINS WATER R G Shaw

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Figure 1. Multiple use trains for saving water (approx. 50 lpcd each) .

Introduction For many years, Sydney Water has supplied Sydney with abundant, ch eap, high quality drinking water. We became a city of single-use water guzzlers. 450 li cres per capita day was the water consu m ption average before che current water restrictions scarred to rake effect.

T his water abundance appears co have ended th rough factors outside our control and experts cell us we muse change our water habits. We muse reduce our consumptio n co suit the water available.

reduce household water consumption by as much as 90%. Water, including rain water, can be reused up co six rimes.

him an extra $500 on modifications.

However, $ 1500 will not cover many hours of a licensed plumber at $70 per hour.

However, plumbing practices and health guidelines have ro be redefi ned to allow such high water efficiency in the home.

Co nventional rain water ranks are too expensive and cake up too much exp ensive city space. Rain water ranks muse cake up very little city space and can cost only about $300 to be cost effective.

Cost imperatives Water is cheap. Saving water must therefore be ch eap or it is not worthwh ile.

A householder, if he is a diligent water saver, migh t reduce his annual water bill by $250. If he wanes his money back in fou r

The biggest hurdle is the health guidelines for grey water reuse.

By rearranging a home's major water users: gardens, showering, laundry and toilers in multiple use trains combining some flow restriction and rain water subscirucion, ic is possible co dramatically

46 MARCH 2005

water

years he can only spend $1000 on plumbing modificatio ns.

If a householder saves most of his hoc water consumptio n, he can also save about $ 120 per annum of energy cost allowing

Any form of fo rmal greywacer treatment and disinfection is also too expen sive.

Again, abo ut $300 is all chat can b e spent on greywacer treatment. Even third pipe treated sewage redistribution, if fu lly costed, is coo expensive.

Fo rtunately we have many hardware stores char sell pipe and fittings at low prices, particularly black poly-propylene irrigatio n piping fo r the D IY irrigation installer. This pipe is quite suitable for redirecting greywater flows in the h ome towards multiple use although it is of course rhe wrong colour. A little lilac paint can fix chat.

Health guidelines and water efficiency

Table l

The biggest obstacles ro water efficiency in the home are the health guidelines on reuse of greywacer. In the present water shortage the present guidelines represent co nsiderable overki ll. T rearm enc requirements are identical to chose for treatment of municipal sewage where che health risk is very subscancially higher.

Fortunately these guidel ines are presen tly under review in the Department of Local Government.

The illicic surface reuse of uncreated greywacer is presently widely practised as the general population sees nothing wrong in it. The Department of Health appea rs ro be turni ng a blind eye to chis. Some local councils are actually recommendi ng surface reuse of uncreated greywacer. No one appears to be geccing sick.

The defini tion of greywarer is nor legally or techni cally clear in rhe guideli nes. There is confusion about when cap water beco mes greywacer and hence what you are allowed to do with it.

The guidelines are also co ntradictory and illogical. T here is a general prohibition of

Mod. No. Description

Mod. l Mod . 2 Mod. 3 Mod. 4 Mod. 5 Mod. 6 Mod. 7 Mod. 8

Material cost

20 30 30 60 40 30 60 0

0 0 0 0 80 40 0 0

30 25 85 60 0 120 150 0

$270

$120

$470

Totals: reuse of uncreated greywarer, bu r you are allowed ro rinse-save or suds-save in che laundry and maybe shower or bath with a frie nd in the bathroom, all of which involve the reuse of uncreated greywacer. You ca n reuse laundry greywacer in the laundry but nor Aush the toiler with it - even if the toilet is in the laundry.

Similarly there is a proh ibition on scoring greywacer. Yee suds-save and rinse-save, which are allowable, muse involve storage.

All greywacer is lumped together in che guidelines, yet laundry greywacer and shower

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greywacer are quire differenr in ch aracter.

Shower greywacer is suitable fo r th e garden but gees odorous in storage. A lirrle aeration by pumping scops the odours. Laundry warer is alkaline and saline from d etergent bulking agents, so stores well but is not char suitable for the garden. Ir is ideal for Rushing toilers as there is no human contact.

A few years ago, rainwater ranks were nor all owed for health reasons because the ranks would encourage mosquitoes and rainwater was full of faecal co li forms (from bird droppings) etc. Now they are co mpulsory

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demand management on new dwellings, so there is hope fo r commonsense co prevail.

Eight plumbing modifications There are eight plumbi ng modifications required on a typical single storey home co convert it co a highly water-efficient home.

Obviously there can be many variations depending on individual house layout.

Water flows are arranged in rwo rnulri-use trains each approximately 50 litres per capita day as shown diagrammatically in Figure I. One train is fed by roof-co llected rain water and one by mains rap water.

Referring co Figure 1, The rain water train is as fo llows: â&#x20AC;˘ Rain water co swimming pool co laundry with rinse-save co toilet flushing co sewer.

The mains water train is as fo llows: â&#x20AC;˘ Mains water co shower with recycle co water trearmenr and disinfection by solar oxidation then co garden by spraying.

Since the major water uses in the home are highly discretionary it is easy co balance the uses in each train.

Nor shown on Figure 1 are minor water users such as wash hand basins, sinks and the kitchen which can amount co another 25 litres per capita day. These are left on single use mains water then co sewer co cur costs.

T he eight modifications are as follows: 1. Rain water diversion co swimming pool.

2. Laundry rinse-save.

3. Swimming pool rainwater co laundry.

4. Laundry water co coilet flus hing, then co sewer.

5. Shower flow restriccor.

6. Recycling rhe shower water.

7. Shower water after solar oxidation co garden by spraying.

8. Swimming pool rainwater to the garden by spraying.

(Kirchen, sinks and hand-basins left unchanged).

The material coses and annual water and energy savings associated with each plumbing modification are tabulated in Table I.

Handy Hints on plumbing modifications Wherever possible, 19mm black polypropylene irrigation pipe and fittings should be used because this is the cheapest pipe. It can handle flows up co 15 litres per minute which is all chat is required in the high water efficiency home. Even when diverting rain water co the swimming pool or rain water tank, it can be used provided chat gutters are kept free of leaves.

Proprietary gutter shield systems can be 48 MARCH 2005

water

expensive ($25 per linear metre of gutter) but household fly screen is a cheap and effective way of keeping leaves our of the gutter ($3 per linear metre).

15-18% of existing homes (40% of new homes) have swimming pools and rhey lose water mainly from evaporation . In Sydney, one rain water downpipe diversion is generally sufficient co cop up evaporation.

If you want co run rhe laundry on chlorinated water from the pool filter pump yo u will need co divert another rwo good flow downpipes co the pool. The cop 200 111111 of rhe pool can be used as rain storage if you have a suction type pool cleaner.

This gives the writer 7,000 litres of rain storage.

If you do not have a pool a row of reconditioned plastic 200 litre drums ($20 each) connected together and hidden under the house is the next cheapest alrernarive.

You may well find yo u have co chlorinate the rain water anyway if you want co use ir in rhe laundry.

200 lirre drums are also suggested fo r scoring laundry greywater for coiler flushing, again hidden by plants or trell is. A plastic storage box twice rhe size of rhe washing machine bowl is suitable for rinsesave, mounted at head height above the washing machine or adjacent rub.

A pump-aerated pond is probably rhe besr way to score and treat shower water for the garden, lawn and pot plants ere. The BOD load associated with shower water is low, perhaps 5 grams per capita day. For solar oxidation, a pond with a surface area of 1 square metre per person is suggested.

Pump aeration helps co stabilise and deodorise the shower warer. This idea is still being studied. An alternative co the pond could be pump-aerated drums with tablet chlorination.

Some pumping arrangement is required to dispense shower water to rhe garden but only rwo metres of head are required, not

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40 metres. 12 volt bilge pumps from a boat shop are quite adequate, cheap and safe electrically. The shower recycle is also contrived with a 12 volt pu mp. The swimming pool pump and washing machine pump both usually have sufficient performance for Figure 1 operation.

There are intellectual property rights associated with recycling showers which the writer has not studied.

Sydney Water has had considerable success wirh irs offer of cheap AAA shower heads wi th a flow of only 9 litres per minute. Your old shower head can also be modified by simply inserting a 3.2 mm resrriccor in the 15mm fitting where the shower head comes our of the wall.

Conclusion With SMH head lines "Turn off taps for good, city cold" 24.9.2004, it is clear char a major rethink of how we use water is necessary. Rainwater from commercially available rain water tanks is expensive water (more th an $ 10 per kL) because of tank, city space and/or excavation cosrs. Similarly third pipe sewage effluent recycling schemes are expensive warer because of extra treatment cosr and rhe cost of the third pipe. Multiple use of all water including rain in the home could be the way co go, provided health officials can be kept happy.

Sydney's water consumption appears co be stuck at 1400 megali rres per day and dam levels continue co drop.

The writer has thus far succeeded in reducing household water consumption in Sydney from 900 litres per day co well under 200 litres per day in a rwo person house whilst still enjoying all the normal water using mod cons: swimming pool, dish washer, washing machine etc. and a wee garden. Potentially ir is possible co get tap water consumption down below 50 lpcd if everyone in the home is prepared co wash their cloches in rainwater (provided ir rains enough, of course) and if everyo ne recycles showers. The writer has met some resistance co these new ideas in his own home!

The do-ic-yourselfer for an outlay of around $500 in materials, and say double ir co $ 1000 co allow for time, gets his money back in less than four years in water and energy saved.

The Author Robert G Shaw is an experienced chemical engineer and was rhe Chief Engineer of Allied and Aeration Technology Pcy Ltd till his retirement enabled him to apply his ideas around his house in suburban Sydney.

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demand management

PRICING OF DRINKING WATER VS RECYCLED WATER: FAIRNESS AND SATISFACTION A Hurlimann, J McKay, G Geursen Abstract

Table 1. Some real cost esti mates for the provision of recycled water in Australia.

This is the third of three articles exploring responses of a section of the Australian community, at Mawson Lakes, South Australia, to having reclaimed wastewater and stormwater pl umbed into their toilet and used externally for garden wateri ng.

Results ind icate that respondents think recycled water sho uld cost $0.46/kL, wh ich is 76% of the price they think drinking water should be, $0.60. Th is was found to be significantly influenced by perceptions of fairness in recycled water pricing, and is also different fo r peop le according to their age, gender and education levels. Income was not found to be an influencing factor in relation to the price of recycled water, but was found to be an influencing factor for drinking water.

The paper highlights the importance of engaging with communities involved and establish ing a prici ng strucrnre fo r recycled water that is perceived to be fai r.

Location

Use

Recycled Price/ kl

Real Cost Estimate

Drinking Price/ kl

Springfield, QLD

Residential - toilet flushing, garden

43c

$1.45

Per quarter: 65c < l 00kL 90c l 00- l 50kl $1.30 > 150kl

Rouse Hill, NSW

Residential - toilet flushing, garden

28c

$3 .00 - $4.00

98c

83c

$1 .60 !operating costs only)

98c

77c

Not available

44c < l 25kl $ 1.03 > l 25 kl

Introduction Establishing appropriate and acceptab le pricing structures for recycled water will be of major importance to ensure the sustainable use of recycled water in Australia and rhe provision of infrastructure to reticulate the water.

Three major issues surrounding the pricing of recycled water will be discussed in this paper. Firstly a discussion of the economic feasibility of recycled water projects in Australia, reviewing current recycled water policy and discussing possible improvements. Secondly a discussion of the importance of establishing

Olympic Park, NSW Residential supply toilet flushing, garden, laundry Mawson Lakes, SA

Residential - toilet flushing, garden watering

Source: Australian Academy of Technological Sciences and Engineering (2004) and Hotton MacDonald (2004)

a price for recycled water that is relevant, satisfacto ry and perceived as fair ro com munities involved. Thirdly, results of a survey of the Mawson Lakes population on their view of what the price of recycled water and drin king water should be.

Knowing the price respondents chink recycled water and drinking water should

varying fro m case to case. This inconsistency is unforrnnate because it makes che economic feasib ility assessment of furnre recycled water projects more difficult to undertake. Real cost estimates for the production and delivery of existing recycled water projects ind icate that che provision of recycled water is seldom

A pricing mechanism must be perceived to be fair. be, and understanding why they think this, can help establish sound boundaries and policies for setting the price of recycled water.

Pricing and the Economic Feasibility of Water Recycling in Australia Throughout Australia, policies established for pricing recycled water often lack transparency and are inconsistent,

economically feasible and rarely meets full cost recovery. T able 1 provides an overview of some real cost estimates for select Australian recycled water projects. As shown, the price charged for recycled water is much lower than the real cost estimate provided. The difference is in effect a subsidy borne by rhe community at large.

Coses of producing and del ivering recycled water vary greatly from site to site

Working with Victoria's Essential Services Commission on the new regulation of the water industry Anthony Seyfert aseyfort@landers.com.au 03 9672 9154 600 Bourke Street Melbourne Victoria 3000 123 Pitt Street Sydney New South Wales 2000 Member of Mackrell International Telephone 03 9672 9111 Facsimile 03 9670 2723 Telephone 02 9233 5092 Facsimile 02 9233 5091 www.landers.com.au

50

MARCH 2005

water

refereed paper

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depending on factors such as site characteristics, technology used and pricing policy. C an the production and delivery of recycled water be economically feasible? The answer is complex, and will require a cross-disciplinary app roach, which could include the following: â&#x20AC;˘ Restructuring the inherently low cost of drinking water in Australia, to allow for full cost recovery, as sought by the Council of Australian Governments (CoAG) water reform agenda. It is imperative that funds generated through such a restructure go directly and wholly to the sustainable management of water resources. â&#x20AC;˘ Acknowledging the externalities of supplying drinking water (eg. marginal cost of extra supply) . Factoring in the reduction in sewerage by recycled water p rojects.

The Prime Ministers Science Engineering and Innovation Council (PMSEIC) has highlighted the importance of ensuring sound pricing policies for recycled and drinking water. PMSEIC recommended Australian cities recycle water for some uses to reduce the demand on potable water. One of the report's key recommendations was that the CoAG 's N ational Water Initiative should include pricing policies for drinking and recycled water that ensure effi cient use of these resources and include externalities (PMSEIC, 2003).

Recencly, further impetus fo r increased water recycling in Australian cities, has been p rovided by CoAG through an agreement reached in August 2004 to develop a National Water Initiative (NWI). The aims of the NWI include encouraging water conservation in Australian cities through better use of stormwacer and recycled water (CoAG, 2004).

When establishing policies fo r pricing of recycled water, most jurisdictions have adopted policies chat charge co nsumers a price that does not reflect the full costs, despite the CoAG water reform process seeking to achieve fu ll cost recovery. The price is often set to en courage use of recycled water and achieve other goals, such as reduced drinking water consump tion, rather than recover costs. Policies for establishing the cost of recycled water seem to be based on causal empiricism rather than sound research and are predicated on the exp ected negative psychological reactions the consumers may have to recycled water. The dominant policy has been to set the price of recycled water as a discounted amount, a percentage of the price of drinking water rather than co nsidering the coses of production and delivery.

Some Pricing Practices for Recycled Water and Drinking Water Overseas I n the C ity oflrvine California for many years, new d evelop ments have had co be built with d ual water supply systems for landscape irrigatio n. Sewer charges have been lowered by 36.5% over several years and reclaimed water is sold at 90% of the price of domestic drinking water (Irvine Ranch Water District 1994) . The price of reclaimed water is highly variable throughout California ranging from 75% - 100% of the d rinking water price, Byrnes (200 0) noting that reclaimed water tariffs vary according to the sirnatio n that has driven the reuse.

Reclaimed water infrastructure costs are often met through Government grants and bo nds, low interest loans, tari ffs and property taxes (Byrnes 2000), an effective way of funding the projects.

G) MWH Meeting the challenge

Australia Sydney's Rouse Hill is a greenfield s subdivision supplied with one of Australia's fi rst dual water supply systems. Charges fo r

refereed paper

demand management recycled water are set at a maximum of $0.27/kL (plus CPI bur minus GST) in addition to an access fee for the recycled water of $5 .75 per quarter (Independent Pricing and Regulatory Tribunal of New South Wales 2000). As seen in Table 1, this does nor meet the estimated costs of producing and delivering rhe recycled water, and is only about 25% of the $0.98/kL charged fo r drinking water. This extremely low price was established to encourage recycled water use in rhis pilot project, as there were concerns that co nsumers would be unfamiliar with rhe concept and may not use the recycled water. An implication of rhis low price has been to encourage over-use of rhe recycled water. Consumption by Rouse Hill residents is reported ro be 20% higher than orher Sydney single dwellings (MTSE, 2004). This higher figure may also be attributed to the fact that lot sizes at Rouse Hill are larger than those of greater Syd ney, corresponding to larger garden and lawns ar Rouse Hill, and thus greater demand for water.

The Sydney Olympic Park Authority Development (SOPA), was constructed

with a dual water supply system, and established some time after the Rouse Hill development. T he price of recycled water at rhe SOPA development was ser at $0.83/kl which also does nor cover the estimated costs of production and delivery, as shown in Table I, and is approximately 85% of the cost of drinking water. There have been no reports of excessive water use in this development, perhaps indicating that a recycled water price that is 85% the price of drinking water is sufficiently high to disco urage excessive consumption.

Ar Mawso n Lakes, rhe price of recycled water will be $0.77 /kl , 75% of the price of drinking water in excess of 125 kL/ year. An estimate of this cost as a percentage of the price of drinking water is more difficult, because the price of drinking water srarrs ar $0.44 for use up ro 125kL and increases to $1.03/kL fo r use above 125kL (as per metropolitan Adelaide) . While the average yearly household water co nsumption in So uth Australia is 235kL (SA Water Corpo ration 2004) Ir is estimated that about l 0% of households in rhe Mawson Lakes area (single or small households, or households wi th a small garden) use less

rhan 125kL per year. For these households, the volumetric cost of recycled water will be more than drinking water. However, when considering the annual connection fee for drinking water, the effective price per kilolitre is much greater than $ 1.00, varying depending on exact co nsumption. At Mawson l akes there is only a once-off connection fee of $264.00 (2004/2005 rare) for recycled water. Having only a once-off connection fee, and no annual access fee provides an additional saving for co nsumers of recycled water. T he real cost estimates for rhe production and delivery of rhe recycled water ar Mawson Lakes have nor yet been made publicly available. Until the delivery of recycled water co mm ences, drinking water is being delivered through the recycled water network at the price of recycled water ($0. 77/kL). Further information about the Mawson Lakes development and community attitudes to the dual water supply scheme can be fo und in McKay and Hurlimann (2003) and Hurlimann and McKay (2004).

Pricing Satisfaction and Fairness Understanding a co mmunity's perception of the price they think recycled water

demand management should be will help establish values placed on the resource, give an indication of willingness to pay for recycled water, and inform the economic feasibility of urban water recycling for residential use.

W ill ingness to pay fo r recycled water, and perception of the price recycled water 'should be' will vary from communi ty to community dependent on a number of social, demographic and climatic influences unique to each commun ity. I n some cases the community may not be willing to use the recycled water, an important consid eration given a number o f recycled water p rojects have fa iled due to lack of suppo rt from the community.

Establishing an appropriate price for recycled water is imperative, to help avoid unwanted consequences from an inappropriate price. As d iscussed by the Australian Academy of T echnological Sciences and Engineering (2004) if the price of recycled water is too low, perception will be that the q uality is low and possibly result in over use or inappropriate use, as has occurred at Rouse Hill. Such a pricing structure will also contribute to the inability to achieve full

Table 2. Summary statistics, respondents' view of the price dri nking water a nd recycled water should be.

Price drinking water 'should be' ($/kl)

Price recycled water 'should be' ($/kl)

64

67 0.46

N Mean Median Mode Standard deviation

0.60 0.45 0.42 0.28

be able co use recycled water for outdoor use. Conversely people were will ing to pay $55 to avoid using recycled water fo r drinking purposes.

cost recovery. H owever if the price is coo high, che use of the recycled water may be d iscouraged, especially when linked with concern abou t quality and safety. Recycled water is more costly to produce than drinking water, but the community rightfully perceives it has a lower q uality.

Given the quality d iscrepancies between drinking water and recycled water, what price do consumers chin k is fair fo r chis lower quality p roduct?

Martins and Monroe (1 994) suggest chat willingness to buy is closely related to perceived value and perception of fairness.

Marketing li terature on retail 'fasr moving' consumer goods, demonstrates chat consumers perceive information on quality and value of products through their price (Erickson and Johansson 1985), but the extent to which price is used as an indicator of quality d epends on the availability of alternative information. As price increases

In a study of en vironmental values of water supply optio ns in Canberra, Blarney, Gordon and C hapman (1 999) found people were will ing to pay $47 annually to

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61~ 1~ 1~ ECOIIViSe Environmental

demand management so to does perceived quality (Erickson and Johansson 1985) . H owever, water as a commod ity cannot be assumed co follow chis pattern.

In terms of t he perception of fairness, Xia et al (2004) highligh t the possible impacts that percep tions of u nfairness have on the proficability of firms, demonstrating that it can lead co damaging behaviour, incl uding spreading negative information, and buyers leaving the exchange relationship (ie in the case of Mawson Lakes, possibly reverting co use of d rinking water only). They note char there are many factors chat influence perceptions of unfa ir price, including: • Similarity berween competitive produces • Consumers' understanding of why che price was sec • Buyer-seller relacionshi p and crust • Perceived value Xia et al suggest char by making relevant cost and quality information transparent, retailers can help customers sort out fairness attributes of the p roduce. This theory was developed in response co research that fo u nd consumers perceive

cost-based pricing as fairer chan market based pricing (Maxwell 1999), b ur consumers often have little knowledge of retailers' actual coses and profits (Bolcon et al, 20 03).

Mawson Lakes Research Methodology Surveys were conducted over the pho ne by professional interviewers during August and September 2004. Interviews were co nducted ac the household level wich 136 households surveyed in coral. Interviews took an average of 30 minuces co complete.

Information collected included; respondent's attitudes co different attributes o f recycled water fo r d ifferent uses, responses co a series of accicude and percep tion statemen ts, and demographic information about the respondents. T his was the second survey of a panel/repeated cross sectional survey, assessing community attitudes co using recycled water. T he first benchmark survey was completed in September 2002. The fi rst rwo surveys have been completed prior co the commencement of recycled water use.

Results Respondents were asked the following questions: 'What should you pay per kilolitre of recycled water?' and 'What should you pay

per kilolitre ofdrinking water?'While a figure in dollars and cents was requested, many respondents could not do so, fo r drinking water responding 'more' or 'less' than the current price, and for recycled water responding as a percentage of the price of drinking water. A high percentage of respond ents 'did not know' (30% and 43% respectively) . The responses were coded into categories represented in Figure 1. Only cwo respondents thought the cost of d rinking water should be zero, saying water "is a right." O ne respondent though t both recycled and drin king water should be $10/kL. This answer was omi tted from analysis because it significantly skewed resulcs.

For dollars and cents figu res given, average prices were calculated (see Table 2).

The mean price respondents thought recycled water should be was $0.46, which is 76% of the mean price they thought drinking water should be, $0.60. This

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refereed paper

suggests the majority of respondents perceive the quality of recycled water to be lower than that of drinking water. These results indicate char che present price of recycled water at Mawson Lakes is much more than respondents chink it should be.

Ir is interesting to note chat the price they think the recycled water should be is 76% of the price of drinking water, which approximates the chinking behind the recycled water charges at Mawson Lakes (75% the price of drinking water in excess of 125kL/year).

Responses for recycled water and drinking water were plotted for each val id response and are shown in Figure 2, with the line of best fit indicated in black. Other lines were drawn co indicate recycled water as various percentages of the price of drinking water. Regression analysis was performed (see Figure 2) , determining the relationship between the price respondents chink recycled water (Pr) and drinking water (Pd) should be.

Notable observations in the response distribution displayed in Figure 2 include: • Clusters around $0.44 and $ 1.00 for drinking water

60 - . - - - - - - - - - - - - - - - - - - - - ~ .l!l 50 C:

a,

"g 40 0 C.

~

• Drinking water

0...

~ 20

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:i

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Figure 1. Price recycled water and d rinking water shou ld be, as viewed by future urba n South Australian consumers of recycled water.

• Clusters around $0.50 fo r recycled water • Only 8 respondents thought the price of recycled water should be $0.75 or greater

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refereed paper

For drinking water or irrigation water

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demand management In order to perform furthe r analysis (cross cabs), responses for P, and Pd were categorised as follows: low $0.00 - $0.39; lower medium $0.40 - $0.69; higher medium $0 .70 - $1.00; and high $1.00 +.

The following demographic trends were observed for the price respondents thought recycled water should be. Significant results are noted with Chi-square fi gures.

• P, decreased as age increased µ = $0.58 < 3 1 years old th rough to µ = $0.43 >5 1 years old (Chi-square= 9.20, 6df, sig = 0 .16).

• Females (µ=$0.50) thought recycled water should be a higher price than males (µ= $0.45) • P, increased as education increased, pri mary/secondary µ = $0.41 through to university degree or higher µ= $0.59 (Chi -square= 10.38, 6df, sig = 0.1 1) • There was no real difference observed fo r P, and different income grou ps. I r was noted that 19% of respo ndents chose not to disclose

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their income. There was a significant difference between Pd and income groups, ranging from µ = $0.52 for respondents in the lowest income bracket th rough to µ = $0.65 for respo ndents in the highest income bracket (Chi-square= 7 .27, 6df, sig = 0.29).

Indicating income was an influencing factor for d ri nking water but nor recycled water.

Perception of Fairness Respondents were asked to rate their agreement with the statement '/ think the current pricing structure for recycled water at Mawson Lakes is fair' on a scale of 0-10 where O = very strongly d isagree and 10 = strongly agree. 56.5% of respondents disagreed, while only 23% agreed. Further details of the results can be found in Figure 3.

Responses were furthe r analysed, with trends evident for Pr and the fai rness statement. Those who strongly d isagreed that the current pricing structure for recycled water is fa ir thought recycled water should be a lower price (Chi-square= 11 .63, 8df, sig = 0. 16).

General d emographi c observations for responses to the statement include: • Those aged under 31 years of age most strongly agreed • Females disagreed more than males • Those with household income greater tha n $80,0 00 disagreed most

Responses to Other Price Statements The following resu lts were obtained for responses to a number of statements about p rice, rared on the same I I-point scale:

'I would be willing to pay a higher price for drinking water that is more aesthetically pleasing' 40% agreed, 33% disagreed, indicating overall agreement.

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'The potential to save money associated with the dual water supply system contributed to my decision to live at Mawson Lakes' 68% disagreed, 17% agreed, indicating overall disagreement with this statement, indicating char the potential to save money associated with the dual water supply system did not con tribute to the majority of respo ndent's decision to live at Mawson Lakes.

'/ am concerned that costs associated with the dual water supply system may increase in the future' 77% agreed, 10% disagreed, indicating overall agreement. Females agreed significa ncly more

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0.25

0.50

0.75

1.00

1.25

Drinking water price($/kl)

Figure 2. Comparison of the price recycled water and drinking water 'should be' as viewed by future South Austra lia n consumers of recycled water.

refereed paper

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demand management than males (Chi-square= 7.05, 2d f, sig = 0.029)

'Current pricing structure for recycled water is fair'

Discussion A limitation of the survey results is that for the questio ns: 'How much should you pay for recycled water?' and 'How much should you pay for drinking water?' a high percen tage of respondents did not respond in a dollars and cents fig ure. T his red uced the sample size to N = 67 and 64 respectively. H owever, a solid sample still remained .

The two-tier system for charging fo r water in metropolitan Adelaide influenced the response. M any resid ents, (beyond the 10 % with low consump tion patterns) maintained a perception that the price of water was only 44 c/kL, referring to 125kL as their 'quota' or 'minimum water allowance.' Their perceptio n of the price of the recycled water ($0.77) was that it was much more expensive than d rinking water.

They were no t happy with this p rice, which may be d ue to the fact that prom otio nal material provided by the developer indicated they would 'save mo ney' by using recycled water (which is true when the high

Disagree • s trongly D Moderately 0

10

20

30

40

60

50

Percentage of Respondents Figure 3 . Perception of fairness in of the current prici ng structure for recycled water.

rate of 103c/kL is considered ). At a residents' meeting held in March 2 004, some claimed they would revert back to using drinking water in the garden as ic would be cheaper and some concerned because no drinking water tap was installed ou tside. T his perception of p ricin g unfairness could result in buyers leaving the exchange relationship (Xia 2004).

H owever, further results of this survey indicated that only 17% of respondents agreed that the potential to save money asso ciated with the d ual water supply

system contribu ted at Mawson Lakes.

to

their d ecision

to

live

T he mean price respondents though t recycled water should be was $0.46 /kL, 7 6% of the average price they tho ugh t d rin king water should be, $0.60/kL. These p rices are much lower than the overall volumetric price of both produces and is surprising given Adelaide is perceived to be water scarce. The introduction of permanent water restrictions in the Adelaid e region as o f O ctober 2 003, and the current Waterproofing campaign may

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well in the longer term increase the community's perception of the value of recycled water, and so increase the price they think it should be, and increase their willingness to pay for it.

Are the prices people think recycled and drinking water should be, an indication of what they are willin g to pay, or are they significandy over o r underestimated ? Ir is thought chat the responses relating to 'how much should you pay for water,' are an underestimate of willingness to pay, based on related ideals for both drinking and recycled water being a 'public good,' or perhaps related to strategic behaviour. Further investigation of chis will be undertaken.

Results indicate chat strongest suppo rt for a h igher price for recycled water will come from h ighly educated people under the age of 31, more likely to be fe male. Income was not found to be an influence on price of recycled water b ut was found to be for drinking water.

Results indicate chat rhe most influential factor determining the price that respo ndents thought recycled water should be is their perception of fairness. T his indicates to recycled water retailers and water policy managers that in order to achieve greater acceptance for the price of recycled water by the co mmunities involved, rhe creation of a p ricing mechanism char is perceived to be fai r is imperative. Only 23% of survey respondents agreed chat the current pricing structure for recycled water at Mawson Lakes is fa ir.

Potentially the respondent's overall perception that the pricing structure for recycled water is unfair is more than simply about the price of recycled water, but abou t the p rice of recycled water in relation to their expectations of what the price should be compared to chat of drin king water. 77% of responden ts are concerned that the costs associated with the recycled water may increase in the futu re, which is someth ing for managers to be aware of.

Conclusions An implication of these results may be chat the pricing structure of d rinking water in Adelaide be reviewed to remove the tiered approach and allow a straightforward comparison of the price of the two products in the mind of present and futu re recycled water consumers. An alternative approach would be to have a tiered approach to the price of recycled water similar to char of drin king water, perhaps $0.35 for the first 125kL and $0.8 5 for use in excess of 125kL. Another alternative would be to introduce concession rares similar to those available to consumers of drinking water, to make the price 'fairer'. All these suggestions to achieve greater perceived fairness would no doubt require a complex process, and may not even be suitable, or achieve full cost recovery. The restructure of recycled and drin king water charges would increase greater perception of fairness and increase participation in recycled water use, maximising rhe infrastructure and environmental benefit of rhe scheme. I r is suggested that future recycled water developments should ensure the structure of recycled water charges are transparent and set in consultation with the community, while ensuring they remain economically feasible, even perhaps demonstrating the external co st considerations to the community for their greater understanding. Many water policies in Australia seek to address these issues but progress to date has been slow, and needs to be accelerated.

Acknowledgements T he authors thank the following people and organisations for their assistance and interest in our research; C hris Mad es, Professor Don Bursill, Dr John Boland, Professor Phil

New South Wales Ph: 02 9958 8029 Fax: 02 9958 5414

refereed paper

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The Authors

Anna Hurlimann is a PhD candidate, and Cooperative Research Centre for Water Quality and T reatment scholarship holder. Anna is a member the Centre for Comparative Water Policies and Laws at The School of Commerce, University of Sou ch Australia. Email : anna.hurlimann@unisa.edu.au; Jennifer McKay is a Professor of Business Law, and Director of the Centre for Comparative Water Policies and Laws hccp:/ /business.unisa.edu.au/waterpolicylaw at the University of So uth Australia. Emai l: jennife r.mckay@unisa.edu.au; Gus Geursen is Professor and Head of che School of Marketing at the University of South Australia.

Email: gus.geursen@unisa.edu.au References

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water

~+: f

Australian Academy of T echnological Sciences and Engineering (2004). Water Recycling in Australia. Melbourne, Ausrralian Academy of Technological Sciences and Engineering.

Blamey, R. , J. Gordon, et al. (1999). "Choice modelling: assessing the environmental values of water supply o ptions." The Australian journal ofAgricultural and Resource Economics 43(3): 337-357.

Bolton, L. E., L. Warlop, et al. (2003). "Consumer Perceptions of Price (Un) Fairness." journal of Consumer Research 29: 474-49 1.

Byrnes, P. (2000). Reuse in California - an Australian Perspective.

Water Recycling Aust ralia, Adelaide, CSIRO & AWA. Council of Australian Governments (2004, Viewed 21 September 2004 <http://www.coag.gov.au/meeti ngs/250604/ iga_national_water_ initiative.pd f>). " Intergovernmental Agreemenr on a National Water Initiative, Canberra."

Erickson, G . M. and J. K. Johansson (1985). "The Role of Price in M ulti-Attribute Product Evaluations.'' Journal of Consumer Research 12 (September) : 195-199.

Hat ton MacDonald, D . (2004). The Economics of Water: Taking Full Account of First Use, Reuse and Return to the Environment. CS!RO Land and Water Client Report. Adelaide, CSIRO. Hurlimann, A. and J. McKay (2004). "Attitudes to Reclaimed Warer for Domestic Use: Pare 2. Trust. " Water 3 1(5): 40-45.

Jndependenr Pricing and Regulatory Tribunal of New South Wales (2000) . Sydney Water Corporation, Prices of W ater Supply, Sewerage and Drainage Services, Medium-term price path from I October 2000. Sydney, Jndependenr Pricing and Regulatory Tribunal: 70.

Irvine Ranch Water D iscricr (1994). Water Reclamation and Reuse: An Exemplary Program. Irvine, Irvine Ranch Water District: 4.

Martins, M . and K. B. Monroe (1994). "Perceived Price Fairness: A New Look at an Old Const ruct." Advances in Consumer Research 21(1 ): 75-78.

Maxwell, S. (1999) . "The Social Norms of D iscrete Consumer Exchange: Classification and Quantification." American Journal ofEconomics and Sociology 58(4): 999- l O18.

McKay, J. and A. C. H urlimann (2003). "Attitudes to Reclaimed Water for Domestic Use: Pare I Age." Water 30(5): 45-49.

Prime Minister's Science Engineering and Innovation Council (2003). Recycling Water For Our C ities. Canberra, Federal Government of Australia.

SA Water Corporation (2004). SA Water Annual Report 2003-04.

Adelaide, Government of South Australia.

Xia, L., K. B. Monroe, et al. (2004). "The P rice Is U nfair! A Conceptual Framework of Price Fairness Perceptions." journal of Marketing68: 1-15.

refereed paper

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demand management

DI

REDUCING DOMESTIC WATER USE: LESSONS FROM MARKETING AND ECONOMICS M Wallace, G Barrett Abstract Reducing water consump tion co a level consistent with even minimal water quantity/quality in our rivers is a major dilemma for sustainable resource use in all Australian cities. Social marketing and water pricing are essential components in resolving chis dilemma. This paper recommen ds a carefull y crafted social marketi ng campaign and a substan tial price increase co influence water con sumers' life sryle choices.

Encouraging use of water-effi cient technology

Attitude change Reduc ing domestic water consumption Legislation

P rice increases

Introduction Boch marketing and economics have lessons for reducing domestic water use.

Boch disciplines fo cus on the d emand for water. In chis paper, we would like co answer two questions: How can marketing best be used co reduce domestic water consumption ? And how co uld price increases work co reduce our use of water in the home? To answer these questions, we draw on the d iscip lines of social marketing and economics.

Demarketing Water It is never easy co ask consumers to give up what they enjoy- in chis case, cheap, abundant water. T o expect chem co reduce consumption in the lo ng term, not just d uring a drough t, is even more challengi ng.

For chis reason we envisage that an integrated scracegy will be most effective, combining attitude change, legislation, water effi cien t appliances and price rises.

Attitude change is an essen tial pare of the strategy, because only when consumers accept the need co use water responsibly, wi ll they abide by legislation, willingly use water-effi cien t appliances, and vote for governments chat preside over rising water prices.

Social Marketing O ur integrated strategy is based on the concept of social marketing, which "seeks co influence social behaviours not to benefit the marketer but co benefit th e target audience and the general sociery". (Kotler and Andreasen 1996) Whereas most people

68 MARCH 2005

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ch in k of marketing as synonymous with advertising, co a social marketer advertising is only the most visible part of a much larger strategy designed co promote and assist behavioural change.

What Can We Learn From Social Marketing?

The value of research The starting poin t for effective marketing muse b e research into co nsumer attimd es and behaviour, looking at questions such as how do co nsumers use water? H ow can we communicate with chem effectively? W hat co uld encourage chem to install water efficient appliances? (See Scinchcombe and Wiltshire, 200 3). And what are the differences between various consumer groups? For exam ple, it is likely chat teenagers and aged pensioners would di ffer in their attitudes co, and use of water.

Choose which consumers to target Research should indicate which consumers are worth targeting with marketing campaigns, and how these campaigns should be tailored to each rargec group. Some groups will already be us ing minimal water, and other groups will b e highly resistant to change. It is important not co waste marketing resources on these groups. Instead, resources should be used where they can effect the maximum ch ange in attitude and behaviour.

Use attitude-change strategies These will need co be based on research and tailored to the target groups. They could be either positive, to make consu mers feel good about doing the right thing, and/or negative, co make chem feel bad about wasting water. As the water shortage is a long-term problem, it would be most effective co change attitudes in the young .

Significant changes in the consumers' lifestyle can best be achieved by an approach in which price increases, regulation and water efficient technology work together.

Cultural differences may also exist- for example, migrants from, say, the Middle East and the Philippines would be highly likely to d iffer in th eir attitudes to saving water. This research can be used as a benchmark co measure the changes that may cake place as a resulc of marketing campaigns.

Recognise the difficulties in changing consumer behaviour Consumers enjoy cheap, abundan t water, and will have no wish co give it up. A successful strategy w ill need to consid er ways to make it easier for consumers co change. Here we can learn from Australia's successful anti-HIV campaign, which relied

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not just on education and advertisi ng, bur also on needle exchange programs and the easy avai lability of co ndoms. Research is needed to cell us how ch is model might be used in water conservation, but some suggestions follow:

Be aware of 'virtue fatigue' The recent rise in HIV races in Austral ia suggests chat people are prepared to modi fy their behaviour for some years in response to a marketi ng campaign, but that eventually they weary of th is behaviour and begin to become careless. [f we apply this pattern to water saving, we co uld expect that co nsumers might take virtuously shore showers for a certain period, bur that eventually they wo uld begin to indulge themselves again. So, wherever possib le we should aim for one-off, long-rerm changes, such as the installation of a water efficient showerhead or a drip irrigation system, rather than relyi ng in the long term on consumer virtue (Kotler and Andreasen, 1996) .

Consider ways of helping consumers 'do the right thing' Depending on the outcome of research, we may find char some of these strategies are useful: • Subsidising rhe purchase/installation of water efficient appliances • Assisting low- income ea rners with the costs of eliminating leaks.

• Providing advice on landscap ing and plant selection, possibly in co njunction with rhe nursery industry (Waterwise programs with the nursery ind ustry have been trialled in several States - see deVos and Dawson, 2004) .

• Rewarding consumers who achieve low levels of water use.

• Making it easy for consumers to monitor their water co nsumption, by redesigni ng meters and/or by providing more in formation on water bills.

Legislate Especially where consumers are resistant to change, legislation may accelerate rhe adoption of the targeted attitude and behaviour changes. (Kotler and Andreasen, 2004) Legislation may be used to penalise the wasteful use of water, to set standards for water-consuming appliances, or as in the case of BASIX in New South Wales, to regulate residential building des ign . T he

BASIX approach is notable fo r the flex ibility it allows: e.g. builders must achieve a certain number of points for water efficiency, bur each builder can choose the combination of water- efficient features used to gain chose points.

Pricing The measures suggested above, such as research, attitude change, and practical support for consumers, are all potentially hugely expensive to water utilities or State governments. If they succeed in reducing water co nsumpti on, they will reduce the revenue gained by the sale of water, unless they are offset by an increase in the price of water. Pricing is also an important tool for marketers in man ipulati ng demand, and for chis reason, the rest of this article explores the role of pricing in reducing water co nsumptio n.

Economics

Economics has lessons for red ucing domestic water use. Economics focuses o n the following determinants of de mand, for goods such as water: price (of the good and its substi tutes and complements), consumer's income, population, tech nology and tastes.

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demand management The price of water is crucial to an economic analysis of water demand. The relationship between the price of water and the consumption of water is known as the price elasticity of demand. Typically as the price of a good, such as water, increases co nsumers reduce their purchases of that good. This is a co mmon experience for consumers.

Econo mics has an extensive liceramre measuring the strength of this negative relationship. See Barrett (1 996) and Dalhuisen et al (2000) for overviews of estimates from around che world. Most estimates fall within the range of 0.1 to 0.7.

This means chat a I 0% increase in water price is expected co reduce water consumption by between I% and 7%.

Thus, price is not a strong determinant of water use and substantial in creases in water price are needed to achieve modest reductions in water use.

For Sydney, there have been two estimates of the price elasticity of demand for urban water. Warner ( 1996) estimated char a 10% increase in water price would reduce demand by 1.2%. Barkatullah (2002) estimated that a I 0% increase in water price would reduce demand by 2.1%.

These estimates are low by co mpariso n with the lireramre, where a 5% reduction wou ld be more typical.

ls a price increase necessary? le is possible to model the impact of a price rise usi ng a price elasticity of demand for Syd ney of a 2% co nsumption reduction for a I 0% price increase, the current Sydney Water price of about $1/kL and average Sydney per capita consumption of around 400 litres per person per day (1/p/d). Using this model, the price necessary to achieve policy goals such as Sydney Water's license req uirement to reduce water co nsumption t0 364 1/p/d by 2004/05 and 329 1/p/d by 2010/1 l can be estimated. A price increase from the cu rrent $1/kL to around $1.45/kL (365 1/p/d) and $J.90/kL (329 1/p/d) would be required to achieve these two goals.

The effect of rising consumer incomes on water use In reality nor only price wi ll change.

Higher in comes fo r co nsu mers typically increase the deman d for goods such as water. Economics measures chis positive relationsh ip as the income elasticity of demand. For Syd ney there have been two estimates of the income elasticity of demand for urban water. Warner (1 996) estimated char a 10% increase in water co nsumer's income would increase water demand by l.6- l.9%. Barkamllah (2002) estimated char a I 0% increase in water co nsumer's income would reduce demand by 0. 7%.

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Taking an income elasticity of demand for Sydney of 0.2 and assum ing a per capita income increase of 20% over the next ten years, Sydney's water consumption would rise from 400 1/ p/d co 4161/p/d. Using pricing to keep consumption co nstant, at 400 1/p/ d, would require the current price of arou nd $1/kL to increase to $ t.20/kL. A price in crease from the current $ 1/kL to around $ 1.60/kL (3651/p/d) and $2.05/kL (329 1/p/d) would be required to achieve Sydney Water's co nservation goals with rhe higher income.

The effect of population growth

The growth of Sydney's population has been a major source of growing demand for water. If the Sydney's growing population is to use its water sustainably (currently estimated as extracting 600 billion lirres per year from its rivers) then per capita consumption must fall. If Sydney's popu lation grows by l 0% over the next ten years, th en per capita consumpti on will need to fall by 10% in order to remain within the sustainable extraction limit. T o achieve the 10% reducrion from 400 1/p/d ro 360 1/p/d wo uld req uire a price increase from the current $ 1/kL to $ 1.50/kL. Including th e 20% rise income would require a larger price rise to $ 1.70/kL. The effect of technological change on water use

T he demand for water is influenced by rhe price of its substitutes and co mplements. Most water-com pl ementary (water using) goods are household devices such as dishwashers, washing machines an d showers, which are almost universal in Sydney households. Falling prices for these goods is unlikely to be associated with increasing adoption, bur rather with replacement of old technology with newer, water-savi ng technology. The main exception is swim ming pools, where price falls would be associated with increased adoption and increased water use.

Improved technology in new water using appliances and greater adoption of swimming pools will offset each other, but it is not clear which will dominate.

Tastes or attitudes also have a major influence over water use. Economics typically assum es char tastes are co nstant (ceteris paribus). However the earlier discussion of social marketing shows tastes can be changed and are the major determinant of water co nservation.

Overall it is clear that using pricing to reduce water use will require substantial price increases, potentially a doubling of price to $2/kL.

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demand management Institutional influences Understanding how a major water price increase is achieved is in the realm of institutional economics (North 1990, Dinar 2004) . Price is determined in an insti tutional fra m ework and is a major incentive to organisational and insrimrional change. Insrimtions are a human ly determined set of restraints (rights or rules) on human interaction. Organisations are groups of people with a com mon purpose.

T he instimrions (rules) govern rhe incentives (eg price), which govern which organisations are successful.

Sydney's water is governed by a specific sec of institutions (rules) and organisations.

Crucial insrimrions are scare ownership of both river water and water supply infrasrrucmre, government-determined water prices, and government-determined dividend payments by Sydney Water ($ 115 million in 2002-03) and Sydney Catchment Authority ($25 m illion in 2003-04) . C rucial organisations are Syd ney Catchment Au thority (bulk water supply), Sydney Water (retail water supply), Environmental Protection Agen cy (river water management), Independen t Pricin g and Regulatory T ribunal of NSW (water price determination) and water co nsum ers.

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Currenrly !PART sets rhe water price ch ar Syd ney Catch ment Authority charges Syd ney Water and the price Sydney Water can charge to water consumers. This charge provides an incentive to water consumers to conserve water. However the low p rice elasticity of demand and the low price m eans char water co nservation regulations are the p rincipal means of reducing water use (Barrett 2004). Higher water prices raise the profitability and divid end payments of Sydney Water and Sydney Catchment Authority.

This means char rhere is an incentive to increase water sales rather than achieve water conservation. T his in stitutional eco no m ics analysis suggests char water conservation would be most effective if rhe Sydney Catchment Authority was charged an absrracrion fee, determined by the EPA to reflect the water q uality and q uancfry costs of water abstraction and impoundmenr. Th is would p rovide a water conservation incentive right thro ugh th e water use chain.

Conclusion Domestic water conservation requires signifi cant changes in the co nsumers' lifestyle. This can best be achieved by an

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integrated approach in which price increases, regulation, water efficient technology and change in co nsu mer attimde all work together. Attimde change will be the most important of these elem ents as it will facilitate the acceptance of price rises, the adoption of water effi cient technology, and compliance with regulations. T his will require a significant investment in social marketing.

The Authors Margaret Wallace is a Lecrurer in Marketing at the Un iversity of Canberra.

Ph one (02) 6201 5488, email maw@managem ent.canberra.edu .au ; Greg Barrett is a Lecmrer in Econom ics at the University of Canberra.

Phone (02) 6201 5916, email gkb @managem en r.canberra.edu.au

Bibliography Barkacullah, N (2002) OLS and Instrumental Variable Price E lasticity Estimates for Water in Mixed- Effect Models Under a Multiparr Tariff St ructure, (http:/ /www.londecon . co .uk/Publicarions/DEM l .pdf) Barrett, G (2004) "Water conservation: The role of price and regulation in residential water consumption", Economic Papers, Vol 23, No. 3, September, PP. 27 1-285.

Barrett, G (1996) The Impact of Pricing and Household Income on Urban Water Demand: Explaining the Variations, Contributed Paper, 25th Annual Conference of Economists, Canberra, 22-26 September 1996 Dalhuiscn, J, Florax, R, de Groot, H , and Nijkamp, P (200 I ) Price and Income Elasticities of Residential W ater Demand, T inbergen I nstitute Discussion Paper TI 2001 -057/3 . (http://www.tinbergen.nl/ d iscussionpapers/0 I 05 7 .pdf.

De Vos, R., and Dawson, R., (2004) Outdoor Water Conservation and rhe Nursery and Garden I ndustry, paper presented to the Australian Water Association Conference, October 2004 D inar, A and Salerh, R. M (2004) The Institutional Economics of Water. A CrossCounny Analysis of Institutions and Performance, Edward Elgar, Cheltenham, UK. Kotler and Andreasen, (1996) Strategic Marketing for Non- Profit Organisations, Prentice H all , New Jersey.

North, D (1990) Institutions, Institutional

Change and Economic Performance,

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Cambridge University Press, Cambridge.

Stinchcombe, K. and Wilshire, M., (2004) Water-efficient Showerhead Schemes as a Demand management Strategy: paper presented to the Australian Water Associat ion Conference, October 2004 Warner, R. ( 1996) Water Pricing and the Marginal Cost of Water, Occasional Paper No I, December, (Urban Water Research Association of Australia).

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demand management

SHOWERHEAD RETROFIT SCHEMES: A SOCIAL MARKETING PERSPECTIVE K Stinchcombe, K Wildman, M Wiltshire Introduction Schemes chat encourage res idents to retrofit their bathrooms with m ore water effici ent showerh ead s (Figure l ) have beco me a principle component of demand management programs right across Australia. Conventional showerhead s consume sign ifi cancly greater quantities of water compared co che new generation of "low-flow" models. Addicionally, because water h eating accounts for one of the largest energy uses in a home, reducing water consumption in the shower can also significancly reduce greenh ouse gas emissions (Wilkenfield , 2004). Because o f chis "two-for-one" environmental potential as well as the low cost and ease of installatio n of che devices themselves, numerous water or energy provid ers and regulacors now offer various forms of rebate, retrofit or giveaway schem es. Toca! national investment in these programs is now well inco che tens-of-millions annually.

T he purpose of chis paper is co compare and critique different water efficient showerhead retrofit (WESR) scheme delivery mech anisms. The research deals with programs targeted at retrofitting existing residential dwellings only.

P rograms that target new construction, such as plumbing stan dards or minimum produce performance standards, while clearly important, are considered outside of chis research scope. The paper d raws conclusions from a m ajor research project completed o n the Gold Coast in 2004 involving a cross-j urisdictional stud y and extensive m arker research. Through a social marketing lens, the paper con siders che question: what is che most efficient and effective delivery mechanism co encourage residents to retrofit pre-existing h o m es w ith water efficient showerheads?

Community Based Social Marketing The field of community based social m arketing (CBSM) has emerged ouc of a growing awareness chat conven tional environm ental programs such as educational campaigns can be effective in raising public awareness abouc issues.

However, they often achieve limited results when it comes co

74 MARCH 2005

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Figure 1. Water efficient showerheads . achieving long last ing sustainable behaviour change . As a result, drawing heavily from research in social psychology, CBSM focuses o n identifying che barriers chat prevent people from engaging in sustainable beh aviours (McKenzie-M ohr and Smith, 1999). Emphasis is placed on analysis of empirical evidence co determine what works and, in particular, on a community's willingness co engage in a p rogram.

questio ns include: what are people's perceptions of these d evices? What has shaped these perceptions? What are che barriers chat prevent people from installing these devices in their h omes? In conducting chis fou ndational research, it is also helpful co look co the successes and problems experienced by programs already offered elsewhere.

Analysis of the barriers and motivators that compel people to change environmental behaviours.

By engaging in chis type research before planning a water or energy conservation scheme, empirical evidence suggests chat efforts are much more likely co be successful compared co cradicional app roaches to program design (M cKenzie-Mohr and Smith, 1999). The approach therefore provides an appropriate analytical lens for assessing different modes of delivery fo r WESR programs. size of area served.

Importancly, it is critical co ask residents direccly about the barriers and mocivacors chat inhibit and encou rage behaviour change rather than relying o n the impressions or assumptions of policy m akers or marketers . With showerhead retrofit programs, for example, key

Tobie 1. Breakdown of programs by Area Served

Number of Programs

Entire state

3

Large city (> l 00,000 people)

7

Town, shi re or regional area (< l 00,000 people)

6

TOTAL

16

Comparison of Australian Showerhead Retrofit Programs Our research started with a study co compare existing programs in place across Australia.

Our goal was co first determine what types of delivery models have been used co gee people co change their showerheads.

Another goal was co gain insight into how successful these programs had been.

We began by selecting sixteen representative programs from across Australia. Programs were funded and delivered by a range of providers including water utilities, energy ucilicies, loca l governments, and scare governments. T he breakdown of che size of the area served by each program is sec out in Table 1.

Data on each program was collected primari ly ch rough interviews with key staff in the providing agency. A pre-set questionnai re was used to collect in fo rmation by phone during an informal 15 co 30 minu te interview. T he questionnaire covered a range of issues incl uding program deli very merhods, prod uct choices, program coses, up take levels, fra ud prevention measures and predicted water and energy savings. As well, any avai lable wricren material was referred co, including pro motional material, annual reports or (in a few cases) evaluation reports.

Followi ng data collection, we compared all 16 programs qualitatively based on their delivery characteristics. Information fro m cen programs was also co mpared using a variety of quancicacive tech niques and ratio analyses, wh ich examined matters such as program coses and penetration levels.

(Resul cs for six programs were discarded for this intensive analysis due co a variety of data defi ciencies, generally related co the face that chey were coo new co ex pect meaningful results. However, all 16

programs were used in higher-level qualitative analysis.) The objective was co try and determine if any trends cou ld be discerned or if one program model emerged as clearly superior co another.

Results for Program Comparison T he most notable fin ding of the comparative research is ch at all of the 16 programs surveyed fit neatly into one of four distinct delivery models: • Rebate programs; • Direct home retrofits; • New-for-old swaps/giveaways; and, • Enhanced marketing only.

T he first model, rebate programs, was by far th e most frequently used, accounti ng for eight of che 16 programs. Under this approach, residents are provided with a rebate cowards che purchase price of the water efficient showerhead at point of sale, by cheque in che mail, or through water bill reductions. Rebate amounts ranged fro m

$ 10co $30.

Under che second approach - direct home retrofits - residents are provided wi ch subsidised services of a qualified plumber who actually comes into the home co replace showerheads, usually in co njunction with ocher low cost water efficiency work.

Residents therefo re receive both che service and the products at a nominal fee. T his model accounted for four of the 16 programs surveyed .

With a new-for-old swap approach, the resident is provided with a new showerhead at little or no cost in exchange fo r recurning an older inefficient model, thereby providing assurance co che provider char che

device will accually be installed in che home.

This approach accounced for two of the 16 programs. A variation would be co simply give away showerheads through any number of venues, although none of che programs surveyed used this approach.

T he fin al model - enhanced marketing was used in cwo of the 16 programs. T he approach could incl ude a grab bag of methods including: joi nt promotions with retailers; Internee sales through che provider's website; advertising the benefits of efficienc showerheads; promotion of discount vouchers or coupons in conj unction with retailers or m anu fact urers; or, public demonstrations. Almost every retrofit scheme will have some m arketing co mponent. However, the key element of this model is chat the provider only fu nds marketing rather chan directly s ubsidising the cost of the device or its installation.

This catego risation system will be recurned co in che analysis below.

Add itionally, che comparative resea rch also yielded a number of ocher important lessons. T hese conclusions are generalisations only based on th e researchers' observations and ar e obviously not statistically reliable given th e small sample size. However, they shoul d likely be at least considered in program design. Some of our observatio ns include the fo llowing: • Generally, direct retrofit programs appear co outperform rebate programs in terms of annual per property/per capita penetration.

Mose of the rebate programs we examined achieved penetration in the order of 3% of total dwellings in the serviced area per yea r.

T he direct retrofit programs ach ieved

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demand management significantly higher penetration. However, the small sample size and newness of most programs must be borne in mind in drawing this generalisation.

• With rebate programs in particular, the higher the value of the rebate awarded by the provider, the greater the program penetration. In other words, higher rebates do appear ro result in greater participation; • Not surprisingly, per unit cost for direct retrofit programs were significantly higher than costs for other delivery models.

Obviously, this will be related ro the costs of providing plumbing services on top of product costs.

• Also not surprisingly, higher program expenditure generally results in greater program uptake regardless of delivery model; • Interestingly, less populous locations such as rural sh ires and small towns appear to have more delivery options at their disposal. The new- for-old swap option, in particular, seemed attractive in these locations, but is probably less attractive at the city or state level. We attribute this to overwhelming logistical challenges for sizeable providers to manage showerhead inventories and to administer this type of program at a large scale.

• Local factors appear to have a critical impact on program results. These factors may include past community experience with drought and restrictions, community attitudes towards conservation and the influence of "local heroes" within delivery agencies (i.e. highly committed individuals who aggressively drive p rograms). With a number of programs, this factor appeared to have much more influence on uptake than the type of program offered.

Unfortu nately, beyond these very general conclusions, o ur q uantitative analysis of different programs did not show any clear trends in the data. Uptake levels across p rograms were highly variable, both in per capita and absolute terms. There was no clear correlation between per capita u ptake and any particular delivery model. Two programs with ostensibly similar population sizes and conditions and using the same delivery model could achieve remarkably different results.

In short, probably due in part to the small sample size and the relative newness of most programs, our analysis in the first phase did not provide any "smoking gun" evidence o f superiority o f any one delivery model. Generally, the direct retrofit approach did appear to outperform the rebate approach in terms of penetration.

However, we were unable to conclusively back up th is assumption. As such, it was 78 MARCH 2005

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% 33

Knowing it was saving water 29

If I received a rebate

15

Knowing it was savi ng money

12

If it was free

10

If someone installed it for free/small fee 8

Knowing it was good for the environment Kn owing it was saving energy

5

If it was reasonably priced / cheap A lready have one Other Nothing

5

8

8

Don't know

Multiple responses accepted, therefore total > 100% Base: Gold Coast residents interviewed 2- 15 June/04: n

= 80 I

Figure 2. Motivators to install water efficient showerheads.

with a number of unanswered questions that we turned attentio n to the next phase of the research, where the results were far more definitive.

Market Research Phase The CBSM lens shows that the one o f the most important drivers in the success of a community environmental program is the extent to which the barriers preventing people from taking pare are systematically addressed and overcome. As such, the market research phase focused on examining people's perceptions about the devices and their p refe rences for the various delivery models id en tified in the comparative research (Enhance Management, 2004).

T o meet these objectives, a multi-stage research process was developed. Phase One involved a series of six in-depth interviews with a heterogeneo us sample of Gold Coast residents. T h is phase assisted in the scoping of the fo llowing phases.

The quantitative phase of the research Phase Two - consisted of 801 telephone interviews co nducted amo ng Gold Coast residents. Interviews were conducted using Compu ter Assisted Telephone Interviewing (CATI) by a trained field force. Data was weighted to reflect the age and sex of the Gold Coast population, based on Australian Bureau of Statistics 2001 Census data (ABS, 2001 ). T he maximum margin of error associated with a sample of 80 1 is ±3% for a 50% result at the 95% confiden ce level.

Phase Three consisted of two discussion groups with che aim o f resting various WESR programs. The groups ran for

approximately two hou rs, moderated by an experienced qualitative researcher and participants were fin ancially reimbursed.

Phase Four consisted of a second quantitative telephone survey among 300 Gold Coast res idents. T h is phase was required to validate and re-test key fin dings from the earlier phases. The second telephone survey has a maximum margin of error of ±7% fo r a 50% result ac the 95% confidence level.

Motivators for Installing Water Efficient Showerheads W hen it comes to buying and installing water efficient showerheads, the single largest motivator is saving water (33%) .

However, in combination, a larger proportion (56%) cite factors related to saving money. T h ree of the top five motivators relate to fin ances - receiving a rebate, saving money on bills, or receiving the device for free. Relatively few mention benefits relating to installation or energy savmgs.

There were also demographic differences.

For younger residen ts and/or family households, the enticement of a rebate is particularly appealing (18-34: 34%; 35-59: 31 % ; 60+: 19%). Having the device installed is a greater motivator for females than males (13% vs. 7%). Interestingly, retirees are more likely to feel nothing would motivate chem to buy and install the device (15%), perhaps because they perceive themselves to already be thrifty with water.

Figure 2 shows the relative p roportions of motivators for residents uncovered by the first telephone survey (n=801 ).

Discussion group participanrs generally validate these findings. Parcicipanrs menrioned being motivated by saving water and money and by helping manage water supplies for the future.

% Inertia

33

Insta llation issues

19

Negative perceptions

Barriers to Installing Water Efficient Showerheads Anecdotal evidence might suggest char the greatest barrier co com munity uptake of water efficienr showerheads would be negative perceptions about rhe qual ity of the shower. Most demand management professionals will be familiar with stories abou c peoples' bad experiences wi ch rhe older, poor qualiry models char pervaded the Austral ian marker a decade ago when the technology first emerged.

O ur research challenges chis assumption, at least co some extent. Figure 3 shows the results when residenrs were asked what would discourage chem from installing a water efficient showerhead. T hey indicated char rhe greatest barrier is nor negative perceptions, bur rather a collection of responses char we have labelled simply inertia (33%) . Residents describe their inertia in terms of nor needing co change their current showerhead, nor getting around co changing rhe device or nor getting co the score co purchase it.

While havi ng so meone install rhe device is nor deemed co be a great motivator, installation issues ( 19%) are perceived co be a significant barri er.

Perceived insrallacion concerns relate specifically co che cost of getting rhe device installed, time taken, or lack of knowledge on how co install the device themselves.

Negative perceptions do fig ure prominently in the responses, bur only third on rhe list (1 8%).

Reasons cited include chat the device doesn't work properly or has lower water pressure. Men are particularly likely co hold th is view.

In rhe second telephone survey, one question focused on the disadvantages ofhaving a water efficient showerhead, as opposed co che barriers to installing one.

Residents participating in the second survey rend co focus more on rhe negative aspects of rhe device (36%), with che major drawback relating co the water pressure being coo fine or light.

Interestingly though, even when asked specifically co focus on the disadvancages, 18% indicated that rhey did nor know any and 26% said char there where no disadvantages.

18

P rice ofshowerhead

14

Lac k of k nowledge

9

Already have w.e.s.h.

5

Renti ng

5

Already wa ter consc ious Other

4

None/nothing DK

15 4

Multiple responses accepted, therefore total > I 00% Base: Gold Coast residents interviewed 2-15 June/04; n = 80 I

Figure 3. Barriers preventing installation of efficient showerhead.

Followi ng cost related concerns (14%), lack of knowledge (9%) also emerged as a significant barrier in rhe first survey.

Interestingly, this factor was more prominenr in che discussion groups, as the following comments ill ustrate: "I wouldn't m ind having one. I don 't know why I don't have one. I just don' t know where to get o ne and I don't know how to install it. " [Female , 40+, Family]

"Lack of awareness [is a barrier] - the fact that you could install a device to save water." [Male, 18-39, Couple]

Further Lessons About Negative Perceptions The two discussion groups also provided other cl ues co help refine our understand ing of che negative perceptions barri er when we applied an inrerescing "before and after" exercise. We began with parcicipanrs seared

•

• •

• Dorot

water

MARCH 2005 79

demand management checkmark was assigned where the program design does address the barrier. In cases where rhe delivery mechanism is particularly strong vis-a-vis any one barrier, a double checkmark was assigned .

around a rable. Following a series of introductory questions, we asked participants for their views on water saving showerheads.

Initially, negative perceptions were even more predominant than would have been expected from the telephone survey results.

Led by a small number of vocal individuals, virtually all participants expressed some form of disapproval of the devices.

Sentiments seem ed to have been derived from experience with whar sounded like older or cheaper devices or from "hearsay" based on rhe experience of relatives or fri ends. Negative views were mainly related to cost or pressure factors, as the following comments illustrate:

The resu lts are set out in Table 2 from wh ich one program - the direct retrofit approach - emerges as the clear winner.

Because ir demands little from residents in terms of rime sacrifice or instigation, this approach is rhe only one that intrinsically and systematically addresses the inertia issue. Similarly, only chis program addresses installation concerns, wh ich was the second most prevalent barrier cited by respondents.

Finally, if fees to participants are kept low (as was the case in rhe programs we examined), chis approach offers superior value to residents with respect to rhe cost barrier.

"I don't like them. No water comes our!

Ir's really soft." [Female, 18-39, Family] "For me, it's a design thing. If they just did something co make the pressure better." [Female, 18-39, Family] We then uncovered a previously hidden display panel that had eigh t different AAA rated showerheads manufactured by four national companies mounted on ic. This panel allowed participants to touch and see a range of new products w ith a range of prices. We also revealed a device leant to us by a local manufacturer chat demonstrated the different flow races for an efficient shower compared to an inefficient model.

This "live" demonstration unit also allowed participants to feel the flow races by getting their hands wet under the showerhead (see Figure 4).

Attitudes about the devices shifted markedly following this experiential exercise. Reactions ranged from being quietly pleased to vocal surprise. Comments were made in relation to the look and feel of the devices as well as the resulting water use reduction. A number of participants commented on how "normal" the devices looked: "Thar's one of the better ones. Usually they are little tiny things." [Female, 40+, Couple]

Figure 4. Showerhead demonstration unit.

Synthesis T he fi nal step in our research was to synthesise the findings of the comparative study with those of the market research project. In particular, our goal was to determine which of the delivery mechanisms identified by the comparative research would go furthest cowards addressing the key barriers as identified by the market research.

The methodology we used is qualitative and based on established CBSM methods (McKenzie-Mohr and Smith, 1999).

Using simple matrix analysis, we compared each delivery mechanism identified in the comparative research against the top five barriers identified in rhe main telephone survey (n=801; see Figure 3). A cross (X) was assigned wh ere the delivery approach does nor, in our view, syscemacically address any one key barrier from rhe resident's perspective. Conversely, a

80 MARCH 2005

water

Participants were not entirely taken with the rebate approach. Apathy, lack of information and costs were cited as the main barriers. Older participants, some of w hom commenced about the perceived

Table 2. Installation barriers and delivery program matrix.

Delivery Mechanisms

"The pressure is still quire light, bur I chink I could get used to ir, especially if you knew you were saving char much water." [Female, 18-39, Family] For the researchers, the lesson from chis pare of the study is chat even wh ere negative perceptions about water efficient devices are held, it is possible chat these feelings are not deeply rooted. Further, with many individuals, attitudes can likely be shifred significantly through simple marketing and education programs, particularly where a direct experience component can be included.

This analysis also shows rebate and swap/giveaway approaches to have some merits, though fewer than the direct retrofit approach. The enhanced marketing only approach emerges as problematic from the point of view of the resident, though chis may be offset by the fact char chis approach is likely to be low cost for rhe providing agency.

Our findings in favour of the direct retrofit model were greatly substantiated by rhe responses from the participants in the two discussion groups. In another exercise, we described each scheme in detail to participants and then requested comments for and against each. Giveaways and swaps were treated separately in this exercise. Enhanced marketing was not included based primarily on the face char it would be difficult to explain chis model to discussion group participants.

VI

Inertia Installation Issues

I,..

(I)

¡c I,..

,a

co

:m:nmlGm:mlll ., ., X X

Negative Perceptions

.,

Price

v

Lack of Knowledge

.,

., ., ., ., ., .,

..

X

X

X

X

., ., .,

.,

v

X

.,

Note: it is assumed that all approaches would involve some element of communications and promotion that will target lack of information and negative perceptions barriers. As such, one checkmark was assigned to each delivery mechanism for both these barriers.

difficulty in installing the device, least favoured th is approach. T he process of acquiring rhe rebare was also see n by som e as a hindrance and viewed as overly bureaucratic.

Simi larly, installation issues were also cited as impediments ro giveaway and swap schemes. Others mentioned the difficul ty of getti ng the devices - for example, if they had to drive to a Council office to pick it up. There was also widespread senti ment that schemes offering a free device were suspicious. In particular, participants felt free deals are open ro greediness and abuse by residents.

In contrast, the direct retrofit was clearl y favoured out of th e different schemes. Indeed, there was a surprising level of enthusiasm about chis approach, as illustrated by th e fo llowing quotes: "Th is op tion is very good , as it covers everything." [Male, 40+, Couple] "T har's fan tastic, t har's magic." [Female, I 8-39, Fam ily]

Conclusion T his research supports ch e direct home retrofit approach as che most likely ro succeed from a community based social marketi ng perspective, at least in terms of its capaciry ro address barriers and mocivarors identified by resid ents on rhe Gold Coas t. Boch qualitative analysis and direct marker research show it robe superior in its ability ro systematically eliminate key barriers such as in ertia, insrallacion issues and cost factors.

O f course, ocher factors besides community perceptions and accirndes muse be considered when des igning a program. Th is research has shown , fo r exampl e, that local factors such as che providing agency's capacity and th e size of th e popu lation in the delivery area can critically affect success. As well , lack of knowledge and negative perceptions emerge as persistent, albeit likely remediab le barriers in th e eyes of residents. As such , a well-designed communications campaign would be recommended as pare of any progra m, regardless of che selected deli very mechan ism. Finally, che issue of cost ro che providing agency undoubtedly requires attencion.

Noc surprisingly, th e progra m most likely to be favoured by residents is also likely robe che most coscly per unit fo r the deli very agency.

W hen designi ng a retrofit program , each providing agency will have ro weigh these fac tors individually, ideally supported by marker research co nducted locally. ln any case, careful consideration and accencion to the moci varors and barriers that drive or preve nt people from taking part in shower retrofit programs will greacly increase the likelihood of success.

The Authors Kirk Stinchcombe is Deman d Man agement Coordinator, Gold Coast Water, email kscinchcombe@goldcoasrwarer. com .au; Karen Wildman is Research Manager, En hance Management, Brisbane, email karen.wildman@enhance.net. au; Mark Wiltshire is Environmental Planner, Gold Coast City Council , email mwilrshire@go ldcoasr.qld. gov.au.

References ABS, 200 I . ABS 2001 Censw of Population and Housing, prepared by the Australian Bureau of Statistics, C ommonwealth o f Australia, Canbe rra.

Enhance Management, 2004 . Attitudes Towards Water Consumption and Water Saving Devices, prepared for Gold Coast W ate r, Brisbane, September 2004 .

McKenzie-M ohr, Doug and W illiam Sm irl1, I 999. Fostering Sustainable Behaviour: An Introduction to Community-Bm ed Social Marketi ng, New Society Publishers, Gabriola Island, C anada.

W ilken field , George and Associates, 2004. Regulation Impact Statement: Proposed National System of Mandatory Water Efficiency labelling and Standards far Selected Products, prepared fo r tbe Department o f Environment and Heritage, Australia, Sydney, February, 2004 .

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111

THE Ps AND Qs OF RISK ASSESSMENT D Deere, A Davison Abstract

1. What is the risk?

One useful way of categorising different types of risk assessment is accordi ng to their level of quantification. These can be grouped according to "three Ps": "Pathways", "Priorities" and "Predictions". Figure 2 illustrates these different levels diagrammatically and Table 2 compares each with one another.

T his paper categorises some of the risk assessment approaches currently being applied by water management professionals in Australia. T hree types of risk Continuous assessment are identified, each diffe ri ng according to Cycle 3. How do we 2. How do we quancicacion level, categorised know manage the here as three "Ps" - "Pathways", the risk risk? is managed?

"Priorities" and "Pred ictions".

Pathways Each level of risk assessment is Conceptualising how and what explained using examples. The risks may arise is typically the first predictive risk assessments vary Figure 1. The risk assessment and management process step in any risk assess ment. Flow with respect to what is (ofter Davison et al 200 l). diagrams help to illustrate where quantified, categorised here as water comes from, how it is three "Qs" - quantitative captu red, created and distributed chat are now being applied in water quality "microbial", "chemical" and "health" risk risks may arise (e.g. Figure 3). and where management. assessment. The disability-adjusted li fe year The approach is promoted in all the (DALY) concept is explained along with the example guidelines and regulations given in Three Levels of Risk Assessment possible implications for fu ture public Table 1 and is suitable for low income and Quantification fu nding of water sector investments. regional systems. The output provides a Risk assessment paradigms begin by visual map of risk pathways which ca n be Introduction asking the same key questions, starting with produced as si mple line and box flow "what is the risk endpoint, i.e. to what are During the past few years a significant diagram (e.g. Vigneswaran and Deere 2003) we assessing risks?". Next, the microbial, number of substantive guidance and or as graphical illustration to support physical or chemical agents that might legislative documents have emerged chat communication (e.g. Ferguson et aL2003). cause harm ("hazards") and the causal have promoted the adoption of risk events and scenarios that lead to their management principles in water quality management (Table I). An illustration of The disability adjusted life year the generic risk management process was presented by Davison et aL (2001 , Figure 1) (DALY) concept explained. which shows chat the first seep in the risk management process is the assessment of Priorities presence are identified with respect to the risk. The phrase "risk assessmen c" is now risk endpoint.

However, at the detailed T o help set priorities, a number of used so broadly that it is ambiguous in the level, there are many ways of doing this structured approaches to ranking risks can absence of context and qualifiers. T his not all risk assessments are done the same be applied. Such approaches are promoted paper summarises some of the by most of the example guidelines and way. co ntemporary risk assessment paradigms

Table 1. Exa mples of contemporary risk assessment and management guides and regulations (based o n Rizok and Deere 2004).

Document

Organisation

National Health and Medical Research Council (Australia) Framework for the Management of Drinking Water Quality

Reference

NHMRC/NRMMC (2004)

Department of Human Services (Victoria, Australia)

Risk Management Plan legislation and accompanying regulation

GoV (2003)

Ministry of Health (New Zealand)

Public Health Risk Management Plans and related regulation

MoH (2001)

World Health Organization

Water Safety Plan

Davison et al (2003), WHO (2004)

World Health Organization

Hazard Analysis and Critical Control Point

Havelaar (1994), Deere and Davison (1998), Deere et al (2001) and Gissurarson (2004).

International Water Association

Bonn Charter

Deere (2004), Rizak and Deere (2004)

84 MARCH 2005

water

refereed paper

water quality

-----2_.,S

IPredictions !r-

Priorities f------.,,

Pathways

Semi-quantitative risk ranking

Conceptualised risk pathways

Figure 4. QRA Paradigm (adapted from WHO/FAO 2003) .

Figure 2. Levels of risk assessment (after Davison and Deere 2004). illustration of the estimated uncertainty to accompany the risk score and an example of a simple scheme is given in Table 4.

Predictions

Figure 3. Example flow diagram to define risk pathways for the consumption of oysters contaminated with viruses from sewage (after Deere

regulations given in Table 1. The process involves characterising risk by combining available evidence, (which is often limi ted) , with the best peer judgement of people with technical and local operational knowledge. The output is a list of prioritised risks but although semi-

et al 1998).

quantitative, che output is not applied to cry to predict actual levels of risk, just to rank relative levels of risk in somewhat arbitrary terms. The level of complexity applied co the prioritisation can vary and examples of these different levels are given in Table 3. It is possible to add an

oe:===,,~- ~- .. . ..

• • JI_

JI_

•

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Figure 5. Example of how DALYs are calculated . For each symptom multiply duration x severity x probability, add the DALYs for each symptom to give total DALYs per infection, in this example, 0 .015 .

86 MARCH 2005

water

Quantitative risk assess ment (QRA) is used to predict as quanti tatively as possible "relative" and "actual" risks . lm portanrly, although QRA is "quantitati ve", its outputs are often highly uncertain and are, at best, predictions of the quantitative level of risk.

Therefore, we reco mmend describing QRA as "predictive" modelling to avoid the percep tion that the output is certain.

T here are three "Q"s of QRA: Chemical (QCR.A assessing chemical risks), Microbial (QMRA assessing microbial risks) and Health (QHRA assessing both chemical and microbial risks to health simultaneously). QRA involves the use of models to predict the infection or disease burdens associated wi th specified exposure routes and hazards. The models are mathematical and logical expressions of current knowledge in fo rmed by the data availabl e and structured acco rding to a fi vestage paradigm (Figure 4) . The level of sophistication chat can be applied in QRA is almost limitless. Ac its most simple, a simple point estimate of risk is predicted.

Ac its most co mplex, a fu ll quantitative and probabilistic assessment is undertaken. A comparison of these different levels is given in Table 5. Furth ermore, the endpoints can be infection races, disease incidence or disease burdens (Table 6 and Figure 5). An illustrative scheme for a probabilistic QMRA estimating disease burdens is given in Figure 6.

In most contemporary applications, QRA models predict disability-adjusted life years (DALYs) as the endpoint (Table 6 and Figure 5). The use of DALYs in decisionmaking has been promoted by WHO fo llowing the Global Burden of Disease analysis of Murray and Lopez (1996) and DALYs are now widely used for public health reporting and decision-making by

refereed paper

water quality Table 2. Three " Ps" of risk a ssessment Feature

Pathways

Predictions

Priorities

pathways

Focus attention an

Predict probabi lities of specific risks

prioritised risks

Purpose

Identify risks

Tool

Flow charting

Who

Small group of those with subject matter Peer group of those with subject matter expertise Specialist risk analyst informed by people with and detailed loca l knowledge and experience subject matter expertise a nd quanti tative expertise a nd some local knowledge knowledge al the system under consideration

How

Through circulation of drafts, sometimes including a workshop

Usually centred around a workshop

Through targeted literature review and circulation al written material describing assumptions of the model

Breadth

Extensive: Broad classes of risks, generic ca uses

Broad: Many speci fic ri sks and causes

Narrow: From one to a few speci fic risks and causes

Complexity

Simple: usually only a fl ow diagram required

Intermediate: usually a table or spreadsheet is required

Complex: usually specialist software

Output

Possible risks and their general causes are illustrated on a flow diagram

Risks ore predicted (in terms of infection or illness Risks o re ranked, often on a scale between insignificant and catastrophic (g iven the product within a given timelrame and population size) as of their likelihood of occurrence and severity of a probability consequence) in a table or spreadsheet

Mathematical model

Spreadsheet or table

Quantitative risk assessment (QRA) [health (QHRA) , microbial (QMRA), chem ical (QCRA)]

Risk ranking, risk scoring, rapid ranking, qualitative risk assessment, sem i-quantitative risk assessment

Other names Conceptual model, risk map

When

As a first step in any risk assessment to see what risks are possible

To identify whether or not ri sks are at acceptable When the sheer number of identified risks is unmanageable and focus on the top priorities is quantitative levels or what level of miti gation is required required

Example references

Ferguson et al (2003), Deere el of (200 1), Vignesworon and Deere

AS/NZS 4360 (2004), WHO (2004), N HM RC/NRMMC (2004), Davison et a/ (2003), Deere el a/ (2001 ).

(2003).

QMRA: W HO / FAO (2003), Haas et a/ QCRA: W HO ( 1999)

(1999);

Table 3. Levels of complexity applied in pri oritising risks (ada pted from Deere et al (200 l )) .

Feature

Basic

Intermediate

Complex

Severi ty of consequence

M erged with likelihood, not separately ra ted

Rating scale, usually 1 to 5, wi th descriptors such as "m inor, major, catastroph ic"

Several criteria , including approxi mate population exposed, wether impact is inconvenient, harmful or fatal and costs of impact

Likelihood of occurrence

Merged with consequence, not separately roted

Rating scale, usually 1 to 5, with descriptors such as " low, moderate, high"

Frequency of occurrence estimated in terms of return event frequency

N umber of possible outputs

O nly two: " Significant" or "Insignificant"

The product of the total number of categories an each rating scale: usually scores from 1 up to 25

Extensive range of possible outputs, depending on how many criteria and categories ore used, often with a number of continuous scales being used (frequency, population, dollar values)

Example reference

Melbourne Water (2004) Recycled Water Quality Management Plan.

AS/NZS 4360 (2004), WHO (2004), NHMRC (2001), Davison el a/ (2003), Deere el a/ (200 1).

Deere el a/ (2001) describing the Sydney Water Catchment to Tap Risk Assessment program begun in 1998.

health agencies wo rldwide. T he use of DALYs in water-related scenarios has recently been promoted by WH O (Havelaar and Meise 2003, WHO 2004).

As the name suggests, the DALY is a metric of a disease's impact on human health based on years of life lost (YLL) due to death as well as the number of years lived with a disease-related disab ility (YLD). T he DALYs are normalised to a value of 1: one disability-adjusted year of life lose. The calculation of DALYs for an y particular disease is a quite complicated process, beyond the scope of chis paper, but the basic co ncept is quite simple. A person suffering a very severe bout of diarrhoea with a 7.3 days (duration 0.02 years), 8 8 MARCH

2005

water

might be considered to have a level of disability equivalent co 50% (severity 0.5) for chat period which multiplies to give a DALY (YLD) of0.01 . lf thac person then dies due to diarrhoea at age 50 in a commun ity where the life-expectancy was

70 they would be considered to have lost 20 fu ll years of life (duration 20) at a level of disability equivalent to 100% (severity of l ) which multiplies to give a DALY (YLL) of 20. T he total DALY for chis example would be 20.01.

Table 4. Simple a pproach to ranking uncertainty (ada pted from Water Futures (200 4 )).

Uncertainty Score

Criteria Is event known to occur?

Is significance of event known?

Unknown

Unknown

M edi um

Known

Unknown

Low

Known

Known

High

refereed paper

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water quality Table 5. Comparison of deterministic a nd probabilistic risk assessment.

QHRA component

Deterministic approach

Probabilistic approach

Parameters used

Point estimates for each parameter in model

Frequency distributions for one or more parameters in the model

Input data

Estimates of median and limiting values

Frequency distributions fitted to many (at least dozens) of data points or estimated

How uncertainty and variability are handled

Upper and lower values are estimated for parameters

Frequency distributions encapsulate variabil ity and uncerta inty

When used

When only med ian or worst case risks are to be assessed, such as during a simple first pass or a worst case risk screen

To represent variability and uncertainty as a risk distribution and/

Standard computers as the process only involves simple mathematical relationships

Fast computers req uired as the process involves i terative fitting and iterative "Monte Carlo" randomised simulations

Software

Simple spreadsheet

Proprie tary risk analysis or mathematical software

Skills

Good general technical and mathematical skills

Specific expertise in probabilistic statistics and subject area expertise to ensure plausible distribu tions are used

Outputs

Point estimates: usually median and "worst" and "best" case risk probabilities

Frequency distributions : usually histograms with med ian a nd 95 percentile ri sk probabilities being reported

Examples from water supply

Wastewater: Deere

Hardware

et al I1998)

or when percentiles other than median are to be assessed and there is a need to avoid over or under estimation that can arise from deterministic models

Large urban water: Teunis

et al I1997);

Small rural water: Deere

et al (2004)

Summary and Conclusions In general, risk assessment as undertaken in the Australian water secror starts with a conceptual analysis of the pathways by which risks arise. More often than nor, this leads ro a process of semiquantitative ranking for prioritisation of risks. Very occasionally quantitative p1·ediction of specific risks is undertaken, first at the screening level and, if required, in more derail using probabilistic models.

Quite rightly, the proponents of water supply and sanitation investments often cite public health benefits as paramount in their business cases. With the advent of the universal "DALY" metric health benefits can be compared between investmen ts in different sectors. Ir is possible chat in future water utilities making claims about public health benefits arising from their investments will need to quantify chose benefits in terms of DALYs. Pub lic health benefits attributed to water secto r investments may begin to be traded off against public health benefits attributed to related investments and investments in ocher sectors. Water utilities have rapidly embraced the use of risk assessment principles in prioritising risk management activity. There may be a need for utilities to become adept at understanding how to apply risk assess ment at the pointy prediction end in order to maintain support for some investments.

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The Authors

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Dr Dan Deere and Dr Annette Davison formed Water Futures in lace 2003 and Dan Deere has been a Program Leader with the CRCWQT si nce 200 1. The authors have undertaken water cycle risk assessment and management projects fo r water utilities, aid organisations and environmental and health regulators both in Australia and overseas. Each author has 8 years experience in water quality risk assessment including NHMRC Framework pilots, WHO mo nographs, a variety of water and recycling risk management plans and a range of predictive quantitative risk assessments.

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Figure 6. Example of probabilistic QMRA. Probability distributions are multiplied together iteratively to give a risk distribution. The dose response relationship is fitted to human-feedi ng trial data (Gerba et al 1996). The "acceptable risk" level of 10·6 DA LYs is shown not be often exceeded in thi s example.

refereed paper

water quality References AS/NZS 4360 (2004) Risk Managemenr Standard. Scandards Australia/Standards New Zealand.

Davison A.O., and Deere D. (2004) Risk Assessment in Water Supply. National Water Quality Surveillance Conference, Dhaka, 4-6 July Davison , A.D., Howard, G., Stevens, M. , Callan, P. , Fewcrell, L. , Deere, D. and Bartram, J. (2 003) Water Safety Plans.

Managing drinking-water qual ity from catchment to customer. !WA Publishing, London , UK. E=inal Draft.

Davison, A.D., Schneider, P., Langdon, A., & Toop, P. (2001 ) Getting your priorities right: assessing and managing hazards . 19th Australian Water Association Federal Convention April 2001, Canberra.

Deere D, Cole C, Williams JA, McConnell S, Bechel M, and Ashbolt NJ (1998) Assessment of human health risks to support decision-making on wastewater treatment options, Proc. AWWA/I WA Recoverable Resources Conference, Moama, NSW, 7-9 May. Deere, D. , Teunis, P. , Cunliffe, D. , Donlon, P. and Davison, A. (2004) Health Risk Assessment of Fire fighti ng from Recycled Water Mains. Water Services Associarion of Australia, Occasional Paper No. 11.

Deere, D (2004) Workshop Report: Effective Drinking Water Quality Management.

Heald, Scream, Cooperative Research Centre for Water Quality and Treatment, Issue 33, 1-3.

Deere, D. and Davison, A. (1998) Safe water are food guidelines the answer? Water 25:2124 Deere, D. , Stevens, M., Davison, A., Helm, G. and Dufour, A (2001) Managemenr Strategies. In: Water Quality: Guidelines, Standards and Health. Assessment of risk and risk mantlgement far water-related infectious disease. Fewtrell L. and Bartram J. (eds). !WA Publishing, London . ISBN I 900222

28 0. Ch 12. p 257-288

Table 6. Com pariso n of possible endpoints used in QRA. Feature

Infection with a microbial hazard

Disease incidence due to a microbial or chemical hazard

Disability-Adjusted Life Years

What it is

The presence af an infection in a person whereby a pathogen is able to grow and multiply within a person's body.

Units How it works

Probabi lity of infection The infection probability is calculated based on an assumed number of pathogens ingested [usually, but could be inhaled or contacted), normally calculated from the estimated pathogen concentration and volume consumed.

The presence of a disease in o person whereby a chemical [usu ally, but could be a pathogen) is able to trigger a symptomatic disease in a person.

Probabi lity of disease The disease probability is calculated based on an assumed dose [usually, but could be a concentration) of chemicals [usually, but could be pathogens), normally calculated fram the estimated chemical concentration and volume consumed or otherwise contacted.

The amount of harm ("disease burden") caused by a chemica l or pathogen in terms of both death and illness, normalised as disability-adjusted life years [DALYs).

Probable DALYs lost DALY is calculated from expected consequences of becoming diseased. The DALY is normalised to a value of 1: a person being dead for one year. For example, for death, if life expectancy is 70 years, and a person is pred icted to die at 50, a loss of 20 DALYs is predicted.

For ill ness, having severe diarrhoea might be equivalent to being only "half alive" [severity 0.5).

If the duration is 7.3 days [0.02 years) the DALY is the product [0.01 ). To get the final DALY value for a disease, the various illness and death scores ore added, in th is example, 20.0 1.

The endpoint is an illness and represents The endpoint considers both illness and death, and Many infe ctions occur without any Pros symptoms, i.e. infection is not the some some disease burden. Both microbial and the severity and duration of illness, or the years of expected life lost through death . Both microbial as illness. Therefore, this is a conservative chemical hazards can be considered and chem ical hazards con be considered against against this endpoint. means of assessing risk. th is endpoint. For a ll hazards, the endpoint is comparable so health outcomes due to various hazards con be token into account.

Pathogens vary in the extent to which they Diseases vary in their severity with some The disease burden values are debatable and add Cons on additional layer of uncertainty, variability and cause illness. Some ore often fatal, others being usually fata l and others being debate to the modelling process. There ore ethical usually recoverable. Even where death ore usually mild. Using infection as the issues associated with discounting death over time is the outcome, this may occur at endpoint doesn't allow for these health and with assigning disability values between 0 different ages. Using disease as the outcome differences. The technique is and 1 to symptoms, particularly cognitive limited to microbial hazards. This makes it endpoint doesn't toke into account all impairments or aesthetic impacts of disease. the health outcome differences. This difficult to fai rly compare dissimilar makes it difficult to compare dissimilar pathogens and even more limited in hazards or diseases. comparing to chemicals.

10-5 excess lifetime risk of cancer [WHO 10-6 excess disabil ity-ad justed life years per Example 10¡4 per person-year (USEPA 1989) person-year [WHO 2004) Reference Level 1993) "Plain English" One additional infection case per 10,000 One additional cancer case per 100,000 One additional disability-adjusted life year lost per reference level people per year orisi ng from the exposure people over their lifetime arisi ng from the 1,000,000 people per year from the exposure exposure being considered. being considered. being considered.

What concentration of a given chemical or How much drinking water con be What level of treatment is required to Example problem reduce Cryptasparidium to a concentration consumed for a given concentration of a microbial hazard con be permitted in recycled water where a population is ingesti ng that water a t which the population ingesting drinking chemical hazard for a population at a particula r volume for one year before one water for one year hos a probability of ingesti ng that water containing the additional DALY is lost per 1,000,000 people suffering less than one additional infection substance at a particular concentration due to that water? for 70 years before the probability of per 10,000 people due to that water? cancer exceeds one additional case per 100,000 people due to that water?

Example reference

The probability of infection is not adjusted for illness, i.e. whether or not the infection actually makes a person ill, but the presence of immunity con sometimes be token account of in the modelling.

The probability of disease is not adjusted for severity, i.e. whether or not the disease is likely to be fatal, or how much a person suffers once ill.

Teunis el a/ [1997)

WHO (2004)

92 MARCH 2005

water

Hoveloor and Meise (2003)

refereed paper

r4

Ferguson, C., Altavilla, N., Ashbolr. N. and Dee re, D. (2003).

"Prioritizing watershed pathogen research ". journal ofthe American Water Works Association. 95 92-102 Gerba, C.P., Rose, J.B., H aas, C.N. and Crabtree, K.D. ( 1996) W aterborne rotavirus: a risk assessment. Water Research 30( 12):2929-2940 G issurarson, L. (2004) Case St udy #4: HACCP and ISO Systems at Reykjavik Energy, First A udited 1997. HACC P in Water Utilities Conference, National Sanitat ion Foundation and World H ealth Organization, Ann Arbor, Mich igan, 4-5 May. GoV (2003) Safe Drinking Water Act 2003. Act No. 46/2003.

Government of Victoria. http://www.dms.dpc.vic.gov.a u/sb/2003_Act/ AO 1263 .html.

Accessed 9 March 2004.

H aas, CN; Rose, JB; Gerba, C P ( I 999) Quantitative Microbial Risk Assessment, Jo hn Wiley & Sons.

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H avelaar, A.H. ( 1994) Application of HACCP to Drinking Wate r Supply. Food Control 5: 14 5- 15 2 Havelaar, A. H . and Meise, J.M. (2003) Quantifying public health risk in the WHO gu idelines for drinki ng-wate r q ua lity. RJVM Report No. 73430 I 022/2003 Melbourne Water (2004) Recycled Water Quality Management Plan. Western Treatme nt Plant Lagoon System 55 East to W erribee Irrigation D istrict. Melbourne Water.

MoH (200 I) Public H ealth Risk Management Plan Guides for D rinking Water Supplies. N ew Zealand Min istry of H eald,. http: // www.moh .govt.nz/ moh.nsf/wpg_index/ Publications-Public+ H ealth+ Risk+ Managemen t+Plan +Gu ides +for+Drinking+ Water+Supplies. Accessed 9 March 2004.

Mu rray C.J.L. a nd Lopez A.O. ( 1996) The G lobal Burden of Disease: a comprehensive assessment of mortality and disability from diseases, injuries and risk factors in 1990 and projec ted ro 2020. H a rvard: Harvard School of Public H ealt h.

NHMRC/NRMMC (National H eald, and Medical Research Council/ Natural Resource Management Min iste rial Counc il) (2004) Australian Drinking \\'later G11idelines National Water Quality Management Strategy. IS BN Online: 1864961244 Rizak, S a nd D eere, D (2004 ) Risk Managem ent S trategies for D rinking Water U tili ties: The Role of HACC P, Ma nagem ent Systems and Water Safety Plans . Health Stream, Coope rative Research Centre for W ater Qualiry and T reat me nt, Issue 34, 4-5 .

Teun is, P. F.M., Medema, G.J., Kruide nier, L. a nd H avelaar, A.H. ( 1997) Assessme nt of the risk of infection by Cryptosporidiu111 o r Giardia in d rinking water from a surface water source. Water Research 31 (6): 1333- 1346.

USEPA (1989) National Primary Drinking Warer Regulations.

Final Rule. Federal Register 54, l 24, 27486.

Vigncswaran , B. a nd D eere, D . (2003) . Best pracrice strategies for cyanobacterial risk assessment and management fo r the SCA reservoirs. Proc. XXth Bien nial Federal Conven tion of the Australian Water Associat ion, Perth, 6- 10 April.

Water Fut ures (2004) G uide to preparing Risk Management Plans consistent with t he Safe Drinking W ater Act 2003 (Vic) for Water Storage Managers. I st Edition. Prepared for Goulburn Murray Water, Southern Rural Water and Grampians Wimmera M allee Water.

WHO (World H ealth Organization (I 999) . Principles for the assessment of risks to h11man health from exposure to chemicals.

Environmental H ealth Criteria: 2 10. World Health Organisation.

W H O (World H ealth Organization} (1993) . Guidelines for Drinking-water Quality. Second Edition.

WHO (World H ealth O rganization}/FAO (Food and Agriculcure Organisation of the United Nations) (2003) .

Hazard characterisation for pathogens in food and water: Guidelines.

WHO (World Health Organization) (2004). Guidelines for Drinki ng-water Quality. T hird Edition.

refereed paper

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water quality

DETERMINING BENEFITS OF A REGULATORY FRAMEWORK FOR DRINKING WATER QUALITY R Deighton-Smith, B Labza Introduction The Safe Drinking Water Act 2003 established a new legislative framework for assuring the quality of drinking water in the state of Victoria, Australia. The legislative framework is based on: • The adoption of a 'catchment to tap' risk management approach; • The specification of standards at the customer rap for key water quality criteria; • T he establishment of information disclosure obligations for water suppliers; and • T he adoption of systemic comm unity consultation processes.

Procedural requirements in many jurisdictions require that the benefits of new legislation can be shown to outweigh the costs attached to it. This reflects the economic perspecrive that overall social welfa re is only enhanced by a legislative or other initiative if there is a positive net benefit. But how can chis requirement be met in practice?

Although it is usually possible to calculate the costs attributable to new activi ties, the expected benefits of regulatory frameworks are necessarily subj ect to considerable uncertainty. T his degree of uncertain ty is, in part, the result of the relatively limited data available in relation to a number of key variables.

In the case of drinking water quality legislation, it also reflects the fact that major outbreaks of waterborne disease and illness are relatively rare and unpredicrable events in developed nations, with widely varyi ng consequences. T hus, estimation of benefits chat, in large part, relate to reducing the incidence of these events, is necessarily difficult and uncertain.

This paper was developed from the cost benefit process undertaken fo r the Victorian drinking water quality regulatory framework and , more specifically, from the Economic Impact Analysis and the Regulatory Impact Statement 1 developed as part of the legislative and regulatory process.

The paper focuses on the methodology that was used for determining benefits derived fro m improved microbiological water

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quality, including its limitations. Case studies from a model developed in Victoria and for incidents in Sydney NSW and Walkerton (Ontario, Canada) are presented. In doing so, it is hoped that rhe paper will be useful when similar matters are considered in comparable jurisdictions.

Types of expected benefits The most common and widespread health risk associated wirh drinking water is the presence of micro-organisms chat can cause illness (pathogenic organ isms). Producing safe drinking water means minimising rhe risk of endemic illness as well as epidemic illness, by killing, removing or rendering harmless pathogens and ocher co ntaminants.

and improvement in the efficiency and effectiveness of actions taken to deal wirh problems that occu r.

Following from this, the potential benefits from improving drinking water quality are of several types. Firstly, there are health benefits in terms of reduced in cidence of infect ious disease outbreaks (epidemics) and reduced severi ty of outbreaks as a result of improved management. Secondly, there are health benefits in terms of reduced endemic incidence (i .e. long term or background levels) of disease. Thirdly, there are the benefits associated wich the reduced need to cake costly avoidance action in the case of contamination incidents or disease outbreaks

The potential costs of large-scale outbreaks of disease are enormous.

In addition, the level of chemical contaminants which may have chron ic health -related effects should be minimised.

In general, benefits from improved management of drinking water quality include a reduction in the incidence of water quality fall ing below acceptable qual ity levels, better detection of any problems that do arise

(e.g. purchase of bottled water or bo iling tap water fo r drinking).

Fourth , there are rhe benefits of increased consumer confidence that drinking water is free from risks to health and chat water system management and monitoring are of a high standard. While essentially intangible and thus unquantifiable in nature, ch is public

Box 1. Risk assessment.

Risk assessment generally considers rhe probability of an event occu rring, its magn itude, and rhe effect on public confidence or health . Techniques used for estimating carcinogenic chemical risk, non-carcinogenic chemical risk and microbiological risk all di ffer signi ficantly. All have their own shortcomings, with microbiological risk assessment arguably the most arbitrary.

For example, to determine the likelihood of water con rai ning Campylobacter reaching a consu mer's tap it would be necessary to defi ne the probabilities of Campylobacter being in the raw water (o r other source of contamination), combined with a treatment plant malfunction and the co ntaminated water reaching rhe tap fo r consumption. Dara on the infective dose, age and susceptibility of the exposed population, patterns of personal mobili ty, water consumption patterns and personal hygiene wo uld then have to be defined in order to calculate the health risk. In addi tion, the illness should be able to be reliably and consistently detected, reported and diagnosed.

Finally, data about losr productivity due to disease, direct medical cost of treatment of the disease, indirect cosrs of the disease, cost of managing an outbreak, averring behaviour, opportunity costs, the costs of water treatment works or interventions and then extrapolating cl1is data to particular situations would be required to determine the economic and publi c health impact.

con fidence benefit is of considerable importa nce. T he recem experience of contamination of the Syd ney NSW drinking water supply indicates the pocemial sign ificance of ou tbreaks chat undermine chis public confidence.

Fifth, there are the utility benefits gained by consumers from having access co water of higher aesthetic quali ty. For example, chis may relate co water with improved taste and odour or reduced levels of turbidity (cloud iness) . T hese characteristi cs have a high importance fo r consumers and are fundamemal co the perceived quali ty of drinking water.

Indicative quantitative benefit estimation The main quantifiable benefits of improved drinking water qualiry are those relating co reduction in acute disease. This essentially co mprises reduction in the incidence of waterborn e intestinal infectious disease (JID).

Endemic disease T he potential benefits of reduced TI O races as a result of water qualiry improvement are critically dependent on exisring water qual ity. Evidence of the quality of Melbourne water is available from a 200 I srndy of rhe incidence of llD in Melbourne2. T his study involved 600 people, hal f of whom drank unfil tered cap water over the period of the srndy, while the remainder dra nk filtered cap water. The resulr of rhis study was chat there was no significant difference detected in the incidence of 11D between the rwo groups.

T his suggests that the quality of drinking wa ter is such chat there are few if any incidences of ll O chat are attribu table co waterborne microorganisms where the water is obta ined from highly protected catchments, such as chose supplying the Melbourne merropolican area.

T he potential health benefits in rerms of en dem ic disease reduction attributable co further significant improvements in the microbiological quality of drinking water in Melbourn e may therefore be limi ted .

I c is arguable char the potential health benefits of improved microbiological water quality are greater in non-metropolitan areas. If the microbiologi cal quality of a water supply remains below the necessary standard, there may be a sign ificant incidence of fI O attribu table co microbiological water quality. T herefore there may, as a result, be substantial healch-relaced benefits from improving water quality.

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Epidemic disease Epidemic disease is characterised by infrequent, shore-term but widespread gascro-intescinal disease events, affecting up co 80% of people drinking che water. In general, risk reduces as the degree of treatment increases. Historically, the most effective method of minimising waterborne !ID has been co provide and maintain several barriers berween pathogen sou rces and the final produce, particularly effective disinfecrion.

The largest reported waterborne outbreak of epidemic cryptosporidiosis was in Milwaukee USA in 1993, where an estimated 430,000 persons (around 25% of the exposed population) became ill, with some 4,400 hospitalised. T he local water creacmem plant complied wirh the creacmem regulations and microbiological water qual ity standards applying at the rime of the outbreak, but may have been operating incorrectly and unable co cope with a shore-term deterioration of source water quali ty chat cook place at the time.

An outbreak of crypcosporidiosis occurred in Oxfordshire and Swi ndon UK in 1989, origi nati ng in drinking water drawn fro m the Thames River and groundwater aquifers. There was no evidence of treatment plam failure in chis case. T here were 5 l 6 confirmed cases of the disease, with a median duration of illness of three weeks. Many ocher outbreaks of waterborne disease are associated with poor operation of treatment plants, higher than usual turbidi ty, poor or no disi nfection and, most significantly, poor source water quality.

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water quality Most historical events in Victoria (such as chose affecting the towns of Robinvale in 1973, Healesville in 1982, Sunbury in 1987 and Kyabram in 1997) were believed co be due co shore-term contami nation of the water supply wh ich was not detected by rourine monitoring of drinking water supplies. In the Sunbury 1987 incident, an estimated 35% of the population (mainly infants and children) suffered gascro-incescinal disease traced co contami nated water supply.

T he causative organism was never identified but was believed to be a virus. To min imise rhe likelihood of such epidemic events, reliable creacmenc and operation and a means to aud it compliance with reliability targets are needed.

Ir can be expected rhar the proposed regulatory framework for Victoria will red uce the probability of outbreaks of epidemic disease and lead to imp roved management of any such outbreaks, so as ro reduce their duration and severity. Because such outbreaks are relatively uncommon, and their severity can vary considerably, iris not possible to provide fi rm estimates of the expected benefits of improvements in this regard. However, a number of indicators of the magnicudes involved can be considered .

While data are incomplete, it is estimated char a significant waterborne disease outbreak may occu r with a frequency in che vicinity of once every ten years in Victoria. A general model for considering the monetaty costs of acute waterborne disease was developed in a study conducted for the Department of H uman Services (Victoria) by Monash University an d the National Centre for Epidemiology and Population Healch 3.

The model attempted co quantify the influences on the economic costs and benefits of interventions co improve rhe microbiological quality of drinking water. The model assumed char water quality

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im provements lower the background race of endemic disease and reduce the probability of epidemic disease.

The model secs out the fo llowing major sources of coses due co an outbreak of IID: • Direct costs of illness. These include the costs of medical treatment and the associated coses of drugs prescribed co treat the illness; • Indirect costs of illness. T hese are the production losses associated with absences fro m work and, more speculatively, with reduced productivity on days when the sufferer attends the workplace; • Costs of avoidance behaviour. These are the coses people incur via their attempts co avo id catchin g the disease in circumstances of an outbreak; and • Management costs. These are coses borne by governments in investigating and managing disease outbreaks and chose borne by water suppliers and consumers in complying with the orders of government regulators.

Coses relating co the number of mortalities due co IID and to pai n and suffe ring associated with IID occurrence can be added co the above categories. These coses are, necessari ly, more diffic ult co quantify.

Probabili ties and coses were estimated for hospitalisation, medical treatment, drugs and lose productivity and fa mily income. T he model then compared the economic costs and benefits after interventions with rhe economic costs and benefits before the interventions. The model did not consider the ocher considerable economic and public benefi ts derived from water that was aesthetically or chemically improved. Capital , finance and operating coses of water treatment plants were converted co equivalent annual costs.

T he relative importance of the quanti fiable coses noted above was fou nd co vary with assumptions as to disease incidence. However, in the Monash/ANU study's base case, the distribution of these coses in relation co epidemic disease was as follows: • Direct costs: 3.2 per cent • Indirect costs: 19.5 per cent • Costs of averting behaviours: 65.8 per cent Management costs: 11.5 per cent The Monash/ANU study is based on costings for a 'typical' town of 11 ,000 people. For such a town, the cost of an epidemic outbreak of IID if it occurred was estimated at $1.8 million (based on an epidem ic attack race of 50%).

Potential benefits deriving from the reduction in epidemic frequency or severity could notionally be derived from chis figure. For example, a 50 per cent reduction in epidemic severity due co earlier detection and better incident management would have a notional benefit of $0.9 million.

Taking rhe coses estimated by the Monash/ANU study, and applying the assumption chat the average costs of an outbreak are directly proportional to the population of the town, the two most recent disease outbreaks in Victoria may have entailed coses of rhe order of $4.2 million. As these calculations are at 1995 prices, the equivalent in 2004 prices would be approximately $5.3 million.

If it is assumed char these known outbreaks of waterborne disease represent the only occurrences in Victoria over chis cimeframe, the figu re of $5.3 mill ion may represent the upper bound of potential benefits due to reduced outbreak severity and incidence. T he actual benefit from chis source constitutes some proportion of the $5.3 million, accordi ng to rhe expected effectiveness of the proposed regulatory framework in reducing outbreak incidence.

For example, if it were assumed char outbreak related coses would be reduced by 50 per cent, the benefit would be $2.6 million over chis fifteen year cimeframe, or around $175,000 per annu m. On the ocher hand, to the extent chat ocher disease outbreaks have, to dace, gone

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water quality unreported, this figure would underestimate rhe true benefits of improved management.

The above indicative data is necessari ly subject co a further uncertainty, in addition ro those already discussed. Given rhe infrequent nature of outbreaks of epidemic waterborne disease, rhe observation of rwo outbreaks over fifteen years does nor necessarily represent a long-term average incidence of outbreaks. Thar long-term average is borh inheren tly unknowable and subject co significant variance.

An additional benefit of improved water supply system management is rhar of reducing the risks of a large scale epidemic outbreak, wirh potential costs significantly greater rhan those esrimared above. Depending on assumptions made about che degree of risk aversion of rhe population in relation co these issues, this represents a potentially significant additional source of benefits.

As noted above, rhe relative infrequency of major outbreaks of disease prevents precise estimation of their probability and, therefore, of the expected value of actions that reduce that probability. However, T able l provides data on a range of known outbreaks of giardiasis and cryprosporidiosis in che United States in recent years.

Table I serves ro illustrate that such disease outbreaks constitute a real risk, even in developed countries. The apparent frequency of these disease outbreaks serves co indicate q ual itarively the potential benefits of improved water quality management.

Potential costs of large-scale outbreaks and contamination incidents The following discussions of che incident in 1998 in which rhe Sydney water supply system was co ntaminated with Cryptosporidium and Giardia, and rhe disease outbreak in Walkerton, Ontario (Canada) in 2000 indicates che potential costs of such large-scale outbreaks. As noted at rhe outset, the calculations ser out below should be seen only as providing an indication of rhe order of magnitude of rhe costs rhac can be associated wirh major waterborne disease outbreaks and hence of che benefits.

Sydney NSW · 1998 Cryptosporidium and Giardia contamination incident During July and August 1998, borh

Cryptosporidium and Giardia were dececred in rhe Sydney water supply system.

Contaminated samples were identified in relation ro a large number of resti ng sires across rhe Sydney water supply system.

Management of che incident involved the issuing of three boil water alerts during this period, with the alerts being in place for a coral of 35 days. T he geographical extent of

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Table 1. Selected outbreaks of cryptosporidiosis and giardiasis. 4 Outbreak

Year

Details

Carrollton, Georgia, USA

1987

13,000 cases of cryptosporidiosis, caused by suboptimal filtration of drinking water.

Jackson county, Oregon, USA

1992

15,000 cases of cryptosporidiosis, due to water trea tment failures.

Milwaukee, W isconsin, USA

1993

403,000 cases of cryptosporidiosis among a population of 1,600,000, due too failure of effective filtrotion.

l as Vegas, Nevada, USA

1994

At least 20 deaths of HIV infected persons as a result of a cryptosporidiosis outbreak.

Rome, New York, USA

1975

5,300 cases of giardiasis.

Pittsfield, Massachusetts, USA

1985·6

3,800 cases of giardiasis among a population of 50,000 in a chlorinated but unfiltered wafer supply.

USA (total)

1965 1984

90 outbreaks of giardiasis reported in the USA in this period, totalling 23,776 cases. Approximately¾ of these were linked to contaminated water supplies.

these alerts varied during rhis rime according to changes in rhe resting results. Few adverse effects on acute health were detected during chis rime. A Royal Commission was established during the course of rhe incident ro investigate its causes and che management ofir.

The Productivity Commission recently published estimates of rhe costs ro Sydney Water Corporation rhac are accribucable ro chis incidenc5. Overall, the incident was reported ro have resulted in an abnormal operating expense of $55.4 million and fo regone revenue of $ 19.2 million . T he abnormal operating expense was composed of rhe fo llowing elements: • $15 payment ro each affected customer (rota!, $ 19.2 milli on); • Paid and esti mated outstanding insurance claims (ro ral , $14.0 million); · • Additional monitoring and resting cosrs (total, $ I 2.5 million); • Coses associated with the McClellan Inquiry (roral, $2.0 million); and • Orher costs (total $7.7 million).

The foregone revenue of $ 19.2 million was rhe result of a decision ro defer a planned price increase for twelve months.

The above represents rhe costs of rhe incident only from the viewpoint of Sydney Water Corporation. For rhe purposes of econom ic im pact assessments of public policy proposals, ir is necessary ro consider costs from the whole of society viewpoint.

From this latter perspective, rhe bulk of rhe foregone revenue of $19.2 million represents a transfer from Sydney Water Corporation ro its customers, rather than a real resource cost.

A similar perspective applies in relation ro rhe $15 rebate ro affected customers. Thus, the real resource costs among che rota! costs borne by Sydney Water represent $36.2 million, rather than rhe $74.6 million its accounts indicate as rhe roral costs ro rhe organisation.

The roral resource costs ro society comprise nor only those borne by Sydney Water, bur rhose borne by irs customers, rhe NSW Government and other parties. The Monash/ ANU model discussed above indicates rhar key additional costs robe taken inro accoun t are rhe following: • Direct health costs. These costs may have been near zero, as no measu rable increase in TIO was detected in Sydney during rhe course of the incidents.

• Indirect costs. These roo will be near zero if there was no elevation in the incidence of IID. • Costs of averting behaviours. T hese costs are likely ro have been extremely large, as boil water alerts were in place across large areas of Sydney for extended periods. T he Monash/ANU study argues that estimates of rhe ri me and resource costs of avoidance measures such as pu rchasing bottled water or ocher rap-water subscirures or boiling cap water muse be considered as part of rhe cost of rhe outbreak. In addition, losses of utility due ro activities abandoned as a result of the water alerts should also be included, as should the costs associated wirh an increased incidence of scald injuries (wh ile engaged in boiling water) . Thus, rhe coses of averri ng behaviours are incurred partly as cash expendi tures and partly through loss of utility (i.e. rime, convenience, ere.).

• Management costs. The $2 mill ion cost ro Sydney Warer Corporation of irs participation in rhe McClellan Inquiry represents one part of these costs. However, a much larger part of these costs were borne by the NSW Government. These include rhe costs of establishing and running rhe Inquiry and the coses of other NSW Government agencies' representation at rhe Inquiry.

Management costs would also be borne by non-governmental bodies.

Esti mation of rhe likely size of these additional costs is very problematic. Some

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water quality evidence able to indicate the general order of magnitude is contained within the Monash/ANU report, which quotes an earlier study in relation to rhe costs of averting behaviours associated with a giardiasis outbreak6. T his contains a best estimate of these costs of $3.59 per exposed person per day. T his is equivalent to $4.89 in 2004 prices.

T he contamination incident in Sydney in 1998 lasted fo r a total of35 days, although the extent of the incident (i.e. the area covered by the boil water alerts) varied during this rime. For much of the ti me, however, the alert applied to all areas served by rhe Prospect water filtration plant, wh ich supplies around 85 per cent of Sydney's drinki ng warer7.

If it is speculated that half of Sydney's population of 3,600,000 was affected by the boil water alerts during their 35 days total duration, this would imply total aversion behaviour costs equal to: $4.89 per day x 35 days x 1.8 million people = $308.1 million Thus, adding this estimated cost of total aversion behaviour to the cash costs to Sydney Water noted above, the total econom ic cost of the Sydney NSW water contamination incident may have approached $350 million.

Box 2. The statistica l va lue of a life .

T he co ncept of a statistical value of a life is needed to facilitate public policy choices as to different possible expendirures char will have the effect of reducing the risk of death - i.e. of saving lives. In effect, the stariscical value of a life is a measure of what society is willing to pay to reduce the number of deaths caused in a particular context, by maki ng some imp rovement in safety. T he values arrived at via research vary considerably depending on factors includi ng rhe size of the risks involved and the nature of those risks (e.g. whether individuals have any degree of control over the risk) . T he figure of C$8 mill ion used by Livernois is a typical figure in this context.

The potential for chis to occur in a developed country context is indicated, inter alia, by an incident principally caused by the presence of a pathogenic (disease causing) form of E. coli bacteria in the drinking water supply of W alkerton, Ontario (Canada) in May and J une 20008.

Walkerton, a town of aro und 5,000 people, is located in a rural area of Ontario, Canada. T he drinking water supply draws from bores which abstracted ground water from an aqu ifer beneath adjacent fa rm ing land. After heavy rainfall in May 2000, water from chis aqu ifer became contaminated with efAuent from farmi ng activities. The water supply system at the time was nor fil tered, nor was it effectively disinfected. As a result of this contamination, a total of seven people died, while approxi mately 2,300 were made ill.

The waterborne disease outbreak in Walkerton led to rhe esrabl ishmenr of an Inquiry in June 2000, which reported in 2002. Commissioned Paper No. 14 9, prepared fo r the Inqu iry, estimated rhe tangible economic coses of the outbreak and arrived at a total figure of C$64.5 mill ion (A$76.0 million). This figure was arrived at

via a survey of 400 households and most businesses in Walkerton to ascertain the impacts on them of the outbreak. Table 2 summarises rhe major elements of the above cost estimate (as shown in Canadian dollars) .

The follow ing list of major responses to the disease ou tbreak at Walkerton provides some backgrou nd for the above cost estimates: • A boi l water alert was in place fo r a total of seven months (cf. 35 days in Sydney in 1998); • A water distribution centre was established at the time of the outbreak and was stil l operati ng over twelve months later. T he distribution centre provided bottled water to residents, which is provi ded by the provincial govern ment; • A class action lawsuit was commenced and subsequently settled (cost currently Walkerton, Ontario (Canada) - 2000 unknown); outbreak of waterborne disease • Some C$ I 1 million of upgrades to the The above estimate of the coral costs of rhe town water supply system were implemented Sydney incident relates to an event in which as a direct resul t of the outbreak, includi ng rhere were few identifiable adverse health an ultrafilrration system 10; im pacts. It is apparent char substantially • The Inquiry contin ued for approximately larger costs are likely to be incurred where two years before delivering its final reports. there are incidences of illness and death.

The cost estimates contained in the study do nor include the intangible costs of lives lost or ill nesses caused, arguing that such valuation is impossible. However, a Wind powered, water remediation for: companion paper 11 does incl ude surface water, waste water and liquid sewage. such estimates, based on a statistical value of a life saved of C$8 million and of a serious illness avoided of Eliminates &/or Reduces C$J 5,000 (see Box 2).

• odours • mosquitoes • silt build up Usi ng these fig ures, the statistical • algal blooms • stratification • sludge build up cost of the lives lost and ill nesses • fish kills • chemical use attribu ted to rhe outbreak totals • aquatic weeds C$90.8 million. Adding chis figure to the value of the tangible costs, Benefits cited above, brings rhe total • Reduced energy costs estimated cost of the outbreak at • Improved image/functionality • Minimal maintenance Walkerton to C$155.3 million . This • Chemical free is equivalent co A$182.9 mi llion.

• Portable This cost estimate relates to a • Solar & electric available town with a population of only 5,000 people. Comparing this Email: enquiries @windhill.com.au Phone: 08 9454 5334 estimate with the cost estimate of Pty Lti Fax: 08 9454 5339 Web: www.windhill.com.au around A$300 million for the recent

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100 MARCH 2005

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The future is Table 2. Summary of cost estimates - Wal kerton outbreak.

Category Water authority costs of remediation/ repair Walkerton Inquiry costs Costs to households Other local government costs Walkerton health study Cost of drinking water Cost of local public health unit Long-term health costs Walkerton business costs Lost productivity Household property values Private legal expenses

Estimated Cost (CS)

$9,222,215 $9,000,000 $6,916,949 $6,548,523 $5,000,000 $4, 167, 139 $2,775,000 $2,497,932 $1 ,460,1 39 $1 ,234,296 $1 , 106, 136 $1 ,000,000

Source:

Livernois, D. Commissioned Poper No. 14 /2002), Walkerton Inquiry.

Sydney contamination incident clearly indicates the potential fo r very much higher costs to be incurred in the event that substantial health impacts result from an outbreak. T hus, the potential benefits flowing from even a relati vely small reduction in the probability of such incidents, due to the better water supply system management expected to flow from th e regulatory fram ework, are extremely substa ntial.

T here remains substantial uncertainty as to the probable frequency of such outbreaks, as well as the likely effectiveness of changes to the legislative framework in reducing this probable frequency. O ne feas ible approach to the benefi t/cost issue is to calculate a range of probability reduction scenari os and present these in terms of both a "break even" analysis - via comparison with the identified costs of the legislation - and in terms of plausible net benefits. Such an approach has the merit of transparency, while avo iding the need to make simple and probably unjustifiable assum ptions about regulatory effectiveness.

Consumer confidence benefits The fo llowing section identifies direct and indirect costs likely to be related to an outbreak of disease due to co ntamination of the water supply. While data limitations, particularly in relation to frequency of occurrence, prevent the calculation of expected values for such coses, it is theoretically possible to calculate these costs. By extension, benefits due to a reduced probabi lity of disease outbreaks can be determined.

However, such expected value calculations necessarily imply a riskneutral population. That is, th ey assume that a population is indifferent between a higher frequency of disease outbreaks and a lower one, provided that full compensation is received for the costs they incur in con nection with disease outbreaks.

In practice, populations are likely to exhibit significant degrees of risk aversion in respect of drinking water supplies. If risk aversion exists, there is an additional benefit in improving water safety, beyond that implied by the reduction of direct and indirect costs associated wirh disease outbreaks.

The substantial and long lasting adverse public reaction to the I 998 Sydney NSW water con tamination incident can be taken as indicative of this risk aversion . Surveys undertaken by Sydney Water have indicated that levels of customer satisfaction with drinking water quality dropped substantially after the 1998 incident and are only now returning to pre- incident levels 12 . T he public reaction to the Walkerton incidem in Canada also supports this view. T he adverse

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MARCH 2005 101

water quality impacr of a waterborne disease ourbreak on public perceprions of water safety is rherefore likely to be long-standing.

While the degree of risk aversion is theoretically quantifiable, it is not considered possible to provide quancicarive estimates of rhe value of these benefits in the current concexr. However, it is clear chat the size of chis benefit is significant and that it must be considered in determining the merits of any proposed regulato ry framework.

Increased co nsumer confidence is expected to result from knowledge of the requirements for systemic risk management activities to be undertaken, fo r regular auditing of those activities, and from in creased monitoring of actual performance.

Conclusion T here are consid erable uncertai nties in relation to the quantitative aspects of this process of determining benefits. The authors acknowledge rhat such a methodology is at thi s time only likely to yield an indicative scale of benefits. Nevertheless, ir forms a useful model chat ca n be used when constructing benefit cost cases. In rhe case of the newly developed regulatory framework for drinking water qual ity in Victoria , ir was possible to show rhat the dollar values for benefits derermined from the merhodo logy shown above were significantly above conservative and specific cost escimares amiburable to the proposed legisla tion.

Acco rdingly, the argumenr was able to be developed chat net benefits would accrue for Victoria.

The absence of such arguments can significantly weaken the case for progressive developments in risk management or regulatory

frameworks for drinking water. This is particularly the case where rigorous procedural requirements, such as those current in Victo ria and chose implemented in respect of nationally uniform regulatory arrangement via the Council of Australian Governments (CoAG), are in place and must be satisfied.

Moreover, as the above analysis also demonstrates, an appropriate benefit cost approach for use by policy-makers should involve a sophisticated integration of quantitative and qualitative dimensions of the analysis. Such an approach guards against the possibility th at important considerations will, in effect, be neglected in the decisionmaking due to the impossibility of quantifying them or converting them in to dollar terms.

As a closing remark, it should be noted that th e Second Report of the Walkerton Inquiry, released in May 2002, made 93 reco mm endations about key areas of water supply management for Ontario Canada 13. Th ese recommendations, includi ng catchment to tap risk management, appropriate standard setting, legislation and regulatory oversighr, are very similar in effect to rhose in th e drinking water quality regulatory fram ework for Victoria.

The Authors Rex Deighton-Smith is the Director of Jaguar Consulting Pcy Led. Brian Labza is a Senior Policy Advisor, Water, at the Department of Hu man Services in Victoria. Both authors have worked extensively on the recently developed drinking water quality regulatory framework for Victoria. Further information from Brian.Labza@dhs.vic.gov.au or (03) 9637 4088 .

References I.

"Drinking Water Quality Reg11/at01y Framework far Victoria - Regulato,y Impact Statement for the Saft Drinking Water Reg11!atio11s 2004" (Deparnn ent of H uman Services (Vicroria), September 2004), available from: www.healrh.vic.gov.au/ e nvironmenr/ warer/drinking

2. 'A rando mised blinded controlled trial investigating the gastrointestinal health effects ofdrinking water q11ality. ' Hellard M E, Sinclair Ml , Forbes AB and Fairley C K. (200 I ). Environmenral H ealrl, Perspectives I 09(8): p773-8.

3. 'Drinking Water Q11ality: Risk Assessment - Cost Benefit Analysis Report'.

D epartment of Epidemiology and Preventive Medicine, Monash U niversiry, and N ational Centre fo r Epidem iology and Population H ealth, Ausrralian National University (ANU). 1997.

4. From Sydney Water I nqui1y - 5th Reporr. Derails a re at \1/\V\V. premiers. nsw.gov.au

5. 'Financial Performance of Government Trading Enterprises, 1995-6 - 19992000'. Productiviry C o mmission, Canberra, 200 1, pl 20.

6. 'Epidemiology ofSalmonella solia in Australia '. H arringron CS, Lanser JA, Manning PA, Murray CS. Applied Environme ntal Microbiology, 199 1, 57: 223-7 .

7. See 'Sydney's 1998 Water Quality Crisis'Clancy, JL, American Water Works Association Jo urnal, March 2000.

8. T he disease and dearhs were also attributed ro Campylobacterjejuni bacteria from the water supply system.

9. 'The Economic Costs ofthe Walkerton Water Crisis' Joh n Livernois. The Walkerton Inquiry, C ommissioned Paper N o. 14, T oronto, 2002.

10. 'Walkerton - One Year Later' by Patrick Raftis. Walkerton H erald-Times,

15 May, 200 1.

I 1. 'Value of Life Estimates in an Economic Cost Assessment'. John Livernois.

W alkerton Inqui1y, Commissioned Paper No. 15, Toronro, 2002.

12. 'Giving Cwtomers A Voice: Sydney \J.1/ater's Experience; Roseth N , AWA W ater Jo urnal, June 2002, p25.

13. 'Part Two Report of the Walkerton lnqui1y: A Strategy far Saft Drinking Water', Ontario Ministry of the Atrorney General, Canada, 2002 . Details at www.attorneygeneral.jus. gov.on.ca/english/about/pubs/walkercon/

102 MARCH 2005

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CUSTOMERS HELP ASSESS OPTIONS FOR TASTE CONTROL P Mosse, J Busch Abstract

----~~--

A small group of cusromers was used ro assess the success of process modifications at a Water Treatment Plant ro manage a caste problem in a water supply. A medicinal or phenolic rasre was occasionally present in cold cap water bur became more noticeable in boiled water.

Five treatment mod ifications were trialled over a 3 month period. These included chlorine dosed ro provide 0. 1mg/L, 0.35 mg/L (normal operati ng conditions) and 0.8 mg/L free chlorine residual , chloraminarion and Powdered Activated Carbon (PAC) dosing. The effect of extracting che raw water from one of 3 differen c bores was also assessed.

The cusromer group consisted of Sale residents located at 29 separate sires. The sires provided a representative sample across rhe Sale disrriburion system. fndividuals maintained daily logs recording their experiences with rhe water over the 3 month rrial period . The log sheers required entry of both a numerical assessment of the water quality and description of the rasre and odour of rhe water.

The cusromers were able ro distinguish between most process mod ifications and the different raw warer sources. The low dose chlorine regime and PAC dosing bo th produced water chat was generally more pleasing ro rhe panel.

Introduction The Australian Drinking Water Guideli nes (ADWG) (Draft 2002) state chat "che caste and odour of drinking water should be acceptable ro most people". The definition of chis is challenging. Mose

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104 MARCH 2005

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Chlorine 0.35

Figure l. Summary of responses to the different treatments. The blue bars re present the total numerical score while the brown bars represent the total of the averaged water quality scores. A higher score represents water with a poorer taste a nd odour profile.

beyond the budgetary capabilities of many Aurhoricies. This srudy describes an attempt ro use a small group of cusrome rs and ro run a treatment trial ro assess whether different creacments could result in a more aesthetically acceptable water. This approach is in keeping with rhe ADWG chat srace chat "A small panel (5 ro 8 people) can be trained ro identify specific odours and castes associated with comm on contaminants. These panels are useful for assessing complain cs by consumers, identifyi ng che source of a contaminant and for che in itial assessment of a new or improved creacmenc process" . The project was designed, planned and implemented by Gippsland Water staff without th e need ro

A small panel of customers was able to distinguish between most process modifications and different raw water sources.

Water Authorities make some assessment of the palatability of che water they supply usually via cusromer questionnaires. These may identify some problems however che solution ro che problems are difficult and often not addressed furthe r.

While iris desirable ro design extensive sraciscically balanced studies these are often

-----

employ outside staff. le was therefore conducted as pare of the normal operations within the Authority. While the statistical basis of the study could be questioned the results clearly show that it is possible for Authori ties ro investigate and remedy caste and odour problems without the need fo r large budgetary expendicure.

Background T he C iry of Sale in Gippsland, Vicroria has a hisrory of inrermi rrenc dirry water, and rasre and odour problems. Water ro rhe City is supplied from fo ur deep bores drawing water from depths between 70111 and 180111. The bores are situated ar distances between 200111 and 2 km of rhe Water Treatment Plane (WTP). T he water undergoes conventional treatment with clarification, fil tration and disinfection.

The cause of the dirty water has been investigated over several years and fo und ro be due primarily ro low levels of iron and manganese in che raw water. The introduction of lime and potassium permanganate dosing ro the WTP in July 2000 led ro a sustained and significant decrease in dirty water complaints. (Mosse and Bugden 2002) The permanganate dosing also resulted in an overall improvement in the caste of the water, however overall sarisfacrion with rhe water in Sale continues ro be rhe lowest fo r all rowns supplied by Gippsland Water, as determined by annual cusromer surveys.

Wh ile rhe permanganate dosing removed rhe overall slighrly "swampy, sulphurous" rasre and odour from rhe water, a new taste became apparent ro rhe residents of Sale.

refereed paper

water quality T his new taste occurred irregularly and was more noticeab le in certain parts of Sale.

The unpleasan t and very characteristic rasre was most noticeable in boiled water typically used fo r preparing tea and coffee; however ir was sometimes noti ceable in the cold water.

The taste was nor detected in the raw water alone or after treatment. Formation of the unp leasant tasting chemica l only occurred after rhe water was chlorinated.

Based on labora tory tests, the higher rhe chlo ri ne dose the more noticeable rhe unpleasant taste. Preliminary monitoring suggested that the compound responsible may be a bromophenol or possibly a chlorinated bromophenol. The co mpounds 2,4,6-tribromophenol and 2-bromophenol were detected above rhe detection limit on several occasions. Brominated rrihalomethanes are also present in the Sale water at higher concenrrations than other supplies in the region . Th ese findi ngs are co nsis tent with resu lts presented by Heitz et al (2002, 2003) who have been investigating similar taste and odo ur problems in drinking water sourced from ground water in Western Australia. ln contrast to the Western Australian experience, the form ation of the taste compounds in Sale does not appear to be rel a red to the use of the water in household appliances.

A number of alternative treatment regim es were planned to see if they could improve the taste and odo ur of the water in Sale. T he treatments were selected based on laboratory trials or info rmation from the literatu re.

Since the residents of Sale were the ones most affected by the taste and odou r of the water, Gippsland Water Felt it was appropriate to engage the residents themselves to assess rhe success or otherwise of the proposed treatments. T o this end, a customer panel was established.

Methods

participating in the gro up. Once a list was established, the 45 individuals were contacted by pho ne and subjected to a screening interview. The primary objecti ve of rhe screeni ng interview was to identi ~, individuals who, I. Drank water from the rap, either as cold water or in hot beverages 2. Did not have any in line fil tering systems in place 3. Had expressed commitment to the proposed trial After screening, the final reference group represented 29 sires spread widely and relatively evenly across the Sale distribution system. Si nce this interactive approach to a customer prob lem had nor previously been used by Gippsland Water, it was thought desirable to limit rhe size of the panel to allow regular in teraction with the members of the panel. Th is app roach was taken to try to maximise participation to rh e end of the trial and ro keep the trial with in the operational capability of Gippsland Water.

The panellists were briefed on how to record their observations on a standard record sheer and were provided with di fferent samples of water to enable them to taste the range of water types they migh t expect duri ng the trial. T he panellists were asked to co mplete daily record sheers based on rheir experiences of the water during rhe day.

D uri ng the trial, contact was maintained with the participants via a newsletter and

•

informal direct contact by pho n e and personal visits by members of the Gippsland Water, Water Quali ty Group.

The trial lasted for approximately 3.5 months and terminated at the end of December 2003.Of the 29 sites, 11 returned complete data sets and 9 returned data sets with only one or two weeks dara missing as a result of holiday or work related absences during the study period.

Five si tes formally withdrew during the first half of rhe trial. The reasons given for withd rawal were main ly due to fami ly reasons. The remai ning sires returned incomplete data that was able to be used for the analysis of some of the rreacm enrs only.

At the completion of the tria l, a follow up questionnaire was sent our to assess participants' satisfaction wirh the trial. A final reporring session was held in March 2004 to present the results of the trial and to formal ly thank the panel.

Treatment Trials

The normal operating condit ions ar the WTP were in terspersed with four alternative treatments. T he normal conditions were those rhar had b een in place ar rhe plan r for many months and in volved dosing chlorine to give a free chlorine residual leaving the plant of 0.35 mg/L. T he treatment sequence is listed below.

• High chlorine dose ( 0.80 mg/L free ch lorine)

Large Capacity Grit Capture Systems

Customer Reference Group

The Gippsland Water customer database was searched fo r Sale residents who had previously expressed concern with the taste and odour of their water. These customers were considered suitable for rhe trial si nce they were well ' trained ' in rhe taste and were sensitive to it. In addition Gippsland Water staff living in Sale were asked to nominate themselves or Fami ly or friends who might be interested in

refereed paper

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water quality • Low chlorine dose (0. 10 mg/L free chlorine) • Normal chlorine dose (0.35 mg/L free chlorine) • Chloramination (0.8 - 1.2 mg/L total chlorine) • PAC dosing (20 mg/L, approximately 20 minutes contact time) • Normal chlori ne dose (0.35 mg/L free chlorine) The full trial commenced on 15th September 2003. The process changes at the plant were made by the operator. T he treatment type and duration were only known to a few people within the operations section at Gippsland Water.

This was done to minimise any bias in the data that may have arisen from any preconceptions relating to the treatment type.

Data Collection and Analysis Participants in the trial were asked to rate the strength of any taste or odour of the water according to the following numerical scale.

• O Ni l • l Faint • 2 Mild • 3 Strong • 4 Very strong T hey were also asked to describe the taste or odour according to the fo llowing descriptions, • Chlorine • Plastic • Burnt Rubber • Medicinal • Metallic • Earthy or to describe the taste in their own words if none of the above descriptors marched the taste.

T he data was transcribed to an Excel spreadsheet for analysis. Periods for analysis were carefully selected so as to ensure that all Sale residents had received the particular water type. Hydraulic modelling of the distribution system showed that it took up to 48 hours for water to travel from the WTP to all parts of the distribution system.

Consequently the data analysed for each treatmen t modi fication covered the period from 48 hours after the treatment cha nge to 48 hours after the completion of the treatment modification.

The numerical data for each period was su mmed to give a total water quality score for the period. In this semi-quantitative system, a high score represented water with a significant taste and odour and a low score, a zero to faint taste and odour. To

106 MARCH 200s

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Site 2

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DChlorine 0.35 • Chlorine 0.80 O Chlorine 0.10 DChlorine 0.35 • Chloramine D PAC

Figure 2. Results obta ined at four ind ividual sites showing the range of responses from the participants. A higher score represents water w ith a poorer taste and odour profile For Site 4 the PAC score was zero. allow better comparison between data sets the numerical ratings were averaged according to the number of responses provided by the panel member. T he average was multiplied by I 00 to give an intege r value for the site. In sim ple terms the higher the score the lower the perceived quality of the water.

Results Figure I is a su mmary of all the treatments at all the sires. T he figure shows both the total scores and the averaged sco re. Both show similar trends. PAC treatment resulted in the most favou rable respo nse, while the chloramine treatment was identi fied as the wo rst treatment.

Indeed the chlorami11arion trial was shortened by several days due to the number of co mplaints received from the res idents of Sale. T he results also show that, on average, the participants were able to distinguish between the different chlorine doses in particular the low chlorine dose.

The total and averaged data however conceals addi tion al information. Figure 2 shows indi vidual data from four sites.

T hese have been selected to demonstrate the range of responses seen. Quite different patterns are apparent.

Analysis of the individual resu lts show that the majority of the participants found the chloraminared water unpalatab le and rhe PAC dosed water the most palatable.

The individual com ments on the record sheers fully supported these general observations. T here were however notable inconsistencies (see Figure 2).

The trial was planned to run using only one of the th ree bores fo r the duration of the trials. One bore, Bore 6, had been identified from historical turbid ity and colour data as having lower quality water than the other bores. This bore was selected for the trials as the most likely to generate the unpleasant taste and would therefo re provide a baseline to better judge the effect of the process modificatio ns. During the period of operation of the plant between the end of the chlorination and co mmencement of the chloramination tria l all 3 bores were used. lt quickly became evident that the switch to Bore 2 resulted in water that was less acceptable to the panel. Figure 3 shows the averaged data for the respo nse during this period. Clearly Bore 6 was the preferred raw water source with water from both Bore 2 and Bore I resu lting in less acceptable water.

T he change ro the different bores has made the interpretation of the data more difficult. Bore 2, which was identified as resulti ng in poor quali ty water after completion of th e trial , was running during the chloramin ation and PAC trials. It is likely that because of this the chloramination scores were higher than they might have been had Bore 6 been running and the PAC results may well have been lower had Bore 6 been running.

Discussion T he study described here had two broad objectives. Firstly to assess whether a relatively small customer panel could be used to evaluate changes in water quality resulti ng from changes in treatment process. Secondly, to use the information fro m the panel to assess which treatment

refereed paper

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water quality regime trialled in chis study produced better quality water based on the customers perception of caste and odour.

T he results show that it is possible to successfully engage a commun ity to assess complex issues such as taste and odour with minimal specialist training.

No attempt was made to standardise the numerical ratings of the participants.

T herefore the individual numbers recorded by the participants reAect different sensitivities to the caste and odours of the water and also different expectatio ns fo r the water. H owever, the composite data from the panel was able to provide co nsistent information that allowed clear trends to be discerned.

While individual di fferences in perception of the water quali ty may explain some of the spatial differences evident, there are sufficiently stro ng trends co suggest that there are real differences in the quality of water in different parts of Sale. Such spacial differentiation can only result from the distribution system itself. The mechanism of the alteration is not clear and is worthy of further study. Some preliminary stud ies using UV-Vis absorbance of water have shown sign ificant differences in the absorbance spectra from different pares of the Sale distribution system (Mosse 2003).

The study has also shown chat the customer panel were able to detect differences in quality of water resulting from the use of the different bores. This is perhaps surprising since the bores are relatively close together and drawing water from roughly the same depth range and reportedly drawing from the same aquifer.

In terms of the preferred treatment regime for Sale, the customer panel identified the low dose chlorine regime and rhe PAC treatment as the preferred treatments. Nor surprisingly rhe low dose chlorine trial produced water with a more acceptable caste and odour profile. Whether rhe Sale system can be run permanently at chis low dose remains to be seen, however since rhe raw water comes from a relatively deep aquifer with a low risk of contam ination by microbiological species it could well be possible. Many European and Scandinavian ground water systems do just chis.

PAC treatment also produces palatable water. To introduce permanent dosing of this type would be quite expensive, an d would be introduced as a permanent rrearment only if other mechanisms fail to impro_ve the customers overall perception of rhe water. To chis end the Sale system is currently bei ng run using the most favourable bore and a relatively low chlorine dose of approximately 0.2 mg/L.

108 MARCH 2005

water

350 , - - - - - - - - - - - - - - - - - - - - - - - - - - -

300

250 ~

8 Cf)

.?:

200

iii

:,

0 ~ 150

~ 100

50 0

' - - -__j._ _ ___,___ _ _ __ jL __ __j___ _ _ _ __L___

Bore 6

Bore 2

_

_ [_ __J

Bore 1

Fig~re 3. Averag ed water quality scores for the different bores used during the period that the plant was operated at 0.35 mg/L free ch lorine.

The ch loraminarion trial was complicated by the fact char, although it was unknown at the time, the initiation of the trial coincided with rhe use of the most unfavourable raw water source. From a purely scientific perspective, rhe trial should be repeated however considerable effort would be required to do this. Should che situation change in rhe future then it may be appropriate to repeat chis process modification.

It is also poss ible chat if the chloraminacion trial had been extended the problems may have reduced. Experiences in ocher pares of rhe world have found chloramination to help reduce caste problems of chis type.

The resu lts showi ng the different water types in rhe different bores are interesting.

While the reason for chis is nor clear, it would seem chat there is a very real possibility chat whatever is causing the 'taint' in the unfavourable bores could eventually appear in the favou rable bore.

T he challenge will be to develop monitoring to detect chis. If and when chis happens, PAC dosing may well become the only option to produce acceptable quality water.

Acknowledgements A project such as this requ ires a ream effo rt. T he authors wish to acknowledge the significant involvement of Joanne Dye, Theresa Garvey, Russell Mack, Trevor Marcin and Ian Soutar. Special thanks are also extended to the people of Sale who wi lli ngly participated in the trial.

The Authors Dr Peter Mosse (peter. mosse@ gippswarer.com.au) works part time with Gippsland Water on special projects and also works within the wider water ind ustry providing specialise tech nical assistance in water and wastewater treatment. Jillian Busch (j illian.busch@gippswacer.co m.au) is a Water Quality Technologist with Gippsland Water.

References

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For information on advertising rates, please contact Brian Rault at Hallmarl< Editions, Tel f03) 9530 8900 or email brault@halledit.com.au

H eitz A, Blythe J, Allpike B, Joli CA and Kagi R (2002). Plastic tastes in drinking water: Factors affect ing the chemistry of bromophenol format ion . Proceedings Enviro 2002 Heitz A, Blythe J, Allpike B, Trolio R, Smith R. and Joll C (2003). Factors contributing to bromophenol related tastes in drinking water: Field studies. Proceedings Oz Water 2003.

Mosse P. and Bugden K. (2002) Cleaning up a water supply system. Water 29:36-40 Mosse P (2003). Off tastes and distribution systems. Studies using UV Vis Spectroscopy.

WaterWorks June 2003: 44-46 NHMRC. (2002) Ausrralian Drinking Water Guidelines. (Draft 2002)

refereed paper

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m

water quality

DETERMINING ALKALINITY CONSUMPTION BY COAGULANTS P Gebbie, R J Turney Abstract

Table 1. Properties of some com mercial ly available polya luminium coagulants.

There is lirrle published quantitative information describing how coagulants, including prehydrolysed compounds, impact on rhe alkalinity and pH of water and wastewater in treatment processes. This makes the use of models, for example RTW, somewhat limited, especially when newer chemicals are being considered.

An experimental method is ourlined whereby the specific ratio - mg alkalini ty consumed per mg coagulant dosed - may be determined. Such values may then be inserted into the RTW or ocher models to examine rhe effect various coagulant doses will have on water chemistry.

Excellent agreement was obtained between theoretical an d experimentall y determined values. The method is particularly relevant when coagulants containing free acid or alkali are being considered in candidate treatment processes.

Keywords: Alkalinity, Coagulants, Polyaluminium, RTW

Introduction Several models are available to pred ict the alkalini ty an d pH of a water followi ng coagulant addi tion in a proposed water (or wastewater) treatment process, e.g. RTW (Rothberg, Tamburini and Winsor, 1996).

The RTW model, in particular, features a cable allowing rhe selection of various chemicals to be used in a candidate treatment process. Add itional chemicals can also be inserted into rhe cable if the designer knows beforehand the specific alkalinity and acidi ty ratios for these co mpounds, when expressed as mg CaCO3 per mg of coagulant.

The widespread availability of newer coagulants, such as prepolymerised aluminium and iron chemicals, leaves the designer often in a quandary as to what impact these coagulants will have on rhe alkalinity and pH of rhe dosed water.

Hence the likely alkali doses chat may be required in the rrearmenr process to ensure a satisfacto ry coagulation pH , as wel l as ensuring the treated water is stable and non-corrosive to the distribution system, may be problematic.

110 MARCH 2005

water

%w/w PRODUCT

EMPIRICAL FORMULA

ALU M , LIQU ID

Al, (SO,l,.18H20

10X30 18X35 16X40

666.4 233.5 228.0 222.4

AS Al203

ASIS

7.5 10.0 18.0 16.0

49.0 22.9 40.2 34.9

BASICITY

%

MOLAR RATIO

EAC1, mgALK/ mg Al

THEORETICAL c2, mg ALKALINITY/ mg COAGULANT

0.0 30.0 35.0 40.0

0.0 0.9 1.1 1.2

5.55 3.90 3.60 3.35

0.45 0.90 0.86 0.81 0.71 0.48 0.34 0.29 0.18

Ali(OH}u C~ 2

PACI

A½(OHl, 1Cl31

PACI

Al1(0H}2,Cl,o

2 2 2 2

Al 2(0Hl,Cl3

2

3.00

211.4

10.0

20.7

50.0

1.5

2.80

PACI

Ali(OH}.,Clu

4.20

PACI

Al2(0H}, ,Cl 12

2 2

189.2 178.2

23.0 23.0

42.7 40.2

70.0 80.0

2.1 2.4

1.65 1.10

Al 2(0HJ,CI

2

4.98

174.5

23.5

40.1

83.0

2.5

0.95

A½(OH~, c~,

2

5.40

167.1

10.0

16.4

90.0

2.7

0.55

3

4

23.5X83 PAC1

10X90

0.00 1.80

EMPIRICAL WT

PACI

10X50 PACl

23X70 23X80

n

m

PACI

2.10 2.40

4.80

1. EFFECTIVE ACID CONTENT: mg alkalinily consumed (as Caco, ymg metal (Al)

2. E: mg alkalinily consumed (as CaCO, Ymg coagulant 3. PACI AVAILABLE IN AUSTRALIA 4. ACH AVAILABLE IN AUSTRALIA

Some limited information has been published on rhe impact polyaluminium coagulants have on pH and alkalinity (Lind 2002; Chappell and Letterman, 1998).

However, there is a need fo r a method to determine rhe specific ratio of alkalinity co nsumption fo r these new chemicals an d to confirm the ratio for different batches of co nventional coagulants as they are manufactured.

This paper outlines such a method. The value so determined can then be entered into rhe RTW or alternative model to investigate rhe impact the coagulant will then have on water chemistry, with concom itant alkali doses required then able to be determined.

of a dosed water will be depleted by 50.05/(666.41/6) or 0.45 mg CaCO 3 per mg alum added and hence this compou nd has an £ value of 0.45 .

In determining the effect dosing a coagulant will have on raw water alkalini ty and pH , hydrolysis reactions must be considered.

With alum, aluminium ion is hydrolysed on solution to form alum inium hydroxide floe as wel l as hydrogen ions. The hydrogen ions will react with the alkalinity of rhe water and in rhe process, depress the pH of the water as seen from Equation (1) .

Alz(SO 1)3.18H 2O ~ 2Al3+ + 3SO/- + 18H 2O ~ 2Al(OHh + 6H+ + 3SO/ - + 12H 2O - (1)

An experimental method for testing commercial coagulants for acid demand.

Theoretical Considerations Theoretical values of rhe specific alkalinity consumption ratio can be com pured if rhe molecular or empirical fo rmula of a coagulant is known. W hen expressed as mg alkalinity consumed (as CaCO 3) per mg of coagulant dosed (denoted as£ in this paper), it will be eq ual to rhe equivalent weight of calcium carbonate (50.05) divided by the equivalent weight of the chem ical in question.

T his follows from rhe stoichiometry of the reaction between rhe chemical and alkalinity in the water. For example, using alum (as Al2(SO4h .18H 2O), the alkalinity

Similarly for aluminium chlorohydrare (ACH), a prehydrolysed coagulant, the followi ng reaction takes place: Al 2(OH)sCl ~ Al 2(OH) 5+ +CI-+ H 2O ~ 2Al(OHh + H+ + CI-(2) Nore chat from Equation (2), only one mole of hydrogen ions is produced, reflecting rhe hydroxylared nature of chis compound.

Polyaluminium chloride (PACI) also shows similar hydrolysis as represented by Equation (3). In this reaction, three moles of H• are formed.

Al2(O HhCl3 ~ Al2(OH)33• + 3CI-+3H2O ~ 2Al (O Hh + 3H• + 30-(3)

refereed paper

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water quality Chappell and Letterman (1998) defin ed the Effective Acid Content (EAC) of a coagulant as a measure of the amount of protons released following che fo rmation of hydrolysis products when added to a nacural water.

EAC will depe nd on the distribution of metal hydroxy species chat form following hydrolysis and this in turn is related to the basicicy of the coagulan c.

For prehydrolysed or hydroxylaced coagulants, basicicy is defined as the molar ratio of hyd roxyl ions to the metal coagulant ion of co ncern. For example, in the case of aluminium chlorohydrace, Alz(OH)5Cl, che basicicy of chis compound will be: 5/(3X2) = 0.833 or 83.3%. An alternative definition of basicicy char is also often used in che li ceracure is the inverse of the above ratio, i.e. (3X2)/5 = 1.2.

The basicicy of hydrolysed aluminiumbased coagulants may be determin ed in the laboratory by a cirri metric procedure.

Aluminium is first precipitated from a diluted sample of coagul ant usi ng potassium fluoride after the addition of a known volume of standard acid. This is then followed by back-titration with standard caustic soda to determine the remaining excess acid using phenolphthalein as the endpoint indicator.

Whilst most hydroxylaced coagulants co mmonly employed are aluminium-based, several ferric compounds are also co mmercially available. In particular, hydroxylaced ferric sulp hate (polyferric sulphate) has found use in potable water treatment.

The application of a recently developed hydroxylaced coagulant - polyaluminium ferric chloride (PAFC) - has been descri bed

by Goa, Yue and Miao (2003) .

Chappell and Letterman (1998) indicated char for coagulants without free acid present, assuming the predominate end hyd rolysis produce is M(OHlJ, EAC can be determined from Equatio n (4).

EAC = 50.05(300 -3B)/(l 00A) -(4) where: EAC = Effective Acid Content, mg CaCO3/mg metal M B = basicity of the coagulant, % A = atomic weight of the metal species M: 26.98 for aluminium and 55 .85 for iron It follows from Equation (4) chat for aluminium-based hydroxylared coagulants: EAC = 5.565 - 0.056B -(5) Wh ilst for iron-based coagu lants: EAC = 2.688 - 0.027B -(6) Hence, the EAC of an aluminium- or iron-based coagulant cah be directly computed if its strength and basiciry are known.

112 MARCH 2005

water

12.0 11.0 10.0 9.0

::c

0.

8.0 7.0 6.0 5.0 4.0 0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

VOLUME ACH, ml

Figure l . Titration curve for aluminium chlorohydrate.

The result computed from Equations (4) through (6) muse be multiplied by the ratio %w/w metal per %w/w coagulant to yield a result expressed in mg CaCO3/mg coagulant, represented by the authors as "e" to distingu ish it from EAC. As an illustration, for polyaluminium chloride solution with a basicicy of 50%, EAC will be 2.79 mg CaCO 3/mg Al from Equation (5). W ith an Al con tent of l 0.0% w/w Al 2 O 3 (5 .3% w/w Al) and strength as 20.8 % w/w PACI, e wi ll therefo re be 0.71.

Similarly, for aluminium chlorohydrate, th e corresponding data are: B 83.3%, Al 12.4 % w/w and strength 40.1 % w/w ACH. Hence, £ may be calculated as 0.29.

For alu m, B is zero and therefore for liquid alum with 4.0% w/w Al and 49.0 % w/w strength, e will be 0.45; as previously calculated. Similarly, fo r aluminium chloride, which also has zero basiciry, e is 1.1 3.

Applying the same reasoning to the example of polyferric sulphate coagulant with a basicicy of 10%, yields a value of e of 0.7 I and fo r straight ferric sulphate without any free acid present, e will be 0.53.

Values of £ for alum, fe rric sulphate and ocher co nventional coagulants (and ocher chemicals com mo nly used in water treatment processes) have been widely published (e.g. Boby and Solt, 1964; Gebbie, 200 la). Lind and Ruehl (1998) have presen ted some data on the consumption of alkalinity by high basiciry polyalumi nium chloride coagulants, poi nting out the advantage of these coagulants compared to traditional chemicals such as ferric chloride. As well as listi ng values of EAC and e for a range of aluminium-based coagulants, values of e are also given for various alkalis com monly used for pre- and pose-treatment pH adj ustment in water treatment processes.

Polyaluminium chloride coagulants may be characterised by the general formula AJ,,(OH) 111 Cl(3n-m) and Tab le l summarises the properties of commercially avai lable grades of such coagulants based on data presented by Lind (2002).

Also included for comparison are details for alum, and grades of PACI and ACH chat are readily available in Australia.

T his table also includes information on the basicicy, strength and empirical formulae of the various coagulants as well as theoretical values of£.

The accual EAC ore value for a coagulant may be determined by alkalimetry. Th is involves titration of a sample of the coagulant under consideration wi ch a strong base to an endpoint of pH 7.0. Knowing the strength of the alkali and the co ncentration of the metal species in the coagulant, the EAC (and therefore E) value may be calculated from Eq uation (7) (Chappell and Letterman, 1998).

EAC = 50.05NX/(YZ) -(7) where: EAC = Effective Acid Content, mg CaCO 3/ mg metal N = normality of caustic soda used as rirrant X = volume of caustic soda to reach an endpoin t of pH 7.0, mL Y = volume of coagul ant ri crated, mL Z = concentration of metal species in coagulant, mg meral/mL

Methodology Samples of twelve commercially available liquid coagulants were obtained fro m local manufacturers. The samples included three pre-polymerised coagulants for which there is little or no published data on £. Five "co nventional" coagulants (alum,

refereed paper

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water quality The dilute coagulan t aluminium chloride, ferric Table 2. Analyses of coagulant samples. sample titrated therefore chlo ride, ferric sulphate and SGat BASICITY, STRENGTH, % w/w had a concentration of 5.33 COAGULANT g/L sodium alumi nate) were also % 20°c Al ASIS Al2O3 g/L ACH. Using a 50 mL included in the experiments sampl e of caustic soda A lum to test the methodology and 52.1 1.31 0 4.22 683 7.97 solution with an alkalinity to compare results with 83. 1 1.33 23.41 533 - - 12.39 40.1 Aluminium of 110 mg/L (as CaCO 3), calculated theoretical values 83.5 12.28 39.7 524 1.32 23.20 1 Chlorohydrate and the above titre to reach of£.

82.5 524 1.32 23.22 12.29 39.7 pH 7.0, £ is determined to The metal content of each Aluminium 82.4 1.29 22. 15 11.72 37.9 489 2 be 0.28. Th is may be coagulant sample was Chlorohvdrate compared to the theoretical Polyaluminium determined using a 55.8 1.18 10.66 5.64 22. 1 261 Chloride value of0.29. titrimetric method. The 3 The results of coagulant alumi niu m content was 0 1.24 10.77 5.70 28.2 Aluminium Chloride 349 determi nations obtained are determ ined using 0 1.44 sum marised in Table 2, 392 Sodium Aluminate4 16.95 8 .97 27.3 complexation with disodium where the metal content, EDTA and back-titration of STRENGTH, w/w SGat BASICITY, COAGULANT g/L SG and basicity analyses for % 1 the excess with zinc 20°c Fe (Ill) Fe2O3 AS IS each sample are presented, su lphate, using xylenol 10.0 632 1.53 Polyferric Sulphate5 17.3 12.10 41.3 together with the calculated orange as the indicator. A strengths of each. similar method was used to 6 1.45 612 Ferric Chloride 20.8 14.54 42.2 0 determine the ferric conten t Table 3 gives the values 7 of the iron coagulants of £ values determined.

1.56 968 Ferric Sulphate 17.6 12.33 62.0 0 examined with salicylic acid Theoretical values for £ are 8 422 1.34 Ferraq™ 19.9 13.89 31.5 also tabulated. Note that f, used as the indicator.

0 Hydrogen peroxide was first values for the aluminium 1 MEGAPAC 23 , ALCHLOR-AC, PAC-23 added at pH l to oxidise any and ferric coagulant 2. ACH CATIONIC POLYMER BLEND (MEGAPAC 23-1070 ) 3. ASAICI, ferrous iron presen t. samples analysed have a 4. AS NaAIO negative value, since T he specific gravity (SG) 5. PFS ™ BASICITY ASSUMED VALUE BASED ON EMPRICIAL FORMULA OF Fe,(SO, ) 21 (OH),e alkalinity is co nsumed by of each coagulan t sample at 6 AS FeCl 3 addition of the chemical.

7. MEGACLEAR 12 AS Fe, (SO,),.9H O a room temperature of 8 AS FeCl 2 However, f, for sodium approximately 20°C was also aluminace is positive since determined by weighing alkalin ity is increased as a known volumes of both the I : 10 dilution, with very similar resu lts consequence of adding chis chemi cal. coagulant and distilled water. obtained.

T he agreement with the theo retical and Following calibration of a pH meter, the actual values is generally good. However, alkalinity of a sod ium hydroxide so lution Results and Discussion thee value determined for the samples of was determined by titration with a 0.021N A typical titration curve for a sample of sodi um aluminate and Ferraq are noted to standard sulphuric acid to a pH end-point an aluminium chlorohydrate coagulant is be co nsiderably higher. These differences of 4.5. shown as Figure 1.

From chis plot, the titre are due to excess caustic soda and Each coagulant was dilu ted to I: I 00 requ ired to reach pH 7.0 may be read off as hydrochloric acid respectively being present using bo iled, cooled distilled water. A 50 3.97 mL in che coagulant samples. mL aliquot of rhe standard ised caustic soda This particular sample of coagulant Additional caustic soda is added to solution was then carefully citrated with the returned alumi nium content of 12.39% sodium aluminate to increase the stability dilute coagulant using a micro-burette and w/w as determ ined by EDTA titration of the coagulant during storage and the pH of the solu tion recorded fo llowing analysis, which is eq uivalent to 533 g/L as typically the free NaOH content is 11-13% each addition of coagulant after reaching a 100% alumi niu m chlorohydrate. w/w (Aluminaces, 1998). Ferraq, which is steady value. The titration was continued derived from waste pickle liquor, until a pH of 4.5-5.0 was reached. contains 1-2.5% w/w excess The observations of pH and hydrochloric acid and this will volume of coagulant added were Table 3. Actua l and theoretical £ values, & EAC values in crease the value of£ (Actewthen used to construct a titration for coagulant samples.

AGL, 2003) . curve. The volume of coagulant THEORETICAL E, mg ALK/mg COAG T hese cwo examples illustrate EAC, required to reach a pH of 7.0 was COAGULANT mgALK/ chat experimentally determined THEORETICAL read from each such plot. Fro m ACTUAL mg Al or Fe values of e are more appl icable chis volume of coagulant, the Alum -0.41 -0.45 5.56 than theoretical, as actual values ratio of mg alkalinity co nsumed Aluminium Chlorohydrate -0.29 0.94 -0.28 determined acco unt for any free per mg coagulant added (E) could Polyaluminium Chloride 2.78 -0.71 -0.70 alkali or acid that may be present then be determined. Two samples Aluminium Chlorid e -1 .1 3 5. 59 - 1.17 in the particular coagulant of coagulant were cicrared in each Sodium Aluminate +0.61 2.38 +1.31 supplied. This excess can case and the mean of the results Polyferric Sulphate -0,71 2.42 -0.74 substantially impact on the acid obtained cons idered.

-0.94 -0.93 2.70 Ferric Chloride or alkali doses required for pH The above methodology was -0,53 2.67 Ferric Sulphate -0.57 adjustment in the proposed also followed using several FerraqTM -0.86 -0.79 1.79 treatment process. coagulant samples prepared at 2

2

11 4 MARCH 2005

water

refereed paper

water quality As indicated from Table 4. £ val ues determined from actual ACH analyses.

Equation (5), it follows chat STRENGTH, % w/w by knowing che basicicy and 1 ACH BASICITY 1 SG the strength of a % g/L 1 ASAI ASACH AS Al O 2 3 polyaluminium coagulant, 1.34 the value of£ may be then 39.9 83.0 530 23.3 12.3 direccly computed.

83 .1 1.34 23.8 12.6 40.8 550 Table 4 gives values ofe 40.4 1.34 540 23.6 12.5 86.9 --· - ··- ---- calculated from accual 23.5 12.4 40.2 83.3 N/0 analyses of commercial 1. ACTUAL ANALYSES SUPPLIED BY CHEMICAL MANUFACTURER batches of aluminium NID. NOT DETERMINED BY MANUFACTURER chlorohydrace as provided by va rious chemical been confi rmed by field experience and manufacturers as pare of standard quality observations made du ring laboratory jarcontrol practices. Similar values for £ were cescs by che authors. computed for three of the four analyses Ferric chloride and fer ric sulphate both reviewed. One sample recurned a low value depress alkalinity significantly, as indicated of e and this is attributable co che high by che magnitude of corresponding EAC basicicy of the lot in question. and £ values. T his will especially be che case These results indicate che value of if any free acid or alkali is present in the determining e for each load of coagulant produce. delivered co allow accurate modelling and optimum operation of the water (o r wastewater) treatment process.

From che cheo recical values of EAC, expressed on a weight AJ3+ or Fe 3+ basis given in Table 3, it may be seen chat ACH is the most "economical" coagulant in terms of alkalin ity co nsumprion, wich alum and aluminium chloride being the highest.

T he value of£ fo r aluminium chlorohydrace determined supports experience chat chis coagulant does not have a major impact on che alkalini ty of che raw water and hence the pH is not depressed co che same extent as alum on a weight AJ3+ basis. Gebbie (20016) has discussed the advantages of using polyaluminium coagulants in potable water treatment processes, highlighting this benefit.

Alum , as expected, will have a greater impact on raw water alkalinity and pH than both ACH and polyaluminium chloride, again on a weight AJ3+ dosed basis.

The value of EAC for PACI on th e basis of mg of AP+ dosed, is much higher than for ACH. This indicates che raw water alkalinity will be more significantly affected when using chis coagulant, in spice of it being parcly hydrolysed. This again has

Conclusions A procedure has been ouclined whereby the specific alkali nity consumption ratio (o r e value) of commercially available coagulants can be experimentally determined. Good agreement has generally been obtained between these and cheorecically determined val ues.

The method highlights how cheorecical values used in models such as RTW can underestimate che effecr che coagulant can exert on alkalinity consumption and hence pH due co the presence of free acid. This excess acid or alkali may be from che manu faccuring process itself or may be added co assist with coagulant stability and preservation.

Using routine analyses avai lable from chemical manufaccurers, accual values of e can be calculated fo r each batch of coagulant delivered. This mea!ls chat operators and designers alike are in a position co more realistically model the treatment process.

Finally as a plea, it would be very helpfu l co designers if coagulant manufacturers could provide values of che ratio£ with each batch of chemical produced as part of

E.

mg ALK/ mgACH

0.29 0.29 0.23 -(f29-

water

The Authors Peter Gebbie is Senior

Process Design Engineer, Earth Tech Engineering Pry Led, Level 2, 71 Queens Road, Melbourne, Victoria, 3004, Australia.

Communications co: pecer.gebbie@ earchcech. com.au. Bob Turney, long known in che industry, is a Water Technology Consultant, 5 Tincern Rise, Glen Waverley, Victo ria, 3 150, Australia.

References Actew-AGL (2003) . Fermq Specification , Private Commun ication.

Aluminates Ltd. ( 1998) . Sodium Aluminate - S

Gmde Specification, SPEC-07b, Rev 0, Aluminares (Tas) Pry Ltd. Boby, W. M. T. and Solt, G. S. (1964) . "Water T reat ment Dara: a Handbook for C hem ists and Engineers in Industry", Hutchinson, London.

C happell , R. J. and Lette rman, R. D. (1998). "A method to estimate the performance of aluminium salt coagulants in removi ng NOM from raw drinking water", Proceedings 1998 Annual Conference, American W ater Works Association, June 22-25, Dallas, TX. Gao, B; Yue, Q; and Miao, J. (2003) .

"Evaluat ion of polyaluminium ferric chloride (PA FC) as a composite coagulant for water and wastewater treatment", Water Science & Technology, 47, l, 127- 132.

Gebbie, P. (200 l a). "Water conditioning and stability assessment: an introduction", Water, M arch, 50-56.

Gebbie, P. (2001 6), "Polyaluminium coagulants in water t reat ment: some Victorian examples", Water, September, 38-43.

Lind, C. and Ruehl, K; (1998), "A practical summary of water t reatment practices: Parr Two", Public Works, July, 16-20.

Lind,C. (2002), "TOC removal by PAC I coagulants", Proceedings 6th International Conference Coagulants and Flocculants, May 22-24, C hicago, IL. Rothberg, T amburini and W insor, Inc; (1 996), "Model for Corrosion Control and Process C hemistry", Version 3.0, American Water Works Associarion, Denver, CO .

Turn to page 39 to find out all you need to know about pressure sewer. ..

116 MARCH 2005

their manu faccuring quality control and documentation procedures.

~

AQUA TEC FLUID SYSTEMS

refereed paper

SURFACTANT FOAMING AT THE BENDIGO WATER RECLAMATION PLANT H Hall Summary During May 2004, significant amounts of surfactant foam (suds) began fo rming and accumulating over the tertiary treatment area of the Bendigo Water Reclamation Plant (WRP). T he suds covered the surface of the dual media fi lters, the fi ltered water tank and the UV disinfection channel. The suds interfered with th e ultrason ic level senso rs, givin g fa lse ' high high' filter water levels, instigating unnecessary filter backwashes and reducing filter run rimes.

An inves tigation was undertaken to identify its primary conscirnenr and determine a likely source, in an attempt to eradicate rhe foam. Testing was completed and the surfactant id entified as a nonyl phenol erhoxylare (N PE) from a local tannery.

Excessive biological foam at the Bendigo WRP (September 1999).

Background The Bendigo WRP is a Modi fied UCT biol ogical nutrient removal plan e. In February 2002 the plane was upgraded to include tertiary treatment. Effiuenr from th e secondary sedimentation tanks is dosed with alum, prior to being discharged to the lagoon system. From the lagoo ns the effluent is pumped up to the fil ter influent channel, where alum is dosed again. T he effiuent undergoes dual media (sand and anthracite) fi ltration before entering the filtered water rank. From here it flows into the UV channel, where it is disinfected prior to discharge to Bendigo C reek.

Filtered water from the fil tered water rank is used during filter backwashi ng.

Foam is a normal part of wastewater treatment plant operation. Biological foams, which are th ick and brown, are usually a result of increased populations of filamentous bacteria, namely Nocardia and Microthrix genospecies. T his is generally seen in and down-scream of aeration ranks as the bacteria cells, which are hyd rophobic, attach to air bubbles. A less common type of foa m char occurs in wastewater treatment planes is due to non-biodegradable detergents. This is often present in areas of agitation, bur is only clearly identifia ble

refereed paper

wh en biological solids are removed (clarification and tertiary rrearmenc), leaving characteristic white surfactant 'suds'.

Many surfactants enter the wastewater system. Domestic wastewater con tains some biodegradable detergems, usually present in relatively low concentrations. Industrial wastewater generally contains a wider vari ety of surfacta11ts, often prese nt in higher co ncentrations than in domestic

Operationally, the foam interfered with the ultrasonic level sensors. These sensors provide a feed forward signal to the actuated fil ter ouclet valves to maintain a fi xed water level. When a large m ound of foa m passed under a level senso r the control system received a 'high high ' water level and immediately instigated a backwash (or queue the filter for backwash if it was unable to backwash directly) . This meant th at the plant output capacity was reduced ,

Chemical analysis identified the reason and customer consultation tracked down the source. wastewater. Alth ough most surfactants are biodegradable, many pass through biological wastewater treatment processes relatively unchanged.

Ar the Bend igo WRP, small amounts of suds have bee n present since the tertiary plane was co mmissioned. However, a dramatic increase in quantity appeared around April 2004 and persisted through aurnmn. The suds accum ulated on rhe surface of the fil ters, around the fil ter ourlers, over the fil tered water rank and in the UV channel.

as more filtered water was used fo r backwashing. In addition, when the foam dried , it left a slippery, unsightly residue. Ir was also blown about by rhe wind and created an OH&S hazard.

Action Token In the short term, the treatment plan e operational staff hosed down the foam with water to physically suppress it. T h is was required at lease twice a day. A silicone based anti-foaming agent, drip-fed into the tertiary plant pump station, was then

water

MARCH 2005 117

wastewater trialled . T his effectively reduced che amoun t of foam being produced on che surface of the fil ters; however the anti-foaming agent appeared co be stripped ouc by the filters, as the foa m reformed at the fil ter outlets, filtered water tank and UV channel. There was also concern that long term use of rhe anti-foam may have been detrimental co the filter med ia.

A long term solurion was required. T he approach taken was to have the foam reseed co determi ne its primary conscituencs and to gather information on che decergencs entering the treatment plane. Ac che end of July 2004 cwo foam samp les were obtai ned and sent to a NATA Certified laboratory fo r analysis. The laboratory was asked co determine che nature of che detergents in che sample.

Letters were sent co trade waste contributors connected co che Bendigo sewer system char were likely detergent users. The trade waste users included several commercial laundries, a bakery, a cannery, a dairy processor, livestock sale yards and rubber, carpet and textiles manufacturers.

The trade waste users were requested to provide materia l safety data sheers (MS DS) for any cleaning agent used and approximate daily amounts of clea ning agents char do/may enter che sewer. Trade waste users were also asked if they had changed cleaning produces in the six months prior co July 2004.

Outcomes The operato rs continued to manually co ntrol che foa m by hosing it down and dosing with anti-foami ng agent, with reasonable results. The tertiary crearmen c plane continued to function, although some extra fil ter backwashes still occurred.

T he laborato ry examined che samples using nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. Due co the range of impurities in che sample, the NMR was unable make a precise identification. T he FTIR spectrum was able co make a clear determi nation that the sample was a nonyl phenol echoxylace (NPE).

Nonyl phenol ethoxylares are non-ionic surfactants. The nonyl phenol forms the hydrophobic ' head' of the surfactant molecule, while the echoxylace chai n fo rms rhe hydrophilic 'rai l'. This rail can vary in length, depending on the number of echoxylace units. The laboratory analyses determined chat the nonyl phenyl echoxylace in the sample most likely contained cwo ethoxylate units.

The maj ority of the trade waste users provided the informatio n as requested. Of these, the information from the tannery was

118 MARCH 2005

water

Surfactant foam on the surface of the filters.

of the most interest. Their letter (received 23 August 2004) seated that for the last cwo years they had been usi ng a nonbiodegradable NPE surfactant to wash their raw lamb skins, at approximately I 00 kg/day. T hey also stated that they had ceased using this product on the !Och August 2004 and had switched co a biodegradable fatty alcohol erhoxylace detergent. To confirm rhac the prior use of the NPE surfactant and the occurrence of foam ar the plane were linked, che plant operators were asked if the tertiary treatment plant was still experiencing excessive foam. They responded char the foam had actually subsided arou nd che 10th of August. This ind icated chat che cannery was the likely source of the identified surfactant and hence che foam.

From che informatio n received from che other trade waste contributors, their cleaning produces co nsisted of low co ncentration detergents and acid and alkal i 'cleanin g in place' (CIP) solutions. Mose of these were used in very low daily volumes ( I to 5 Lid), although the dairy processor used an average of 338 Lid of sod ium hydroxide solution and 125 Lid of sulphuric acid solurion. T hese were not co nsidered to be disruptive to the operational and biological processes at che treatment plant and were not investigated further.

Discussion NPE is used as an industrial and domestic detergent and is also used in pesticides. Reviews (Servos 1999 and Magui re 1999) have reported char N PE and its degradation product, nonyl phenol, persist in rhe environment and are acutely

toxic to fish, invertebrates and algae.

Because of their effects on aquatic environments, N PE are listed on the second Priority Substance Lise (PSL2) of the Canadi an Environmental Protection Act (CEPA 1999 , Section 76) and the Lise of Chemicals for Priority Action (2002) of the Oslo and Paris Commission (OS PAR) Actio n Plan (1992).

From the data sheets provided by the cannery, it was stared char rhe NPE in the detergent had nine erhoxylace units. The laboratory resting fou nd rhac che foam contained NPE with two ethoxylace uni ts.

Ying et al (2002) exp lains che biodegradacion of alkyl phenol erhoxylares in chis case NPE - as the 'progressive shortening of erhoxylare chain ' with one of rhe most frequ ently observed groups of degradation products being NPE with one to four echoxylare units. le is interesting co note that many researchers (Scott & Jones, 2000; Planas et al, 2002; Ying et al, 2002) have found chat, in both rreacmenc planes and the environment, NPE readily degrades completely to N P with little evidence of degradation intermediates.

Although the can nery stated that they had been using che NPE surfactant fo r rwo years, it was likely that increased production lead co increased surfactant use, until it became a problem ar the treatment plane.

Further communication with the cannery found their reason for changing detergent was due to a request from an international custo mer. The customer's audit of the cannery's work practices found chat they were using an NPE deterge nt. To align themselves with international practices, the cannery ceased using NPE, replacing it with a biodegradable surfactant.

refereed paper

wastewater Conclusion Ir was an excellent result rhar rhe source of rhe surfactant was so clearly identified during rhe inves tigation and even better rh ar rhe use of NPE had already ceased. Ir was anticipated rhar a defin itive outcome was unlikely, given the number of trade waste contributors an d rhe ra nge of co ntaminants.

From the outcomes of rhe invesrigarion, rh e importance of seeking rhe ' righr' inform ation became clea r. For example, if rhe trade waste users had nor been asked if they had changed cleaning products in che previous six months, rhe link between product use and foam ing subsidence, and ulri marely surfactant source, may nor have been made.

From rhe outcomes of rhis invesriga rion, a number of recom mendations can be made. T hese may help Water Authorities to be more proacti ve in rheir identification of nuisance and potentially harmful sewage contaminants. T he reco mmendations are: â&#x20AC;˘ Water Auth orities main tai n in their Trade Was te Agreements a file of each trade waste contribu tors' effluent characteristics, including material safery data sheers (MS DS) â&#x20AC;˘ Water Authorities undertake risk-based periodi c, indi vid ual trade waste characterisation, th rough sampling, resting and in formatio n gathering and collaborate with their customers Although the surfac tant was invesrigared because ir caused operational issues at rhe Bendigo WRP , this investigation has resulted in an increased awareness of rhe contaminants entering the treatment plant and rhe local waterway. N or only has rhe foaming and its resultant problems ceased, a harmfu l contam inant is no longer entering the local waterway.

Surfactant foam coming up through the grating of the UV channel.

References CEPA Environmenral Rcgisrry 2004, The Acr. Retrieved: Ocrobcr 13, 2004 , from h rrp://www.cc.gc.ca/CEPA Regisrry/ rhe_acr/ OSPAR Convenrion for rhe Prorecrion of rhe Marine Enviro nment of rhe Norrh-Easr Atlantic 2002, OS PAR list of chem icals for prioriry acrion. Rcrricvcd: Occober 13, 2004, from hrrp://www.mumm.ac.bc/Downloads/ 02- l 8e_prioriry_chemicals.pdf Yi ng, G.-G., Wi lliams, B. & Kookana, R. 2002, 'Environmenral fare of alkylphenols and alkylphenol erhoxylares - a review', Environmental fntemntionnl, vol. 28, pp.

2 15-226. Retrieved: September 20, 2004 , from Science Direct.

Score, M.J. & Jones, M.N. 2000, 'The biodegradarion of surfacranrs in the envi ronmenr', Biochimicn et Biophysic,, A ctn, vo l. 1508, pp.

235-25 I. Retrieved: September 2 0, 2004, from Science Direct.

Planas, C., Guadayol, J.M ., D roguec, M., Escalas, A., Rivera, J. & Caixach , J. 2002, ' Degradation of polyerhoxylarcd nonylphenols in a sewage treannenr planr.

Quanrirarive analysis by isotopic dilutionH RGC/MS', W{fter Research, vo l. 36, pp.

982-988. Retrieved: September 20, 2004, from Science Direct.

The Author Hilary Hall graduated BE Chem Eng (Hons) from RMIT Uni versity in 2002 and is currently completing a Master of Engineering Scie nce in Water and Wastewater Management partrime through UNSW. She works as a Process Engineer for Campaspe Asset Management Services (CAMS) in Bendigo, Victoria. CAMS is rhe service provider of operations and maintenance services to Coliban Water, including rhe Bendigo Water Reclamation Plant.

Email hilaryh@coliban. com.au

refereed paper

Aquarius Technologies is a world leader i n the design and manufacture of water quality monitoring and control equipment w ith 24/7 data logg ing and remote access.

We'll be launching our new range of control equipment including our Key Performance Indicator equipment with corrosion level based inhibit or dosing and remote communicat ions.

See us at work on stand X209 9 -11th May.

AQUARIUS T lt:CHNOLOG ll: S

water

P TY I.TD

MARCH 2005 119

wastewater

AUSTRALIA'S LARGEST ULTRA-FILTRATION RECLAIMED WATER PLANT A Davey, P Miller, F Knops

.

Abstract Earth Tech has developed the Eastern Irrigation Scheme (EIS) at Carru m Downs, near Melbourne, Australia, by utilising a Design Build Finance and Operate (DBFO) method of project delivery. The project will assist Melbourne Water co meet its goal of 10 per cent water recycling by the year 20 [0.

The AUD$24.8 million design and construct project includes a 30 ML/d Ultrafiltration (UF) membrane treatment plant and approxi mately 50 km of pipeline.

The Initial Treatment Plane (ITP) will be the largest UF system creating wastewater in the Southern Hemisphere. Earth Tech will own and operate the C lass A treatment plane and pipelines fo r 25 years. The project will be operated under the company name of "TopAq".

Initially the scheme will produce approximately 5,000 ML per year of Class A water, which will be provided to some 50 agricul tllral and horciculwral customers. In addi tion, chis Class A water will be provided to golf courses and residential developments fo r toilet fl ushing and garden maintenance

Figure 1. Dead-end filtration.

in the Melbourne metropolitan area. Urban reuse requires reclaimed water to be free of pathogenic bacteria, parasites (protozoa and

Pathogen removal by UF and chloramination produces Class A ejfiuent. helminrhes) and viruses. T hus reliable treatment muse be maintained to eliminate pathogen levels to less than 1 in 50 L (in

Table 1. Sum mary o f Econo mic Costs.

Typical Annual Operation Costs $ Treatment Plant Option l : Dual Media and UV

Option 2: Ultrafiltration

$21,089,800 $275 $9,631 ,000

$1 7,72 1,360 $231 $9,184,000 $667,850 $81,200 $251,065

Energy Chemical

$896,385 $79,360 $$117,965 $72, 130 $451,860

Labour

$172,500

NPV @ 25 years Cast per ML (@25 years) CAPEX $ OPEX $ per annum Maintenance - Mech/ Elec Membrane Replacement UV lamp replacement

accordance with EPA Class A requirements), particularly for higher infectious agents such as roravirus.

The combined pressure of water conservation and the need to protect commun ity health are encouraging sewage reuse and imp rovements in the level of membrane filtration.

This paper addresses the issues associated with achieving microbiological standa rds at the level of treatment required for non potable urban reuse (i.e. where there exists a risk of people coming into direct contact with reclaimed 'highly created sewage' water.) Furtherm ore we describe the practical issues of designing and operating the Interim Treatment Plane, in particu lar focus on the ad van cages of the chosen technology.

For example the use of: • Low cost membrane filtration versus the relatively high power cost of ultra-violet technology due to che low cransmissivicy of che secondary effluent from ETP; • Pressurised feed from ETP chat suits a UF system and remove the need fo r repumping; • Micro-strainers and their ability co protect the membranes from algae blooms and large particulates; • The ability of the UF membrane to remove all suspended solids (TSS) and pathogens;

$$7,580 $155,505 $172,500

1. Maintenance costs of 0.5% of civil works, 2.5% of mechanical/ electrical, 2. Power costs based on $0.065/kWh 3. Membrane replacement every 8 years and UV lamps every 12,000 hours of operation 4. Full time plant operation 200 days per year

120 MARCH 2005

water

Figure 2. Pressure vessel with membrane element mounted .

wastewater • An auromared onlin e inregriry resr on rhe memb rane pla nr (recommended for reuse applicarions requiring high microbial rejecrion); • Mod ular rechnology for ease of expansion in rhe fu rure; and • Chlorine residual ro co nrrol biofilm in the disrriburion pipe-wo rk and ensure that Reclaimed Warer is even more consistent and reliable ar irs poinr of use.

Figure 3. 30 ML/d Ultra-filtration Plant.

Introduction An integral parr of the Eastern lrrigarion Scheme (EIS) is rhe consrrucrion and operarion of a rrearmenr planr ro improve rhe qualiry of rhe seco ndary n eared wasrewarer from the Easrern Trearment Planr (ET P) owned by Melbourne Water Corporarion (MWC) . The product warer fro m rhe proposed plant will be C lass A in accordance wirh Vicrorian Figure 4. Full scale Disc Filtration System.

EPA Reclaimed Water Guidelines (EPA Publicarion 464. I) and EPA's The Viable Treatment Options Disinfection of Treated Wastewater T here are several ways of trearing Guidelines (EPA Publicarion 730). secondary effluenr ro gain a Class A Whi le wastewater is widely regarded as a standard ; in particular two options were porenrial water source Class Awarer has nor reviewed in derail based on their abili ty as a been used in many re- use appli carions. T he pathogen barri er and cost efficiency. avail able pressure in the outfall pipe (o r Option l: Dual med ia filcracio n, Ulcraviolct energy) from ET P suits a pressurised (UV) System and downstream chlorin ation Ultrafi lcracion (UF) system rem ovin g the Option 2: Micro-strainers (MS), need for a re-pum ping stage. The Ulcrafiltration System and downstream technology is suitab ly modular co allow for chlorin ation expansion of plant capacity in rhe furu re.

Econom ic analys is was based on capital and annual costs for treatment pl ane only, The Choice of Process straight line dep reciation of assets and a T he UF technology and in particular the residual value at the end of 25 years. membranes suppli ed by Norit X- Flow, Under Ca liforn ia's T itle 22 regulatio ns a demonstrate che abi lity co fil ter and supply UV dose of 100mW/cm2.s is usually wa cer free of pathogens for urban reuse. The X-Flow SXL membrane, (with a membrane area of 40 111 2) operates in a dead-end fi ltration process (refer ro Figure I). T o remove solids built up on rhe membrane surface during filcracio n under co nstant feed pressure, the system is backwashed at regular inrervals of 15 ro 24 minutes, by reversing flow d irection through the membrane Figure 5. X-Flow SX L membrane trial. fil ter.

Dead-end Filtration (Figure 2) is perfor med inside-out, i. e. feed water (represented in che green colour) is fed inro the lumen of che fibres and exits the membrane ac the shell side. T he filt rate (or permeate) is collected at the centre and exits che membrane element th rough a cenrral fil trate pipe (represented in a blue co lour).

Figure 6. Pilot Plant Co ntai ner.

adopted ro give adequate factors of safety related co possible variab ility of the effluent incl uding Ultra-violet transmissivity (UVT). The UV system muse be des igned ro achieve at least a 4log reduction of Adenovirus. Pilot studies of feedwater from ETP highl ighted the difficul ties in improving ultraviolet transmiss iviry of the feed water beyond 45% UV-r for effective disinfection (particularly inactivation of viruses) as well as relatively high chem ical doses required fo r effective treatment under a variety of feedwacer condi tions.

T he review strongly favoured the option of UF on the basis of: • Lower energy consu mption given no repumping is required; • Reduction of coagu lant dos ing co create micro-fl oe wichouc the need fo r additional chemical ai ds; • Relatively high power of ul era-violet technology due ro low cransm issivicy; and • Effective and reliable physical barrier ro pathogens.

Th e UF plane effectively provides a physical barrier through che exclusion of phage and viruses, such as MS2 and enteric viruses greater than 35 nm in size. While oth er larger viruses like che Ade noviruses sti ll need ro be removed, removal rates are much higher fo r these larger vir uses with UF. The UF has che ability co remove all T SS and pathogens.

Pilot Plant Study T he objectives of che pilot plane study were ro evaluate the suitability o f che proposed des ign on seco ndary effluent from the ET P. T he pilo t plane was operated fo r a period of fou r months durin g which th e pre-treatment technology, flu x, coagu lation, organ ic fou ling, backwash o p timisation, and chemi cal enhanced backwash (CEB) frequency and effective chemical cleaning solutions were investigated.

T he containerised pilot plane was supplied by X-F low in a 20ft co ntainer, and consisted of a feedwa rer tank, feed pump, backwash pu mp, dosing pum ps, two hollow fibre membrane elements housed in an eight inch fibr e glass rei nfo rced pressu re vessel, produce/ BW tank, control panel and data logger, and com piece with valvi ng and inscrumen cation.

A back-washable fi ne micro strainer (generally referred ro as a disc filter), comprised of a filter pod, wi th a number of grooved polypropylene discs stacked onro an expandable filte r spine was used for pretreatment. The degree of filcracion could be altered by changing

water

MARCH 2005 121

wastewater the disc grade, fo r the trial evaluation a 100 µm disc was selected on the basis of removing particulate material, which could potentially block the lumen of the hollow fib res, and remove some of the T SS loading onto the UF plane. During pilot resting, the disc filtration analysis of particle size distribution curves showed mean particle sizes were between 8 and 4 1 micron and the particle distribution ranged from 5 µm up to maximum 200µm in the feed water.

There was at least 30% removal (by size) of the particulate population with the l 00pm disc filter. T he d isc filter had the abili ty to protect the memb rane from algae blooms and large particu lates.

In order to reduce the Total Organ ic Carbon (TOC), Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD) and colour removal capabilities of the X-Flow system, a coagulant was added upstream of the UF plant. The optimum coagulant dose was dependant on factors such as feed water quality characteristics, process complexity and the specific fi nished water quality objectives. It was fo und that Alumi nium Chloro-hydrate (ACH) offered the most efficient removal of T SS in the feed stream. During the pilot study the coagulant dosage ranged from 1.5 mg/L ro 4 mg/L as I 00% aluminium co ntent. At an ACH dose of 3 mg/L, a target fil trate tu rbidity of less than 0.5 NTU was achieved wirh the UF pilot plant, satisfying Class A water requirements. The apparent colour of the treated samples was consistently in the range of 50 to 60 PCU. The UVT of the sample dosed with 3 mg/LACH was found robe 48.6% (Table 2). Tt was fo und that an increasing dose of ACH failed to give an eco nomically justifiable improvement in the UVT of the filtered water.

Potenti ally any particles greater than 8pm are extremely resistant to UV due to problems with UV scatter. It is believed that the colloidal particles can harbour virus and bacteria partially protecting them from UV light. If the TSS is removed then UV transmission could be improved by greater than 50%.

T he analytical results shown in Tab le 3 were obtained du ring test work undertaken from August to December 2004. T he results revealed higher than expected turbidity, COD and BOD values that could be attributed to peak wet weather flow events at ETP. Over the period of pilot testing at least 5 turbidity spikes were enco untered. Figure 7 illustrates a turbidity spike spanning over a few minutes, peaking at 50 NTU. T he trans- membrane pressure (TMP) profile shows the UF plant can absorb and cope with the spike in the secondary effluent.

122 MARCH 2005

water

Table 2. O ptimi sa tion of UV transm issivity w ith AC H. Feed: ACH Cone as mg/ I as Al

pH

App. Colour

NTU

%UV Transmissivity

UV absorbance

No dose

7.16 7.16 7.16

120 60 50

3.7 <0.16

35. 1% 48.6%

49.2% 35.1 % 31.3%

3.0 7.0

53.0%

Table 3. Physioc hemica l characterisation of feedwater.

Permeate Removal

Feed

Parameter Median Unit

ss

mg/L Total N mg/L Total P mg/L BODs mg/L BODI mg/L True Colour PCU Units pH COD_OM mg/L EC µS/cm TDS mg/ L NH3-N mg/ L Alkalinity ppm Turbidity NTU

%

Max

90% ile

Pilot

MWC

Pilot

MWC

Pilot

MWC

Pilot

Pilot

16 21 5.5 12 5.5 80 7.4 75

12 28 8.2 19 7

28 23 6.4 30 12

56 44 12 49 26 120 8.2 215 1200 800 40 260 27.3

> 99

100 7.5 118

53 28 7.3 52 21 120 8.4 420

<1 20 . 25

80 7.4 75 960 480 20 190 7.5

36 34 9.4 33 16 100 7.7 110 1000 546 29 223 13.8

20 170 11

23 190 20

It was fo und during the pilot study that the fo llowing performance parameters were obtained with secondary effluent: • The T ransmembra ne Pressure (T MP) varied from 0.2 bar (wi th rhe membrane in a clean state) to 0.6 bar (at the end of the fi ltration cycle prior to backwashing) while operating at flux rates ranging fro m 50 lmh (l/m2 /hr) to 62 lmh.

• T he instantaneous permeability varied from 250 lmh/bar (with the membrane in a clean state) to 150 lmh/ bar (at which point membrane fo uli ng occurred and a Chemical

27 200 50

<5 < 10 <5 50 . 60

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Cleaning of the membrane with a solution containing both sodium hydroxide and sodium hypochlorite was fou nd to be the most effective in removal of organic fo ul ing.

• Overall the UF unit had a recovery of 86.9% fo r med ian feed water parameters and up to 80.3% under worst case operating condi tions with seco ndary effluent.

• BO D removal after coagulant dosing co the feedwater of the UF unit was fo und to be > 75%, with measured BOD in rhe UF

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permeate being less than l mg/L The filterable co mpon ent of the BOD was fully removed by the UF sys tem, however smaller more so luble organics were able to pass ch rough the membrane which has a molecular weight (MW) cur off of around 150 k Dal tons.

• Th e feedwacer colour ranged from 80 PCU to 120 PC U and the permeate colour ranged from 50 to 60 PC U. T he average removal of colour was 20 to 30% throughout the course of the study. The colour in municipal wastewater has been, historically, has been difficult to remove.

• During the study feed water rnrbidiry was nor recorded until late into the srndy and permeate turbidity was recorded on-line. The raw wa ter samples taken during plane operation ranged from 1.5 NTU to 30 NT U and after filrracio n the permeate rnrbidicy was consiscencly less rhan 0.5 NTU. Figure 8 illustrates typical operating parameters for the UF SX.L membrane with T M P, permeability, net flux, temperature and turbid icy over the month of October, 2004.

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Viruses and Protozoa Issues Urban reuse requires recl aimed water free of pathogenic viruses, bacteria and parasites (protozoa and helminthes) and viruses. T hus reliable trea tment muse be maintained to eliminate pathogen levels to less than 1 in 50 L (in acco rdance with EPA Class A requirements), particularly fo r higher infectious agents such as enteric viruses and C1yptosporidi11m oocyscs.

With prior chemical dosing and filtration, it is expected that th e log reducti ons over the IT P will bear lease: • 6-log reduction of E coli, • 4-log reduction of viruses, • 5-log reduction of protozoan parasites and helminth es, • BOD < IO mg/L, and TSS < 5 mg/L The membrane plant includes an online incegrity test (a reco mmendation for reuse applications requiring a high bacterial rejection). T he UF membranes are designed to provide a barrier to path ogens with membrane pores being smaller than enteri c viruses.

Hen ce th e integrity of the membrane system is monito red and defecti ve fibres detected by either particle countin g or on line integrity resting.

Typically, particle councs in the permeate greater than 6 micron size range are ex pected to remain below IO ccs/ mL. A sustained spike in particle coun ts may indicate a breach of membrane integrity. An alarm will initiate an air di splacement rest. However, higher than normal counts may also be attributed to non-co ntinuous flow through the pa rticle counter ca using air bubbles in the line, which are counted as particles.

An integri ty test will be initiated at least on ce a week automatically by the Control system fo r each skid system (o r more frequencly if ini tiated by the operator). T his test is based on a natural phenomenon chat air will not pass through wetted pores with out a certain pressure. T his pressure is related to the size of rhe membrane pores. During rhe airflow rest, compressed air is supplied to the feed side of the membranes.

In rhe case of fi bre failure, the airflow ch rough the comprom ised membrane will be in che order of magnitude higher than normal (membrane integrity) . By measuring th e water flow displaced by che air at the permeate side, membrane fibre failure can be detected. [n the evenc rhar a broken fib re is detected (i. e. I in 12,000 fib res in che membrane mod ule), the event is logged on the Control system and the vessel can be isolated and the appropri ate maintenance carried our if necessary. If the membrane integrity is in tact (i.e. no fi bre breakages) then a Log Removal Value (LRV) of 4.0 is obtainable for enceri c viruses and 4.5 fo r Cryptosporidium oocyscs.

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water

MARCH 2005 123

wastewater Inactivation through Chloramination Due to the high levels of ammonianitrogen that will be initially present in the secondary effi uent from the Eastern Treatment Plant (ETP), any chlorine-based disinfectant added will be converted to monochloramine (NH 2Cl).

Monochloramine (a form of combined chlorine) does not have the same disinfectant strength as free chlorine but has the benefit of having a relatively long decay time compared to chlorine. Combined chlorine residual will therefore persist within the extensive EIS reticulation system.

Retention time is provided within the Reclaimed Water Storage T ank and reticulation system following dosing with Sodium Hypo-chlorite (NaOCl), in order to ensure adequate contact of the disinfectant with the UF product water prior to transfer to the EIS customers.

Conclusion In co nclusion, we have demonstrated that UF technology together with a disin fection barrier such as chloramine can provide a satisfactory barrier to both pathogens and protozoa achieving EPA Class A standards for dual pipe reuse.

With UF and coagulant dosi ng alone, removal of greater than 99% removal of TSS and 75% of organic matter are achievable satis~ri ng C lass A water requirements.

Ch art of PIiot Plant Op eration 1-10-04 to 22-10-04

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The X-Flow SXL225 membrane wi th an operational Aux of 62 LMH, recovery of 80 to 85%, performs well below turbidities of up to 30 NTU together with organic loads up to 20 mg/L of filterable BOD from the ETP. Furthermore the pilot study has proven that a back-washable disc fil ter with 100 ro 120 pm gauge can cope with algae outbreaks and high turbidity eve nts and provide safe protection for the UF system.

Particle analysis of the screened effl uent indi cated that the vast majority of the

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particles in the feed water are very fine and colloidal in nature.

The Authors Anthony Davey is Technical Manager IMO , Earth T ech, Melbourne, Australia, (anthony.davey@earthtech.com.au; Peter Miller is Regional Manager, Asia Pacifi c, X-Flow B. V. , petermillersyd@compuse rve. com; Frans Knops is Senior Process Engineer, X-Flow BY and Norit Process T echn ology BV, Enschede, The Netherlands (f.knops@noritpt.nl).

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124 MARCH 2005

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wastewater

DECENTRALISED VS CENTRALISED SEWERAGE D Cameron The aurhor of rhis paper has pu r his money and effort to back his belief rhar there is far more potential for a modern managed on-sire system than is usually recognised. He has spent eleven years developing, perfect ing and now selling stand alone and networked Biolyrix TM systems. He acknowledges some good competing systems, bur his own has recently been judged a double winner on the ABC TV's The New Inventors and was recently selected by the Australian Government as one of the top five Eco Tech produces in A ustralia, and it has been nominated fo r the World Expo Eco Tech Awards in Japan.

A description of the Biolyrix TM and Biowarer systems, and results of a mulri-unir trial are published in a separate paper in chis issue.

Abstract Whi le the US is saving billions of dollars by implementing decentralised sewerage systems for almost half of their new wastewater infrastructure they barely register on the radar in Australia.

Most Australi an design ers still consider decentralisation an inferior sewerage option.

Tenders are often written to actively preclude it here, despite the face char new reliable systems have been developed and the legal, institutional and technological ba rriers against it were addressed rwo decades ago in the US. This paper reviews and argues against some of the reasons that are still being given by some authorities.

The Reasons Given Against Decentralised Sewerage "Reason" l - Requires a Paradigm Shift Regulations Onsite or clustered wastewater rrearmenr sysrems are already mandatory and accepted as rhe only viable alternative for all existing rural res idential development outside sewered areas.

Local authori ties have th e power to, and already do, require seco ndary rrearment or

better for specific locations and lot densities. The issues slowing the adoprion of dece ntralised sanitation in urban developments in Australia are predominantly in the regulato ry structures and practices rhar create barriers to innovation and allow rhe use of unsuitable technologies. These include: AS 1546. l for onsite treatment systems is inadeq uate in rhar ir fails to cackle what treatment standard should be re quired fo r sustainable trench dispersal or certify rhe

Introduction In co nsidering wate r and sanitation infrastructure options for a new urban growth region in South East Q ueensland, rhe extensive Gold Coasr City Council "Pimpama Coomera Water Future Maste r Plan " exam ined onsire and decentralised technologies. The key summary points of the study rega rding these bea r a strong resemb lance to those cited by the US EPA in irs landm ark Repo rt to Congress on the barriers to implementing decentralised sewerage in 1980 and several subsequent indep th reviews in the 80s and 90s culminating in the US EPA2000 Guidelines For Management of OnsitelDecentralized Wastewater Systems.

Bur where rhe US EPA was highlighting the barriers to rhe more logical and cosreffecrive decenrralised options so char they could be tackled and overcome, the Pimpama Coomera summary dismisses decentralised options. A closer look at their reasons highlights why new technology, such as rhe BiolytixTM Filter, now makes decentralised sewerage in urban developments a far more plausible and attractive option.

water

MARCH 2005 125

wastewater perfo rmance of primary treatment systems.

As a consequence better and more rel iable treatm ent technologies remain underutilised because of this prescriptive and anti-competitive standard .

AS 1546.3 is also inadequate in char compliance certification testing does not require a holiday stress loading, as is requ ired by NSF 40 in the US or a chemical stress regime, which wo uld ensure that approved systems were actually fit for their purpose and could cope with real wo rld conditions.

Each state has its own regulato ry/ approval bureaucracy and some states like Queensland have no mechanism fo r even approving better pri mary treatment alternatives to septic ranks. Subsidies fo r sewerage services in some states currently do not extend to decentralised schemes, even if they can provide a better environ mental outcome.

"Reason" 2 - Social acceptance may be difficult to achieve

T his is dubious. In the US, the majority of che impetus for decentralised schemes from the early 80s has come from the grass root with commu ni ties wanting to have more logical and cost effective solutions than the centralised schemes chat were often fo isted onto chem. T he "S mall Flows" movement, cost transparency and the growing adoption of fu ll cost accou nti ng principles have significanrly boosted onsire and decentralised adoption in the US marker.

In Australia there already is acceptance of onsite systems for ru ral residential developments, and a significant number of households in this situation choose to install seco ndary treatment systems, even where they are not mandated, since they appreciate rhe benefit of recycled water fo r 1rngacion.

If purchasers of "serviced" residential lots wi th dual reticulation were aware chat more than $30,000 of rhe land purchase price was goi ng to pay for their water and sewerage infrastructure, and th at this cost could be halved by using decentralised technology, then centralised utilities could well fi nd their schemes are socially unacceptable.

"Reason" 3 · Ongoing operation and maintenance costs to property owner

With any sanitation op tion, it is ul tim ately the ratepayers or equipment owners who pay fo r the provision of services and the operation and maintenance coses. Since long-term local authority debt repayments for major centralised water and sewerage schemes are often hi dden in general rate revenue, onsire equipment

126 MARC H 2005

water

operators often unwittingly pay extra fo r services they are not entirl ed to .

The issues fo r decentral ised systems are really: Who owns che equipment/ infrastructure? W ho are che service providers? Who manages it? And who bills the property owner? T he comparison should not be between centralised and decentralised sewerage bur between centralised and managed decentralised systems. (West, 2001 ) "Reason" 4 · On-site systems cannot produce water of the same quality as centralised treatment plants, especially with respect to nutrients and disinfection

Yes and no. When operating at design hydra ulic flow races, a modern BN R plant with membrane or non-ch lorine disinfection wi ll produce a better effluent quality at the discharge poi nt than even a well-des igned sand fi lter, tex tile fil ter or BiolycixTM Filter. le is certainly better than rhe typically inconsistent results produced by co nventional onsice aerated treatment systems. (Beavers et al 1999.)

During wee weather peaks, however, centralised planes, even rhe fan cy ones, are vulnerable and often perform poorly. Four co six environmental discharges per annum are typical fro m Centralised STPs (Pollard , personal communi cations re Lora creek catchment study 2004) and result in sign ificant shore-term public health risks.

T hese are far higher chan chose posed by good onsice technologies.

The results from field performance of the BiolycixTM Fileer show chat onsice perfor mance using ch is new technology is in face better than a co nventio nal Centralised Plant in terms of co nsistent BOD5 and TSS removal (Cameron, chis issue). W hen che soil is co nsidered as an integral pare of the treatment train fo r decentralised systems, the performance of even the bes t centralised treatment plan rs will be comparati vely wo rse on virtually every effl uent performance parameter.

"Reason" 5 · Conventional on-site systems are notorious for poor operation and maintenance

T his is rrue fo r conventional aerated onsite treatment systems and is partly due to inadequate testing requirements in the AS 1546.3, as noted earlier. It is also to do with rhe fact chat mai ntenance co ntracts have not generally been enforced . Add to this the fact that visible/audible alarms, as required by rhe standard, are useless fo r up to 80% of the occas ions they are needed based on actual relemetry alarm logs.

Ir is not surprising that the US has generally not taken the track of using aerated treatment systems as part of a decentralised network. US sanitation engineers have adopted a mo re pragmatic approach: they kn ow that septic tanks give poo r performance, bur rhey at least give reliably poor perfo rmance, tha t is nonetheless good enough to be pumped to as a common effluent to a community sand filter, textile filter or conventional treatment plant. Th is saves a huge amount in the collection sys tem cosrs.

Few if any decentralised propo nents expect that indi vid ual owners should be relied on to main tain their equipment.

Simple, reli able equipment controls and relemerry monito ri ng coupled with only annual servicing allow Biolyrix™ to im plement a complete management regime rhat is as hands off for the user as sewerage.

"Reason" 6 · Potential odour issues

T he best onsice technologies no longer generate anaerobic odours. Fo r example, BiolytixTM uses a patented humus fil tration system that actually absorbs odour. No odour is guaranteed as pare of its 20 year performan ce warranty.

"Reason" 7 · Stringent Wastewater standards

Regulations in relation to wastewater are beco ming ever more stringent in an increasingly litigious environ ment. This has led to over-the- top wastewater regulation .

Good legislation shou ld be underpinn ed by good science. Setting efflu ent standards for irrigation or reuse which exceed the background levels in your average water body, is rarely justified. Every day large numbers of kids are bath ing in river water that is objectively worse than the standard required to flush a toiler. Epidemiological studies by the Wo rld Health O rganisation (1989) and World Bank (Shuval, 1989) show that the effl uent standards required for food crops are overly cautious but these findin gs have been largely ignored by legislato rs in the developed countries. The latter paper points out the fact that very few natural agricultural water sources (or indeed collected rain water) would meet the standards our regulators are proposing for effl uent reuse.

With a central ised system with third pipe recycling for internal and external use there is a high risk of cross con nection so more stri ngent treatment standards for communal recycling schemes are justified.

However, when an onsite system is co upled with an onsire microftlcer or engineered soil fil ter for pathogen attenuation, the risks of cross infection are greatly reduced. Class A effl uent can now be reliably produced

wastewater onsice by several affordable technology combinations, and used by rhe source household for non-potable purposes.

"Reason" 8 - Potential impact on soil and groundwater

Incer-cacchmenc mass transfers and nucriencs are rhe main issues here. If the created water is co be used for subsurface garden irrigation or recycled, instead of discharged co a waterway, ic often doesn't matter char che nitrogen and phosphorous levels are higher. Signifi ca nt so ils adsorption of phosphorous and uptake and denirrificacion of nitrogen are proven co occur in soils using slow rare drip irrigation.

(Thompson et al, 2000) T he pragmatic approach in pares of che US of setti ng boundary limits for important enviro nmental contaminants, such as <2 mg/l T N (New Jersey Pinelands Commission, 1980) makes more sense than expensive BN R planes although ir does mean signi ficant irrigarion areas are requi red. le is also more incell igenc in che concexr of a current lack of regulatory control over che use of garden ferti lisers in subu rban areas, which currencly co ntribute far more co environmental loads than onsice or centralised wastewater crearmenr sys tems.

(Feacure article from V(/atershed Protection Techniques 2( I): 239-246 2002) Water systems are fa r more vul nerable co nutrient and organic loads than so il.

(Brodie et al,2000) T he coral nutrient and organic load per person serviced by centralised systems char discharge co water is most likely higher than if they are serviced by an onsi re or decentra lized system discharging at low rares (e.g. 2 - 5 mm/day) into rhe soil.

Raising or dep letion of rhe aquifer is really dependent on the source and des ti nation of rhe water, nor on che rype of sewerage infrasrruccure used. If water is imported from another catchmen t and discharged into rhe so il, then there is potential for rising ground water and che attendant problems ir can bring.

Co nversely, if rhe water is harvested locally and discharged in another catchment or waterway, then there could be falling groundwater levels. T he ideal scenario is local harvesti ng and local discharge so che water cable maintains its origi nal balance.

This is consistent with decentralised systems, and rarely with centralised schemes, so for chis parameter decentralised is clearly becrer.

"Reason" 9 - Requires adequate available land area

This is true for onsire-only systems.

However, if a coupled system produces Class A water or is irrigated below gro und

chis can be irrigated anywhere it is needed in che catchment - along road verges, in parks and public gardens or for peri-urban horciculcure, as well as at its source. The footpr int of modern onsice rrearment systems is as lirrle as 2.5 111 2, so there is virtually no minimum !or size requirement bur obviously people- frie ndly planni ng with sufficient open space for irrigation is desirable.

"Reason" l O - Disposal issues i.e. blocked spray nozzles

T his can be the case if using co nventional suspended bi omass aquatic systems. Bue bio-filcer systems and sa nd filters produce reliable efflu ent quality. Spray irrigation has terminal constraints for public irrigation anyway bur there are no issues with effluents sui table for drip irrigation in any case.

"Reason" 11 - System capacity to withstand shock loads

The biggest flaw in the rnrrenc AS I 546.3 rest standard for AWTS is char it does nor cake into account real world load variatio ns. Holidays fo llowed by peaks or even average loadings cause major percurbacion for aquatic based treatment systems. T he BiolycixTM Filter, as with so me ochers, with an attached active biomass, can genuinely wichscand shock loads.

Conclusion As with ch e US, decentralised sewerage solutions are likely to be suitable for at lease half of the ex isting infrascruccure demand in Australia. le remains robe seen whether they will achieve their optimum level of use in che shore or medium term.

Studies in the fucure need to examine why decentral ised sewerage in America is so widespread and what we can learn from chis. They also need to look at potential decision-maki ng influences of new scare-of-

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che-arc technology and nor lock themselves into expensive centrali sed strategies char are increasingly inappropriate fo r che 21 sr century.

Government regul ations need to be addressed, so char decentralised treatment techn ologies are adeq uately reseed for potential failures. Ar che same rim e, new regulations fo r wastewater standards need to be scientifi cally based so rhey are nor over-regulating in some areas, whi le underregulating in others. Most imporranrly, legislative ini tiatives must be prioritised co pave che way for small local authorities co imp lement ownership and management scruccures fa r more appropriate for community san1racion.

If chis paradigm shift is not inade by industry decision-makers soon, th ey could become che fo llowers rather than leaders.

Ratepayers are increasingly beco m ing awa re of che cost and lifestyle implicat ions of che old way of chi nking, and are sca rring to demand a better way.

Acknowledgements T he author thanks Jenny Allen and Gary In gram for their critical reviews a nd suggestions for che manuscript.

The Author Dean Cameron is an inventor and Managing Director of Biolyrix TM Technologies. He spent 11 years developing the BiolycixTM Filter.

Email deanc@biolycix.com

References Brodie J , C hristie C, Devlin M. Haynes D, Morris S, Ramsay M , Waterhouse J.and Yorksron H., (2000) Catchment Management and the Great Barrier Reef Beavers P, T ully I, Woolley A (I 999) Abmact from onsite 99 - Performance E11al11atio11 of On-Sire Aemted Wastewater Treatment Systems New Jersey Pinelands Commission ( 980) Pinelands Comprehensive Plan, Trenton, New Jersey. "Warershed Protection Techniques". 2002 Nutrient Movement fi'om the lawn to the Stream 2( I): 239-246, Shu val H , (] 989) Wastewater Irrigation ln Developing Countries-Health Effects and Technical Solutions - Summary of World Bank Technical Paper Number 5 I) Thompson TL, W hi te SA and. Maurer MA, (2000) Development of Best Management Pmctices far Fertigation of Young Citrus Trees W esr S (200 I) Centmlised Management: The Key To Successful On-Site Sewerage Service World Health O rganization, J 989. "Health Guidelines far the Use of Wastewater in Agriculture and Aquaculture." Report of a WHO Scientific Group- W HO Techn ical Report Series 778. Geneva).

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MARCH 2005 127

wastewater

BIOLYTIX™ - A LOW COST, HIGH PERFORMANCE SEWERAGE ALTERNATIVE D Cameron Why a new sewerage treatment technology?

Secondary treatment is increasingly being specified for onsite sewerage treatment systems, but conventional aquatic based technology ca n't deliver the treatment standard required in real world usage applications. Aquatic processes rely completely on microbial biomass to degrade the orga nic matter in rhe sewerage. During normal operation with consistent inflow rares rhe biomass can be maintained ar adequate levels, bur as soon as there is a noflow situation the nacural microbial kinetics results in rhe rapid loss of biomass. A period of normal usage following a holiday period produces effluent char is nor biologically treated. This is rhe ch ief mode of failure with AWTS. BiolycixTM filtration was developed to provide high secondary creacmenr consiscenrly, and without odour, under fluctuating loads and normal usage of household chemicals.

The Biolytix™ Technology Biolycix TM Filters treat all types of domestic wastewater and some industrial effluents. Three filter types are available, which can treat wastewater to either a pumpable, primary or high seco ndary standard.

T he BiolycixTM Filter mimics the intricate natural ecosystems char fuel the deco mposition of debris on a river's edge.

The Biolycix ™ system immediately separates solids from che water in raw sewage and ocher househol d wastes.

The Biolytix system explained.

Whereas conventional systems leave rhe waste in the water to settle ou t in an odourproducing septic stage, or be broken down by mechanically pumping air into che water, che BiolycixTM system removes rhe waste from the water immediately. Worms and ocher soil organisms then convert the waste into structured humus, which acts as an aerobic filte r to puri fy the wastewater for scare of the arc drip irrigation.

BiolycixTM has the patent for ' using the structured humus produced by the breakdown of waste material in wastewater

128 MARCH 2005

water

Biowater™ Advantages Houses on small lots need only standard sewerage plumbing connections to odourless filters. No grease traps are required and In-sink garbage grinders are welcome!

Section of a typical Biowater

as the filter for cleansing the wastewater.'

This cleverly turns the problem (the waste) in to rhe solution (th e humus to filter and clean the wastewater) .

Performance The BiolycixTM Filter was reseed by SAI Global to Australian Standards and achieved certification to AS 1546. 3 in 2003. le also achieved a further certification in 2004 with a higher strength wastewater comprised of domestic sewerage plus 2.5kg/day of food waste from a garbage disposal unit. Tc is che only system approved under chis standard with fo od waste disposal. Although nor currencly requi red under the standard, BiolycixTM has successfully conducted irs own trial to simulate rhe US NSF 40 holiday stress loading res t ro demonstrate its ability to cope with chis common usage pattern.

Biolyrix™ Fileers need just 0. I 6m3/EP treatment volume which makes chem che most co mpact biological waste treatment system available and reflects their order of magnitude improvement in treatment efficiency over aquatic processes.

Strengths • The treatmen t coses just 0.140kWh/m3 a fraction of an aerated treatment system

• No need for expensive or hazardous chemicals, such as chlorine • Low ongoing costs - on ly one annual service • 20 year perfo rmance guarantee offered • Resilient to household chemicals • Shallow excavation requirement of 1550mm • Easy to transport and install • The filtration medium is humus, wh ich is an excellent odour absorbe nt • Can be recroficced into existing septic ranks • T reats food scraps (these need to be pu t through an In-Sink-Erator).

The Biowater™ Decentralised Sanitation Network T he Biowater™ tech nology is a neighbourh ood network of che BiolycixTM Filters. They are connected ch rough a shallow network of smalldiameter pressurised pipes . This exclud es the infilr rac ion probl ems char plague con ventio nal sewe rage co ll ection systems .

The Biowacer™ Netwo rk can be install ed incrementally, without a cost premium to new hous eholds or areas as rhey come onli ne. T his reduces headwork coses.

wastewater Table 1. Macleay Island Biowater™ - a ggregate sam ples, March to Dece mber 04.

Date Sampled

3-Mar-04 10-Mar-04 17-Mar-04 24-Mar-04 31 -Mar-04 7-Apr-04 14-Apr-04 21-Apr-04 29-Apr-04 15-Jun-04 14-Jul-04 11-Auq-04 8-Sep-04 20-Oct-04 24-Nov-04 22-Dec-04

Sample No

S28115 S28187 S28245 S28301 S28336 S28425 S28503 S28524 S28639 S28989 S29235 S29466 S29724 S30087 S30091 S30598 Average

oH

TSS

VSS

BOD

5.5 5.9 6.2 5.1 5.0 6 .0 5.5 5.9 4.9 6.2 6.5 6.6 6.4 6.3 6.3 6.3 5.9

mall 26 7 5 8 5 6 2.0 4 12 2.0 4 7 3 4 2 2 4.9

mall 8 4

mail 11 3 <3 5 3 4 4.0 2.0 ND 5 3 5 2 3 3 3 3.2

4

3 4

4 2.0 3 4 2.0 2 6 3 3 2 2 3.2

Dean Cameron, inventor, in front of the cross-section of the Biolytix Waste Treatment System that he made to show on The New Inventors. By the time the sewage has reached the top layer it is cleaner than septic output in a tank twice its size. By the second

Macleay Island Biowater™

layer it is as clean as secondary waste treatment and by the third stage it is as clean as sand filter output.

Aggregate samples from March to December 04

Instead of exporting primary rreared effluent fo r further rrearmenr, which is the most common practice in the US, Biowarer produces high secondary effl uent onsire suitabl e for drip irrigation without supplementary fi ltration.

Biowarer™ has advanced significantly on rhe best practice decentralised solutions evolved in th e US. An AWIT, Redlands and BiolyrixTM fu nded demonstration Biowarer ™ System was ins talled on Queensland's Macleay Island in late 2003.

Ir rakes sewage from 20 homes an d the Golf Club House and treats it to irrigate the

Sampling and resti ng by Red land Water.

Independent monitoring has confirmed ch ar the process and perfo rmance have nor missed a beat, an impressive start up record fo r any sanitation im plementation. ln rhe Macleay Island trial half of rhe houses and rhe Gol f C lub Ho use have In Sink Erators for food waste disposal. The residents were deliberately nor given instructions on how to use their systems, they were simply rold to use the systems as if they were on sewerage. T here has been no odour or operational problems. T he Biowam·TM system has produced drip irrigation standard effluent without any odour conti nuously - something few centralised plants cou ld gua rantee.

local golf course. The initial results were described by Professor Ted Loudon of Michigan Scare University as " remarkably good " with BiowarerTM outperform ing conventional systems.

COD/Tl mqll 47 39 34 33 31 32 44

29 28 29 43 50 36 35 36 36 35.7

Turbiditv

TN

TP

NTU 29 7 5 12 5 9 3 2 31

mqil 46.4 29.1 42.7 44.6 56.2 40.3 55.3 46.6 ND 61 .2 55.9 62.5 63.6 55.5 49 36.8 50.0

mall 7.9 5.7 3.2 3.8 10.3 7.3 11.4 9 .1 ND 12.2 13.5 16.5 3.3 15.6 15 10.3 9.1

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DO mail 4 0.6 4.3 4 3.9 4.1 4.0 4.1 4.6 2.8 1 1.3 0.1 0.7 2.1 1.1 2.6

The MED U design for the Macl eay Island Project used a conservative 2 mm/day DIR with nitrogen being the constraining nutrient. In rhe fu tu re, some bore log work may confirm whether this loadi ng rare is too conservative, which is likely if it is to irrigate a home orchard or gardens. This assumption is based on establ ished crop nitrogen requirements fo r productive citrus trees of more t han l kgN/yr.

The CRC fo r Waste Management and Pollution Control and G HD engineers have both looked at the economics of Biowarer™ and concluded rhar it can save up to 60% in rhe up fron t capital required for co nventional graviry sewerage. Their independent feasibili ty reporrs a re avai lable on www.biolytix.com or directly from these orga nisations.

The Author Dean Cameron is an invenror and Managing Director of Biolyrix TM T echnologies. He spent 11 years developing the BiolytixTM Filter.

Email deanc@biolytix.com

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Scum, Sludge & other Unmentionables Tel. (02) 6581 0744

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water

MARCH 2005 129

odour control

II

PRODUCTION OF H2S IN SMALL DIAMETER RISING MAINS B Hutchinson, G Hamilton Summary Hydrogen sulfide (H 2S) generation in rising main sewers has long been recognised as a cause of odour and corrosion issues fo r m any water au thorities. Empirical equatio ns from numerous previous studies generally related che wastewater characteristics to the H 2S production rate. The app lication of these race eq uations to calculate che concentration of H 2S p roduced over the length of a rising main have incorporated the assumption chat the H 2 S production race is constant over the length of th e rising main. To dace, verification of ch is assumption h as relied on samples taken o nly fro m the beginning and the end of the risi ng main. This study investigated the relationship between the hydraulic residence time (HRT) of the wastewater in the rising main and the H 2S concentration by 24 hour sampling at various intervals along the length of a 3km long 100mm diameter rising main and a 1km long 150mm diam eter rising main. The results indicated the assumption the H 2 S prod uccio n race was constant over the length of the rising main did not hold .

H ence, these resul ts ind icate furth er research is required in to m odifying H 2 S management strategies to account for the non-linear H 2S production race .

Introduction

Overview of Gold Coast Water's Wastewater System Gold Coast Water's (GCW) sewer network services approximately 185,000 properties with sewerage ret iculatio n infrastructure comprising some 560 wastewater pumping station s and over 2700km of sewer mains. Odour and corrosion in sewer mains have previously been lin ked, amongst ocher facto rs, to hydrogen sulfide (H 2S) generation which is known to occur in rising mains (Bo on, 1995). T hese issues are of particular concern for GCW as approximately 340km of GCW's total sewer system are rising mains. H ence GCW spends annually about $0.5 to $1 m illio n on corrosio n induced sewer rehabilicacion. This is likely to be even an underestimation of the total d amage as it is d ifficult to measure corrosion in undergro und assets since the

130 MARCH 2005

water

damage caused by corrosion may not be visible for several years bm rather o nly evident upon the exposure of th e d egraded infras tructure.

Science of H2S Sulfate (SO/·) is common in domestic wastewater, with sources includi ng p otable water and detergents although the concentration present in domestic wastewater may sometimes be significantly influenced by ground water infiltration or industrial wastewater discharges . (T SC on H 2S, 1989; Boon and Vincen t, 2003).

Under anaerobic conditions, which are common ly p resent in rising mains, SO/· is reduced to H 2S by su lfate reducing bacteria (SRB).

Bacteria such as SRB are known to attach to the walls of rising mains. This retai ns the SRB, which would otherwise be washed out due co their slow growth rate, thereby allowing th e SO/· reduction reaction to occur (Hui sman, 2001). ln a rising main, there is no head space hence on ly a liquid phase is present. In the liquid phase, H 2 S is predom inantly dissolved and causes no appreciable odour and/or corrosion issues.

the gas phase include the wastewater's temperature, p H and H 2 S concentrat ion as well as turbulence (Holder, 1994; T SC on H 2S, 1989). These facto rs have co nsiderable significance for management strategies for minimisation of corrosion and od o ur).

In the rising main, the surface area to volume ratio of is an important factor for considerat io n as this influences the rate of SO/· reduction in a given length of rising main. Ocher factors chat have been identified as in fl uenci ng the rate chat SRB p roduce H 2 S are the wascewater's temperature and pH, wastewater velocity and the absence of inhibitors as well as the co ncentrations of SO/· and the electron donors (biodegradable organics) (TSC on H 2S, 1989).The total amount ofH 2S, as opposed to che rate of H 2S production, has been iden cified as proportional to the hydraulic residence time (HRT) of che wastewater in the rising main (HvicvedJacobsen, 20 02; Boon , 1995; Pomeroy, 1959) .

The rate of H 2S production, and in fact the am ount of H 2S produced , as a fun ction of the HRT of the wastewater in che rising

Sulfide generation in small diameter rising mains is not linear with length.

(H owever, in a subsequent gravity main, a p roportion of the H 2S is transferred to the gas phase (TSC on H 2S, 1989). Not only does an odour problem arise bu t sulfide oxidis ing bacteria, living in the slime predo minantly along the intermittently wetted wall, convert the H 2S to the high ly corrosive sulfuric acid. Factors chat contri bute to the rate H 2S is transferred to

main is indeed of interest as it would provide an insigh t into optimisation of some of the numerous H 2S management strategies currently available.

Empirical Rate Equations Nu m erous empirical equations have been derived to describe the race of H 2 S production (Po m eroy 1959; T hisclechwayce 1972; Boon and Lister

Table 1. Empirical H2 S Production Rate Equations.

Reference

Equation

r, =MxBOD5 x l.07r-io

Pomeroy (1959) 4

8

r., = 0.52x 10- xuxBOD/- xSO/ xl. I39r - io 3

r,

= 0.228xl0-3 xCODx l.07r- 2o 3

r, = I.5x l0- x(COD- 50) Note:

112

x l.07 r -io

Thistlethwayte (1972) Boon and Lister (1975) Hvitved-Jacobsen et al. (1988)

Pomeroy (1959) reported various values for the coefficient M. The coefficient value of 1.5 x 10·3 for the equation by Hvitved-Jacobsen et al.

(1988) applies to domestic wastewater.

refereed paper

odour control 1975, and Hvitved-Jacobsen eta!., 1988) and are listed in Table I. In general, these rate equat ions have related th e H 2S prod uction rate (r,) to the wastewater's temperature and electron donor co ncentration (COD or BOD) and have been of the form of [Equation I ].

r, = constant x electron donor concentration x temperature correlation coefficient [ 1] Where: • r, = H;S production rate (units ofgS m·2h- 1).

• Electron donor concentration has been based on the wastewater's COD, COD5 or BOD5 concentration. Hvitved-Jacobsen et al. (1988) has attempted to take into consideration the biodegradability ofthe electron donor source by including the term (CODs - 50), as the SRB are only able to utilise the readily biodegradable soluble organic carbon as an electron donor source (TSC on H;S, 1989).

• The temperature correlation coefficient takes into consideration the influence oftemperature on the SRB SOi 2 reduction rate by relating the activity ofthe SRB at the wastewater's temperature to the activity ofSRB at a particular reference temperature. With the exception ofThistlethwayte's (1972) equation, this coefficient has been calculated based on the assumption that over a temperature range

Table 2. Selected Risi ng Main Criteria.

Criteria

Rising Main from PS UC09

Rising Main from PS UC10

No upstream rising moin .

No upstream rising main.

2

No RM inject into the RM from PS UC09.

0.56 km before the end of the rising main from PS UC 10 a rising ma in does inject into the main. During the sampl ing session, the injecting rising main was turned off prior lo sampl ing and time allowed to flush the section of the rising main.

3

The PS services a domestic catchment w ith on averaged dry weather flow of 148.5 kl/day.

The PS services a domestic cote hmenl with on overage dry weather flow o f 23. 1 kl/ day.

4

The rising main from PS UC09 is a 150mm diameter uPYC rising main with length of about 1. 1km .

The rising main from PS UC 10 is a 100mm diameter uPYC rising main with a length of about 3km.

5

The alignment of the rising main from PS UC09 followed the a lig nment of the footpath and in one section went through a council owned pork, enabling topping points to be installed in accordance with the criteria.

The validation study did not req uire the installation of as many topping p oints as were required for the initial study. A topping point was installed in accordance with the criteria and the air valve pit was also used as a lopping point.

of5°C - 25°C, the SRB's SO/ 2 reduction rate will double ifthe temperature is increased by lrl'C (Boon, 1995). Thistlethwayte's temperature correlation coefficient also accounts for the influence oftemperature on diffusion rate. For all equations a reference temperature of2rl'C has been used so for

optimal accuracy, these equations should only be applied to situations where the wastewater temperature is within a Jew degrees above or below 2(l'C (TSC on HiS, 1989).

W ith the exception of Thisrle chwayte's (1972) equation , all authors have assu med the SO/· concentration was available in

odour control excess. N ielsen and Hvicved-Jacobsen (1988) have defin ed excess as S = 5 - 15 mg /L (SO 4 15-45 mg/L) . T his was considered a very im porran t assum ption to verify as SO/ · is effectively the substrate that leads to H 2S production.

To date, the application of the rate equations to calculate the concentration of H 2S generated through a particular rising main has involved the calculation of a constant ra over the length of the rising main (T SC on H 2 S, 1989; Boon, 1995; Hvicved-Jacobsen, 2002).

T he assumption of co nstant race has not been verified although ic was considered important for veri ficatio n of earlier beliefs.

Mose previous scudies only measured H 2S production over rhe course of the rising main by raking sam ples of wastewater at the begin ning and end of a rising main (H vicved-Jacobsen et al. 1995; Matos and de Sousa 1992). Th is provides no verification of the assumption of consta nt rate within the rising main.

T his scudy aimed to investigate the relationship between the H RT of rhe wastewater in the ris ing main and wasrewarer's H 2S concentration by sampling at various intervals along the length of the rising main . This would provide an insight into the H 2S concentration profile.

Materials and Method Rising Main Selection and Descriptions Two rising mains were selected for field studies.

Rising mai n selection and justification cncena: 1. No rising main upstream ofthe rising main of interest. An upstream rising main may infl uence rhe characteristics of the wastewater, such as pH and in itial H 2S levels char influence H 2 S levels and generation races.

2. The absence ofrising mains that inject along the sample rising main. T he H RT and composition of rhe wastewater in the rising main of interest would be effected.

3. The rising main is supplied by a domestic wastewater catchment. Industry wasrewarer inputs have the potential to inhibit or enhance rhe production of H 2S. 4. The rising main must be at least I kilometre in length. 1 kilometre, which is a relatively long rising main for Gold Coast Water, was selected to ensure that more than one pump cycle was required for the wastewater to pass through rhe rising mai n and hence greater potential for H 2S production.

5. Easy access to the pump station and the selected rising main. Easy access for 132 MARCH 2005

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Figure 1. Initial study : dissolved sulfide results from Site 5 (8 2 8 m fro m PS UC09 W et W ell) .

insrallarion of rapping points and sampling is a pre-requisite fo r chis project. Regular rapping points necessary to record wastewater characteristics along the length of the rising main.

The rising mai ns from Pu mp Station (PS) UC09 and PS UCl0, both located wi thin rhe H elensvale Wastewater catchment, were selected fo r the ini tial field scud ies and subsequent validation, respectively. Table 2 derails how the selected rising mains satisfied each of the above-mentioned criteria.

T he surface area to volume ratio has been shown to be significant determ inants for H 2S production (Hvicved-Jacobsen, 2002).

For this reason rhe rising main used for the validation had to be of similar diameter to rhe rising main from PS UC09. The rising main from PS UCI0 mer this criteria ar 100mm diameter which is similar to the rising main from PS UC09 at 150mm diameter.

G rab samples taken at the wee well and discharge manhole, for both the rising mains, indicated chat a significant amount of at least 6mg/L H 2S was produced along the length of each of these rising mai ns, validating their selection.

Initial Study Continuous sampling was co nducted along the length of the rising main from PS UC09 over a 29 hour period starring Wednesday 18th February 2004 at 4pm.

Samples were taken hourly from the wastewater entering the wet well and 4 sites along the length of the rising main in order to obtain an ind ication of the diurnal H 2S production pattern. The infl uence of reactions that occur in the wet well, were taken into account in the assessment. A sampling period of 29 hours was selected as a safeguard to ensure chat even if there were some problems at rhe beginni ng of rhe sampl ing session, samples would be obtained over a complete 24 hour period.

The characteristics of the wastewater chat entered the rising main were established by raking samples from a rapping poi nt located in the rising main service pit (abo ut 1m downstream of rhe pumps). The selection of sampling sires and duration of the sampli ng episode enabled sufficient samples to be taken in order to determine how the wastewater's dissolved sulfi de and SO/· levels changed along the length of the rising ma111 .

Validation Study T he validation scudy involved collecting samples along the length of the rising main from PS U C l 0 over a 29 hour period starting T uesday 15th J une 2004 at 2.00pm. A sampli ng duration of 29 hours was selected for the same reason mentioned above.

For the validation scudy, samples were taken of rhe wastewater entering the wet well, 2 sites along the length of the rising main and at the discharge manhole. T he pu rpose of the validation study was to validate rhe resul ts from rhe previous scudy so not as many sampling points were required.

The impact of a small rising main injecting into the UC1 0 main near its end was eliminated by transporting the wastewater to another system. The injecting risi ng main did however appear to have contaminated the fi rst few samples taken from the PS UCl0 discharge manhole so the suspect periods were removed from the analysis.

Analytical Procedures For the initial study, samples were analysed fo r SO/· and dissolved sulfide.

The dissolved sulfide testing methods, however, do nor consider suspended and precipitated sulfides, such as FeS and Z nS, which has been estimated to be half of the total sulfide concentration (Thisclechwayte, 1972) .

refereed paper

odour control Sampl es rhar were to be analysed for dissol ved sulfide were imm ediately fixed in copper-DM P reagen t to prevent oxidation.

T he samples fo r S0 4· 2 analysis were filtered on sire through a 0.45pm filter and rhen put on ice.

In order to confirm rhar rhe preservation methods were adequate for rhe initial study, samples were analysed on-sire within half an hour of rhe sample being taken, later at the Gold Coas t C ity Council (GCCC) Scientific Services Laboratory. Samples analysed fo r dissolved sulfide were analysed using the dissolved sulfide DMP Method (Method Code AS 3550. 1) while samples analysed for SO /- were analysed using rhe SO /- ru rbi dim erric method (Method Code APHA 45 00S04E) . T he on-sire analysis involved rhe use of a Hach Spectrophoto meter to analyse rhe sa mples while a Ca rey Spectrophotometer was used at rhe GCCC Scientific Services Laboratory.

Samples from the validation study were preserved in copper-DMP reagent and analysed fo r dissolved sulfide by GCCC Scientific Services using rhe disso lved sulfide DMP method with in 48 hours of rhe sample being taken. T he initial study's SO/- results indicated that there was no agreement between the onsire and lab resul ts so SO/· resting was not undertaken fo r the va lidation study.

" 11

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,.

,.

,.

,.

"

HRT(hou,s)

Figure 2. Initial study: dissolved sulfide results plotted against HRT.

Discussion As Figure 3 clea rly indicates, rhe dissolved sulfide concentration (which approximates H 2S concentration) increases along rhe rising main (represented by increasing H RT) in a non-lin ear fashion. This is co ntrary to rhe previously accepted belief whereby H 2S concentration as a fun ction of HRT was assumed to be linear (TSC on H 2S, 1989; Boo n, 1995; Hvirved-Jacobsen, 2002).

T he curve generated using th e resul ts from the initial study was used co calculare the H 2S production race (Figure 4). As Figure 4 clearly shows che race is not accurately approx imated as co n stant, a face that has not been reported elsewhere. H ence previously accepted assumption s of constant H 2S production rate over the c ourse of a rising main would over-estimate H 2S levels.

However, after about 7 hours in the risin g main changes in the H 2S production rate may be approx imated as linear bur at H RT

....... . .

I\ Filtration Media

Initial Study

Sand, Gravel, Coal, Garnet, Manganese Greensand

T he H 2S dara showed a strong diu rnal variation (Figure 1).

The H RT of the wastewater was determi ned using a pump draw-down rest and the pump station monitoring data to account fo r diurnal in fl uence.

A relationship between the dissolved sulfide and HRT was determined using a Ma tl ab curve firri ng program to generate a curve of best fir. Th e dissolved sulfide was measured as an approximation of H 2S concentration. Thisrlerhwayre (1 972) has noted dissolved sulfide concentration can be approximated as between 40 and 60% of to tal sulfide concenrrarion (note H 2S is the majo r component of dissolved sulfide). As can be seen in Figure 2 rhe curve of besr fir fined the data points well and accounted fo r over 79% of rhe variation in the dara points (R2 = 0.791 3).

refereed paper

,.,.

6

Results

Validation Study The curve developed from the study at PS UC09 was applied to rhe dara collected from PS UC IO fo r rhe validation study. The curve accounted fo r 84 .61 % of rhe variability in the dara (R2 = 0.846 1) and fi ned rhe dara well (Figure 3).

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MARCH 2005 133

odour control values less than this, a linear rare cannot be adopted.

This data can be used to provide better understanding and therefore ultimately enable more informed management of H 2S issues associated with rising mains.

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Conclusions Odour and corrosion management in GCW's sewer main system is currently a significant cost and H 2S generation in rising mains contributes significantly to both . Previously published equations for the rare of fo rmation of H 2S were derived from measurement of the H 2S concentration and other significant wastewater characteristics at che scare and end of rhe rising main and assumed a constant H 2S production race over che course of the rising main, i. e. a linear relationship of H 2S concentration as a fu nction of HRT. This investigation has shown chis assumption to be inappropriate for the rising mains studied.

This project has given insight into che dynamics of H 2S generation which will assist GCW in further optimisation of H 2S mitigation methods. Future invescigarive work will be undertaken under an ARCLin kage Grant awarded to the Advanced Wastewater Management Centre (University of Qld) with GCW and Sydney Water as co-sponsors.

Acknowledgements Ben Kenny from Gold Coast Water's Scientific Services for his assistance in organising and perform ing the on-site lab analysis. Ocher staff from Gold Coast Water's Scientific Services, in particular Kristy Dernedde and Rex Belt, for their efficient analysis of che large q uancicies of samples.

Ian Johnson, John Beecham, Wayne Organ and John Terry fro m Gold Coast Water for their assistance with the preparation and participation in the sampling campaigns.

Shaun Corrie from rhe Advanced Wastewater Management Centre (The U niversi ry of Queensland) for his participation in the sampling campaigns.

This field work was undertaken by Gold Coast Water as pare of a collaborative research project GCW is currently undertaking with Zhiguo Yuan and Jurg Keller from the Advanced Wastewater Management Centre (The University of Queensland).

The Authors Belinda Hutchinson is a chemical engineer in the Process Audits and Research section of Gold Coast Water,

134 MARCH 2005

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Figure 3. Disso lved sulfide results from the equation a nd each of the studies versus HRT. Hvitved-Jacobsen, T., Jutte, B., Nielsen, P. H . and Jensen, N. A. ( 1988) H ydrogen su lfide control in municipal sewers., In Prec,-eat. in.

Chem. Wat. and Wast. Trear., Proceedings of the 3rd International Gothenburg Symposium(Eds, Hahn, H. H. and Klute, R.), Gothenburg, Sweden, pp. 239-247.

Hvitved-Jacobsen, T., Raunkjaer, K. and Nielsen, P. H. (1995) Volatile Fatty Acids and Sulfide in Pressure Mains, Wat. Sci. Tech., 3 1, 169 - 179.

Matos, J. S. and de Sousa, E. R. ( I 992) T he Forecasting of Hydrogen Sulphide Gas Bui ld-up in Sewerage Collection Systems, Wat. Sci. Tech., 26, 915 - 922.

Nielsen, P. H. and Hvitved-Jacobsen, T. (1988) Effect of sulfate and organic matter on the hydrogen sulfide fo rmation in biofilms of filled sanitary sewers,journal WPCF, 60, 627 - 634.

Pomeroy, R. (1959) Generation and Control of

bhucchinson@goldcoascwacer.com.au; Geoff Hamilton is che Coordinator of che Process Audics and Research section of Gold Coast Water, gham ilton@goldcoascwarer.com.au

References Boon, A. G. ( I 995) Septicity in Sewers: Causes, Consequences and Contain ment, Wat. Sci. Tech., 3 1, 237 - 253.

Boon, A.G. and Lister, A. R. ( 1975) Formation of sulfide in rising main sewers and its prevention by oxygen., Prog. Water Technof. , 7,289.

Boon, A. G. and Vincent, A. J. (2003) Odour generation and control, In Handbook of

Water and Wastewater Microbiology(Eds, Mara, D. and H oran, N.) Academic Press, London.

H older, G. A. (1994) Application ofBiofilm Theory to the Prediction of Sulfide Production from Biofilms, Wat. Sci. Tech., 29, 537 - 543.

Sulfide in Filled Pipes, Sewage ofIndustrial Wastes, 31, 1082 - 1095.

T hisdet hwayte, D . K. B. (1972) The Control of Sulphides in Sewerage Systems, Butterworths, Sydney, Australia.

T echnological Standing Committee on Hydrogen Sulphide Corrosion in Sewerage Works (TSC on H 2S). (1989) Hydrogen

Huisman, J. L. (2001) Transport and transformation processes in combined sewers PhD t hesis, IWH at the Swiss Federal lnscute of Technology (ETH), Zurich.

Sulphide Control Manual Septicity, Corrosion and Odour Control in Sewerage Systems,

Hvicved-Jacobsen, T. (2002) Sewer Processes Microbial and Chemical Process Engineering of Sewer Networks, CRC Press, USA.

Melbourne Metropolitan Board of Works, Melbourne.

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refereed paper

ACTIVATED SLUDGE DIFFUSION FOR ODOUR CONTROL V Barbosa, RM Stuetz Odour con trol by activated sludge diffusion (ASD) is a techniq ue char has been practised for som e 30 yea rs, bur has limited accep tance as an effective odo ur abatem ent process co mpared to rradirio nal rrearmenr technologies. Pilot plant reactors were used ar rwo wastewater treatm en t plants in the UK to evaluate th e effectiveness of hydrogen sulfide (H 2S) ASD as an effective odour abatem ent process . H 2S removal rates of up to 99 - I 00 % were ob tained for inl et H 2S concentration of 25 to 175 ppm, with no noticeable in crease in odour concentration as measured by di luti on olfactomecry. The impact of H 2S d iffusion on wastewater treatment performance was margin al, with little effect o n nitrifications o nce the process had stabilised and microbial biomass had accl imatised. It was concluded that ASD is an effective technique for the removal of H 2S odou rs and that the process should be m ore widely accepted as a dualpurpose system for odour control.

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Figure 1. Schematic Representation of a Dual Role Activated Sludge Process. performance derai ls from wastewater treatmen t p lants using ASD fo r odour control are limi ted (Bowker and Burgess, 200 I). The effect that ASD for od orous compounds has on nitrificatio n of the

Up to 100% removal of H 2 S can be obtained.

Background The release of odorous co mpounds fr om wastewater treatment faci lities can have an impact on a local population causing annoyance, resulting in complaints to che process operators. T he odorous components from wastewater t reatment planes, which are rhe major odour stimuli comprise hydrogen sulfide (H 2S), organic sulfur compo unds and nitrogenous compounds (Vince nt and Hobson, 1998). Odorous emissio ns can be managed by preventing their release into the atmosphere using a range of physical, ch emical and biological odour abatement systems.

The activated sludge process has been used in a dual-role (Figure 1) for the crearmenr of wastewater and degradation of odorous compounds for som e 30 years. AS d iffusion (ASD) offers economic benefits with regard to maintenance, space and operation, com pared to rradirional odour treatment processes, such as chemical scrubbers, bio-scrubbers, bio-rrickling fil ters and bio-filrers. Although most published literature (Bielefeldt et al., 1997; Bowker, 2000; Bowker and Burgess, 2001) has shown excellent odour rem oval (particularly for H 2S) by AS D , operational and

fund amental studies in applying ASD as a dual purpose system fo r odour abatement and wastewater treatment and summ arise rhe (i) ab ility of an activated sl udge system to remove H 2S based odours and (ii)

wastewater and o n the microbial population is also nor well documented , making the techniq ues nor widely ap plied.

determine the impact of H 2S diffusio n o n the wastewater treatment performance, in terms of traditional wastewater p aram eters (BOD, COD, SS and NH 3 removal) and changes in rhe m icrob ial community .

This paper will evaluate rhe current scare of k nowledge and discuss some recent

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water

MARCH 2005 135

odour control Recent Experimental Trials Laboratory, pilot-scale and full-scale trials at an operational wastewater treatmen t plane were used to establish whether activated sludge diffusion is an effective odour abatement technique fo r the removal and treatment of H 2S based odours. Seven activated sludge types were used to study the so rpcion behaviou r of sludge's to different H 2 S concentrations (5, 25, 50 and 75 ppm) (Hardy et al., 2001) .

Pi lot-scale studies, utilising a 60 L aeratio n rank, were used to study che effects of varying concentrations of H 2S diffusion on activated sludge treatment and odour abatement using range of AS plant configurations, consisting of fine and coarse bubble diffusers and different aeration tank depths (Barbosa et al. , 2004). The pilot planes were initially located at the C ranfield University sewage works for the different configuration trials, after wh ich they were located at Bedford sewage works fo r fullscale trials using the optimum AS configuration. Detailed description of pilot plane operating conditions and analysis are described in Barbosa et al. (2004) .

Activated Sludge Removal Performance T he absorption capacity of di ffere nt activated sludge's (nicrifyin g sludge, nicri fying sludge with iron , industrial sludge and non- industrial sludge-pilot plane) are dependent on its wastewater source (Figure 2). Industrial and iron based sludge's generally have a higher H 2S absorption capacity than domestic sludge, chis difference in H 2S absorption is largely dependent on the inorganic composition of the wastewater, but also on the sulfide preexposure of the sludge to enable and maintain a higher proportion of sulfu r degrading bacteria within the bacterial population, suggesting chat the source of the sludge is a significant component in determining whether a AS plant would be suitable for ASD for odour control.

Activated sludge trials at two operational wastewater treatment plants were used co determine the impact of different design configurations (fine and coarse diffusers and diffuser depth i.e. call or short aeration tanks) on the performance of ASD fo r odour control. T he results showed chat although all combinations of configurations gave 85- 100% removal of up to 25 ppmv H 2S, a combination of fi ne bubble diffusers in call or short tanks gave the best resulcs with regard to H 2S removal (94 and 99%, respectively) , suggesting chat diffuser depth is not as important as diffuser bubble size (Barbosa et al., 2002). Diffuse r depth was however, important in the configurations

136 MARCH 2005

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with coarse bubble di ffusers, with 85% removal being obtained fo r a short tank and 99% fo r a call tank configuration (Barbosa, 2004) .

Additional long-term H 2S ASD trials were undertaken using the fi ne bubble diffusers in shore aeration ranks configurarions using 25, 75 and 150 ppmv and variable impact load of up to 150 ppmv using 25 ppmv as the continuous H 2S baseline. T hese trials were operated fo r up to 6 months: an example of che H 2 S removal performance for continuous H 2S diffusion at 25, 75 and 150 ppmv is shown in Figu re 3. The resulcs show that 99- 100 % removal efficiency was obtained for all concentrations. Odour concentrations measurements by dilution olfacco metry were also carried out to determine whether there was any increase in total odour emiss ions owing co che H 2S diffusion at 25, 75 and 150 ppmv (Figure 4) . No noticeable increases in odour concentrations were observed throughout the trials (Barbosa et al., 2004) .

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AS D trials were used to evaluate the impact of H 2S diffusion on wastewater treatment performance by analysing standard wastewater characteristics (NH 3, nitrate (N0 3) and sulfide, biological oxygen demand (BOD 5), mixed liquor suspended solids (MLSS) chemical oxygen demand (COD) and SO/ - (Barbosa et al., 2003).

Barbosa et al. (2003) showed chat a marginal impact was observed in B0D 5, COD and N H 3 removal. N itrification reduction occurred during the commencement of H 2S diffusion; however chis affect decreased once the system had stabilised and the microbial population had acclimatised co the changed sulfide co ncentration in the wastewater. Similar

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odour control observations of improved system stab ili ty with accl imatisation were observed for the variable AS D trials using H 2S peak of up to 150 ppmv (Barbosa et al., 2004). MLSS concentrations have also been fo und co va ry during conti nuous H 2S di ffus ion trials (Figu re 5) chis variation is most likely related co changes in the wastewater feed, as the MLSS was observed co decrease and then increase with increasing co ncentrations of H 2 S. The increase in MLSS concentration however, did occur duri ng the highest dosing period, which may suggest the biomass is accl imatising co the H 2S (Barbosa et al., 2003).

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Biomass acclimatisation Recent studies have given evidence of che importance of an acclimation period for ASD for odour treatment. Figu re 6 shows the results of H 2S sorpcion studies fo r unaccl imacised and acclimatised activated sludge from an ASD trial (Hardy et al., 200 I). The pre-exposure of rhe activated sludge co low H 2S concentrations (5 ppm over 2 months) enab led the activated sludge populations co maintain a sufficient concentra tion of sul fide-degrading bacteria

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thus permi tting degradation of the H 2S when the concentration was increased co 50 ppmv during the H 2S sorprion. T his suggests chat the H 2S removal capacity of differen t types of activated sludge can converge after a period of acclimatisation, and may be irrespective of th eir initial

degradative abili ties as suggested in Figure 2.

Microbial studies using PLFA, DGGE and real-rime PCR were used co evaluate changes in the microbial biomass chat may reflect these improvements in ASD due co

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MARCH 2005 137

odour control acclimatisation (Barbosa, 2004) . PLFA analyser showed no major shifts between either groups of AS microo rganisms with time or with increasing H 2 S dosing, however, when exam ining individual PLFAs amounts, it was observed that alJ microbial groups showed an increase in the amounts of PLF As from the beginn ing to the end of the trial , with the increases always being larger in che test bioreactors. The PLFA results indicate that common AS species are not inhibited

by H 2 S and suggested chat individual species, possibly sulfur oxidising bacteria such as Thiobacilli co uld be increasing within the biomass. DGG E and real-time PCR were used to quantify the level S-degrading bacterium , Thiobacillus thioparus in the AS bioreactors (Barbosa, 2004). DGGE analysis showed that T thioparus was more prominent in the H 2S AS D bioreactor, chis was support by the real-ti me PCR which showed a marked increase in the population of T thioparus in spice of a decrease in the H 2S ASD biomass concentration , compare to the control. These findings suggest that as well as acting as effective bioscrubbers fo r H 2S treatment, H 2 S ASD is acting as a bio-augmentation technique for the sulfu r degrading bacteria in order to improve che biodegradacion of the su lfur compounds.

Conclusions • Hydrogen sulfide removal by activated sludge diffusion is effective and che degree of removal depends on the origin of the sludge.

• H 2S removal efficiency up to 100% ca n be obtained with no noticeable increase in ocher odoro us emissions from the aeration process.

• The impact of H 2S diffusio n on wastewater treatment performance was marginal, with little effect on nitri ficatio n once the process had stabilised.

• Acclimation of the sludge to H 2S improved its ability to remove peak loads.

• Activate sludge diffusion is a promising odour abatement process that should be more widely accepted as a dual purpose treatment system.

Acknowledgements This work was support by the UK's Engineering and Physical Sciences Research Council and Anglian Water Services (UK) with technical assistance from SRI and IGER.

138 MARCH 2005

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Authors Vera Barbosa was a PhD student, School of Water Sciences, Cranfield Un iversity, UK. Dr Richard Stuetz is a Se nior Lecturer, Centre for Water and Waste Technology, The University of New South Wales, email: r.stuetz@unsw.edu.au, www.odour.unsw.edu.au

References !Es0y, A., 0 degaard, H. and Bentzen, G. ( 1998). The effect of sulfide and organic matter on the nitrifi cation activity in a biofilm process. Wat. Sci. Tech., 37(1), I 15-122.

Barbosa, V.L., Brookes, A.W.R. , M orton, S., Burgess, J.E. and Sruerz, R.M. (2002).

Activated sludge diffusion for cost effective biological treatment of odours from wastewater t rearmenr works. In: Proceedings

of WEF Odours and Toxic Air Emissiom 2002 Speciality Conference, Albuquerque, NM, USA, 28 April - 02 May 02.

Water Advertising To reach the decision-makers in the water field, you should consider advertising in Water Journal, the official journal of Australian Water Association.

For information on advertising rates, please contact Brian Rault at Hallmark Editions, Tel (03) 9530 8900 or email brault@halledit.com.au

Barbosa, V.L., Dufol, D., Blanco, E., Callen, J.L. and Sruetz, R.M. (2003) Impact of act ivated sludge H 2 S diffusion on wastewater nitrification. Proceeding 9th

/WA Large Wastewater Treatment Plant Conference, Praha, 1-4 September, 8pp .

Barbosa, V. L. (2004) Biological Treatment of HiS by Activated Sludge Di/fusion. PhD thesis, Cranfield University Barbosa, V. L., Burgess, J.E. and Sruetz, R.M. (2004) Activated sludge diffusion : ls ir an effective odour trearmenr process?

P.-oceeding Enviro 04 - Odour conference, Sydney, CD-Rom I I pp.

Bielefeldt, A.R., Stensel, H.D. and Romain, M. (1997). VOC t reatment and odour control using a sparged shallow activated sludge reactor. WEFTEC Proceed ings, V. I Research: Municipal Wastewater Treatment, Alexandria, USA. Bowker, R.P.G . (2000) . Biological odour control by diffusion into activated sludge basin. Water Science & Technology, 4 l (6), 127-132.

Bowker, R.P.G . and Burgess, J.E. (2001 ).

Activated sludge diffusion as an odour control technique, I n: Odow~ in Wastewater

Treatment: M easurement, Modelling and Control (R.M. Sruetz and R-B. Frechen eds.) !WA Publishing, New York.

Buisman, C. , Ijspeerr, P., Janssen, A. and Letting, G . ( 1990). Kinetics of chemical and biological sulfide oxidation in aqueous solutions, Water Research, 24, 667-671 .

Hardy, P., Burgess, J.E., Morron, S. and Stuetz, R.M. (200 1) Simultaneous activated sludge wastewater treatment and odour control. Water Science & Technology 44(9), 189-196.

Vincent, A. and Hobson, J. (I 998). Odour Control. CIWEN monographs on best practice No. 2. C hartered Institution of W arer and Environmental Management, London, 3 I pp.

MICROBIAL CONTROL REDUCES SULFIDE R Chandler Abstract

Glenpark Drive Sample taking point____

As microbes are responsible for the breakdown of wastewater ro its constituent pans, th e ab ility to control microbes offers the prospect of radically altering the way we manage wastewater systems in rhe future.

One applicatio n is to virtually eliminate the bacterial slime that generates H 2S in sewers.

This paper is a brief summary of a rrial using the proprietary Bioso l™ BR X2 product conducted in a component of the Yarra Valley Water system in Melbou rne.

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Introduction In 1996 the first breakthrough in mi crob ial control ca me when scientists recognised char bacteria have to commu nicate with one another in order co form and maintain biofilms or slime co mplexes. This commu nication occurs at the cellular level and elicits a range of respo nses from the bacteria. T hese respo nses range from the resusci ration of dormant planktonic bacteria to the fo rmation or disintegration of biofilms.

Encouraging reports of the trials of a new product.

Today microb ial control is an emerging technology and is one of the fastest growi ng b ranches in b iological science. It has huge potential with applications ranging from medicine, to food preservation , agriculture and food prod uction, water supp lies and wastewater systems. In fact its applications will occur where ever bacterial control is required, even to things like tooth paste to control plaque and u nder-arm deodorants.

Odour and Corrosion Control in Sewage Catchments I t has long been recogn ised chat about 99.9% of malodorous gasses formed in sewage catchments are fo rmed in th e biofilm or slime complexes found in the submerged portions of the pipes and in pressure mains.

The removal of these biofilm co mplexes would in theory remove 99.9% of odour production at its so urce.

Without th e sulfides being generated , sulfuric acid could not be formed in the airspace and s ulfuric acid corrosion of

Creek

km

McKerral Rd.

Figure 1. Trial Layout. infras tructure would no t occur. This would substan tially increase infrastrucm re asset life as shown by Pomeroy's Corrosion Model (Bowker et al, 1985) . I r was the investigation of chat theory that led to the development of Biosol® products, which have proven effective in the control of odour and co rrosion in wastewater systems both in Aust ralia and internationally.

Varro Valley/South East Water Odour Control Trial During 2004 Biosol® conducted a trial, jointly sponsored by Yarra Valley Water and Sou th East Water on a componen t of the Yarra Valley Water sewage system. The trial looked at a range of parameters bur chis article is restricted to H 2S gas odour control and corrosion reduction.

The trial sire was located on a part of th e Brushy Creek sewage catchment shown in Figure 1.

Biosol® produce BRX2 was dosed at t he J umpi ng C reek pu mp station at rates varying fro m 7 ppm to 4 ppm across the trial. Odour generation was meas ured at t he end of the Kerry Road Pump Station p ress ure main at McKerral Road, using Ap p-T ek, OdaLog H 2S data loggers. Yarn Valley Water coordinated the placement and removal of the OdaLog at M cKer ral Road. T hey also coordinated the download ing o f the data fro m the OdaLogs fo r Yarra Valley Water and Biosol, weekly.

An average 94% reduction in H 2 S gas levels was achieved across the tria l, which indicated that in frastructu re corrosion would be sign ificantly reduced. OdaLog

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water

MARCH 2005 139

odour control instruments were set to measure H 2S gas levels at minute intervals throughout the trial. This data was used to quantify the average reduction in H 2S gas shown in the graph (Figure 2). Analysis of temperature impacts (using Pommeroy's equat ions) on the reduction in sulfides has shown chat this could only account for a maximum 40% reduct ion in the sulfide readings, against the 94% shown in these results.

Removal or disintegration of the b iofilm complexes in the catchment pipes should reduce the oxygen demand by bacteria in the catchment and the d issolved oxygen levels should rise. The graph (Figure 3) shows increasing levels of dissolved oxygen as rhe trial progressed which supports reduced microb ial oxygen demand. The increasing levels of DO also ind icate a substantially reduced ability to gen erate su lfides in the system and therefore reduced infrastructu re co rrosion from su lfur ic acid.

Dissolved oxygen levels were measured from water samples co llected weekly at Glenpark D rive. WSL Labo ratories were comm issioned to undertake char work.

Yarra Valley Water reported no beneficial or adverse impacts on sewage treatment at rhe Brushy Creek treatm en t plant during or after the trial. No

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Figure 3. Redline increasi ng levels of DO . measurable impacts at rhe treatment plant were anticipated as the dilution factors were too great.

Research is continuing at both the laboratory and fi eld level with ongoing trials under way or planned with South East Water, Yarra Valley W ater and ocher water au thoriti es .

The Product Biosol® prod ucts are the result of contin uing Research in Microbial Control in wastewater systems. T hey are liquids

"More UFRVs for your money, and better quality water"

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water

2/06/04

Time (Days )

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140 MARCH 2005

--,-l

containing natu ral ly derived, specifically targeted microbial con trol agents or the synthetic derivatives of such agents . These agents can be used to accelerate or retard m icrobial activity. The liquids are generally injected into sewage catchments at pump stations in the upper catchment. T he products are neither toxic nor hazardous and require no cap ital-intensive infrastructure.

Conclusion Infrastructure corrosion is an underestimated expense that costs millions of dollars annually. Odour is a political cost chat req uires immed iate attention . Current Biosol® research is ind icati ng that by min im ising odour, infrastructure corrosion is likely to be red uced to a point where there is a net return o n th e investment to the auth ority from using th e technology.

Acknowledgements Biosol would like to acknowledge the assistance given by both South East an d Yarra Valley Water with this trial.

The Author Ross Chandler, M.Env.Sc, is co-author of Victoria Felix, Improving Rural Land with Trees. Past Research Awards. "BHP Landcare Research Award (Vic) for Revegetation R esearch , Waste Management and Environment "Award of Excellence in Waste Management Tech nology" (1991) , for M edical Waste T echnology. Biosol® trademark was established in 200 1 after 1 1 years research in microbial control in itially in land systems and then wastewater.

E mail: ross@biosol. net

Reference Bowker R, Sm ith J, Webster N, 1985 " Design Manual Odor and Corrosion Control in Sanitary Sewage Systems and Treatment Plants" United Stares EPA

WATER SUPPLY AND SANITATION IN A VIETNAMESE VILLAGE T Wrigley 2000), and by the World Health Organization's seeps to accelerat e che healch ga ins of safe water to th e remaining population by improved treatm e n t and sto rage of water at che household level (Sobsey 2002).

This study was pa re of the AusAID funded Cuu Long Rural Water S upply and Sa ni tation Project which was to reduce poverty and ro improve che overall living standards and health in the Cuu Long (Mekong) delta fo r 500,000 rural poor by ass isting chem to gai n sustained access to improved water and sanitation services.

Abstract Low technology water supply, treatment and sanitation techniques were reviewed in a Vietnamese village in rhe Mekong River Delea as part of an AusAID Project to reduce poverty and to improve che overall living standards and healch in the Cuu Long (Mekong) delta fo r 500, 000 ru ral poo r. l t was fo und char the daily use of alum or PAC coagulation fo llowed by hypochlorite dos ing of canal water in 200L cerami c jars provides a high level of treatment fo r drinking water at a household level in a rural setti ng. T he low levels of bacterial co ntamination found in drinki ng water after dosing is likely to have buil t up a level of immunity within these populations.

Fish ponds are an appropriate form of sa nitation in low lying areas of the Mekong Ri ver Del ta even though their use is banned by Government decree. This may be because of the risk of Clonorchis infection within th e communi ty as a result of earing fish fro m these ponds. Detailed in vestigation is required of the likel ihood of this disease within the co mmunity.

Introduction Infectious agents associated with diarrh oeal disease are transmitted chiefl y through the faecal-oral route. A wide variety of bacterial, viral and protozoan pathogens excreted in the faeces of humans and animals are known to cause diarrhoea. Many of these are potentially waterborne transmitted through the ingestion of co n cam inated wa ter (Leclerc et al.

2002).

Accordi ngly, a number of interventions have been developed to treat water. T hese include (i) physical removal of pathogens (e.g. fil cracion, adsorption and sed imentation); (i i) chemical treatment (e.g. assisted sedimentation, chemical disin fection and ion exchange); or (iii) heat and ultra violet (UV) radiation. Because of the risk of recontami nation (Clasen and Bascable 2003), interventions to improve water quality also incl ude seeps to main tain the microbiological

Fish pond toilet on the Mekong River Delta.

Canal waters coagulated by alum or PAC, then hypochlorite, are reasonably safe.

quali ty of safe drinking water, such as piped distribution, residual disinfection and improved sto rage.

T hese efforts are expected to receive addi tional priority as a result of the United Nation's commitment to reduce by onehalf of the 1.5 billion people without sustainable access to improved water, one of the United Nation's Millennium Development Goals (United Nations

To assist the project in chis mission, it was proposed ro investigate the microbial drinking water quality of a several households within a Vietnamese community in che Mekong delta, Vietnam.

If the study established char the prese nt method of dosing canal or river water with alum or poly aluminum chloride (PAC) or PAC with hypochlorice at th e ho usehold level, was providing acceptable drinking water quality, chis techn ique could be co nsidered as Table 1. Water Testing Parameters. another option to assist the very poor Microbiologicol Physical Chemical in rural situations.

T he aims of chis study were to Totol coliform Turbidity Pesticides investigate the changes in microbial Faecal coliform pH Aluminum water quality, pH, aluminum and E.coli Salinity turbidi ty values of fi lled 2 0 0 L clay Streptococci jars after treatmen t with alum , or Vibrio Cholera poly alum in um chloride (PAC) or PAC with hypochlorice over a 24 hour peri od.

Table 2. World Health Organization (W HO) Water Quality Guidelines for Rural Drinking Materials and Methods Water Supplies ( 1998).

Testing was carried out at che E. coli count per 100 ml Classification Chanh Hoi Commune, Vinh Long Province. This village was located 0 Conforms to WHO guidelines next to a canal from which much of 1-10 Low Risk its domestic water supply was drawn.

10-100 Intermediate Risk Domestic water use was al so High Risk 100-1000 supplemented with rainwater >1000 Very High Risk gathered during che wee season and

water

MARCH 2005 141

overseas projects stored in jars. Jars were either made of clay or concrete and were either 100 or 200 L capacity. The alum and PAC plus hypochlorite were mixed in a full jar of water before water was removed from rhe jars for drinking or cooking within 3-4 hours of mixing.

The following experimental procedure was undertaken.

• Three treatments and a control were used: • Rock alum (daily cost 1- 2 cents) • A commercial package of Poly aluminum chloride (daily cost 3 cents) • A commercial package of Poly aluminum chloride with hypochlorite (daily cost 5 cents) • Two (2) 200 litre jars were used for each treatment.

• Water samples were collected from all eight (8) jars at the following times post treatment - 1 hr, 2 hr, 6 hr and 24 hr.

• Water samples of canal water were also collected at O hours.

• Water samples were collected using sterile glass pipettes and bottles.

• The following parameters were measured and/or analysed on each collected sample (Table 1).

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30

20

- - Fbly Aluninium Oiloride with Hypochlorite - b

Time (hrs)

Figure 1. Changes in turbidity after alum dosing over a 24 hour period.

-+- 0:mtrol - a Changes in total coliform colonies (per 100 mls) after alum dosing over a 24 hour period R:x:kAlum- a

2500 G)

R:x:k Alum - b

C

0

0u

1500 e g

Results and Discussion Changes in turbidity Turbidity of water from the canal was relatively low (10 - 12 NTU) (Figure 1).

By contrast Wrigley (2002) recorded turbidity levels in the Tonie Sap River, Cambodia up to 135 NTU. The canal was connected to the river system, though the exchange with the river was restricted by a road and small outlet pipe. Daily tidal pulses provided some exchange to the canal. These levels rapidly decreased after alum dosing to less than 5 NTUs after 2 hours. There was no decrease in the control NTUs after the 24 hour period.

After one hour, turbidiry levels in the jars with crushed alum and crushed alum and chloride were 1-2 NTUs. This water was

Rock A lum - a

-¼- R::>ly Alurrinium

011oride - a

0u 1000

s 0

I-

-+- R::>ly Alurrinium 011oride - b

500

-+- Fbly Alurrinium 011oride with f-+/pochlorite -a

0 0

5

10

15

25

20

30

- - Fbly Alurrinium 01loride with f-+/pochlorite -b

Time (hrs)

Figure 2. Changes in total coliform numbers after alum dosing over a 24 hour period.

Sampling was performed in April, at the end of the dry season, so water in the canal and associated river system had lost much of its suspended wee season load. T he canal banks were generally vegetated and in areas where there was bank erosion, banks of

essentially clear. Jars using rock alum had slightly higher turbidity levels at 1 and 2 hours of 4 -7 NTUs. After (6) six hours, all treated jars had turbidity levels between 1-2 NTUs. T here was little change in turbidity of the control jars over 24 hours.

Table 3. Percentage of samples for each treatment which meet WHO guidelines for E.coli/ 100ml from rural drinking water supplies.

Treatment

Rock Alum· a

Rock Alum - b

PAC - a

PAC· b

PAC with Hypochlorite · a

PAC with Hypochlorite · b

After Boiling of all treatments

75

50

75

25

100

100

100

0

0

0

0

0

0

0

0

0

No risk % (0 E.coli/ l 00mls) Low risk% (l-10 f.co/i/l00mls) Intermediate risk % (10-100 E.co/i/lO0mls) Control (E.co/i/100 mis)

142 MARCH 2005

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25

50 25 75 0 l 00% in high risk or very high risk(> l 00 f .co/i/1 00mls)

overseas projects --+- Control - a Changes in faecal coliform numbers (per 100 mls) after alum dosing over a 24 hour period

Fb:kAlum -a

.,, 2000 . - - - - - - - - - - -- - ---, Cl)

C:

-Âź- Fb:kAlum - b

.2

o 1500 0

...

--+- A:lly Alurrinium

E

g

Oiloride - a

1000

0

~ A:lly

A lurrinium Oiloride - b

0

500

IO

Cl)

0

- - A:lly A lurrinium

Cl)

u.

0

10

20

Qiloride w ~h 1-+jpochlor~e -a - - A:lly Alurrinium Oiloride w ~h 1-+jpochlor~e -b

30

lime (hrs) A mixture of poly a luminium chloride and hypochlorite being added to a jar of canal water.

water hyacinth were tethered co provide bank protection.

T here was little power boar activity in the ca nal water because of the roadway restriction and the large amount of water hyacin th within the ca nal. T he hyacinth would also restrict wind mixing encouraging sedimentation of suspended materi al.

Changes in Total Coliform Numbers T he reduction in coral coliform numbers was high with a 90 - 95% loss within the first hour (Figure 2). Low numbers remained over the 24 hours in all treated jars. The jars treated with poly aluminum chloride with hypochlorite all recorded zero bacterial numbers except one jar on one single occasion.

Wrigley in 2002 also concluded that alum dosing significantly reduced coral coli form numbers in experiments undertaken in Cambodia even at high turbidities (> 100 NTU).

Changes in Faecal Coliform Numbers The level of removal of faecal coliform was extremely high with 95 % removal efficiency for the bulk of the samples tested. The jars treated wi th po ly aluminum chloride with hypochlorite all recorded zero bacterial numbers except for one jar on one single occasion (Figure 3).

Changes in E.coli Count E.coli count in this experiment were reduced by 95% throughout the sampling period. There were no E.coli recorded in the jars with hypochlorite dosing (Figure 4) . E.coli numbers are used by the World Health Organization co determine the quality of drinking water (Table 2).

Figure 3. Changes in faecal coliform count (per l 00 mls) ofter alum dosing over a 24 ho ur period.

A summary of water quality after dosing is presented in Table 3.

Seventy five per cent of the samples co llected showed that E.coli! 100mls in the jars after treatment showed a ' no risk' profile (0 E.coli/100mls) i.e. the water would be considered co be of very good quality fo r drin king (World Health Organization Guidelines for Rural Drin king Water Supply, 1998).

T he PAC hypochlorite jars showed a ' no risk' profile. Rock alum had a 50 - 75% no risk profile while PAC was had a 25 -75 % no risk profile. The remaini ng profiles for both rock and PAC were "intermed iate risks". All control values were high or very high risks.

Changes in Cholera vibrio Numbers No Cholera vibrio numbers were fo und in either the raw or treated wate r sa mples Changes in pH values pH values remained relatively unchanged after alum dosing, indicating a r elatively high alkalinity in the canal wate r. There was an initial drop of up to 0.6 pH units to 6.4 after 1- 2 hours. T he pH of the jar water then rose between 0.3 to 0.5 units and stabilised sligh tly lower than the original pH of the raw water.

Changes in aluminium concentrations Alum inum concentrations in the jars were elevated when compared w ith the control canal samples. T he Vietnamese drinking water criteria of 0.2 mg/L was

--a- Control - b

Changes in E.coli colonies (per 100 mL) after alum dosing over a 24 hour period R:x:k Alum - a

1400 R:x:kAlum- b

1200

cl

'i: 0 0(.)

8 Lil

- - Fbly Aluninium

800

Olloride- a

600 - - Fbly Aluninium

400

Olloride- b

L .,

200

0 0

.

10 Time (hrs)

-+- Fbly Aluninium Olloridewith H,,pochlorrte -a

20

30 -

Fbly Aluninium Olloridewlth

H,,pochlortte - b

Figure 4. Changes in E.coli cou nt (pe r l 00ml) after alum dosing over a 24 hour period.

water

MARCH 2005 143

overseas projects exceeded by the 2 hrs aluminum concentrations of most rrearments. These concentrations then decreased to rhe drinking water criteria within 6 hours except for the jars dosed with rock alum (see Figure 5).

Though these concentrations above the drinking water cri teria, there appears be n o or little risk of chronic health effects by ingestion of treated drinking water.

0.6

.s C:

0

0.4

~

C:

Filly AlurTinium 011oride • b

0.3

8

-llf- Rock Alum- a

E

The WHO suggests that these is confusio n and m isinformation surround the health risks associated with aluminum in drinking water. The link between neurological effects and aluminum in drinking water is particularly elusive because of the high intake of alumin um from foo d (average adul t intake 5.0 mg/day: WHO, 1998), which obscures rhe effects of aluminum ingested in water from additives such as alum. However, after a recent, derailed study, the WHO concluded char: "Aluminum has nor been demonstrated to pose a health risk to healthy, non-occupationally exposed humans. There is no evidence to support a primary causative role of aluminum in Alzheimer's disease, and ... there is insufficient health-based evidence to justify revisions to existing WHO guidelines ... [and] inadequate scientific basis for setting a health-based standard for aluminum in drinking water." (WHO, 1997: p. 11).

<

Overall, rhe results showed char the b ioavailabiliries of aluminu m from food and alum-treated water were similar; suggesting chat the al uminum from alumtreated drinking water does nor have unusually h igh bioavailabilicy.

Calculations suggest char alu minum from alum-treated drin king water would contribute less than one per cent of aluminum to our body burden of aluminum over a lifetime.

144 MARCH 2005

water

b

Rlly AlurTinium 011oride - a

""Jg

::s ·1: 02

The amount of alumi num in the blood and urine of 29 healthy volunteers aged between 26 and 76 was analysed while they were on a strictly controlled diet and drinking alum-treated water.

I

'a, 0.5

Review of health implications of trace aluminium in drinking waters

This WHO conclusion was confirmed by the Australian CSIRO Centre for Advanced Analytical Chemistry which completed a study to determine the amount of aluminum absorbed by rhe body from alum-treated drinking water as compared with char absorbed from food. T h e amou nt of aluminum in drinking water is small compared with that in food, but rhe concern was char it might be in a more bioavailable or readily absorbed form.

- - Filly AlurTinium 011oridewrth l-lfpochlorrte a - - - Rlly AlurTinium Oiloride wrth l-lfpochlorrte -

Changes in aluminium concentration over a 24 hour period

.E

- - Rock Alum- b

::s

-

0

4

12

8

16

20

24

Control a

Control b

Time (hrs)

Figure 5 . C hanges in aluminum concentrations (mg/L} after alum dosing over a 24 hour period.

Fish pond toilets and the risk of

Clonorchis A review was u ndertaken of fish pond toilers within rhe community and their impact on public h ealth. The use of fis h pond toi lers is banned by government decree in Vietnam. However on a practical

level there are no ocher toiler substitutions which have been adap ted by communities in the M ekong River delta.

These toilers are communal and functiona l and are situated near the village.

These ponds also support a valuable fish populatio n which is a part of the d iet of the

THE LIFE CYCLE OF CLONORCHIS SINENSIS (THE CHINESE OR ORIENTAL LIVER FLUKE) Worms mature and produce eggs

.,,

+-V""' -

Metacercaria "excysts" in small intestine and imm ature worm migrates into bile du cts of the liver

t

H uman infected by eating raw or undercook ed fish

~

Eggs passed 1n feces into water

...

'· ,

~

.

Cercariae penetrate the skin of a fish , "encyst" in fi sh muscle as metacercariae

.

-

.. '

-1;- ..,,

.\..... ,

Cercariae exit from snail Miracidi um hatches from egg, infectes first intermedi te host (a snail) l.

-j ,

4-1 _t

! :·

(Parasites and Parasitological Resources)

Figure 6. The life cycle of the liver fluke Clonorchris sinensis.

overseas projects community. A nu mber of fish ponds also receive other livestock wastes e.g. pig's wastes washed down from pens.

T he ponds act as small maturation ponds in a tropical environment. There is a large d ie-off of pathogenic bacteria in these ponds particularly as a result of predation and ultra-violet radiation. The ponds are isolated and may leak to the canal and in doing so provides another disinfectio n ba rrier for canal water. However even with these ongoing disinfect ion processes, fish ponds may still be a significant source of pathogenic bacteria fo r canal waters.

The greatest risk co public health appears co be from the likely presence of the liver fl uke Clonorchris sinensis. T he life cycle of the fl uke is shown in Figure 6. Liver fl uke disease is common in South Ease Asia as a result of ingestion of poorly cooked fish.

The cyst of the liver fluke is still viable in chis fish after cooking and infects the human hose. The fl uke can live for 25-30 years in their human hoses damaging the liver and bile ducts and can result in death.

Conclusions Alum or po ly aluminum chloride (PAC) or PAC with hypochlorire dosing of canal waters at a household level in the Mekong delta significantly reduced the numbers of potential pathogenic bacteria. No bacterial numbers were fo und to be present after boiling of these dosed waters.

Ir would appear chat chis form of drinking water treatm ent is sufficient to mai ntain general good health within the

ocher team members, Chris T rechewey, Greg Thomas and Vince Keogh all provided support and encouragement. Fi nally, to all the Vietnamese staff in the office and the people of Commune Chanh H oi, the support they provided was terri fic and I trust chat chis study may be of some assistance co chem.

The Author

Dr Tim Wrigley is an adjunct Senior Lectu rer in Natural Resource Management in the Department of Geograph ical Sciences and Planning, University of Q ueensland, Email: rim_wrigley@b igpond.com Flocculated canal water after dosing in drinking water jar.

co mmunity. Gascro-intescinal disease events would need co be confirmed to support chis claim. There is also the probability chat residual bacterial numbers provide a high level of immunity for people who drink these waters.

These actions at the house hold level appear to deliver sustainable public heal ch benefits withi n the cultural setting of communities within the Meko ng River delta.

Acknowledgements This project could not have been completed without the wonderful assistance of my Vietnamese counterpart, Vu Dieu Ly. Ray Miles - Team Leader from Coffeys and

References C lasen T & Basrable A (2003) Faecal contaminarion of drinking warer during collection and household storage: the need to extend protection to the poinc of use. j oumal of Water and Health 1, 109- 115.

Leclerc H , Schwarczbrod L & Dei-Cas E (2002) Microbial agencs associated with waterborne diseases. Critical Reviews in Microbiology 28, 371-409.

Sobsey MD (2002) Managing ~\later in the

Home: Accelerated Health Gains fi'om Improved Water Supply.

(WHO/S DE/WSH/02.07) WHO, Geneva.

Unired N at ions (2000) United Narions Millennial Declarat ion. General Assem bly Res. 55/2 ( 18 September 2000).

World H ealth O rganizarion ( 1998) - Guidelines for drinking-water quality, Second edition, Volume 3, Surveillance and con trol of community supplies, Geneva.

Wrigley T (2002): Low cost warer treatment in the Mekong Basin. Water 21, IWA London .

NEW COMPACT PHOSPHATE MONITOR The NEW Ecocech Compact Reactive Phosphate Monitor was originally developed by Monash University, but has now been redesigned and commercialised under licence by Melbourne-based Ecocech.

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T he analyser ach ieves a very high sensitivity with detection limits fo r reactive phosphate of less than 1 pg/L and a typical response time per measurement of only 20 seconds. This is due to the use of rapid sequenced reagent injection in combinatio n with, a mulci-reAection Aow cell.

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Priming Circuit

Hutr19ntConctntrado n 1 Rncllng

I

1

r-....,--, r __ uI __ 7 I 1--~ L - 'l!!!'!.- ...1 Illlc:nproc•sor Il ~1<,-;,I ~ ----~

r-----~

I

I

I

I

:

L!!;;__.K-,t_____J

Schematic of the Ecotech Compact Reactive Phosphate Monitor

T he mulri-cell holder provides the user with a choice of a 28 mm round cell (longest path length of any hand-held) and a 16mm round cell.

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146 MARCH 2005

water