Convention '89 Canberra
Vol. 16, No. 1, April, 1989.
Official Journal AUSTRALIAN WATER AND WASTEWATER ASSOCIATION
CONTENTS My Point of View
Preliminary Findings on Phosphorous Input to the Great Barrier Reef Lagoon: Evidence from Geochronological Indicators
Robyn William s...
Association News President's Report .. ·It Seems to Me .. .
IAWPRC News .. . Industry News Convention Coverage Chairman's Message Opening Address ... Keynote Speakers .. Dr Michael Flynn Award .. The Social Program .. Pictorial Roundup Trade Exhibition Convention Papers Information Technology in the Water Industry - A New Realism Financial and Program Management P J. Guj .. The Oil-from-Sludge Technology; A Cost-effective Sludge Management Option T. R. Bridle, C. K. Hertle and T. Luceks ... Odour Control on the Latrobe Valley Outfall Sewer P J. Dack and P R. Nadebaum.......
P.O. Box 460, Chatswood NSW 2057 Facsimile (02) 410 9652 Telephone (02) 410 9653 Office Manager - Margaret Bates
BRANCH SECRETARIES Canberra. ACT M. Sharpin, G.H . & D.. P.O. Box 780, Canberra 2601 (062) 498 522
FEDERAL PRESIDENT Timothy Smyth , GHD Group Director, Telephone (02) 690 7070
EXECUTIVE DIRECTOR Peter Hughes, Telephone (02) 410 9653
FEDERAL SECRETARY Greg Cawston. Telephone (02) 29 0236
FEDERAL TREASURER John Molloy, Telephone (03) 615 5991
14 15 16 16 17 18
New South Wales Mrs S. Tonkin,Hill , Sinclair Knight & Part. 1 Chandos St .. St Leonards, 2065 (02) 436 7166
G. B. Jones and F. R. Tirendi .......
New Developments in Water Disinfection by Ultraviolet Light
D. Comar ...
Biological Nutrient Removal Calendar ........ Book Reviews ... Plant, Products, Equipment ..
6 6 10 11
24 The Captair1 Cook Fountain jets high over Lake Burley Griffin. The nation's capital hosted the 1989 Biennial Convention. Report within.
South Australia A. Townsend . State Water Laboratories, E. & WS. Private Mail Bag, Salisbury, 5108. (08) 259 0244
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Winnellie, NJ. 5789 (089) 89 7290
WATER A pril, 1989
Convention '89 Canberra MARCH 6-10, 1 9 8 9 - - - - - - - - - KEYNOfE ADDRESS:
Information Technology in the Water IndustryA New Realism D.BEAL INTRODUCTION This convention is part of what has proved to be a valuable dialogue between Wessex Water and the Australian Water Industry. We both face very similar pressures and the exchanges both here and in the United Kingdom have been very helpful in focussing our minds ~n issues and developing our plans for the 1990s and beyond. The pressures now facing us are intense and increasing. In effect, we are being challenged by the community we serve. We are expected to respond to environmental and consumer pressures for better service and value in a political environment that demands a radically different approach. Because water issues have moved up the political agenda, the way we are responding is in the full glare of the media. The effect of this pressure has been a concentration of the corporate mind on what is really important so that the real objectives have come into sharp focus. It is an opportunity to clear the decks of the unnecessarily complex procedures. In the context of this broad debate I want to consider specifically the increasingly expensive role of information technology. If we are shedding labour to improve cost effectiveness, are we sure that the cost of information technology is justified? I think we need to look very carefully at this sacred cow to see how necessary it is. Are the benefits offset by the additional costs and the time and energy required to manage this overhead? More importantly, how can the apparent power of information technology genuinely help us as we face the challenge of the 1990?
HOW RELEVANT IS INFORMATION TECHNOWGY? To serve customers who are geographically dispersed with assets that are also dispersed requires a continuous flow of information around the organization. It always did. In the past, an elaborate hierarchy passed information from the plant operator at the most remote site up to the "management" and the major decisions were based on a collation of many such reports. We are an industry built on regular reports and records. The service provided is too important for us to simply drift along. As demand has grown, so progressively larger organizations have developed. Large cities and large unified schemes for providing water are generally inconsistent with small-scale operations. Meeting the demands of sometimes millions of customers has become a very complex task. To collect and deliver water to the tap and to collect and treat sewage involves interaction between a wide range of activities. Managing and controlling the whole process has required a massive amount of manual information processing which, in turn, has led to management via a large bureaucracy. Because bureaucracies are labour intensive, they are a very expensive overhead when labour costs are high. They are effective when business objectives and the management rules rarely change. But management by paper-based administrative systems progressively ossifies unless subject to regular searching review. Just how complex and ineffective became apparent when data models were constructed based on documents in circulation. When the path of the data found on the many forms was followed, it was often found to be unnecessary or pointlessly duplicated. What were simple activities had become surrounded by an unnecessary amount of data. However, bureaucracy does not sit easily with a political and economic environment which is becoming progressively less stable. It is not surprising therefore that, faced with the need to process high volumes of data and to respond to changing circumstances, the power and speed of electronic information technology has been seen as a savior. 22
WATER A pril, 1989
David Beal - Director of Information Systems J#ssex Water, Bristol, UK.
What should be questioned is the real need for all that information.
PROMISE UNFULFILLED? In line with almost all other industries, our spending on computing has been increasing since the early 1970s. Computer-based systems have migrated from financial to operational activities, from batch mainframe processing to real-time control via telemetry. However, the costs and constraints imposed by the earlier manpower intensive approach seem to be still present but in a different, less comprehensible, form. Those departments responsible for providing such services using computing, communications and telemetry are often seen by their users as a cause of frustration and cost. Surveys across many industries, including the public utilities, reveal users who often regard the service they receive as expensive, delivered ., late, unsuitable and inflexible. When all costs and systems are considered, including both operational control and data processing, approximately 5% of turnover is currently spent in this area. However, the level of processing activity has been increasing at around 20% to 40% per annum during the 1980s in most major water organizations. We seem to have added an extra, expensive ingredient and a new separate breed of employee. In spite of this, there appears to have been a net benefit. Generally, overall efficiency has improved and there have been reductions in manpower and overall costs. What is remarkable is that those directly involved know how inefficient we have been in using the power of information technology. It is difficult to establish the success rate for system developments but if we honestly draw on our own experience or depend upon the results of the few surveys that have been published, then a 50% achievement of the total original goals for systems can be regarded as optimistic. The hope that the next major development from a supplier using a new generation of technology will be the panacea always seems to be rekindled. In mitigation, it is difficult chasing a moving target when the technology on which it is based is also moving. Such is the spread of computing now across most of our organizations that it is unrealistic to move forward consistently on all fronts. The result is a mix of generations of technology which make the highly integrated solutions now technically possible unachievable for those of us in the real world. We simply cannot afford to throw away technology which is not yet at the end of its useful life. However, many of us have survived by virtue of tolerant senior management, a constant re-examination of the issues and a flexible and pragmatic approach. The full promise is unfulfilled but that, regrettably, is often the case.
LEARNING FROM EXPERIENCE How do we build on all this accumulated experience, often painfully acquired, when challenged by major changes to the framework
that contains our industry? Privatization in the United Kingdom is part of a trend now to be seen around the world. New economic and political rules are proposed that appear to radically change the cri· teria by which the industry is judged by introducing the competitive pressures of the market place. Information technology should provide the flexibility to adapt effectively to the changed circumstances. Regrettably, it can also be a very real and expensive constraint. There certainly has been a spate of investment in information systems across the UK industry with a number of announcements of multi-million dollar programs. In some cases, looming privatization has clearly been the spur to correct the deficiencies of the past by belatedly installing telemetry, for example, and realizing the benefits that have been potentially available for some years. Developing both a corporate and an information technology strategy that will be effective under these circumstances is not easy. Simply buying the latest offerings from a major supplier or even buying packages that seem to work elsewhere does not guarantee the benefits - as we all know to our cost. This interaction between technology and management is not easy to understand or manage practically for the outsider, be he supplier or external consultant. Our industry has its own culture and values and so does every organization within it. l'n practice, the text book approach based upon specifying business needs and objectives, identifying critical success factors and relating the information technology and business strategy is a time consuming exercise that often produces a fat report but rarely does it seize the commitment and imagination of the whole organization. In the past the external consultants have come and they have gone - but usually we have been left not quite sure that we are better off for the experience. Success is so difficult to measure when it takes many years for the plan to work through, during which time almost certainly a major change will occur which will move the goal posts. I think we are all older and wiser. Today the consultants' view is sought but rarely is it slavishly followed. Increasingly, we consider the experience of others but we work it through in the terms of our own organization, generally with someone who will not walk away at the end but will be committed to see it through. With so many unknowns in the water industry equation we might be tempted to sit on our hands and just stay with the strategies we embarked upon during the 1980's. In many areas I do not think we can afford to do that. They are inconsistent with the goals we now have. Let me provide some examples.
AVOID LARGE SCALE INTEGRATED SYSTEM FOR OPERATIONS For many corporate systems such as accounting or billing the economics of scale provided by the mainframe make real sense. As we have endeavoured to provide systems to support operational activities such as work planning and customer relations, the results have not always been so satisfactory. This is because operations are g~nuinely dynamic and flexibility is essential. If the computer constrains the response to an emergency or inhibits organizational change, then the system is firmly on the failure side of the 500Jo success rate I mentioned earlier. Many of you have sought the same holy grail ~f a package solution in this area. Surely, all utilities must be faced wtth the same need, we have all said. In practice, many are under development but very often we have overrunning into real problems with both performance and cost. The flexibility required leads to over-design of systems which in turn has led to high hardware and operating and maintenance costs. The hardware suppliers want us to go down this route but, as far as I can see, they have difficulty in providing proven solutions. Implicit within this large-scale integrated approach is usually a very large corporate database. Conceptually, this sour1:ds fine but in practice the overheads in terms of hardware and operation are always larger than planned. These solutions seem to make sense for the banking, insurance and travel industry. Where there is real growth in the market large pro~its are made which can be utilized for further development. In our mdustry the financial issues are different. I would suggest we adopt the same design philosophy that w~ h~ve when designing a pumping station, a treatment works or a ?istnbution system. We design-in flexibility and resilience by breakmg the problem down into modules that can be linked. .
AVOID SUPPLIER DEPENDENCE That design philosophy is part of our culture and values. We know that if the service depends upon a single link or source we must plan for the day when it fails. Similarly, if we design our systems so that in practice we depend upon one supplier for hardware and software, in some way we have lost control of our own destiny and consequently control of our costs. This is a difficult area but one of concern to many of us. I do not malign IBM or DEC or anyone else as, in general, they are highly responsible but their objectives and ours are not directly coincident. We can endeavour to adopt international standards but, in a commercial world, progress here is slow. We can track the standards and attempt always to have a competitive involvement of two or more suppliers. There is no easy answer and, faced with the awesome marketing machines of the big suppliers, it is a tough issue.
FACING UP TO THE 1990s The design and use of information systems must reflect the organization and the objectives they support if they are to be relevant and effective. Where a centralized approach has been adopted in an organization where significant power is in fact decentralized or distributed to its operating divisions, the result is always stress and dissatisfaction with the service. Similarly, if an organization is primarily interested in operations and the systems development staff are only comfortable with financial and commercial systems, so they become isolated. In the past this has led to telemetry being developed separately from commercial systems and a lack of corporate focus. In the same way, I suggest the system strategy for the 1990s must reflect very accurately the issues we will face. The strong financial and competitive pressures now looming are already bringing into question some of the accepted truths of the 1980s. We can speculate about how water industry systems will be characterized in the 1990s. • The emphasis will move towards the communications network to link the locations where data is created and used with the corporate data stores. The network will provide the flexibility and resilience needed by a responsive and probably rapidly changing organization. Homeworking and portable data communications are breaking down 1 the traditional conventions. • Systems development will be driven by the market served by the organization. Customer contact systems, the customer database, supporting new value-added services to customers and the expansion of the organization will have priority. • Corporate systems such as telemetry, accounting, digital mapping will be under continuous pressure to reduce their substantial contribution to overheads. Many major developments currently planned will be threatened when their long term effect upon the profit and loss ' account is identified. • De facto standards will emerge and it is an opportunity to simplify under financial pressure. The luxury of each organization developing its own solutions for every application will disappear. Organizations at similar stages of overall development and of similar style will share or barter the system modules or experience. • Priority will be given to systems that support managing the business as a whole. Management control will be exercised via high level management information systems that automatically collect information from the diverse range of installed systems so that senior management can be presented with regular reports in an easily digestible form . This approach is consistent with high levels of delegated authority and diversity of systems.
SURVIVAL OF THE FITTEST We face an uncertain future. Failure to respond to the increasing needs of our customers carries a very high price. In the United Kingdom the Government are even prepared to name the price. Failure to meet standards published in the Customers' Charter will require the Company to refund £5 ($10) to each affected customer. The information technology used by our industry has not been notable for its low cost and flexibility. In future, the successful organization will not necessarily have to be big or small or be able to afford the latest technology. It will have to have a very clear idea about where it is going and be prepared to use information technology if - and only if - it helps it get there. WATER April, 1989
CONVENTION -'89 CANBERRA This paper shared the Michael Flynn Award at the 13th Federal Convention, Canberra 6-10 March, 1989, and came from the Management and Administration area.
FINANCIAL AND PROGRAM MANAGEMENT P. GUJ FINANCIAL MANAGEMENT IN THE CONTEXT OF PROGRAM MANAGEMENT A 'program' can be defined as a set of planned activities designed to best fulfil a water authority's primary service objectives through purpose-based management and resources allocation. As human and material resources can be quantified using their physical or corresponding cost units, technical and financial management (Fig. 1) are inseparable, at least as concerns planning, executing and controlling. Accounting skills become more crucial for measuring, monitoring/controlling, reporting and auditing in compliance with financial legislation during program implementation. In addition, levels of service must not only be acceptable but also be met at the lowest long-term cost to the community. This, in combination with increased inter-agency competition for financial resources, has in recent years elevated 'living within one's own means' and 'providing value for money' to the rank of powerful and more explicit supporting financial objectives. The concern of management is now clearly directed to ends rather than means, while at the same time meeting the constraints imposed by the commercial realities of the industry, and the continuing need to administer public funds with a high degree of probity. It is now seen as essential to set targets, and performance indicators, which measure the ends - the degree to which program objectives are met and to support these with relevant efficiency indicators. The effectiveness indicators demonstrate whether the industry delivers the goods; efficiency indicators show the costs. The design of and agreement on good indicators has not been easy but the approach is important since there is little merit at being very good at performing certain functions, which in-depth process analysis shows to be not important, or even unhelpful, in the achievement of program objectives. To facilitate management, programs, which are generally very broad in scope and reflect government's and/or an authority's priorities, can be dis-aggregated on the basis of significant characterizing elements into district sub-programs and projects. This will influence the structural evolution of organizations away from traditional functional towards program-based, generally matrix, lines. Programs defined on the basis of government's priorities can transgress departmental boundaries requiring "inter-departmental" task forces for their co-ordination/ management. These are inevitably the most difficult to resource and manage. By contrast programs relating to clearly identifiable service objectives (eg supply of water, sewerage, etc} can in many cases be successfully implemented by "intradepartmental" structural units, which are realistically capable of being assembled and resourced. Aside from formal requirements to do so, many authorities have already arranged their financial management and information systems, and to some degree their structures, along program lines at least in those areas where there were distinct advantages to do so.
Anolysts or Perlormonce / ond Cosl ........... Executing - - - - Mont lortng/Conlrol 1tng Accounting
Figure 1. Financial management process . . 24
WATER April, 1989
P. Gu}, PhD, MBA, Manager Financial Planning and Revenue, Water Authority of Western Australia. After completing a degree in Geology at the University of Rome in 1963, Dr Gu} was awarded a PhD in Geology by the University of Cape Town in 1970 and in 1984 a Master of Business Administration (MBA) Degree by the University of Western Australia. Dr Gu} is a member of the Finance and Corporate Management Committee of the Phil Guj Australian Water Resources Council and of the Urban Water Research Association of Australia.
PROGRAMMING AND STRATEGIC PLANNING Corporate and strategic planning have, by and large, already directed the setting and specification of long-term goals and objectives and the formulation of programs for their achievement more towards: • outcomes (ie the economic, financial and environmental/social impact of planned activities on the community), • outputs (ie number of services, sales volum·es etc), and • optimum combinations of resources inputs, rather than to broad functions as it has generally been the tendency in the past. Performance has in the past been judged more in terms of adherence to budgets than of achievement of program objectives at the lowest possible cost to the community through sound investment decisions. Budget adherence is the line of minimum resistance as long- to medium-term objectives, and related programs and financial plans are harder to formulate in realistic terms. This is in part because they are largely dependent on and sensitive to external and generally more uncertain factors (eg the state of the economy, inflation, interest rates, demographic trends, etc), in part because the political process, while . professing support of medium- to long-term solutions in practice commits resources very much on a year by year basis. The break up of programs into annual budgets, by contrast, exposes decision-makers to a lower and more comfortable level of uncertainty as managers have a greater ability to predict, if not to control, the essential factors influencing budget compliance, at least those which are internal to the organization (Fig. 2). Strategic planning thus relies on environmental analysis and applied economics, while budgeting relies more on management information systems, and particularly good, EDP-supported, cost accounting practices (Fig. 3). Program formulation should ideally entail a series of integrated, economically rational investment decisions involving both creation of new assets and management of existing ones, based on stringent economic evaluation of the 'whole-life' performance of each investment. Depending on its significance, cost-benefit, risk, environmental/ social impact, and at a minimum, financial (discounted-cash-flow) analyses should be required to justify a proposal. Economic analysis and appraisal of an authority's capital works proposals is an essential pre-requisite for rational allocation of that specific authority's financial resources. It does not determine the relative merit of that authority's programs vis-a-vis those of other State instrumentalities. It is indeed a matter of where one draws the boundary. The state-wide evaluation, analysis and appraisal of all proposed capital works programs against consistent economic cost-benefit cri-
LONG TERM ENVIRONMENT
Go a ls and llbJecllv111
lnlerna\ f actor.
PIDnninQ Dn d Programming SHORT TERM ENVIRONMENT
j Ant1lysls or Cost and Perr orman ce
Manag emen t
Externa l Factore
- - ~ Dudget
~ - - - - Tronsocllons
T Au d it
Figure 2. Envirornenlul Anoly~ist Applied Economics [
PL ANN I NG
lnv es lrnent Decision Financ ing Decision
Cash Flow Do se d
Ac co unling Forrnul
I'll Do sed
BUD GE1 < RECURRENT
[ EXEC UT I ON] Figure 3. Realisation of programs/ projects.
teria, (on the general lines as now required by the State lreasury for all large projects carried out by government instrumentalities in NSW) can be an important tool for maximizing the economic welfare of the State. Such a procedure of course still leaves the question of appropriate funding for water authorities unresolved. Given that an authority's programs are actually considered worth pursuing, financial (DCF) analysis of the actual cash flows associated with a project, as contrasted to broader consideration of socioeconomic benefits and costs, is a fundamental step for determination of whether each individual project can justifiably be funded internally within the context of the generally limited physical and financial resources of a water authority or whether some external contribution should be sought. Financial viability will depend on: a) the adequacy of the additional revenue generated by the project (if any) to offset: • its operating and maintenance costs, • interest, or better, the required target Real Rate of Return (RRR) (irrespective of whether a public authority dividend (PAD) may be payable or not), and • replacement cost depreciation; essential if the related service is, as it is generally the case, to be provided in perpetuity. If accrual accounting is used, these three elements are the building blocks of a sound pricing policy which will meet the long-run averagecost of service provision. In many cases, this is a good proxy (Dixon 1988, in preparation) for the long-run marginal-cost which is regarded by economists as more appropriate for optimal resource allocation. The use of a carefully designed two-part tariff can reconcile appropriate economic price signals with the necessity to raise adequate revenue for business viability. The past influence of historical accounting measures in planning and decision-making has, during inflationary times, led to considerable under-recovery of cost and consequently to inadequate provision for the ultimate replacement of aging assets as well as intergenerational inequities. b) willingness of government (both State and Commonwealth) to make good any shortfall by way of appropriate specific up-front grants
or annual subsidies for non-commercial proj,cts considered to provide broader community benefits. c) willingness on the part of the communities benefiting from specific projects to contribute in cash or by co-operative effort to supply machinery and labour for the construction of the facilities. The displacements of costs which would otherwise have been incurred, improve not only the economics of these generally non-viable projects, but also communication and rapport particularly with the rural sector. d) adequate headworks and other contributions by developers preferably negotiated on an individual development basis to reflect any acceleration of the normal 'frontal' development and/or specific financial characteristi,;s of the extension required. e) contributions by major consumers, mainly mining and other industrial users, under the terms of negotiated special agreements requiring payment of true cost including: • a capital contribution both up-front for ccinstruction of facilities required immediately and; notional for future augmentation of existing schemes brought closer in time by their committing spare capacity. Notional capital contributions may, subject to stringent guarantees, be annualized. • the operating and maintenance costs of delivering water, which for limited life (eg: mining) operations need not include replacement cost depreciation. In general, special agreements reduce risk, and, because of their flexibility, provide great opportunities for innovation and entrepreneurship. Projects with evident commercial potential may lend themselves to joint ventures with private industry and/or other government agencies to spread risk, make good use of limited resources, create synergism, attract expertise etc. The secret for success is simple and explicit agreements and high negotiating skills. f) the degree of inevitable cross-subsidy that may be considered tolerable among different classes of customers. Use of internal funds, (sourced from depreciation after principal repayments) and, from profits (appropriated to reserves) or alternatively of borrowings, will be financially justifiable only up to the present value of any expected future operating surplus. Political realities however generally prevent such a degree of financial rationality. Irrespective of funding, proposals should be based on a wellinformed and common perception shared by planners, designers, builders and operators of what the project is to achieve. Considerable cost-savings and clearer undeittanding of possible level of service/cost and risk/ cost tradeoffs can be derived from forward looking 'value engineering studies' aiming for the most innovative and cost effective solutions to current needs. 'Asset management', by contrast, must ensure that maximum value is obtained from those past investments which do not yet warrant replacement by more recent technology, without being influenced by or recriminative about past decisions, philosophies and practices. Objective decisions must be based on clear knowledge of the con, sequences of progressive increases/ decreases in expenditure in specified activities. This knowledge is helped by techniques such as 'zero base' and 'priority allocation of resources' budgeting; these are designed to tap experience and know-how from management to the coal-face. The times of 'over constructing' with unreasonably high and costly safety margins are rapidly going. With more commercial attitudes comes rationality, ie a better understanding of one's risk profile, the search not only to maximize value and to reduce risk, but also the willingness to trade a reasonable level of risk for value.
PROGRAM EXECUTION AND BUDGETING Irrespective of any formal requirem.ent for adoption of program management, the spontaneous current focus on outcomes/ outputs has in general shifted the organizational orientation of public utilities from appropriation-driven to program-appropriation driven. Consequently budgets are evolving from: • traditional government budgeting, broken into line activity items, to . • performance and/or responsibility budgeting, broken into organizational sub-units and/ or business units and linked to their specific objectives, to • program budgeting, linked to the broader objectives of the organization. Provided programs are largely defined in an 'intra-departmental' context, a budgetary hierarchy can be easily established such that WATER April, 1989
sub-programs and projects, essentially defined for best monitoring, control, reporting and auditing, in a form compatible with accounting rather than economic conventions, can be rolled up into their corresponding programs (Fig. 4). Sub-programs must be established on the basis of a matrix of important characterizing elements (Fig. 5), which may include for example: a . the nature of the main services provided, eg water, sewerage, drainage, irrigation, and management of water resources, b. geographic, climatic and human characteristics of the regions serviced, if they bear a significant influence on and differentiate the type of activities to be carried out eg relatively densely populated, high rainfall rural, and scarcely populated, arid, pastoral environment, etc.. c. down to individual large integrated networks to single small town schemes. If broad programs/ sub-programs are established along the above lines, compliance with annual budgets have a better chance of indi_cating whether generally multi-year programs are progressing satisfactorily in less capital-intensive industries. In industries characterized by high capital-intensity and long asset lives, however, annual budgets will not provide a meaningful indication of satisfactory program progress and funds may have to be committed Âˇand their use monitored on a longer time (three to five year) basis. Unless the structure of the organization lends itself to objectiveorientated allocation of resources and collection of costs, difficulties will also be experienced in attempting to reallocate conventional budget items to simulate program budgeting, particularly indirect costs. A program (Smith, 1988) requires not only that its objectives should be clearly identified but also its accountable manager and the allotted resources. Hence implementation of program management may be more suited and lead to better results in the achievement of certain objectives rather than other. It makes considerable sense not to implement program management in a blanket fashion but maximize potential returns by selective and progressive implementation. Adoption of program management will inevitably generate the need for considerable initial and continued changes in the structure of some organizations and in the financial delegation and controls imposed both internally and by government. The crucial question is to what degree program management can be feasibly implemented if programs reflecting government priorities are defined in a way that involves more than one authority/ department, eg economic development of a given region. It would be a potentially-critical mistake to undervalue the degree of difficulty which may be encountered in structuring and effectively resourcing matrix organizations let alone interdepartmental ones. Much can be learned from the experience of the resources sector which for many years has used program budgeting in combination with joint venturing to comply with the various Mining Acts and the need in multi-business enterprises for specific project-related information and accountability to satisfy more than one set of shareholders. Compatible with the difficulties which may be encountered, it is therefore desirable to attempt to satisfy the share-
WATER RESOURCES MANAGEMENT
111111 11111 1111111 111111 11111111 111 11111111 111 11111111~111111111111111111111111111111111
SUB - PROGRAMME
111111 11111111 111111 11111 111 11111111 111 11111 111111111111111111111 11111111111111111 1111111111111111111 11111
OF SOUTH WEST RESOURCES ETC
Figure 4. Hierarchical program based budgeHng. 26 WATER April, 1989
I . Pure Programme Based Budget
Metro North West Goldfields Central South We s t etc .
2. Mixed Programme Based and Responsibility Budget
Metro North West Goldfields Central South West etc.
Figure 5. Water authority of WA sub-program matrix.
holders' or government's wish to know what the use of their money has produced and whether they have been getting value for money.
BUSINESS UNITS AS A PRE-REQUISITE FOR PROGRAM MANAGEMENT ' Even if programs are defined strictly in an intra-departmental rather than an inter-departmental fashion certain specialist functions cannot be realistically devolved to program teams if their services are of a type normally shareq by most groups in an organization, without running the risk of being less rather than more cost-effective. It is preferable to set these functional sections up as business units selling easily quantifiable services to client branches, ideally at prices competitive with private enterprise offering similar services. Transfer prices are a powerful productivity tool in that client branches are forced to recognize the cost of and to re-assess the need for services previously freely available in-house. Business units, which are uncompetitive, are forced to lift their productivity to avoid â€˘ pricing themselves out of business. Problems arise with potentially efficient business units which are unable to reduce personnel or to liquidate under-utilized assets due to past over-investment. Under such constraints, the short-run marginal cost or their competitor's price, whichever the highest, should be charged (as a substitute for cost-based prices) to encourage demand for in-house services until full capacity is approached. At full capacity, contractors/ consultants from outside the Authority should in general be used for peak demand in preference to investing capital in additional in-house facilities with a risk of being not fully utilized. This approach would result in the lowest overall cost for the service to an authority. Any surplus which a business unit is capable of incorporating into acceptable transfer prices represents an increase in productivity by the authority as a whole. There is little point in setting up a fully accountable business unit if its management is to be excessively constrained in targeting the unit's revenue, eg regional branches adopting centrally determined prices and tariffs. It is counterproductive to set up expenditure centres as if they were profit centres unless unnecessary constraints can be gradually lifted .
TOWARDS GREATER PRODUCTIVITY Conventional productivity drives will over time, as organizations become leaner, show diminishing returns.
Further productivity improvement will only be possible through greater employees' participation in the process of planning changes. In this way employees will more readily see the merit . and inter- . nalize the need for adapting work practices and multi-skilling to the demands which program-orientation and the realities of the 1990s will impose. · The organizational culture must be pervasively re-orientated towards a more commercial view: sensitive to costs and responsive to customer needs at all levels. In-depth reviews of what one does, why one does it, and above all, of how one goes about doing it, such as • functional reviews • process modelling studies • reviews of levels of service • priority allocation of resources • value engineering • risk management • human resources planning, etc. which many authorities already successfully implement are very good complementary tools in program management. All these techniques, which are facilitated by powerful EDP-based Management Information Systems, will highlight: • · the factors to which individual costs (fixed and variable) are sensitive and where economies of scale can be achieved • the constraints under which water authorities are currently compelled to operate. The more commercial culture should also be legitimized by government replacing many existing "public service" type constraints or interventions with appropriately broad guidelines and processes. Reluctance to "free" the authorities often stems from the argument that they are not operating within a competitive environment in which market forces would necessarily compensate for reduced government control. It may just be a matter for government to loosen its grip on the provision of private goods (eg water and wastewater services) for which market conditions may be created and/or simulated, while retaining a greater control and funding role for public goods (eg floodplain management, regional drainage, water resources assessment and management, pollution control, etc). The trust implied by greater independence from regulatory and political constraints therefore, must go hand in hand with increased market exposure of: • business units to private sector competition, • allocation of water resources by way of auctioning and transferability of certain water rights, and developments by public participation and joint ventures. • treasury functions, ie ability to issue notes and stocks, to borrow and invest in financial markets in one's own right rather than through a central state agency. Having to go to the public not only for borrowing but also for raising equity funds and having to negotiate prices and charges would impose on water authorities, no longer closely identifiable with government, much of the financial market discipline experienced by private enterprise and therefore could be a part of measures to increase accountability and performance. If an authority borrows from a central state agency its level of debt does not affect the rate of interest charged as lenders rely on the security of the State. This provides a fallacious rationale for: • weakening the significance of an authority debt:equity ratio, • inadequate levels of self-funding, • excessive borrowing in some instances for poorly justified, politically inspired projects, • excessive cross-subsidies, and at the limit, • the payment of cash dividends to government unrelated to cashbacked profits, but somewhat loosely linked to unrealized (and frequently unrealizable) holding gains due to the effect of inflation
A.W.W.A. 13th Federal Convention 1989 PROCEEDINGS - 132 PAPERS Management/A dministration : Distribution Technology : Treatment Technology : Science and Environment : Public Health 28
WATER April, 1989
on certain authority's assets. By contrast in the UK water authorities are allowed to retain their profits to self-fund capital works and to repay debt. Government will, however, still derive substantial cash benefits from their eventual privatization, through sale of their equity to a very willing public.
CONCLUSIONS • Financial management should be focused on the achievement of program objectives, ie on outcomes, outputs and optimal combination of inputs, not merely the explication of functions, administration and the compliance with regulatory legislation. • A program management approach suits certain types of operations more than others, hence implementation should focus first on the areas of potential early returns and less costly climbing of the learning curve. • Financial management is not the exclusive realm of accountants but an integral and cross-disciplinary part of everyday management, permeating the culture of the organization in a capillary way. • Plannii:ig, programming and decision-making should be based on applied economic principles, using cost-benefit, risk and DCF analyses, taking into account the "whole life"effects of proposals/ investments not exclusively their annual budgetary impact. • Selection of projects on the basis of cost-benefit analyses can lead to economic rationality and maximization of the welfare of the State. It does not, however ensure financial viability and an authority's capacity to fund justifiable projects. • Use of internal funds and/or borrowing for a project is justified only up to the present value of future operating surpluses. Any further expenditure should be sourced from beneficiaries' contributions and participation, government subsidies and preferably only limited cross-subsidies. • " Business units" led by truly accountable managers are a prerequisite for allocation of indirect cost in successful program budgeting. • Successful program management/ budgeting will generate the need for regrouping of teams and allocation of resources under the control of program managers. The increased organizational flexibility and very high employees' tolerance for change which will be required, may be facilitated by greater participation. • If programs are defined at an "inter-departmental" level, very complex matrix organizations (task forces) may be required. These are difficult to effectively resource an!l to manage. The need for matrix organizations where the existing structure is unsuitable will also create potential difficulties in "intra-departmental" program teams in the absence of superior, inspirational leadership. • Employees' participation in decision-making and setting of targets and goals will enhance commitment to results becoming an essential vehicle for change (work practices, multi-skilling, reorganizations) and financial management success. * In-depth studies and reviews of what one does, why one does . it, and how one does it, including functional reviews, process modelling, reviews of levels of service, priority allocation of resources, value engineering, risk management, asset management, human resource planning, etc must being on-going if conventional producivity drives are not to show fast diminishing returns. • Sound commercial, financially viable practices are desirable irrespective of the degree of commercialization, corporatization and possible privatization which may be required of an authority.
REFERENCES Smith, N. E. (1988) "Future Directions in Financial Management" - paper presented to the Western Australian Executive Development Program 7. Dixon, P. (1988) "Urban Water Pricing - Progress Report" sponsored by the Urban Water Research Association of Australia. Institute of Applied Economic and Social Research.
2 Volumes - 633 pages - plus abstracts $45 (inclusive of postage in Australia) A.WW.A.
Federal Office PO Box 460 Chatswood NSW 2057.
Institution of Engineers Australia 11 National Circuit Barton ACT 2600.
CONVENTION '89 CANBERRA This paper shared the Michael Flynn Award at the 13th Federal Convention, Canberra, 6-J0th March, 1989, and came from the Treatment Technology area.
The Oil-From-Sludge Technology: A Cost-Effective Sludge Management Option T. R. Bridle, C. K. Hertle and T. Luceks ABSTRACT The OFS technology thermally converts the volatile organic material in sewage sludge to a liquid fuel predominantly consisting of straight chain alkanes and alkenes, much like the principal ingredients of diesel fuel. The byproducts of the process are char, noncondensable gas and reaction water, which are combusted on-site to supply energy requirements for drying the sludge and reactor heating. The oil is to be utilized as a diesel fuel equivalent. Under optimal conditions oil yields of greater than 170Jo are routinely achieved on anaerobically digested sludge, and energy conversion efficiency of 900Jo is common. The OFS technology offers a thermal based sewage sludge treatment process which is similar in capital costs to an incineration plant but substantially cheaper in nett operating costs. The technology also offers environmentally benign end products with heavy metals bound in the ash, pathogens destroyed and air emissions minimised and controlled.
INTRODUCTION Sewage sludge is an unavoidable byproduct of wastewater treatment. It is estimated that over 220 000 dry tonnes of sludge are produced annually in Australia and disposed of at a cost exceeding $35 million. The major sludge disposal options currently used in Australia include agricultural utilization, ocean disposal and incineration. While the costs for incineration are very high, the trend in Japan, Europe and North America is toward these thermal based technologies. It appears the reason for this trend is the increasingly stringent enviromental regulations being enforced for land-based technologies. Of most concern is the fate that heavy metals, pesticides and pathogens in these disposal options. Draft regulations for heavy metals and pesticide levels have been set by the United States Enviromental Protection Agency (Table 1) and these, if enforced in Australia, effectively eliminate land application of sewage sludge. This trend in sludge-use regulations has spurred development of more energy efficient thermal based technologies in attempts to reduce operating costs. ÂˇProcesses such as starved-air incineration, gasification and liquefaction are in developmental stages and a thorough review of these technologies is presented elsewhere (Bridle and Campbell 1983). However, the most promising technology appears to be low temperature conversion of sludge to liquid fuels (Bridle, 1982). The basic concept of low temperature atmospheric pressure conversion of sewage sludge to produce fuel products has been known for many years (Shibata, 1939), but it is only recently that German researchers made significant advances in understanding the mechanisms by which sludge is converted to oil (Bayer and Kutubuddin, 1982). In. 1982 Enviroment Canada embarked on a major technology development program consisting of preliminary batch tests to validate the German results, development and testing of a continuous bench-scale reactor and finally testing of the process using a one tonne day pilot plant. As a result of this work a patented reactor system was developed (Bridle and Campbell, 1986). A summary of the Canadian research has been presented previously (Bridle and Hertle, 1988). NOTE: This paper has been edited to take account of the previous presentation in the August 1988 edition of this Journal, which included a photograph of the pilot plant. 30
WATER April, 1989
Trevor Bridle, BSc(Chem. Eng), MIE Aust, is the Managing Director of Campbell Environmental Ltd in Perth, Western Australia. He has over 20 years experience in the environmental control field in Canada and Australia. Prior to joining Campbell Environmental he was with Environment Canada's Wastewater Technology Centre in Burlington, Canada. Chris Hertle, BE(Hons) Chemical, MIE Aust is an Environmental Control Engineer with Campbell Environmental Limited. He has extensive experience in sludge handling and management techniques with particular reference to sludge dewatering and ultimate disposal. -,. Tony Luceks, First Class Certificate of Competence as an engine driver (steam), is responsible for daily operation of the Oil-FromSludge pilot p lant. He joined Campbell Environmental Ltd in 1988 after retiring from 30 years service at the BP Kwinana refinery as Operations Day Foreman. Table 1. Proposed USEPA Annual Loadings for Land Application of Sewage Sludge Pollutant
Aldrin/d ieldrin (total) Arsenic Benzo (a) pyrene Cadmium Chlordane Chromium Copper DDT/DDE/DDD (total) Dimethyl nitrosamine Heptachlor Hexachlorobenzene Hexachlorobutadiene Lead Lindane Mercury Nickel Polychlorinated biphenyls Toxaphene Trichloroethylene Zinc , â€˘
Annual Pollutant Loading Rate 1 /Kiloorams oer hectare\
0.016 0.7 0 .13 0.8 22.5 10 2.3 0.0055 0.039 0.073 0 .039 0.34 4 4.6 0.78 3.9 0.0056 0 .048 0 .013 8.6
Maximum amount of a pollutant that can be applied per hectare of land per 365 consecutive day period. From Sludge Newsletter, Oct. 12, 1988.
(iii) Diesel engine testing of the oil produced.
Campbell Enviromental Ltd (CEL) with their Canadian partner, SNC has entered into an exclusive licence agreement with Canadian Patents and Development Ltd for the world rights to the technology. In October 1987, CEL commenced construction or a second-generation one tonne day pilot plant in Perth, Western Australia. This pilot plant was completed in April 1988 and is currently generating and extensive database for Australian sewage and pulp and paper sludges. Results from the sewage sludge studies form the basis of this paper.
Process Experimentation To achieve objectives CEL developed a detailed experimental program which will assess sludges from three of WA WA's treatment plants. Subiaco and Beenyup are secondary treatment plants, with Subiaco producing digested and Beenyup producing raw sludge. Woodman Point is a primary treatment plant, incorporating sludge digestion. This gives an ideal mixture of all types of sludge for experimentation. The main operating parameters to investigate are: temperature, feedrate, solids retention time, gas retention time, flow path (co-current, counter current). To ensure successful demonstration of the technology, CEL has been fortunate to contract with the NATA approved laboratories of WA WA, Amdel, CSIRO, Westrail and the State Energy Commission of WA to conduct all the necessary-analyses on the sludges and products. The analyses have permitted CEL to: • Fully characterize sludge, oil, char, reaction water and noncondensable gases . • Complete mass balances on all products (particularly the fate of metals and elements in each of the products). • Complete energy balances of the process. (Characterize each products' energy content and volatile matter). • Identify the optimum operating conditions as outlined above. The important physical and chemical properties of the oil have also been measured. These analyses include all the standard ASTM tests used to characterize diesel fuels (eg, viscosity, water content, distillation, pour point, ash, sediment and stability of blends with diesel). The tests have been developed to ascertain the effect of the fuel on diesel engine performance.
EQUIPMENT AND OPERATIONS DESCRIPTION CEL's second generation pilot plant system, shown schematically in Figure 1, is capable of a nominal sludge throughput of 40kg/ hr. The reactor is subdivided by a helical gas seal into a volatilization zone and a char/ gas contact (catalysis) zone. Solids retention time (SRT) in the reactor is controlled by varying both the sludge feed rate and the reactor inventory. Volatilised material is withdrawn from the fist zone and contacted with the char in either a countercurrent or co-current mode in the second zone. Physical details of the pilot plant were presented in this Journal (Bridle and Hertle, 1988).
Sludg e Hopper
VolaHlisa1,on - ~ - React;o~- -- -
c-=;:-:__--:::-~--=-~:I" ___ · [-rr i 2
_, ~~~e~~ -f
Lpg Su pply
t=.:::::..:..·:::. • __ _ _ _ f-----J I
----~- ~ o
·- ··· ...., ·- •j.
Centrifuge ~ _.
Heat Exchang er
Fig. 1 -
S~ lch es
,,i "r-__:__:----=-- :::._ •
1 _, Screw
While the OFS technology is enviromentally superior to incineration, its economics are greatly enhanced if the oil produced is utilized as a fuel for engines rather than a boiler or bunker fuel (ie, 30c/ l instead of 20 c/ 1). Thus assessment of the oil as a fuel for diesel engines is a significant factor. SECWA have conducted the diesel engine testing program which involved: • Confirmation of feasibility of asing the oil in diesel engines. • Evaluation of the oil using a Varimax research engine. • Extended engine trials to investigate the effects of engine deposits and wear as measured by lubricating oil deterioration.
Cel Oil-from-sludge pilot plant.
Test runs are conducted in the following manner. First the entire reactor is brought to operating temperature. Water recirculation to the condenser is started, as is the disc centrifuge. Dried sludge (950Jo solids) is then fed to the system at the desired feed rate and the reactor screw is set to provide the design SRT and char inventory in the system. Gases are evolved, immediately condensed and separated in the centrifuge. Char discharge is controlled by high and low level microwave switches in the char discharge chute. The system is operated at two to three SRT's before steady state conditions are reached and the data collection is commenced. Operating pressure is controlled by a control valve in the non-condensable gas (NCO) line. The maximum operating pressure is only 35 kPa gauge.
RESULTS Results from the early bench-scale testing and Canadian pilot plant program are presented elsewhere (Bridle and Campbell, 1983, 1984, 1986a; Campbell and Bridle, 1985 ; Campbell et al 1987; Campbell 1988). The results from CEL's current pilot plant program are displayed in Tables 2 and 3.
CEL's DEVELOPMENT PROGRAM
Pilot Plant Results
The research and developmental program was designed to meet the following objectives: (i) Validation of the modified process operating on Australian sludges; (ii) Generation of process design and economic data for full-scale plants; and
After initial pilot plant commissioning the experimental program was commenced in July 1988. It was noted that operation of the pilot plant had the following advantages over the Canadian design: • The temperature control across the reactor was far better with four burners on individual sections of the reactor (heat transfer was not limiting).
Table 2. Pilot Plant Results Anaerobically Digested Sludge
Run Ory Feed
1 2 3 4 5 6 7 8 9 10
39.8 27.5 28.7 30.2 35.9 30.2 21.4 27.1 32 .1 29.8
457 445 453 395 453 496 503 444 448 456
3.3 4 3 .5 4 .6 2.6 4.8 4 .4 10.8 3.6 17
23 30 30 30 30 30 30 30 30 30
Dens g /ml
13.4 16.7 17.5 14. 1 13.8 15 . 1 13.2 13.8 13.4 13.4
8 .7 5.7 8.1 8.6 3.6 2.7 2 .9 4 2.6 2 .7
39 39.5 50. 1 63 51.4 45 .9 29.7 42 .9 40 .6 31.6
0.97 0.98 0.98 0.97 0.97 0.98 0.98 0 .98 0.97 0.98
37.7 35 .5 37 .9 37.0 37.8 38.0 41 .5 37.9 38 .6 38.8
73 56.1 63.5 60.4 57.4 63.2 65.9 64.1 77.5 56 .7
NCG GCV MJ/kg
9.4 10.9 10.4 12 .7 11.5 8.8 9.8 9.6 9.3 9.6
10.6 8 .9 15.2 9.5 20.3 20.3 13.6 19.2 20.6
GCV Yield MJ/kg l %
2 .34 12 .9 8.0 10.6 7 6.4 6 .4
7.7 7.6 2.2 1.5 5.7 11.9 5.0 5.1 2.6 7.2
WATER April, 1989 31
Table 3. Elemental analysis of Sludge and OFS Products (Digested Sludge)
s 0 p
React ion Water
Run No .
33.8 4.8 3.8 1.1
36.8 5. 1 2 .9 0.2
37 .3 4 .9 4 .6 3
34 5.3 4 .3 1
36 .6 5.3 4.3 1.4
NA - Not Analysed
79 10 2 .3 1.6 7.8 ND
78 .9 10 6 0.6 3.8 ND
77.4 11 6 2 4.5 ND
73 .8 9.7 5.1 1.7 4.6 ND
75 9.7 6.4 1.7 4 .4 ND
28.2 1.1 2 .6 1.1
2 31 .4 1.2 1.5 0.3
25.6 0.4 3 2 .7
26.8 1 3.4 0 .6 NA 2.5
30 .8 9.5 3.7 1.2 NA 2 .9
11 0.8 0.2 35 .5 ND
2 3.9 10.8 1.3 0 .1 16.4 ND
11.1 1.7 0.7 19.1 ND
28.6 9.1 2.2 0.2 20.6
11.1 2.6 0.5 30.4
ND - Not Detectable
• The separation of oil from the water phase was far better by using a centrifugal separation (under optimal conditions the oil contains less than 2% water). • With proper sealing of the reactor feed and discharge zones it is possible to maintain an operating pressure of 25 kPa gauge . The results from CEL's demonstration plant show similar trends to that of the North American studies. Oil yields are, however, higher than for Canadian and US sludges (Campbell 1988) predominately due to the higher volatile solids content of Australian sludges (65% versus 550Jo). The data indicates that as sludge throughput is increased oil yield decreases. This is due to less contact time in the reactor system. It is also interesting to note that for runs at 500 °C, 20% gas yields are indicated; showing light fractions of oil being cracked to gas at elevated temperatures. Under optimal conditions (feed rate of approx 30 kg/ hr and 450 °C) oil yields of around 18% are achieved. lypical values of elemental analysis for sludge and the products are shown in Table 3. The sludge used from these studies was dried digested Subiaco WWTP sludge, with a volatile solids content of between 65 and 68%. It should be noted that the H/ C ratio of the oil is approaching that of commercial diesel fuel (1.8) . When the oxygen content of oil is corrected for water content, it shows that decarboxylation (of the carboxylic acids) is occurring and the low nitrogen content indicates some deamination is occurring in the reactor. Tobie 4 shows some important criteria of the sludge oil compared to standard fuel oils and diesel fuel specifications. It shows that the oil generally meets the specification for Shell and Mobil oils currently used by the SECWA on country power stations.
After this confirmation it was decided to use the oil in the Varimax at blends of 25%, 50% and 75% at speeds of 1400, 1800 and 2100 rpm to accurately analyze performance. Results. of this testing indicated that on the day of operation: • Fuel consumption is slightly higher (5%) than with commer~ cial diesel. This is due to the slightly lower calorific value of the oil (39 MJ/ kg) compared to diesel (43 MJ/ kg). • The work performed by the fuel was indentical to that of diesel on the engine. • Exhaust temperatures were indentical to that of diesel. • Exhaust analysis indicated slightly higher hydrocarbon and CO and lower O, contents than for diesel (CO , was similar). • The pressure time trace showed very similar ignition qualities to that of diesel. There was no excessive ignition delay, pinging or other detrimental effects which would appear with an inferior fuel. • At 75% oil from sludge mixture there is a minor noticeable odour in the exhaust. The above analysis indicates that the oil-from-sludge is suitable for burning in diesel engines at mixtures up to 75% for short periods of time. It is expected that reducing the ignition timing will improve engine performance. Engine testing has been continued using the ,Lister engine on 1 50/ 50 blend of diesel/oil-from-sludge for some 100 hours. Results indicated that no wear metals were detected in the lubricating oil and that air emissions, with the exception of oxides of sulphur, were the same as for the engine running Of\_No 1 diesel fuel. The final stage of engine testing is to produce large quantities of oil and operate a large slow speed diesel engine ( < 800 rpm) for at least 300 hours continuously.
Diesel Engine Testing Initial testing involved burning the oil in a Varimax and single cylinder Lister enginer to confirm that combustion of the fuel would occur. Confirmation of this has been shown with two tests. • Operating the Varimax on 100% oil from sludge caused no noticeable problems running for 40 minutes, except a slight fuel flow problem caused by the higher viscosity (30 cSt) of the oil compared to diesel ( < 5 cSt). • Crude fuel consumption tests on the Lister engine operating 1500 rpm with blends of 25%, 50% and 75% oil with diesel fuel.
PROCESS ECONOMICS Incorporation of the OFS technology into an integrated facility is depicted in Figure 2. The integrated plant comprises sludge dewatering, drying and conversion to oil, combustion of byproducts with energy recovery and appropriate air pollution control (APCD) equipment. Sludge dewatering is based on membrane pressure filters, with demonstrated capability of producing a sludge cake of 35% total solids. Drying is based on direct flue gas drying . Such dryers routinely produce sludge at 95% solids.
Table 4. Diesel Fuel Oil Specifications TEST
She ll Mobi l Fuel Oil 215 LF10
Density @ 15uC (kg/ L) Max Min Flash point (°C) Ma x Su lphur (% M) Viscosity @ 4o 0 c (cSt) Max Po ur Point (°C) Max Strong Acid No (mg KOH / g) Max Ash(% M) Max Water(% V) Max Sediment (% M) Max Ce n tane Index Min GCV (Mj/kg ) Min NCV (MJ/ kg) Min Vd (ppm) Ma x Carbon Residue % Max 90% Dist.Temp (0 C) Max Cu Strip Corrosion •
so c 0
32 WATER April, 1989
0 .94 65 1.3 15 * 12 N IL 0 .05 0.5 0.1 NS NS NS NS NS NS NS
0 .89 66 2 11 .7 9 NS 0.02 0.25 0 .25 30 44 41 .8 <10 NS NS NS
OFS Oi l 0 .92 36 0 .6-2.0 20 -60 8 N IL 0 .08 2-8
FLU ID BED
- - --·
< 1.2 5
Fig. 2 -
Integrated O.F.S. plant schematic.
Combustion of the char, reaction water and gas is in a fluid bed combustor. Flue gases are finally cleaned in a chemical scrubber prior to discharge to the stack. A thorough assessment of sludge incineration costs has recently been completed. This study showed that total annual sludge processing costs, including capital depreciation, varied from $350 to $1042 (Canadian) per dry tonne of sludge processed. Operating costs for these facilities varied from $94 to $375/ tonne. (Proctor and Redfern, 1988). Table 5. Costings for Oil-From-Sludge Plant
Capital Costs Total Annual Cost Nett Annual Cost Nett O&M Cost
Plant Size 90 tpd 45 tpd
12.5 322 220 55
$It $It $I t
19.5 260 158 29
Costings for 45 tpd and 90 tpd plants are shown in Table 5. The total annual costs include all operating and maintenance (O&M) costs and the plant capital costs amortized over 5 years. The nett annual cost subtracts the oil credit from the total annual cost. (Assuming fuel at 30 cents per litre). Based on the above comparison it can be seen that while total annnual costs for incineration plants are similar to an oil-fromsludge plant nett operating costs are substantially lower due to the energy efficiency of the OFS technology. Generally the nett annual costs for an OFS plant will be roughly $100-150/ tonne lower than for an incineration plant.
ENVIRONMENTAL CONSIDERATIONS The OFS technology is environmentally superior compared to other thermal based technologies. The technology provides complete destruction of pathogens and pesticides, odour control, metal immobilization and reduced air pollution. Viruses and bacteria are completely destroyed in three consecutive thermal processes, namely drying (at 100 °C), conversion (at 450 °C) and COmbUStiOn (>900 °C). Control of odours in an OFS plant is facilitated by the fact that many of the unit operations are totally enclosed and that foul process air is used for combustion air requirements. Since conventional fuels, rather than wet sludge, are fed to the combustor, odours are low and the water load to the combustor is reduced significantly, normally at least 10 fold. Extensive laboratory and pilot plant data indicate that all the heavy metals, with the exception of mercury, are classified to the char in the reactor system (Bridle and Campbell 1983, Dearborn Environmental Consultants Ltd 1984). Upon combustion of the char the heavy metals are retained in the ash and converted to nonleachable oxides and silicates (Bridle et al 1987). Air emissions will be significantly lower than for an equivalent sludge incinerator, again principally due to the fact that conventional fuels rather than a wet sludge, are fed to the combustor. To minimize air pollution the combustor will be a fluid bed which is the most energy and environmentally efficient system available. Furthermore, hot flue gases from the combustor will be used to dry the sludge and a combination of cyclones and wet scrubbers will be used to clean the off-gas from the dryer. Typical air emissions from 100 tpd OFS and incineration plants are shown in Table 6. Engine testing has shown exhaust analysis from combustion of the oil produced has a slightly higher hydrocarbon content than Table 6. Air Emissions, 100 tpd Plants Pollutant
Emission (tpd) Incineration OFS
CO 2 Suspended Particu lates NOx-N
44 0.022 0.895
122 0.037 3.450
for combustion of commercial diesel. It is, however, certain that through reducing the ignition timing of the engine that this can be reduced significantly.
COMMERCIALIZATION OF THE TECHNOWGY Thermal conversion of sludge to fuel offers the wastewater industry a number of potential advantages. The first is reduced cost for municipal sludge treatment, as discussed above. The second is the energy efficiency of the catalyzed thermochemical conversion which is, in terms of thermal energy, 900Jo to 980Jo efficient (ie 900Jo to 980Jo of the energy in the dried sludge is recovered in the various products). The end product can be stored and transported so that it can be used only when needed. This factor offers great flexibility. The oil can be utilized for in-plant requirements, other uses within the authoritY. or sale as diesel fuel. Most large Australian water authorities require diesel fuel, normally to run stationary diesel generating sets. If the authority can use all the oil produced, avoided costs for purchased diesel fuel can be credited to the OFS process. The third area in which this technology offers a major advantage is in the overall philosophy of treatment plant design and operation. One of the disadvantages of cost effective high-rate treatment systems has traditionally been the increased sludge production and its associated downstream treatment costs. With conversion, increased sludge quantities will result in increased oil production, thus decreasing sludge processing costs. The above discussion is based on the assumption that the construction of a complete new sludge treatment facility is required. The conversion process also has the distinct advantage of integration into existing plants in a retrofit mode. For example, an existing incinerator could be used as the char combustor. Although the economic advantages are not expected to be as dramatic as in the case of a 'turn-key' facility, the process will significantly reduce sludge management costs and increase flexibility. Data generated from the CEL pilot plant developmental program in Perth provides the information required by clients to assess the technical and commerical viability of the <;)FS technology. The pilot plant is available for site specific trials. Keen interest in the technology has already been shown by the Water Authority of Western Australia, the Melbourne and Metropolitan Board of Works, ACT Water, the Gold Coast City Couqcil, the Sydney Water Board, Brisbane City Council and the Ministry of Environment, Singapore. With our Canadian partner, SNC Incorporated, the technology is now ready to be commercialized world-wide.
ACKNOWLEDGEMENTS CEL acknowledges co-funding of the oil testing program from the Minerals and Energy Research Institute of WA. The co-operation of the Water Authority of Western Australia and in particular, permission to operate the demonstration plant at the Subiaco Wastewater Treatment Plant is greatly appreciated. The help from SECWA, especially Mr I. Stann in the diesel engine testing program, is also acknowledged.
REFERENCES BAYER, E. and KUTUBUDDIN, M. (1982). Low Temperature Conversion of Sludge and Waste to Oil. Proceedings of the International Recycling Congress, Berlin, West Germany. BRIDLE, T. R. (1982). Sludge Derived Oil: Wastewater Treatment Implications. Env. Tech. Letters 3, 151-166. BRIDLE, T. R. and CAMPBELL, H. W. (1984). Conversion of Sewage Sludge to Liquid and Solid Fuels. Proceedings 7th Annual AQTE Conference, Montreal, Quebec, Canada. BRIDLE, T. R. and CAMPBELL, H. W. (1983). Liquid Fuel Production from Sewage Sludge. Proceedings of the ENFOR Third Canadian Biomass Liquefaction Experts Meeting, Sherbrooke, Quebec, Canada. BRIDLE, T. R. and CAMPBELL, H . W. (1986) . Process and Apparatus for the Conversion of Sludges. US Patent No. 4,618,735. BRIDLE, T. R. and CAMPBELL, H . W. (1986a). Oil-From-Sludge: A Technology Update. Proceedings 9th Annual AQTE Conference, Montreal, Quebec, Canada. BRIDLE, T. R. et al, (1987). Evaluation of Heavy Metal Leachability from Solid Wastes. Wat. Sci./Tech. 19, 1029-1036. BRIDLE, T. R. and HERTLE, C. K. (1988). Oil-From-Sludge: A Cost Effective Sludge Management System. Australian Water and Wastewater Journal, Vol. 15 No. 3.
Continued on page 48. WATER April, 1989
CONVENTION -'89 CANBERRA This paper was selected as one of the most significant in the Distribution Technology area.
Odour Control on the Latrobe Valley Outfall Sewer P. J. DACK and P. R. NADEBAUM SUMMARY The Latrobe Valley outfall sewer comprises some 50 km of open channel and 50 km of pipe sections, and is being upgraded to achieve a peak flow capacity of 95 ML/day. The wastewater has a high proportion of pulp mill effluent, and odour and corrosion problems have been experienced along the sewer. A comprehensive odour control strategy has been developed following odour modelling, and laboratory and pilot investigations. Nine new side-stream venturi oxygen dissolver stations and an existing Utube dissolver station will be used to control odours along the channel and pipe sections, odours at emergency storages will be controlled by caustic soda addition, and vent gas odours will be controlled by scrubbing where necessary. The use of side-stream venturi oxygen dissolvers to control odours in shallow open channel flow has not been applied in Australia before to the author's knowledge and the design basis developed from pilot investigations is outlined.
INTRODUCTION The Latrobe Valley Outfall Sewer (LVOS) was constructed in 1956 for the Latrobe Valley Water and Sewerage Board (LVWSB) to convey wastewaters from The Latrobe Valley to the 10 000 ha Dutson Downs Treatment Farm. As shown in Figure 1 the system consists of some 50 km of I metre diameter pipeline and 50 km of open channel. The LVOS was originally designed as a gravity system with 95 percent of the pipe section being normally surcharged.The trapezoidal channel was designed with a slope of 1 ft to the mile. In recent years, in-line booster pumping has been added to help cope with the large increases in township flows during wet weather. It is common practice to divert effluent for up to 7 days to 120 ML storages during peak wet weather events. Today the LVOS accepts 17 ML/day of wastewater from townships with a total population of around 60 000 persons, and a total of 18 ML/day from a number of industries including the Australian Paper Manufacturer's (APM) Maryvale Pulp and Paper Mill (15 ML/day), the new Japanese coal to oil pilot plant owned by Brown Coal Liquefaction Victoria, Australian Char's plant and others. Tobie 1 shows typical quality of wastewaters at Rosedale prior to odour control improvements begun in 1984. After commissioning of a new ocean outfall during 1989/ 90, industry will be permitted to discharge to the levels shown in brackets for APM in Tobie 1. Since about half the wastewater comes from the APM Mill, LVOS quality has been extremely variable and prior to 1984 due to the sulphide input from APM and the generation of sulphide within the LVOS, 50 percent of samples taken exhibited liqiud sulphide concentrations of between 36 and 100 mg/L. These high sulphides caused severe odour problems, particularly around Rosedale and throughout the open channel. The Victorian EPA became concerned and required the LVWSB to take steps to improve the situation in 1983. At this time it became obvious that several kilometres of concrete pipe at the high points of the LVOS, were severely corroded and required replacement. Some of this pipe had failed within 8 years of installation.
P. J. Dack is Senior Engineer, Wastes, 1.Atrobe Valley Water and Sewerage Board.
P. J. Dack
Dr Peter R. Nadebaum is Associate Director of Scott & Furphy Pty Ltd.
P. R. Nadebaum
By-Law requiring inputs to the LVOS to meet a maximum allowable liquid sulphide concentration of 1 mg/L. This level was exceeded in wastewater from APM, Sale City and Yalloum North. Unlike other sewer quality By-Laws, which allow exceedence and charge for them, the new requirement did not allow discharge above the limits. As a result, a continuous liquid sulphide monitoring and control system was developed and commissioned on the APM system, whereby if any 15 minute sulphide concentratio!i exceeded 5 mg/L, the Company's pumps were shut off. As a result of this the Company began adding pure oxygen for control of sulphides. Other parameters such as pH, temperature, and electrical conductivity are also continuously controlled.
Gas Scrubbing To control point source emissions of sulphide a number of open headweirs along the LVOS were either closed off, had tall vent stacks installed or were fitted with gas scrubbers. A Pepcon scrubber system has been used successfully on one of the vent systems for over 6 years. This unit operates with both physical absorption and chemical reaction taking place using sodium hypochlorite generated on site. Operating at a pH of around 8 and redox potential of 1000 mV this unit can remove most of the hydrogen sulphide present up to concentrations of around 30 ppm in the gas phase, but is overloaded when concentrations exceed this level.
Sulphide Removal and Generation Caldwell Connell Engineers (1982) looked at the available options for removing sulphide already present within the LVOS and preventing its regeneration. It was concluded that the use of pure oxygen offered the most cost effective solution, however, because of the unique nature of wastewater further testing both in the laboratory and in the field were recommended. This testing was needed to determine the sulphide generation rates, oxygen uptake rates and associated kinetics.
Sulphide generation CHOICE OF ODOUR CONTROL SYSTEMS Continuous Monitoring and Control of Input Sulphides One of the first steps taken to reduce the odour levels known to be caused mainly by hydrogen sulphide, was the intro_duction of a 34
WATER April, 1989
Much has been written on the mechanisms and predictive models for the biochemical conversion process of sulphate to sulphide in domestic sewers. Holder et al (1984) and Nielsen & Jacobsen (1988) have extended the discussion recently into kinetic studies of the process based mainly on laboratory observations.
TABLE 1 QUALIT Y OF LVOS VASTEVATER Paramete r
Mu n ici pa l
Mi xed LVOS
Suspended So li ds BO DS CO D Su lp hate Sulphi de Temperature pH Co l our Ammo ni a-N Or ga ni c-N Total P Di ssol ved Ozyge n
mg / L mg / L mg / L mg/ L mg / L
250 250 380 45 1. 0 18 8.0 170 32 17 12 0.5
( 600 ) 1 ,000 (6 00) 600 ( 600) 3 ,000 (1, 000) 250 (1) 6 35 (8) 10 6, 800 ( 3,000) 0. 8 5.2 1. 0 ( 1) 0
600 410 1,200 200 36 24 8.3 3 ,8 00
P t-Co mg / L mg / L mg / L mg / L
When the LVOS data for sulphide generation rates was plotted against the predictive models available, no uniform agreement was found (Campbell et al, 1981). In this comparison, the predictions using the Pomerory (1974) equation invariably overpredicted the rate, whilst the classic Thistlethwayte prediction was most accurate or produced under-estimates at times. From field studies and from data collected since 1980 for the LVOS, effective sulphide generation rates are known to vary from 0.2 mg/ L/hr to 2 mg/L/hr in both the piped section and the open channel, although rates are lower in the channel due to atmospheric re-aeration. The 10 fold variation in rates could be generally explained by seasonal temperat1,1re variations within the LVOS of from 17 ° to 35 °C. These rates decrease downstream due to the following: • A likely reduction in available food. See Tobie 2. • A reduction in the sulphate concentrations. Holder (1984) describes the dependency of the rate on this parameter for concentrations of sulphate below 500 mg/ L. See Tobie 2. For design purposes in the open channel a sulphide generation rate of 1.5 mg/L/hr was adopted.
VARIATION IN LONG TERM AVERAGE PARAMETERS ALONG THE LVOS - PRE 1985 Site Approx. Distance From APM Inlet (km)
BOD S (mg / L) Temp.
S0 4 (mg/L)
Sulphide (mg / L)
Marwood (1984) has described the process of oxygen uptake by oxygenated, previously anaerobic, LVOS effluent in terms of three dis-
, 9. 3
LATROBE \ 'AL LEY OUTFA LL PIPELINE SEC TI ON
L AT ROBE \ 'ALLEY OUTFA LL CH ANNEL SECTION
LOY YANG SALi 1 E WASTEWATE R OUTFALL PI PELINE
EMERGENCY STO RAGE
SHEEPWASH CRE EK
r •.....-- •_ :_.- •--... •
r-,- -- -
' PEC 29
• ~ • • • _, • • • • • •!• • • £
PEG 17 4 , • • • • •/• • •
L V W SB .
D ISPOSA L ARE.A. PEC 176
LO Y YANG l" STN . AUST CIIAJI
/ ' ""
./ Fig. 1 -;- The Latrobe Valley Outfall Sewer System. WATER April, 1989 35
TABLE 3 LVOS OXYGEN UPTAKE DATA Sample
Initial Mean Sulphide (mg / L)
Mean Sulphide Oxidation Requirement Phase 1 (g0 2/gS )
Mean Duration Phase 1 I Phase 2 (hrs )
Mean Phase 2 Oxygen Uptake Rate (mg / L/ h)
LVOS at Rosedale
Domestic Sewage Aged 24 Hrs
It should be noted that for fresh domesti c sewage, the phase 3 oxygen uptake rate can approach 20 mg/ L/hr. tinct phases. Phase 1 involves the rapid oxidation of sulphide, but some other minor chemical oxidation and biological uptake also occurs. The intermediate period after complete sulphide oxidation and before biological uptake rapidly increases is termed Phase 2. The rate of biological uptake in Phase 2 decreases with the initial age of the sample. Phase 3 is described by a rapid increase in the rate of oxygen consumption due to the acclimatisation of facultative aerobic bacteria. Table 3 summarises the results of laboratory experiments to determine the kinetics associated with phases 1 and 2. From Tobie 3 several conclusions can be drawn. • In all cases, sulphide can be completely removed within 1.5 hours. • Compared with domestic wastewater, both APM and LVOS effluent take much longer for Phase 3 to be reached. Given that the objective is control of odours and not secondary treatment of the wastewater, this factor can be exploited to minimize the number of additions of oxygen required. • To avoid the high Phase 3 oxygen uptake rate mixed wastewater should not be kept in an aerobic state for more than 7 hours. Marwood (1984) also further defined the kinetics of the LVOS sulphide oxidation process by laboratory experiment in a manner similar to that described more recently by Wilmot (1988). Both authors confirm that the sulphide oxidation rate is very temperature dependent and follows the Arrhenius equation. As Wilmot (1988) describes, the rate of sulphide oxidation R, follows the equation [R = K CtC/] where R is in mg/L/h K = rate constant in h-1 at Temperature T
C = sulphide concentration in mg/ L C' = oxygen concentration in mg/ L m0 = sulphide reaction order n = oxygen reaction order Tests on both domestic and mixed LVOS wastewater found no significant differences in mean values for m. The mean value of m was
Tap \.later ( Trara lgon) + 10 ppb Cobalt (2+) + 10 ppb Copper (2 +) + 10 ppb Iron (2+)
Choice of Oxygen Dissolving Equipment Having decided to treat sulphides using oxygen'and having collected sufficient preliminary information on sulphide generation and oxidation, the next requirement was to confirm that large quantities of oxygen could be dissolved into the wastewater, and that there would be minimal additional suspended solids deated by the addition of oxygen. The cost effectiveness of the treatment proposed depended on not having to consider additional solids removal equipment for the LVOS.
Rosedale oxygen diss?lver In June 1984, with the assistance of Commonwealth Industrial Gases (CIG) staff, a CIG Vitox 2, multiple-U-tube dissolver was installed at Rosedale to test the use of pure oxygen for reducing odour levels downstream, especially for the first few kilometres of open channel. The dissolver was installed at a low point in the system which offered a normal static head of 18 metres of water. A rising leg of 2.3 kilometres of pipeline existed downstream with an air vent and gas
TABLE 4 SULPHIDE OXIDATION RATE CONSTANTS Sample
1.07, being about 25% greater than Wilmot's values. For n a similar situation existed with a mean value for the LVOS of 0.33 . Rate constants for various wastewaters as determined by Marwood are shown in Table 4, with some additional indication of the effect of various trace metals as catalysts to the reaction. As Hoffman and Lim (1979) found, trace metal catalysts could help to explain the variation found in rate constants. As can be seen, the oxidation rate for mixed LVOS wastewater is on average greater than for the domestic sewage inputs due to higher values for both K and temperature. For design purposes, a value for K25 ° of 0.3 was adopted to ensure that oxygen is added far enough upstream of points downstream where complete oxidation is required.
ROSEDALE DISSOLVER EFFECTIVENESS ANNUAL AVERAGE SULPHIDE CONCENTRATIONS (mg/L)
Observed Rate Constant K at 25° (hr - 1 ) Min. Mean Max.
Before In stallation
After In s tallation
Upst r eam 15 km
0.400 0.256 0.055
25 . 3
Domest i c Sewage into LVO S
Start of Channel (7 .5 km Downstream)
LVO S at Rosedale
0 . 53
WATER April, 1989
The lower upstream s ulphid es after ins t a ll atio n were due to oxygen inject ion by APM for s ulph i de co ntrol.
meter installed at the first high point. Although injection of 60 mg/ L of dissolved oxygen was achievable, a normal concentration of 45 mg/L was used. The whole sewer flow was passed through the dissolver and dissolving was achieved with a hydraulic loss of some 3 m across the system. Oxygen was metered in proportion to sewer flow to maintain a pre-set dissolved oxygen concentration. The dissolver has operated with minimal attention and had a dramatic effect on sewer sulphide levels at the start of the channel, as shown in Table 5. The important conclusions from this trial are: • No oxygen is wasted and high dissolved oxygen concentrations can be achieved . • Dissolving using the Vitox 2 required a loss of available head from the system which was not available for additional dissolvers. • Whilst sulphides are readily controlled most of the year, in summer the upstream levels are too high for complete oxidation and for desired odour control at the start of the channel. • The formation of additional solids is negligible. • Overall the Vitox 2 system is a good, low maintenance, cost effective system for use at this site. Two interesting phenomena have been noted during testing of the Rosedale dissolver. Firstly it was found that upstream of the dissolver, on the pipe walls there were black anaerobic slimes, however, immediately downstream and lasting for some 5 kilometres white wall slimes have been found. These slimes have been found to contain large quantities of aerobic organisms, particularly yeasts. It is also known that some of the oxygen dissolved is lost to these slimes. Pomeroy et al (1977) describes a method for predicting this loss and suggest that if the oxygen can reach the slime it will be used up readily. Although unconfirmed for the LVOS, if the following equation suggested by Pomeroy (1977) is used for annual average conditions downstream of Rosedale, the loss of injected oxygen over the 7.5 kilometres of pipe section could approach 10 per cent. Investigation is required to verify this figure. Re = 5.3(0)(su)05 
r where Re 0
= mg/ L/hr of oxygen lost to wall slimes =
= mg/ L of dissolved oxygen = 8.9 after sulphide oxidation
and phase 2 uptake s = slope of energy line of system = 2.2 x 104 u = velocity of flow = 0.4 mi s r = hydraulic radius = 0.25 This estimate assumes a travel time of 4.5 hours, a phase 2 uptake of 3 hours x 3.6 mg/ L/hr, an initial dissolved oxygen level of 45 mg/ L and a sulphide concentration of 25.3 mg/ L. The second phenomena noticed was the presence of a methane-rich gas in the gas recycle line · of the oxygen dissolver. When tested the gas was found to be explosive and special purging procedures have been instituted prior to shutdown and dewatering of the system for maintenance. No such gas has been found downstream of the dissolver.
Additional dissolvers It was apparent that more dissolvers were required, for the following reasons: • . Rosedale dissolver could not cope with peak summer sulphide concentrations. • The effectiveness of Rosedale dissolver was only apparent for the first few kilometres of open channel. • Odours were still quite high throughout the channel.
Odour modelling and complaints At this stage, Camp Scott Furphy (CSF) were engaged to • provide advice on the overall odour control strategy; and • assist with the testing and design of further oxygen dissolvers and odour control systems. CSF began by reviewing available data and mathematically modelling the line source dispersion of odour from the channel to identify potential problem areas and to better understand the extent of the odour problem and the measures required to avoid odours in the future. The ISCST multiple source gaussian plume dispersion model was used and results are shown in Figure 2 for. the worst case. Note that caution must be used in modelling sewage odours, because of the difficulties of accounting for masking effects that odour level is defined in terms of odour units, where one odour unit is the threshold of smell.
NOTE :· EXISTING AVERAGE SUMMER ODOUR LEVELS (1084 -1988)
Fig. 2 -
Predicted odour contours for existing average summer emissions from LVOC between Longford and Dutson siphons.
These results together with an analysis of actual odour complaints led to the conclusion that odour complaints have generally not been reported when the wastewater sulphide concentration was less than 8 mg/ L. A maximum design wastewater sulphide concentration for average summer conditions of 5 mg/ L was therefore adopted for the open channel.
Dissolver spacing Based on the conservative design rate for sulphide generation of 1.5 mg/ L/hr it was decided that if dissolvers were placed every 8 hours of travel time and sulphide levels were allowed to rise to 5 mg/ L at 1 worst in summer, between dissolvers, then an excess of oxygen was required above that required for just sulphide oxidation. Figure 3 shows this situation based on the calculated phase 1 rate of 4.5. mg/ L/hr and a phase 2 uptake rate of 3.6 mg/ L/hr. Note that sulphide generation begins almost immediately after the loss of oxygen because sulphide is generated in the channel bottom sludge. This was verified by field tests. Figure 3 suggests that at least 15 mg/ L of dissolved oxygen is required at each dissolving point for the design worst condition in summer.
G:~~=~~~~N - - - i
u z 0 u
i DISSOLVEll N
Fig. 3 -
TRAVEL TIME - hr s
Sulphide oxidation/generation between dis.solvers -
To achieve dissolved oxygen levels of this order it was felt initially that it would be impractical in the open channel at atmospheric pressure. Hence it was decided to first utilise the four inverted siphons which exist along the open channel to take advantage of the additional head for dissolving, although this meant that the even spacing WATER A pril, 1989
TABLE 6 COMPARISON OF METHODS OF AIR AND OXYGEN ADDITION TO THE LVOS(a) Method
Max. Possible D.O. (mg/L)
Typical Oxy Transfer Efficien cy ( %) (a)
Energy for Oxy Transfer (kWh /kg 0 2 )
Approx. Capital Cost ( $ )
Ap pro x. Operating Cost ( $ ) (f)
Air - Coarse Bubble
1. 7 (r ef 8)
Air - Fine Bubble
1.0 (ref 8)
Oxy - Coarse Bubble
Oxy - Fine Bubble
50,000 (e )
Oxy - Venturi Sidestream
Oxy - In- li ne Vitox 2
5.5 ( c )
To achieve 15 mg/L into 25 ML/day= 4.3 g/ s oxygen with 3 m available head in LVOS s iphon.
Us ing a 35 kW pump to deli ver 5 ML/ day in sidestream.
Un us ually high since it was necessary to specially instal l an 85 kW pump to pump complete flow and 3 m boost.
Includes compressor, etc.
Includes oxy vessel, pipe fittings, etc.
Includes power, oxygen and 15% of capital.
of dissolvers could not be s'trictly adhered to. There was still a need to dissolve oxygen at three open channel sites. A further approximate desk top comparison was done as to the cost effectiveness of various air and oxygen based systems. Tobie 6 summarises this work. As shown in Tobie 6 neither of the air systems could provide sufficient dissolved oxygen and were also thought to be too maintenance intensive to be practical. The CIG Vitox 2 system required a new inline booster pump which created an unacceptable capital cost although it offered the potential to achieve higher levels of dissolved oxygen and in time, lower operating costs. This led to the decision to con-
LIQUID OXYGEN STORAGE
duct full scale trials of a venturi sidestream oxygen dissolver system.
SIDESTREAM OXYGEN DISSOLVER DEVEWPMENT The use of a venturi to dissolve oxygen from air is not a recent application. It has been described by Jackson and Collins (1964). Wheatland and Boon (1979) describe a pwre oxygen venturi sidestream system developed by BOC Ltd in the UK for augmentation of secondary treatment tanks. These authors suggest that approximately 50 percent oxygen utilization may be achieved, the cost of which has discouraged use of the system.
The use of oxygen based sidestream dissolvers in sewers in Australia has been limited and as Cadee and Wain (1984) suggest, more information is needed for design use particularly on gravity systems. The problems of poor oxygen transfer efficiencies, and the inability to dissolve sufficient oxygen to maintain aerobic conditions for more than about one hour, are quoted as areas needing further work. It can be seen from Tobie 6 that an open channel oxygen dissolver system can offer a cost effective solution for odour control if reasonably high oxygen dissolving efficiencies can be obtained (in the order of 50 to 75%). Further as shown above, if high dissolved oxygen levels can be achieved (eg 15 mg/ L) then sulphide levels can be maintained below complaint levels for a practical time period (eg 8 hours). It should be noted that the loss of small quantities of oxygen to the atmosphere along the LVOS was not thought of as a problem since there was little chance of gas locking the piped siphons and emission points were all remotely located.
Fig. 4 - Sidr.stream venturi trial at Peg 75 - Equipment schematic. 38
WATER April, 1989
Sidestream Venturi System Trials Thals using a venturi supplied by CIG Ltd were conducted by the LVWSB in November 1986 into the 30()'metre long Peg 29 siphon · of the LVOS channel. Following the success of this trial, CSF recommended further trials in another longer siphon at Longford and in an open channel section at Peg 75. The latter trials were carried out in April and May, 1987. Figure 4 shows a schematic of the system used at Peg 75. The main objectives of these trials were to • Establish oxygen dissolving efficiencies for the LVOS wastewater. • To optimize the main variables of the system and hence minimize the use of power and oxygen. • To determine what dissolved oxygen concentrations could be achieved. • To test components of the system with the aim of minimizing future maintenance. • To confirm downstream sulphide oxidation and oxygen uptake rates. The system functioned by withdrawing between 5 to 200Jo of the mainstream flow, using a pump, passing it through a venturi where oxygen was introduced and then passing the oxygenated sidestream through a nozzle placed in the mainstream. By using various nozzles, different sidestream flows, pressures, and concentrations of oxygen could be achieved, and flows were varied also using valves in the sidestream. In the open channel tests at Peg 75, the sidestream was re-introduced into the narrow 1.2 m wide section of a road culvert which was 20 metres long and 0.5 m deep thereby taking advantage of the increase in flow and mixing energy at this point. During the submerged jet mixing of the sidestream into the mainstream, it is likely that the cone shaped jet expanding longitudinally from the nozzle, is entraining large quantities of the mainstream at the periphery of the jet. At Longford siphon, which is a 900 mm diameter pipe, 5.5 kilometres long, oxygenated wastewater was injected from the sidestream into a down leg, 1.8 km from the siphon outlet. The gradient of the pipe leg was 1:1000. The Longford nozzle was normally under a small head of around 2 metres and during the 1987 trial, the oxygen saturation concentration was approximately 20 mg/L.
TABLE 7 SUMMARY OF OBSERVED OXYGEN DISSOLVING EFFICIENCY AS A FUNCTION OF OPERATING PARAMETERS Dissol ved Di sc harge Oxygen Nozzle Dia . Concen mm tration mg/L
Di sc harge Oxygen Main s tream Di ssolv ing Nozzle Efficiency Headlo ss to (m) Side- (Per cent) stream Flow Ratio
6 7 8
85 60 53
12 15 18
76 57 39
15 11 8
6 7 8
67 50 43
12 15 18
60 47 35
6 7 8
53 42 36
50 40 32
12 15 18
15g , m3
z < z
\ ___ .... V
,, ,,• /
r-.. 13 g,m3
< :::, z z <
SIDESTREAM FLOW , M Vday
Fig. S -
Test results -
Annual cost of power and oxygen.
open channel at Peg 75
From Table 7 it can be seen that • Oxygen dissolving efficiency decreases as the sidestream flow ratio increases for a given nozzle size. • The oxygen dissolving efficiency achieved with the smaller 57 mm nozzle is significantly higher than that achieved with the 81 mm nozzle for similar sidestream flow ratios. However, , the power costs are higher for the 57 mm case due to higher headloss through the smaller nozzle. The estimated annual costs for oxygen and power were determined for three dissolved oxygen concentrations, for a range of flows and nozzle sizes. Figure 5 summarises these results. This figure shows that the lowest annual costs were achieved using the smaller 57 mm nozzle and sidestream flow of 3.0 ML/day (mainstream:sidestream flow ratio of 12:1). Tobie 8 gives the design criteria resulting from these tests. The design criteria was based on an effluent temperature of 22 degrees celsuis which represents the summer maximum at this site. Table 8 also shows the details and performance of the permanent dissolver which was built and commissioned at Peg 75 in June 1988. Note that the nozzle was 65 mm and effluent temperature during this recent testing was 15 degrees. Bracketed values refer to approximate percent of saturation (air) at the nozzle.
8 10 7
WATER April, 1989
Test results -
Longford siphon (submerged closed pipe)
Using similar equipment and test procedures to those used at Peg 75, a set of design criteria were established for this siphon, as shown in Tobie 9. The improved efficiency over the open channel case shows the benefit of utilizing a submerged pipe for oxygen injection even where the submergence is relatively small (eg 2 m). It should be noted that during testing over two days, a small gas build up occurred in the siphon. However, this reached a steady state and at higher oxygen concentrations there was a loss of oxygen to a vent downstream of the dissolver.
Construction of Sidestream Systems As at September 1988, permanent venturi sidestream dissolvers have been constructed and commissioned at Peg 75, Peg 50 (a 300 mm siphon), and at the Longford siphon. Preliminary testing results of the Peg 75 dissolver are shown in Tobie 8 and it should be noted that testing for wastewater sulphides dur-
TABLE 8 OPEN CHANNEL DE SIGN CRITERIA FOR SIDESTREAM VENTURI OXYGEN DISSOLVER FACILITY AT PEG 75 Parameter 1.
Mainstream to Si destream Ratio
Sidestream Froude No . (d is ventu r i)
Design Value at 22°C
Ac tua l Value at 15°C - June 1988 Test ing
10 to 12
6 (sid es tream=4 ML ld )
Venturi throat ve lo ci t y (mis )
Nozz l e head l oss ( m)
Oxygen dose (mg l L)
10 - 30
10 - 30
Oxyge n Di s sol ving Efficiency (%) 1./ast ewate r D. O. = 10 . 0 mgl L 13 . 0 15 . 0 23 .5 26 . 0 30 . 0
75 (ll S) 60 (1 50) so ( 172) -
100 75 60 42 35
ing operation of the three new dissolvers showed that at no point in the channel were sulphides above 0.5 mg/ L. Design is currently being completed by CSF for another four open channel dissolvers and two in the LVOS pipe upstream of Rosedale.
TABLE 9 DESIGN CRITERIA FOR SUBMERGED PIPE SI DESTREAM VENTURI DI SSOLVER AT LONGFORD SIPHON Design Valu e at 22 °c
8 - 12
1. Main s tream to
Si des tream Ratio
2. Sid es tream Froude No. (d is venturi ) 3 . Ve ntu ri t hr oat ve l ocity
4. Nozzle Head lo ss (m)
5. Oxygen Dose (mglL )
10 - 35
6 . Oxygen Di sso l ving Effi cie ncy (%) at D.O. = 15 mgl L = 20 = 25
( 94 ) (1 42) ( 222 ) ( 245 ) (28 3)
S10RAGE ODOUR CONTROL In order to both keep sulphides in solution and to prevent further generation whilst wastewater is being stored in the LVOS emergency storages, CSF have recommended pH adjustment equipment be installed. Investigations carried out by the LVWSB in consultation with CSF have confirmed that if wastewater pH is adjusted to about 10, it can be stored for periods of one week without creating odours. These tests also determined a preference for storing APM 'Xastewater rather than mixed domestic and APM wastewater, because APM sulphide generation rates were negligible over the test period. Simpson (1987) provides data which helps to explain not only why the APM effluent behaves this way but~so why sulphide generation rates differ elsewhere in the LYOS. Enumeration of sulphate reducing bacteria (SRB) was carried out over four months in 1987 and is summarized in Table 10. Note th.at between sites 3 and 4, more than 90 per cent of the SRB present in the bulk effluent were killed. Titration curves have been produced for wastewater to be stored in three of the emergency storages using both caustic soda and lime. Due to the intermittent requirement for dosing and potential maintenance and handling problems for lime, it is likely that caustic soda will be the system chosen for pH control. Dosing of the wastewater' with between 100 and 500 mg/L of caustic soda will be considered.
CONCWSIONS 100 (7 5% sa turatio n)
90 (1 00% sa turation) 75 ( 125% s at ur ation )
TABLE 10 LVO S SRB CONCENTRATIONS (ORGS / mL) Samp l e Site
1. APM 1./as t ewa t er
2. Fres h Domest i c (Traralgon) 1./astewater .
3. Mixed 1./astewater Prior to Oxygenation at Ro sedale
4. Mix ed 1./astewater Af t er Oxygena t ion Plu s 5 Hrs. Tr avel From Ro seda le
To achieve odour control throughout the LVOS system it has been necessary to adopt a range of control systems. By exploiting the chemical and microbiological characteristics peculiar to the LVOS wastewater, pure oxygen can be used in a cost effective manner to oxidize wastewater sulphides and minimize their re-formation. Side-stream venturi oxygen dissolvers offer a practical low capital cost method for dissolving oxygen into the LVOS wastewater at low pressures. Although the wastage of some 25 per cent of the oxygen injected has been accepted on an overall cost basis, further work is desirable to reduce this. Lower wasteages may be achieved by further optimization of the process of remixing the side-stream into the mainstream. Higher effective downstream dissolved oxygen concentrations will be achieved if oxygen uptake by the aerobic pipe and channel wall slimes can be reduced in future. Control of odours from intermittently used LVOS emergency storages is best achieved using addition of caustic soda.
Continued on page 48. WATER April, 1989
CONVENTION '89 CANBERRA This paper was selected as one of the most significant in the Science Area
Preliminary Findings on Phosphorus Input to the Great Barrier Reef Lagoon: Evidence from Geochronological Indicators G. B. JONES and F. TIRENDI SUMMARY Sections of a coral core collected from Townsville in the central section of the Great Barrier Reef Lagoon have been analyzed for phosphorus. Preliminary results indicate that higher levels of phosphorus deposition occur during drought conditions than during wet periods. This alternating cycle of drought wet is important when assessing the effects of eutrophication in the Great Barrier Reef Lagoon.
INTRODUCTION Eutrophication has long been recognized as a major water quality problem in Australia since the mid 1960s when the Port Phillip Bay environmental study was carried out to discuss sewage discharge options for Melbourne (Cullen, 1986). The effects of eutrophication have been estimated by Garman (1983) to cost Australia from $10-50 million per annum. The effect of discharging large and increasing loads of plant nutrients (N and P) to our inland and coastal waterways, especially those which experience low and variable flows, is attracting increasing adverse public criticism (AEC Report 19, 1987). It has been estimated that 9000 tons/annum of P are present in treated sewage effluent in Australia and that of this 2600 tons are discharged into estuaries, coastal rivers and inland lakes. In the Great Barrier Reef Lagoon (GBRL) region increased attention has recently been given to P and its effect on the calcification of corals (GBRMPA, Workshop Nov. 1987). Levels of P above 0.2 ug.atoms/ L are reported to significantly decrease calcification rates (GBRMPA, Workshop No. 1987), whilst levels ranging from 4-8 µg.at6ms. P04/ L are reported to increase the number of voids in the coral matrix (Hopley and Rasmussen, GBRMPA. Workshop. Nov. 1987). In corals collected from Low Isles off both Cairns and Magnetic Island increasing numbers of voids have been detected in the coral. Electron microprobe analysis has revealed a relative reduction in calcification of 5-17.5% between 1940-1984 (Rasmussen, personal comrnlunication). Inputs of P from the use of superphosphate on the canefields have been implicated, but other factors may also be important. In attempting to quantify the input of anthropogenic P to the marine environment it is necessary to also assess inputs from natural sources such as freshwater input, mangroves, groundwater intrusions and planktonic blooms. At Townsville phosphorus input from blooms of the blue-green algae Trichodesmium would be significant from August - December every year (Jones et al 1987). The magnitude of the blooms in the GBRL is only now becoming appreciated through Space Shuttle photography and Landsat imagery (Kuchler and Arnold, 1986); affecting extensive areas of sea surface. To develop a comprehensive understanding of eutrophication in this region, more sophisticated methods of studying it are needed, as well as valid data which spans tens or even hundreds of years. Recent work by Isdale (1984) has shown that skeletons of massive corals Porites can provide centuries of data that are potentially important to climatology, meterology, agriculture, water supply, pollution studies and management of the GBRL. lsdale (1984, 1988), has shown that the use of yearly fluorescing bands in cores from nearshore massive corals on tropical continental margins provides a valuable tool for hindcasting river discharge for periods of several hundred years. This analysis is based on annual time series derived from standardized fluorescence measurements on cores from coral colonies growing within the influence of major rivers in North Queensland. Paleohydrology proxies of these rivers for periods both before and during white 42 WATER A pril, 1989
Dr Graham Jones is the Chief Chemist in charge of Water Quality Monitoring at the Townsville/ Thuringowa Water Boards Laboratory, Townsville City Council, North Queensland. Graham obtained his doctorate from James Cook University of North Queensland in Marine/Environmental Chemistry and has over 15 years experience in environmental impact assessment in tropical waters in the Great Barrier Reef. G. B. Jones
Frank Tirendi is a graduate from the James Cook University of North Queensland (BSc 1980). He is an Experimental Scientist within the Laboratory Services section at the Australian Institute of Marine Science. His interests centre on analytical chemistry with particular emphasis to analytical methodology development and adapting commercially available instrumentation to specific analytical requirements.
occupation/activities show both long and short term variability in discharge patterns, and offer insights into changes in climatic regimes covering centuries. Chemical analysis of the substances responsible for the fluorescent ·bands (Boto and Isdale, 1985) has shown that the yellow-green bands found only in inshore coral appear to result from rivers. In view of the recent importance attached to the effects of P on carbonate deposition in corals, (Rasmussen, 1988) and the difficulty in tracing eutrophication changes with time, a study was initiated to investigate the possibility that the coral core could accurately record P input in the region. Of particular interest in this area .was whether the coral core could pick up the effects of sewage discharge in the bay. In addition, by obtaining the fluorescent record it was hoped to extend the runoff/ rainfall records for the local region by analysis of the proxy records laid down in the core.
AREA OF STUDY AND BACKGROUND 10 THE INVESTIGATION The study area is the Ross River-Cleveland Bay region on the tropical north-east coast of Australia at Townsville, in the central region of the GBRL (Figure 1). The region experiences two main seasons. The wet season usually occurs from December to March with heavy rainfall (800-1200mm), high temperatures (28-30 °C), and high freshwater runoff. The dry season from April to November is usually characterized by low rainfall (300mm), lower temperatures (22-26 °C) and little or no surface water runoff. In 1986 it seemed that the studies being carried our by Dr Isdale's Group at AIMS could be usefully applied to the catchment of the Ross Dam. From 1980-86 the region had experienced severe water shortages and in 1987 the drought was very severe. Ross Dam was down to 9% of Stage 1, only hand-held hoses were permitted and many
Fluorescence and X-ray density measurements N
1 CLE VELAN D BAY
Fig. I -
Map of study area.
residents tapped into the dwindling underground supplies. In June, 1987 the decision was made by the Townsville/ Thuringowa Water Board to build a pipeline to obtain water from the recently completed Burdekin Dam. In November, 1987 the spillway of the Ross Dam was raised 2.3 metres thus completing Stage 2A of the dam. When full, the Ross Dam will provide water for up to 2 years, irrespective of Burdekin water and rainfall. The 1987 / 88 climatic year was one of the driest years on record for the region. The decision to raise the spillway another three metres to stage 2B has not yet been taken. During the last five years the region has experienced rapid growth and development. Irrespective of the developments that have been put into place regarding water conservation/supply the proxy records laid down in the coral skeletons could provide useful data that may aid water supply strategy in this region over the long term.
SEWAGE DISCHARGE From 1940 to 1986, raw sewage, of the order of 12 ML/d, was discharged into Cleveland Bay, at the mouth of the Ross River Estuary direct and from 1963 at Sandfly Creek. The Ross River outlet was closed in 1986 and raw sewage, of the order of 30 ML/ d, discharged at Sandfly Creek onto tidal mud flats. From August 1986 the sewage was treated by an activated sludge plant. To the North of the city since 1972 about 250Jo of the total wastewater has been treated at the Mt St John, Bohle and later the Condon treatment plants, the effluents flowing into the Bohle River. Eventual discharge into the marine environment is buffered by the Bohle estuary and surrounding lagoons, which harbour prolific bird life. Offshore, the wastewater from Magnetic Island was treated by individual septic tanks until 1976, and since that date by an extended aeration plant at Nelly Bay, with effluent discharge being by grassland irrigation. It is considered that discharge to the marine environment from this plant is minimal. In terms of the potential effects of the wastewater inputs from the Ross estuary from 1940 to 1986, and from Sandfly Creek from 1963 to 1988 would be the prime sources of phosphorus.
METHODOLOGY Core Collection The nearest suitable Porites colonies to the mouth of the Ross Estuary are located at Geoffrey Bay on Magnetic Island. Two cores were obtained by AIMS in April 1987. When the core was taken from the skeleton, a small concrete plug was inserted and the living top of the coral rapidly grew back. These cores were returned to AIMS to be sectioned into 7mm slices using a diamond saw and sectioning techniques established at AIMS.
The coral slices were scanned for fluorescence and density data simultaneously using the AIMS "Fluorac" system (Isdale, 1984).
Coral Sectioning Sectioning of the coral for chemical and geochemical analysis necessitates this operation being carried out in a clean environment free from dust and contamination. Consequently AIMS workshop staff produced a perspex chamber to overcome this aspect. This consisted of a perspex box with sliding door, a mounting table with a long-wave UV light source inside. 1\vo glove access compartments either side of the door enabled the introduction of a high speed drill so that sectioning could be carried.out. A tungston carbide dentist's drill of 2 mm diameter was used for sectioning of the bands. Initially dilute HCL was proposed as a cleaning agent to remove any adhering contamination from the core. Observations indicated that the structure of the coral is altered by this procedure. For extraction of fluorescence band material it was decided to remove about Imm of core material from all around the band. The remaining part of the band was then "feathered out" using the drill, into acid-cleaned plastic vials. The vials were numbered and stored prior to analysis. Core material between bands was cut out and stored in vials. Prior to analysis this material was HCLdipped and DDW rinsed to remove any surface contamination. This was necessary in case the core had become impregnated with contamination during sectioning with the diamond saw. This material was then ground to a fine powder prior to digestion and analysis. Comparisons were made with just cleaning the coral between the bands with the drill, and the HCL cleaning technique and no difference in P content was observed.
Digestion and Analysis Approximately 0.2g of the fine dry powdered core material was weighed into acid-cleaned 125mL Erlenmeyer flasks with Teflon stoppers. 1\vo mLs of ARISTAR hydrochlor~c acid was added to digest the sample overnight. The solution was digested for 1-2 hours and then the Teflon stoppers removed and the solution boiled at 150 °C to remove water and HCL. The dry white residue was dissolved in 0.5mL nitric acid and made qp to lOmL. Triplicate blanks and standards (Argillaceous sediment), plus an internal coral standard were run during digestions as checks on contamination and recovery. In the early stages P was analyzed by flow injection analysis (FIA) using the phospho-molybdenum blue method and by inductively-coupled plasma spectrophotometry (ICP). Comparison between the two techniques indicated that ICP gave a more accurate result. Blank values ranged from 0.07-0.09ppm of P Values of P in the Argillaceous Sediment ranged from 193-199ppm (mean = 196ppm), and compare favourably with the certified value of 177ppm + 250Jo.
RESULTS Rainfall A photomicrograph of the coral core is shown in Figure 2. The fluorescent bands are clearly visible and high rainfall/ runoff years are clearly identifiable. For example in 1870 when rainfall records for Towns ville were first taken 22. 7 inches of rain· were registered for February. In 1870 and 1891 two very broad bands are noticed, which coincided with exceptionally heavy rains over the JanuaryMarch periods - 69 inches (1890) and 54 inches (1891). In 1896 a bright fluorescent band coincides with 62.6 inches of rainfall recorded for the January-March period. The fluorescent bands of 1910, 1911, 1917, 1927, 1968, 1974 and 1981 also coincide with heavy rainfall for the region. The differing effect on rainfall from cyclones is also shown in Figure 2. Cyclone Sigma on January 26th, 1903 brought heavy rainfall to the region, whilst Cyclone Leonta on March 9th although registering 23.1 inches of rain did not record a high fluorescent value in the core. Cyclone Agnes on March 6th, 1956 brought 15 inches of rain to the region, with 16.6 inches and 13.3 inches being recorded in the previous two months, but the fluorescence in the band was not high. The flood of 1946 registered 51.2 inches of rain from January-March and high fluorescence was recorded in the core. From 1852-1874 (23 years) only five good rainfall years occurred; 1857, 1859, 1863, and 1869. Three to five year drought cycles are registered in this time frame. From 1982-87 WATER April, 1989
Fluorescent bands in a coral core extracted from a Porites colony, Geoffrey Bay, Magnetic Island. .(Courtesy of P. Isdale and T. Daniels (AIMS) - The high rainfall and runoff of 1974, 68, 58, 40 and 27; and 1896, 70, are clearly visible, as well as the drought years from 1850-1874 and 1982-87). Fig. 2 -
Table 1. Phosphorus in a coral core from Magnetic Island FLUORESCENT BAND DATING
from 1955-86. From 1855-1875 the fluoreSfent record indicates a severe drought period in this region spanning 20 years interspersed with only 5 above-average wets in 1857, 1859, 1863, 1869 and 1875. During this period levels of P ranged from 4-53ppm (mean 26.7ppm). In the drought years of 1982-86 levels of P ranged from 22-31ppm (mean 26ppm), comparable with the drought years of 1855-1874. From 1955-1964 levels of P ranged from 1-3ppm, the lowest levels recorded in the fluorescent bands so far. From 196586 P levels consistently increased despite normal rainfall. This increase in P does coincide with the rapid growth and development of Townsville, but it is not possible, at this stage, to attribute this increase in P to anthropogenic sources. Analysis of N levels in the core may provide more information on any changes in eutrophication which may have occurred in Cleveland Bay during man's occupation of the region. However during sectioning of the core material it was noticed that from about 1906 to 1987 the coral carbonate was much easier to "feather ouf' ' with the high speed drill than older carbonate deposited prior to 1906, which was much more brittle. Isdale (1988), has found that from 1778-1879 and 1900-1986 the local area was experiencing a dry period, whilst from 1870-1900 was, comparatively a much wetter period. Consequently, in dry periods P levels may build up in the marine environment and subsequently affect the coral matrix by its inhibitory effect on calcium carbonate deposition. This is a natural process, but obviously man-made inputs of P during drought periods would exacerbate this process. Âˇ Comparison of the levels of P in the growing surface with other levels suggests that diagenetic changes within the carbonate framework mobilize substantial amounts of P. However the overall result from these preliminary studies indicates that during drought conditions P levels build up in the fluo rescent bands.
1886 1885 1884 1883 1882 1881 1880 1879 1878 1877 1876* 1875 1874 1873 1872 1871 1870 1869* 1868 1867 1866 1865 1864 1863* 1862 1861 1860 1859* 1858 1857* 1856 1855
5 6 10 5 8 5 6 11 26 26
Many people have helped with the work outlined in this report. Firstly, we thank Dr Peter Isdale of the Australian Institute of Marine Science for the opportunity of working on a coral core. The work being carried out by Dr Isdale's groul? is particularly exciting, and has direct relevance to water resources in our local region, and perhaps more importantly to tropical Australia. In addition, we thank Mike Beecher and AIMS workshop staff for the construction of the coral sectioning box, al\(I John Wellington and Alan Knot for assistance with analysis. Dr )oe Baker (Director of AIMS), Townsville/ Thuringowa Water Board, and the AWRAC are also thanked for their support of the project.
1986 1985 1984 1983 1982 1981 1980 1979 1978 1977 1976 1975 1974 1973 1972 1971 1970 1969 1968 1967 1966 1965 1964 1963 1962 1961 1960 1959 1958 1957 1956 1955
27 27 23 31 22 <l
20 34 13 26 19 17 21 29 10 7 4 l
2 5 3 6 <l
3 < < < <
l l l l l
2 2 3
) Drought ) Period )
15 25 19 26 37 34 40 48 53 49 46 41 45 32 8 4 8 8 5 9 9
) Drought ) Period ) ) )
) ) ) )
â€˘ normal rainfall
another drought cycle is clearly registered in the core. The proxy records shown in Figure 2 extend our records to 1814, ie 173 years of data. This extends the knowledge of stream flow in our local region by 300%.
Phosphorus Table 1 shows the P record in the fluorescent bands. From 195586 levels of P ranged from 1-34ppm (mean 13.8ppm), and from 1855-86 levels ranged from 4-53ppm (mean 2l.6ppm). Significantly, more Pis present in core material from 1855-86, than was detected
AUSTRALIAN ENVIRONMENT COUNCIL, REPORT No 19. (1987) Nutrients in Australian Waters. Australian Government Public Service. Canberra. 163pp. BOID, K. and ISDALE, P. (1985). Fluorescent bands in massive corals result from terrestrial fulvic acid inputs to nearshore zone. Nature 315, 396-397. CULLEN, P. (1986). Managing nutrients in aquatic systems - the eutrophication problem. Limnology in Australia. pp539-554. Edit P. De Decker and W. D. Williams. CSIRO Australia. GARMAN, D. E. J. (1983). Water Quality issues in Australia. Water 2000 Australia. Dep. Res. and Energy. Consult Rep No 7. GREAT BARRIER REEF MARINE PARK AUTHORITY WORKSHOP (1987). Series No 10. Nutrients in the Great Barrier Reef Region. Ed. C. L. Baldwin. (in press). ISDALE, P. (1984). Construction of historical analogues of terrestrial runoff inputs to reef areas using fluorescing bands in nearshore massive corals. 6th International Coral Reef Symposium 8th-12th August 1988. Townsville. Australia. JONES, G. B. (1987). Nutrient Input in Cleveland Bay. In Workshop Series No JO. Great Barrier Reef Marine Park Authority. Ed. C. L. Baldwin (in press). JONES, G. B. and THOMAS, F. G. (1988). Effect of terrestrial and marine humics on copper speciation in an estuary in the Great Barrier Reef Lagoon. Aust. J. Mar. Freshwater, Res. 39, ppl9-31. KUCHLER, D. A. and ARNOLD, N. P. (1986). Identification and characterization of a massive phytoplankton bloom within the Capricorn Channel, GBR Australia ..Proc. Beijing Int. Symp. Remote Sensing Nov 1986. RASMUSSEN, C. E. (1988) The use of strontium as an indicator of anthropogenically altered environmental parameters. 6th International Coral Reef Symposium 8-12th August 1988 Townsville Australia. WATER April, 1989 45
CONVENTION. '89 CANBERRA This paper was selected as one of the most significant in the Public Health area.
NEW DEVEWPMENTS IN WATER DISINFECTION BY ULTRAVIOLET LIGHT D. COMAR SUMMARY A comprehensive study is described of the development of an ultraviolet light water disinfection unit. The design parameters were based purely on empirical data utilizing "single variable change" prototypes. Each design parameter was evaluated by an in-use full scale bioassay technique to determine antimicrobial efficacy. The research enabled optimization of the design to achieve an efficiency quotient (Lpm: watts) of 1.7 compared to current technology with efficiency quotients of < 1.
Derio Comar is a consultant microbiologist with Microtech Laboratories, Box Hill, Vic.
INTRODUCTION Water treatment has been one of the major applications of UV radiation, in particular, the disinfection of potable water and process waters in the cosmetic and pharmaceutical industries. In more recent years the technical advances and improved understanding of the factors affecting UV penetration of water have seen major applications in the disinfection of secondary treated wastewaters. Over fifty sewage treatment plants throughout the USA and Canada currently use UV disinfection systems (White, et al, 1986). These replace the traditional method of wastewater chlorination. A major difficulty of UV disinfection technology has been its inability to meet theoretical expectations with respect to in-use performance (Ellner, et al, Severin 1980, Riddick 1979). Numerous factors ranging from under design problems to over zealous marketing claims based on questionable criteria have resulted in a significant level of suspicion concerning the efficacy of UV light as an alternative mode of water treatment. A lack of standards and uniform criteria for its application over a broad range of industries has further contributed to a variable and far from satisfactory record of performance for UV disinfection. UV treatment is a complex interrelationship between UV lamp output, hydraulics, chemical and microbiological water qualty criteria. Theoretical approaches to designing UV systems which are based solely on engineering and physical dose measurements have consistently shown to be inadequate with few designs matching their theoretical performance. In any UV system the actual delivered dose cannot be readily determined. Mathematical modelling has proven difficult for complex hydraulic flows (Haas 1979, Severin 1983). The logarithmic loss of UV intensity as the pathlength increases through the water film, the nature of the turbulence in the reactor and the biological variability of organisms pose fundamental difficulties. Furthermore, in microbiological terms, only a small percentage of the population - less than 0.1 OJo - need to be below the lethal dose to cause failure of the unit. The tolerance for modelling errors as extremely small. Superimposed on these fundamental issues of design and dosage are the physical and biological water characteristics under inuse conditions. Natural or industrial waters are dynamic in nature. Water chemical quality is seasonally variable. Microbiological loading is variable, UV absorption of the water is variable. The protective nature of bacterial aggregates and the intrinsic biological sensitivity of different species is variable (Tobie 1). Manufacturers of UV devices face a delicate balancing act between achieving economical designs and excessive over-designing. 46
WATER April, 1989
TABLE I RELATIVE RESISTANCE OF MICROORCANISMS DOSAGE FOR COMPLETE INHIBITION Mi cro -w ~tl SC'co nd s pC'r c m '
Shigc/111 dy sc11/c rinc F. srhcric/1i11 coli r sc11d,11110111,s ncr11gi 11 nsn S11/11w11cl/11 typhi11111ri11111 Miuococc11s /11/cn
4,200 6,600 lll ,50ll 15 ,2llll 26 ,Âˇllll) -f
In practice over-design is necessary to compensate for worst case situations and a multitude of in-use variables likely to effect disinfection efficacy.
RESEARCH AND DEVEWPMENT PROGRAM Our research was primarily aimed at developing a UV disinfection system which was more efficient than existing systems while maintaining an element of over-design. The following key criteria were adopted. - A system that utilises all the available UV light emanating from a single lamp, represented by a water film surrounding the lamp. - A performance criteria that results in a minimum of 99.990Jo kill for the organism Micrococcus lutea. - All the design parameters to be evaluated utilizing a full scale bioassay rather than theoretical dose modelling. - A design incorporating suitable materials and high water velocity to reduce or eliminate fouling. The approach of the research and development programme was to develop all the design parameters by a systematic empirical study of "single variable change" prototypes, The traditional concept was chosen of a single lamp enclosed in a UV light transparent envelope at the longitudinal centre of a reactor chamber. Such a design would ensure complete utilization of all the UV light output of the lamp. A series of prototypes was built, each varying by one single parameter. The key parameters of chamber diameter, chamber length and flow rate were studied, utilizing a full scale bioassay. For each parameter the relationship of OJo kill versus flow rate was plotted to empirically determine the flow rate at which the unit achieved a 99.990Jo kill of the test organism. Thus data was generated by which the relationship of reactor chamber diameter and length could be plotted at a constant and commercially acceptable UV dose which achieved 99.990Jo kill of the organism Micrococcus lutea ATCC 934.
Concurrently with this research, studies were undertaken to develop a suitable lamp envelope which would achieve adequate UV transmittance yet have some of the antifouling characteristics of teflon. The data generated could also be utilized as a predictive tool for further design changes and optimization of performance.
MATERIALS AND METHODS UV Reactors Prototype units were constructed in PVC with the lamp envelopes being of quartz and/or quartz/ teflon combinations. The lamps were G60Tl5UP (Ultra Violet Supplies Pty Ltd) or experimental lamps of equivalent UV output. Lamp output was rated at 12 200 micro watts per sq cm and maintained as a constant in all experiments.
TABLE II GER MI C IDAL EfT IC/\CY OF UVS ULTRA l'Ulff 5000
Micrococcuslutea % Kill
Flow Rate Lph.
Fl ow Rate 1.ph .
+99 .9999 15 ,()()() 3,500 + 99 .998 ~99 .99 20 ,000 4.400 +99 .9997 5, ()0()' 99 .992 ·Nominal ra tin g of th e UV S Ultril l'ure 5000 O n e L« mp Module . + indi ca tes g rea te r th a n .
f LOW n AlE
Bioassays Micrococcus lutea ATCC 9341 was chosen as the test organism because of its particular resistance to ultraviolet radiation. Cultures of Micrococcus lutea were grown in AOAC Synthetic Broth for 4 days at 25 °C. For comparative purposes limited trials were undertaken on the final designs utilizing the organism Escherichia coli NCTC 8196. Potable town water (Melbourne & Metropolitan Board of Works) was inoculated with the test organism at a rate of 10•-10• organisms per ml. Each 1000 litre batch of test water was mixed by recycling the water for 5 minutes to achieve adequate dispersion of the culture. Water inoculated with the test organism was then passed through a UV reactor prototype in a single pass at various measured flow rates. Triplicate samples of treated and untreated water were taken for quantitative microbiological analysis for each flow rate. Surface plate counts were performed utilizing Plate Count Agar at 25 °C for 3 days. Supplementary tests were also performed utilizing membrane filtration techniques with Plate Count Agar under the same conditions. The geometric means of the untreated and treated samples were calculated at the OJo kill determined. Assays were performed on at least three occasions at any given flow rate utilizing fresh cultures and solutions on each occasion. The geometric mean of the assays was deemed to be the rated % kill at the nominated flow rate.
- - - - - - - - - - - - - - - - - - - - ·..~ ~:~~11~:;sM urms
"I EMl' l ~DECC 7 1% RH
~'• 4 N M I AM I '
l l· rl.llN
(J U ARfl,
1 , i:T f l·L~lN
MI CRO W rER CM.SQ 12('11'(1
c:=i (TI F• TIU N FIi M I
• UIVS FNSOR
~~~EL\J~MrVVS<.;)t.f l C.N
RESULTS For each prototype the flow rate which achieved 99.99% kill was determined. The data generated from eight prototypes over a wide range of flow rates was analysed to assess the most significant design parameters effecting performance. At a constant biological performance the effect of flow rate and water film thickness was examined (Figure 1). An optimum water film thickness was found to occur with a corresponding maximum flow rate. The data presented is factored (Patent pending). This maximum flow rate represents the actual limit of efficiency for a reactor of a nominated length. This key finding was utilized to design and subsequently confirm the efficacy of further prototypes utilizing this optimum water film thickness. Tobie II presents data on the antimicrobial performance of the final design (the Ultra Pure 5000) based on a single lamp module. The performance of the final design was examined as a ratio of the flow rate to the lamp wattage. Table III presents comparative data on Efficiency Quotients (Lpm: watts) calculated for a wide range of UV water purifiers currently on the market. The second phase of the research resulted in the development of an efficient UV transparent lamp sleeve. The final design adopted was a quartz sleeve coated with a continuous film ( < 0.5 mm) of FEP Grade Teflon. Figure 2 presents comparative UV transmission data for a variety of materials presently in use. The combination of quartz and teflon achieved the required structural rigidity with a significantly improved transmittance compared to existing teflon materials.
"., J"Hi\ NS MI SS ION UI' 2~ 4 N M U/V US INC QUARTZ ANO TEl'Ltl N .
L...II-------L----......1~-----......1...J...J WALL TH ICK N ESS TEF .020 & Q UARTZ 063 IN W r> Yri~ h l UVS N ()Vf. MBER IQM,
41 !>11 \212 411/ IC.
CONCLUSION Historically, UV developments have advanced on the basis of improved engineering principles. However an excessive emphasis has been placed on theoretical considerations of hydraulics and attempted measurement of UV dosages. An area of research, seriously neglected, has been the use of the bioassay as the key design parameter tool. The bioassay is the only true measure of performance for water disinfection systems. Full scale biological trials can be readily and economically performed under a wide range of in-use conditions to accurately determine the disinfection ability of a specific design. The use of Micrococcus lutea as a standard for the assessment of UV performance should be encouraged since it introduces a major safety margin for the water flow rating of UV systems under in-use conditions. The use of E. coli as a test organism is unrealistic in rating such systems since it is one of the more UV susceptible organisms available. Under in-use conditions UV systems encounter numerous adverse conditions which can reduce antimicrobial efficacy. Regulatory authorities should consider the introduction of mandatory standards based on bioassays and the organism Micrococcus lutea. WATER April, 1989
TABLE III COMPARATIVE EFFICIENCY QUOTIENTS # MODEL
MAKE O LI PHAN T (A UST) U.V. TECH NO LOGY (A UST. ) TU BUL A R G L ASS W A RE (AUST.) U.V. TECH N OLOG Y (USA) U .V. TE CHNO LOG Y (USA) U.V. TECH N OLOGY (USA) AQ U A FI N E (US A ) AQUAFINE (USA) ELNE R (USA) AQUANO MICS (HONG KO N G) U . V.S. (AUST.)
U FM8 L -200 TL300MP L-36-2 L- 36--1 H -50 CS L-1 2R SL-.J EP-24 SP36SF ULTRA PURE 5000 MODULE
AQUANO MI CS (HONG KONG ) H ANOV IA (U.K.) U . V .S. !AUST.)
LAMPS 8 12 1 2 4 2 12 1
G36T1 5 G36T6L G36T1 5N G36T6L G36T6L G25T8 NOT SPEC IFIED OT SPECIFIED NOT SPECIFIED NOT SPE CI FIED G60T15UP
ULTRA PURE 5000 MODULE
WAITS 560 600 -10 100 200 80 12
so 130 50 -18
ORGANISMS NOT SPECI FI ED MI CROCOCCUS MI CROCOCCUS MI CROCOCCUS M ICROCOCCUS MI CROCOCCUS NOT SP ECI FI ED NOT SPECI FI ED MI CROCOCCUS NOT SPECI FI ED
LUTE A LUTE A L UTE A LUTE A LUT EA
MICROCUCU S Ll'TEA
99 .9 99 .994 99 .95 99.7 99.99 9'l .99 99 .99 99 .99 +99 .9999 99 .99
0.07 0.37 0.5 0.76 0.76 0.25 0.66 0.7h 0.70 0. -10
NOT SPECI FIED 300 HAN 1. 2 KW 1260
ESCHER ICJ-: IA COLI. ESCHERICH IA COLI
99 .9999 + 99 .99
+ 99 .99
â€¢ EF FI CI ENCY QUOTIENT EX PRE SSED AS RATIO O F FLOW RATE (L PM J WA TIS # DATA OBTAI ED FRO M MANUFACTURERS TEC H !CAL BULLETIN S AND SPECIFIC..\TIONS.
The bioassay was shown to be an important predictive and design tool which could quantify performance. The final product design based on this research approach was a UV disinfection unit with a thin water film allowing for both excellent UV penetration and high water velocity in the reactor chamber. The combination of teflon and high water velocity will significantly eliminate surface fouling of the lamp sleeve. The achievement of such an efficient design has significant cost implications in the treatment of potable water and wastewater.
ACKNOWLEDGEMENTS The two year research program on which this paper is based was sponsored by Ultra Violet Supplies Pty Ltd, 8-10 Keith Campbell Court, Scoresby, Victoria, Australia.
P. J. DACK and P. R. NADEBAUM continued from page 41 ACKNOWLEDGEMENTS The authors wish to thank the Latrobe Valley Water and Sewerage Board for permission to publish this paper and LVWSB staff, particularly within the laboratory, for providing much of the base line data collected for this project; also Mr J. Anderson for his contribution to this work whilst with Camp Scott Furphy in 1986/ 87.
REFERENCES I .' CADEE, K., WAIN, R. (1984). Odour Control Problems and Remedies in the Perth Sewerage System. CIG Wastewater Symposium, Proceedings. 2. CALDWELL CONNELL ENGINEERS, LVWSB, (1982). Odour Control Study, Latrobe Valley Outfall Sewer. 3. CAMPBELL, B. L., SOSTE, L., FRENCH, R. (1981). Odour Control of the Latrobe Valley Outfall Pipeline. LVWSB Report. 4. HOFFMAN, M . R. & LIM, B. C. (1979). Kinetics and Mechanism of the Oxidation of Sulphide by Oxygen. Catalysis by Homogenous Metal Phthalocyanine Complexes. Env Sci and Technol, 13, 1406.
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