Water Journal March 2001

MARCH 2001

Volume 28 No 2 March 2001

Journal of the Australian Water Association

Editorial Board F R Bishop , Chairman B N Anderson, P Draayers, W J Dulfer, G Finlayson, GA H older, M Kirk, 13 L1bza, M Muntisov, N Orr,

CONTENTS

P Nadebaum, J D Parker, M Pascoe, A J Priestley, J R.isslllan , F R.oddick, E A Swinton

[ ·,I Water

is a refereed journal. This symbol

indicates that a paper h as been refereed.

Submissions Submissions should b e made to E A (!3ob) Swinton, Features Editor (see below for details).

Managing Editor Peter Stirling PO !3ox 84, H ampton Vic 3188 T el (03) 9530 8900 Fax (03) 9530 891 1

2

FROM THE FEDERAL PRESIDENT: A Name By Any Other Name ...

4 6 8

FROM THE EXECUTIVE DIRECTOR: Time to Rethink Our Approach to Members MY POINT OF VIEW: Mike Keegan, Tyco Wa ter Pipelines

10

CROSSCURRENT: Water News Around the Nation

22

WATER TREATMENT PROCESSES: The Amsterdam Conference: Ma ry Drikas

INTERNATIONAL AFFILIATES: Melbourne to be the Focus for World Water in 2002

Features Editor E A (Bob) Swinton 4 Pleasant View Cres, Wheelers Hill Vic 3 I50 Tel/ Fa x (03) 9560 4752

FEATURES: CENTRE FOR WATER RESEARCH, University of Western Australia

Email: bswimon@bigpond.net.au

Speci ali sing in the dynam ics of la kes and reservoirs, affecting water q ua lity

Crosscurrent Editor W (Bill) R ees PO !3ox 388, Artannon, NSW 1570 Tel +6 1 2 94 13 1288 Fax: (02) 9413 1047 Email: brecs@awa.asn.au

AWA Head Office P O Box 388, Artarrnon, NSW 1570 Tel +6 1 2941 3 1288 Fax: (02) 9413 1047 Elllail: info@awa.asn.au

26 30

Overview: J lm berger, C Wood Lake Kinneret, Israel: Water Quality Management:

34

Lake Burragorang Dynamics: The Sydney 'Boil Water' Alerts: J

36 38

The Swan River: Waler Quality: D P Hamilton Lake Pamvotis, Greece: Management Strategies:

41

Lake Maracaibo, Venezuela:

Anten ucci

J Romero

D Horn, P Yeates, B Lava l, J Im berger,

A Find ika ki s

Water Advertising & Production

46

H allmark Editions

G Gal, T Zohary

Lake Diagnostic System: S Feaver

P O Box 84, H ampto n, Vic 3188 Level I , 99 Bay Street, Brighton , Vic 3186 Tel (03) 9530 8900 Fax (03) 9530 89 I I Email: hall, nark@halledit.co m.au

WATER 48

l \ METALS IN DRINKING WATER IN NEW HOUSING ESTATES: G Rajarat nam, C W inder, M An . First flush is toxic

Graphic design: Mitzi Mann

Water (ISSN 0310 · 0367) is published in January, M a rch, April, Ju ne, Jul y, September, October and December.

Australian Water Association Inc

P Gebbie. A practical look at the physical chemistry of water treatment

57

AWA

~

A.BN 74 054 253 066

Federal President Allen Gale

AUSTRALIAN WATER ASSOCIATION

Executive Director C hris Davis

\ WATER CONDITIONING AND STABILITY ASSESSMENT: AN INTRODUCTION:

SO

·, STABILISATION AND BUFFERING OF WATER: CAUTIONARY ASPECTS: R J Turney, PR Nadebaum

Noting the complicating effects of phosphates and organics

SEWAGE

60

-.:. COMMISSIONING OF ASMALL STP: A "SMALL" SUCCESS: P

R L M asse

Detailed solutions for an underloaded plant

64

·, NITROGEN REMOVAL: COMPARING TWO OXIDATION DITCH PLANTS:

Australia n Water Association (A WA) assumes no

Ev Mi.inch, S Komarowski

responsibility for opinions or statelllents of facts

Comparing design and operating parameters on N removal and sludge settling

expressed by conrribmors or advertisers. Editorials do n ot n ecessarily represent official AW A policy.

Advertisements are included as an infonnation service co readers a nd arc reviewed before publication to

ensure relevance to the water environment and objectives of A WA. All material in Water is copyright and sho uld not be reproduced wholly or in part w ithout the written permission of the General Edito r.

ENVIRONMENT 70 ·, LEGIONELLA TESTING IN COOLING TOWERS:

BUSINESS ·, WATER MARKET POLICIES: CURRENT ISSUES, FUTURE DIRECTIONS: 74 H Bjornlund, J McKay. A lawyer's view on an effective policy framework

Subscriptions vVnrer is sent to all AW A members eight times a year.

It is also available via subscription.

79 80

Visit the Australian Wat4tr soclatlon

R Ben th a m

Closing the gate when the horse has bolted?

HOME PAGE

and access news, calendars, bookshop and over 100 pages of Information at

MEMBERSHIP MEETINGS

OUR COVER: Tire Co11tract R esearclr Cro11p of tire Ceutrefor Water Researclr i11 tire U11iversity of Westen, A11stmlia pro11ides tools a11d services bot/, 1vitlri11 A11stralia a11d overseas. Professor )o('s bnberger's expertise /1as bee11 recog11ised i11tematio11ally, a11d Ire lras oversee,, projects m11gi11g from s/1al/0111 rnb-tropical resel'lloirs to glacial lakes. Photo of a lake i11 tire A ndes by Jaimie Plaz a Van Roon of AUSCAPE.

FROM

THE

PRESIDENT

A NAME BY ANY OTHER NAME ...

I am moving swiftly to the grand status of Immediate Past President. Before reach ing the position of 'feather duster') l wane to use my lase column to address som e philosophical issues o f importance co the water industry.

What's in a Name?

'Sewage trea t ment' h as become 'wastewater treatment' and is well on its way to becoming 'wastewater management'.

'Sludge' is now 'biosolids'; 'cffiuenc' is now 'reclaimed water'. T hese changes in names amount to a softening of old, rather pejorative terms, to sh ift the perceptio n of our industry to one of broad water management. A hobby ho rse of mine is worki ng to get the p ublic's perception ch anged , so renaming things may sm ack of euphem isms to many practitioners.

H owever, the fuct is that people's impressio ns are coloured by words .

Som e words si m ply have load ed connotations for most people - if those connotations are bad, then cve1ything associated with those words w ilJ be tainted in some way. Long traditions in sanitary engineering (which has now become 'environ mental engineering') threw up arcane words for water at each poin t in the cyc le , creating stereotypes, and th ereby denying the real ity that all w ater is in the sa me cycle. The water in dustry m ust make an effort to come up with clear, positive terms to describe water and the byp roducts of working w ith it. AW A has a most important rok co play in educating the comm un ity, b ut so does everyo ne working in our ind ustry.

Standards and Quality versus Cost I sec the water industry, governmen ts and com mun ity as being o n the horns of a di lemma when it comes to standards of service, quality and associated costs. l have no doubts that we will continue to have everincreasing qual ity and standard s of service requirements . H owever, it m ust be recognized that there are substantial costs, both capita l and operating, associated with these.

If we look to w hat is happening internationally, the decision by the USEPA to increase arsenic stand ards w ill result in a whole new treatment regime and multi-biUion doUar coses. And chis affects a relatively smalJ proportion of the USA water industry.

Closer to home , the Victorian government's review of t he regulatory fra m ework for d rinkin g water quality is an adm irable exercise. H owever, l was nervous w hen the Minister for Environment and Conservation, Sheryl Garbutt, said in her announcement of the review at AWA's Victorian Branch dinner last August that the improvem ents could be made at littl e add iti onal cost. l don't believe th is wi ll be the case. H igher level treatment com es at a cost; higher quality managemen t also comes at a cost. T he water industry needs to make 2

WATER MARCH 2001

To remedy that situation, we conducted a small , qualitative survey among a ran ge of difrerent CEOs, fro m the very largest to some much sma ller organisations.

We d iscovered, first of all, that we tend to hide our light u nder a bushel - several good th ings we do were unknown to many of chem, for instance, the (t hen) Su mm er School, now to be run as the Water Ind ustry Short Course. Although participants have always fo und it very valuab le, their ch iefs clearly have not had the m essage. Contrarily, the Mt Eliza course was well known and appreciated, so its place is recogn ised.

Tra ining and professio nal develo p ment was seen by several CEO s as bei ng a key area fo r us to be mo re active. T he other concept receivin g strong suppo rt was the idea o f convening C EO- to-CEO foru ms, w here they could meet w ith peers and d iscuss issues o f co m mon interest.

My tha n ks to t hose C E O's who cont1ibuccd - if you feel aggrieved at not being approached please contact me. l am sure we will foUow up. I will have the charge of introducin g actio ns in response to these valuable contributions over the next few months After all, there has to be some thi ng for a 'feather duster' to do.

Allen Gale

th is point q uite clea rly - we cannot contin ue to have ever- increasing standards w ith out having the in come to m atch. Otherwise we risk a situation similar to Wa lkertown in Ontario where corners were cut while ostensibly complying with regu lations, with d isastrous results.

T his gives me the chance to promote another hobb y horse of m ine . R.ather tha n having to treat all of our water supplies to potable standards, why not consider treating only the small quantity required for drin king Alleu Gale standard to the best possible and deliver in bottles' We can then take the pressure o ff the 98 percen t that docs WATER & ENVIRONMENT not need to be of such high qual ity. Bottled water is here to stay w hy not join the fray?

No doubt someo ne has already studied the MIKE Net - t he professional engineering software economics - l wou ld package fo r the simulation of flows, pressure love to hear from you if you have. distribution and water quality of pressurised water

D!j~

Leaders in Water and Wastewater Network Analysis Software:

CEO Survey Something we should have done long ago is canvass the views of the CEOs of water organisat ions. AW A came in to being in 1962 thanks main ly to the efforts of some committed CEOs, and was saved from possible collapse in the 1970s by the concerted efforts of more CEOs. We have, in practice, become much more inclusive of people at all levels now, whic h is excellen t, but it means we have lost touch with some CEOs.

distribu tion systems. Industry standard EPANET engine, GIS and ODBC lin kages. SCADA interfaces, opt imisation and design modu les.

MOUSE - the integrated modelling packa ge for Urban Drainage Et Sewer Systems. Wet weather and dry weather flo w generation, ·~.water quali ty, linkages to rece iving water model s for load -based assessments. ······--· ..........

Real-time control and ,,·, opt imisation modules.

•,,

Free demo - download from our web site.

Phone: +61 2 4334 6621 E-mail: software@dhiaust.com Web: www.dhiaust.com

1Li;

A revolutionary stormwater quality system has arrived in Australia. Called StormFilter™, this advanced filtration system sets new standards in the removal of pollutants.

StormFilter™ restores lifestyle benefits to .___ _ _ _ _........____________. communities whose local aquatic ecology is being choked by algal blooms, gross pollutants and sedimentation. StormFilter™ is compact and perfect for sites with limited land area. It's economical and easy to maintain. Best of all you get a real partner. lngal Civil Products will help you do the job right the first time. StormFilter™ is the clear choice.

For further information call 1800 803 795 or visit www.ingalcivil.com.au

INGAL CIVIL PRODUCTS A Division of Industrial Galvanizers Corporation pty. Ltd .

StormFilter™is licensed exclusively throughout Australia and New Zealand to lngal Civil Products by Stormwater Management Inc, the world's leading provider of stormwater treatment solutions.

CENTRE

FOR

WATER

RESEARCH

Lake Kinneret, Israel: A Decision Support System for Water Quality G Gal and T Zohary

of the volume of the lake. Over the last few years Israel, and the region, is o nce Lake Kinneret, known also as the Sea again facing an extended period of of Galilee, typically recognized for it's drought, and consequentially the lake is great historical and religious value is also currently at its lowest level on reco rd. of great significance to modem day Israel.

Si n ce initiat ion of a r o ut ine The lake is a m ed ium size, monitori ng program in 1969, the monomictic fr eshwater lake (max lake has been known to exhibit a Lake Level depth: 43 m; mean depth: 25 m , regular spting bloom of the thecate -208 .

-----~ surface area - 170 km2 ) in the dinoflagellate Peridin/11111 gatunense . north of Israel. It stratifies in -209 Nygaard (thereafter Peridini,.,m) .

March-April and turns over in Phytoplankton biomass is usually -210 Decemb er-January. Within 3-6 maximal (- 200 g we t weight m_J weeks of thermal stratification, the 2) in spring (March- May) and ~ -211 hypolimnion turns anaerobic. In decreases abruptly later in Maythe mid-1960's, Israel constructed -212 ea rly June, correspo nding to a complex system. of channels and development and decline of the -213 pipelines, known as the National Peridi11i11n1 spri ng bloom. Berman Water Carrier (NWC) to convey -214 +--~ - ~ - ~ - ~ - - ~ -~ ___j et al. (1995) and Yacobi and water from the lake to the central 1/ 1/86 1/1/88 1/1190 111/92 1/1194 1/1196 1/1198 1/1100 Po llingher (1993), suggested that Year an d southern regions of the alga l population composition and country . Since then, the lake has Figure 1. Plot of the water level in Lake Kinneret for seasonal succession had vari ed provided a major portion oflsrael's the period 1986-1999 little in a 25-year perio d up until drinking water rapidly approaching 1993. Since then however, changes approximately 50%. Additionally, have occurred resulting in the first water from the lake is provided to bloom of the nitroge n-fixing th e Palestinian Authority and cya nobacterium A p/1aniz ome11on Jo rda n as part or the recent ova lispori11n in sum.m er 1994 Middle-East peace agreements. foll owed in winter 1995 by a The lake, th e only natural fresh29 furth er cyanobacterial bloom water lake in Israel, also provides 21 consisting of J\1icrocystis aeruginosa, fis heries and recreational related 25 and lack of the Peridinium spring revenue .

23 blooms in 1996 and 1997 (Berman 21 Lake level is regulated through et al. 1998, Nishri et al. 1998) and the pumping to the N WC and again in 2000 (Zohary, unpub11 through regulating the opening of lished data) . Th is interruption to 15 the outlet to the J ordan River o n the regular sequence of succession 303 313 .12.?

2Y.1 253 the southern side of the lake. Since Time (Julian Day) and its associated effects on the the early 1990's there has been an chemi cal composition of th e water increase of approximately 20% in Figure 2. High-resolution temperature data collected column are clea rly cause for Israel's population . This significant by 20 thermistors linked to the LDS in Lake Kinneret. conce rn and in dicate a need to Water temperature is sampled every 10 min. The data increase in the demand fo r water, understand the processes that may is for the period 30 Sep. through to 20 Nov. 2000 in addition to an erratic precipihave led to the disruption. and clea rly demonstrates progressive cooling of the tation regim e ov e r th e co rresponding period has lead to water column

Introduction

30

WATER MARCH 2001

large fluctuations in lake level (Fig. 1) .

An extended period of low rainfall resulted in low lake levels in 1989, 1990 and aga in in 199 1. T he win ter of199 11992 w as one of the wettest on record resulting in the replacement of a quarter

CENTRE

60

BA C

E

D

I

r

I

40

.0

E

:3

z

...

-~

30

Q)

.,;: !ti

...J

,o 10

0

··-· ...

183

)65

5'8

730

18)

3 65

S'8

730

n ~

Ol 10

E

cQ)

8

Ol >,

X

6

Q)

•

0 "O

> 0Cl) Cl)

i5

2

0

Days from Jan 1999 Figure 3. Upper panel: Lake Number computed from weekly temperature profiles at Sta. A and winds recorded at the KLL meteorological station (1999) and at the LDS (2000) for Jan 1999 - June 2000. The critical value of LN=2 is indicated. Lower panel: the resulting model prediction(·) vs. field data(•) for dissolved oxygen (DO) at 30m depth at Sta. A. Points A through to G indicate: A, E · start of main mixing period; B - brief mixing event; C, F - start of period dominated by stratification; D, G · hypolimnion depleted of DO.

Project Objectives In 1999, the Israeli Water Commissioner approved a mu ltiyear collaborative project between the Y. Alon Kinneret Limnological Laboratory (KLL) in Israel and the Centre fo r Water Research at the University of Western of Australia (CWR) to produce a scientifically-based, operational decision-support system for the management of the water quality in Lake Kinneret. The system is to be based on a combination oflong-term (years) and short-term (days) hydrodynamic simulation models, DYRESM and ELCOM. In addition, an ecological model, CAEDYM, is to be used to simulate the biochemical processes in the lake.

The 9-month feasibility phase of the project was recently concluded successfully leading to the fi nal approval of th e US$l.7M 3.5 yr primary phase of the project.

The m ain objectives of phase 1 were the calibration and validation of DYRESM- CAED0YM based on the existing knowledge of the lake ecosystem and the available data followed by sim ulation of various management scenarios, e.g increased pumping from the lake and thus lowering of the lake level.

Simulating the lake ecosystem As part of the feasibility phase of the project, a lake diagnostic system (LDS) developed at CWR was installed at a centrally located point in the lake. The LDS comprises of well-anchored station main frame with an antenna, solar panels, a wind anemometer with a wind direction sensor all above water. Below 32

WATER MARCH 2001

RESEARCH

WATER

F

so

Q)

FOR

the water surface a chain of 20 thermistors and water sealed canister with a data logger, batteries, and modem. The system is programmed to log every 10 min. Data is downloaded on shore typically every one to two weeks and provides continuous data on the thermal structure of the water column (Fig. 2) The combination of the wind forcing data and the thermal structure allows the calculation of the lake number (LN). In simple terms, LN is the ratio o f the stabilizing moment of the stratification divided by the destabilizing influence of the wind (Imberger 1994, Robertson and In1berger 1994). For LN less than a critical value (2.0 in Lake Kinneret), th e wind destabilizing forces are such as to cause active mixing within the lake .

B y contrast, for LN larger than the critical value, w ind forces are only sufficient to mix the near su rface layers and , in general, do not impact on the deeper parts of the water body and do not permanently disrupt the parent thermocline. Based on calibration of a simpl e sta tistical model, using historical data , it is possible to estimate the concentration of dissolved oxygen (DO) in the water as a function ofLN (Fig. 3). It is then possible to apply the model to the curren t w ind and temperature conditions and predict the DO concentration in the lake. Large deviations would indicate that th e system is undergoing changes and requires further investigation.

Simulations of the hydrodynamic and ecological processes were conducted using DYRESM as the hydrodynamic driver for CAEDYM . The ecological model, CAEDYM is a complex model simulating the main ecosystem processes occurring the lake. The success of the model is highly dependent on extensive knowledge of the numerous parameter values and process rates

u

35

r= 0.98

~

~

,

30

:3

~

~ 25 E Q)

•••

.;; 20 ~

!ti

115 en

10 10

15

30 20 25 Observed temperature (°C )

35

16 r=0.90

..pCl

•

12

_§_ 0

Cl

-0

8

~

(J

'o

!!!

Cl.

4

••

•

• ••

• • • •

•

•

•

ose-- •- -~ - - - -.--- ----r---- ---!

0

4

8 12 1 Observed DO (mg L" )

16

Fig. 4 Plots of observed and predicted mean monthly temperatures (upper panel) and dissolved oxygen (DO) concentrations in the upper and lower 10 m of the water column . Symbols represent predicted values and the solid lines represent a 1:1 ratio. The correlat ion coefficie nt value between the observed and predicted va lues is provided.

CENTRE

coeffi cients. As ma ny of th e param eter va lu es we r e u n k nown th ey we re e,ti maLed th rough calibrati o n of the model. Th e ca li bration and validation o f t he m ode ls were cond ucted fo r a 3-year period fo llowed by simulations of vari ous m anage me nt sce nari os. Simulation o f water-column te mpe rature over th e 3ycar pe ri od w as hi ghly successful w ith a dive rgence of less than 1°C from th e m easured te mperatures (Fig . 4A). E ven given th e high uncertainty associated with many o f the parameter va lues, the models successfull y simulated th e co ncentratio ns o f nutri e nts and chloro ph yll a in the lake (Fig. 4B).

Phase 2 tasks and objectives The primary obj ectives of phase 2 arc to fulJ y develo p the lak e m anageme nt support syste m throug h furth e r impro veme nts and e nhanceme nt to the mo de ls, primarily the ecologica l and 3-D hydrodynamic model. E xte nsive process rate parame ter values w ill be obtained th rough a series o f field and labo rato1y experim ents thereby reducing the uncertainty associated w ith m any o f the C AEDYM param eters,

FOR

WATER

RESEARCH

w hich w ill result in improved simul ati ons of the lake ecosystem. A comprehe nsive field campaign w ill provide important in fo rmation o n th e horizo ntal and vertica l transport properties o f the lake and the process governing the development of the patchy distribution o f algal groups in th e lake . Based o n the newly acquired data a calibratio n and va lidati o n process o f th e mo dels will be comple ted. Finally, a series o f scenario testing simula tions w ill be condu cted to eva luate th e impac t vario us managem e nt sce narios may have o n water quality. Evaluati o n of the predicted wate r-quality will be acc omp lishe d thro ugh use o f a unique wate r-quality index that is currently bein g developed at KLL. Th e index will be integrated into th e graphical user inte rface all owing a graphical representation of the ClllTCnt and predicted water quality give n the scena rio conditi ons.

Upon co mpletio n o f th e proj ect th e syste m w ill be ava ilabl e to lake manage rs fo r testin g of short- and lo ng-term managem e nt scenarios and evaluating solutio ns and reacti o n pl ans to e nviron me n tal crises.

References Berman. T .. U. Pollingher. and T Zohary.

1998. A short history of stability and change in phytoplankton populations in Lake Kinneret. Israel Jo11mnl of P/n111 Scie11ces 46 :73-80.

Berman, T .. L. Stone, Y. Z. Yacobi , B. Kaplan, M. Schlichter, A. Nishri, and U. Pollingher.

1995. Primary production and phytoplankton in Lake l<nneret: a long-term record ( 1972-1993). Li111110/. Ocen110.~r.

40: 1064-1076. lmberger, J. 1994. Lakt: N umber as a tool for water quality management in lakes and reservoirs. Internationa l Symposium on Ecology and Engineering, M alaysia, Nishri, A., T. Zohary. M. Gophen, and D. Wynne. 1998. Lake l<in neret dissolved oxygen regime reflects long term changes in ecosystem fu nction ing. Bio.~eoc/1e111istry 42 :253-283.

R obcrcson, D . M .. and j. lmbcrger . 1994. Lake nu mber, a quantitative indicator of mixing used to estimate changes in dissolved oxygen. lutemntio11nliâ&#x20AC;˘ Re,,111â&#x20AC;˘ der Cesnmrw H ydrobiologie 79: 159- 176.

Yacobi, Y. z., and U. Pollingher. 1993.

Phytoplankton composition and acciviry: response to fl uctuations in lake volume and turbulence. Ver/,. fllrmint. Vari11. Li111110/.

25 :796- 799.

CENTRE

FOR

WATER

RESEARCH

inflows from the Wollondilly and Cox High levels of Cryp1osporidi11111 oocysts we re strong winds. T hese winds were su ffi cie nt to cause a tilting of the n ewlyrivers were colder (and he nce denser) than and C iardia cysts in the potable water suppl y for Sydney were detected during th e ambie nt lake water, and so underintroduced density stratifi cation , pushing J uly to September ·1998, which prompted flow ed the resident water body. Peak flow the stratifi cation downward at the downBoil Wate r Alerts. There were th ree rates during th e first fl ood were 3000 m 3 wind end and upwards at the up-wind sepa rate in cidents, th e second and third s- 1 and 1800 111 3 s- 1, respecti vely. The end. The cessation of th e wind resu lted of w hich were asso ciated with heavy major effe ct of these large, co ld inflows in large osc illati ons of th e density structure, known as internal waves. One rainfall in the catchm ents which resulted was that the water body became stratifi ed in large floods entering Lake Burragorang over a short period of time (approximately internal wave that passed a station near (Warragam b a Dam ) . Th es e we r e three days), suc h that the lower part of the dam wall on August 24 had an associated w ith the boil wate r ale rts the water column consisted of the cold, amplitude of 35 m etres - that is, th e heavier interface between th e warmer and colder flood water and the upper part Scie ntists and e ngin eers from th e regions (known as the me talimn ion o r contained the original warmer, lighter lake Centre fo r Water R.esearc h (CWR.) at thermocline) dropped 35 m etres in a water.

T he University of W estern Australia and matter of hours. T he total depth of water th e Sydney Catc hm ent Authori t y Associated with the weather pattern s at this station was 90 m etres. condu cted several in vestiga tions into that dumped heavy rain on the catchment determining the dynami cs of Lak e The presence of internal waves in Burragorang has major impli Burragorang in response to the flood Lake CS 14~--- - -~ - - -~ - -- - -~ ._ waters. Their aim was to discover the ca tions fo r th e provisio n of wate r ~ lJ supply. A fixed offtake structure lik ely pathways of fl ood-bo rn e located in the region affected by co ntaminants, and the di lutio n rates ~ 12 of suc h contaminants. The study internal waves (up to 35 metres in the .!! involved an investigation of field da ta above case) would have poor water ~ll ' - - - - - ' - - - - - - ' - - -- ' - - - - - ' - - - - - ' c oll ec t ed fro m th e la k e and quali ty periodi caUy advected past the S,p 7 J«ll9 Ju/29 Aug 8 Aug 18 Aug28 catchment, as we ll as numerical offtake. Th e poore r water quality in 10~ - -- - -~ - - -~ - - - - - ~ modell ing studies to confirm and th is in stance was associated with the flood waters , as floods generally wash quantify conceptual models derived ]20 I -€ from the field in vestigation. The catchments of nutti ents, sediment and I' I *30 J num e ri cal m ode ls app li ed were the bacteria . Th e offtake stru ctu res were --- - ----- I laterally-averaged , one-dim ensional mo ved into th e surface layer soon (in the vertical) hydrodynamics model after to take advantage of the high est 50..___ __,__ ___._ _ _ ...___ ___.__ ___, DYR.ESM and the three-dim ensional quality w ater, whic h in this case was J«l 19 Ju/ 29 Aug 8 Aus l8 Aug28 Sep 7 hydrodyn a m ics model ELC OM , present in the lake prio r to the flood both developed by CWR.. even t.

Figure 1. Lake temperature and depth of t he offtakes in Lake Burragorang. Each co lour refers P rior to the first flood eve nt, the This is de mo nstrated in Figure 1, to a different offtake, and the vertical lines water in Lake Burragorang was a w hi c h shows the depth of the uni for m te mp e rature . T h e first offta kes and the temperatu re at represent the onset of the two flood events

l -

!

J.w ~---------------------

34

WATER MARCH 2001

Lake Bun"egÂŤang 1939

S ~ a:cn Tl:-re 1 tir,

Day: 11

81 _[ 6 1

~ 41

:!:

21

~~~=-- L____.____,___

_J

Lake Butragorang 1998

S1mul."lf en Time 11 n.rs

Day 12

81

'E 61

i.1 ]!

21

-~~~~::=-~'----~'--~==~=~~ 10

20

30

40

so

Transect Oi5t11.nce Rm OiVll (k.m)

Figure 2 : Transect of temperature in Lake Burragorang extract ed from the t hree-dimensional numerical model ELCOM during the second flood event .

those depths. Up u ntil August 8, the temperature between 25 and 45 me tres depth was essen tia ll y u n ifo rm . After th is time, the temperature at 45 m etres dro pped due to the cold flood waters. The oscillations in th e te mperature at th e offta ke depths between August 16 and Septe mbe r 3 we re due to large amplitude internal waves.

The num erica l mod els were used to verify and exte nd the conceptual picture described above. DYRESM showed the effect of the inflow o n stratifyi ng the water column in a short period of time, as well as describing the various levels at w h ich infl ows were inserted into the water column.

D ilution of the in flows was found to be minimal - inf'lows tended to maintain the ir initial co ncen trations of all species once inserted, and hence the water column was fou nd to have a strata of discrete layers with water quality si milar to the inflow concentrations. Inflows after th e first major flo od were inserted at mid-depth , and so th e positioning of the offtake structu res at the surface still provided th e highest quality water. ELCO M demonstrated th e complex interplay between inflow events and internal wave activity in th e lake, suc h that field observations could not be reproduced in the m ode l unless attention was paid to mode ll ing the in terna l wave fie ld correctl y.

An illustration of th e interaction between inflows an d inte rnal wave activity is presented in Figu re 2 using data from the three-dimensional hydrodynamics model ELCOM. The top panel shows the stratifi cation at the onset of the seco nd floo d event. In the seco nd pan el, the inflow is flow ing down the reservoir side as a cold , dense underflow.

T he metalim nion (yellow) has risen approximately 5 me tres at the dam wall between the two panels du e to the internal wave activity shown in Figure I. T he combination of approa ches, consisting of fie ld data , one-di mensional and three-dimensio nal modelling, provided an excellent 1111tial understanding of the inflow dynamics into Lake Bu rragorang du rin g these events. Fuw re efforts w ill be directed towards better fie ld measu rements of underflow events, specificall y inflow dilu tion rates and the interaction of inflows with the internal wave field, and developing real- time mon itori ng systems to assist the withdrawa l strategy.

STRAUB Precision Pipe Joint Systems High quality, reliable and durable.

If you're in the shipbuilding, water treatment, petro-chemical in fact any industry that needs simple, high integrity pipe system joints - then STRAUB should be your preferred pipe joining product.

The STRAUB name is synonymous with high quality, reliability, durability and simple installation, and STRAUB couplings are specified in the most demanding applications world-wide.

Available with an outside diameter of up to 2,000mm, STRAUB products accommodate up to 67 bar working pressure in both axial and non-axial restraining versions.

Proven to be a more cost-effective means of joining pipe than butt-welding or flanges, using STRAUB will ensure your project comes in on budget.

When quality can't be compromised, demand STRAUB.

Call 1800 246 167 freecall or email info@gpsaustralia.com.au for more information

CENTRE

Th e Swan R..iver Estuary in Western Australia was central to the establishm ent and growth of the city of Pe rth and is an integral part o f the city's to urism and recreational fishe1y industries. The estuary is used for urban stormwater disposal, co mm ercial fis hing, recreation , transportation and scien tific research. The m aj o r sh ippin g port of Freman tle is lo cated at the estuary m o uth . T h e hydrology o f the estuary was altered su bsta ntiall y arou nd the turn of th is century, w hen the entrance was deepened during th e constru cti on o f Fre mantle H a rbou r. Th is c han ge has all owe d inc reased flushing o f the lower estua ry with relatively uncontaminated marine wate r so that, until the recent toxic bluegreen algal bloom , the re have bee n few water quality problems in the lower estuary (belo w th e 'Na rro ws' , see Figu re

1).

Water Quality T h e Swan R i ver ha s exp eri e nced wa ter qu ality problems in the past. Up unti l the 1920s the estua1y was used fo r the disposal of dom estic sewage eillu e nt fro m th e city of P erth (R.iggerc, 197 8).

Nowa days, howeve r, m ost nutrie nt inputs to the estuary are from diffuse rather than po int sou rces, and managing these inputs over such a large catc hme nt (1 2 1,000 km 2), w iU require great perseverance and commun ity educatio n .

Accu mulati o ns o f nutrient 36

WATER MARCH 2001

FOR

WATER

RESEARCH

The Upper Estuary

0 1 2 3 km Figure 1 . Map of the Swan River

T his part of the estua1y is relatively poorly flush e d w ith m ar in e wa t e r and is considered to be eutroph ic Qohn , 1994) w ith c ases of a lg al b looms well doc ume nted (T hompso n and H osj a, 1996; H amilto n et al., 1999).

T h e seaso nality of P e rth 's ra in fall and river flow produces large va ria tions in salinity in the Swan estuaiy over an annual cycle. Through summer and au tumn , brackish seawater propagates m ore than 42 km from Fremantle along the low-lying Swa n C o astal Plain. In winte r, th e brackish 350 water is flushed fro m th e - 1994 300 - 1995 upper estuary into th e lower - 1 996 basin (below the Narrows), 250 - 1997 ;:;and a salt w edge (brackish -2000 200 water overlain by freshwater) ?: 0 generally occurs be tween 5 u:: 150 and 20 km upstream from the 100 ocea n en trance . D eoxygen50 ation of botto m waters is frequ e ntly obse rved in the 0 regio n of the salt wedge, J F M A M J J A s 0 N D w here th ere is strong strati Figure 2. A comparison of Swan River inflows for 1994-97 fi ca tion and little vertical against the 2000 inflow. Flow gauging data are from Water and mixing of freshwater w ith the Rivers Commi ssion (Western Au stralia). unde rlyin g brackish w ate r.

.,

.s

e nriched sediments in th e u ppe r estuary fu rther compli cate th e management of th e estuary. Controll ing nutri en t releases from these sediments is likely to be critical to improvi ng water quality in the Swan l~ive r an d is being actively tac kl ed by th e Water and R ivers Comm ission through artificia ll y oxygenating bo ttom wa ters.

T h e up per es tuary (a b ove T h e Na rrows) cons ists of lo n g, shall ow stretches ofriver channel (1-3111 deep) that are punctuated by deeper (4-Sm) sections.

CENTRE

The Microcystis Bloom Until 2000 th ere had never been a m ajor blue-green algal bloom in the Swan R iver. In summer and autumn , conditions are highl y co ndu c ive to developm ent of algal blooms as th e water is generally clear, solar radiation and water temperature are hi gh, and the re is gene ralJy an adeq uate su pply of nitrogen , the limitin g nutri ent (T h om pso n and H o sja , 1996) .

Howeve r, the presence of brackish w ater had gene rall y prevente d th e o ccurrence of blooms of nox ious, fr eshwater blue-green al gae that are common in many of P erch's wetlands and w id espread on th e Australian con tinent.

FOR

WATER

RESEARCH

PHOTO: ISAO INOUYE

Figure 3. Cells of Microcystis in a colony formation.

l n J anuary 2000, Pe rch recorded a total rainfall of 111111111, 12 times the J an uary average and the highest rainfal.l on reco rd fo r this month. Most of th is rain (73%) fell ove r the course of a single day, 22 J a nuary . Th e result was ve ry high discharge of fresh water to the Swan l~ver E stu a ry, which co mpl e te ly flu sh ed brackish and marine water from th e upper estua ry and surface water from th e lowe r es tuary. P ea k disc harge of 310 m 3s- 1 (en ough to fil.l an O lympic-size swimming pool in abo ut eight seco nds) occurre d in the A vo n R iver inflow on 25 January (see Figure 2).

th at th e Swa n Ri ver was aga in safe fo r recrea tion .

!Vlirroc)'slis aerugi11osa ofte n fo rms large colon ies (see Figure 3), w hich enhance its abil ity to m ove up and down th e water co lumn th rough changes in de nsity .

These rapid density changes are accom plished m ostly through daily c hanges in carbohydrate content, wh ich it effe ctively uses as ballast . During the day, cell s accumulate carbohydrate w hen they carry out p hotosynthesis, and become denser, w hile at night the ca rboh ydrate is respired so that by daylight the cells may be highly buoyant. This featu re e nabl es Microc)'slis to form la rge blooms, and these we re particularly evide nt in the Swan Ri ver in ea rl y Fe bruary, w hen early morning easterly winds b lew buoyant cell s into

sheltered embaym ents, sometim es fo1111ing scums of several million celJs per mJ. A three-dimensional hydrodynam ic model, ELCO M , developed at the Centre for Water Research (CW R ) at The U ni ve rsity o f W estern Australia has been used to de monstrate the intera ctions of discharge and tides , w hi ch are the e main influ ences on the distribu tion e of salinity in the Swan River estuaiy.

M odel results shown in Fi gure 4 illustrate how the low salinities assisted th e development of th e Microcystis bloom as the freshwater discharge su bsided. The use of the 10 parts per thousand salinity contour from the model simulations provides an approximate indicati on of when th e freshwater 1Vlicroc)'stis co uld be expected to be atte nuate d.

Cleanup Program Th e impl em entati on of the Swa nCanni ng Cleanup Program (SCCP ) is a major initiati ve that is bein g fund ed by the State Governm ent and implem ented through t h e W ate r and Ri ve r s Commissio n. The recent toxic blu e-green alga l bloom on the Swan Ri ver has increased awa re ness of the need for su ch a program and is likely to enhance the rate of imple m e ntati on of chis p rogram.

CWR is working closely with th e W ater and Ri ve rs Co mmiss ion a nd is being funded by the m through the Estuarin e R esearch Foundatio n, to develop computer mode ls of the river to be used fo r predictions of algal bl oo m s, wa t e r qual it y a nd management decision making.

T h is u nusua l situation m ea nt that fr es h water and high levels o f nutrients from ri ve r inflows coi n cided with wa rm summ e r water tempe ra tures (>2 5°C) .

T he large, tox ic bloo m th at occ urred was ve ry unusual fo r the Swan Ri ver Estuary, whic h is usually sa lty during summ e r. le was com pri se d of th e fresh wate r blue- gree n algal spec ies, Micro c)'s lis aemg i11osa . Thi s sp ecies can produ ce th e toxin 10 Mi crocystin , w hic h co ns ists of 20 30 ,o lO 10 a large grou p of closely related organic compounds. Th e tox in , w he n in gested, ca n caus e vo miting , d ia rrh oea, stomach pain and liver damage .

Because o f t he dan ge r of chis toxi n , the Swa n Ri ver had to be closed co th e publ ic for 10 20 30 recreationa l and co mm e rcial Figure 4. Surface salinity in the Swan Rive r in 2000, ac t i v iti es such as fis hin g, based on hydrodynamic model results. The colour scale p r awn ing , sw imm i n g and shows salinity in parts per thousand (seawater - 35 parts boating. Some parts of th e river per thousand). At the bottom left is the Fremantle w e re closed on 11 Fe bruary because of health co ncerns, and entrance and at th e top right is Guildford , approximately closures were extended during 4 5km from Fremantle. Inflows for the Canning River the following days . On 17 trib utary (lower branch) were not available at the time of Fe bruary, some areas we re model runs and salinity in t his regio n is not considered decl a r e d sa fe and o n 22 representative. Model resu lts are from Ben Hodges Febru a ry it w as an noun ced (Centre for Water Research, UWf).

References Hamilton, D. P., Thompson , P. A., Kurup. R . and Ho rner-Rosser, J. 1999. 'Dynamics o f dinofl agellare blooms in the Swan River Esrua1y', in: McCo m b, A. J. and Davis,J. A. (Eds),

Proceetli11gs of rl,e Vrli l11tema1io11al vVetla11tls Co,ifere11ce, Gleneagles Press, Adelaide, South Australia. pp. 273-286.

J ohn , J. 1994. ' Eurrophicarion of the Swan River Estuary, Western Australia and the management st rategy', in: Mirsch, W. J. (Ed.), Global W etla11tls: Old Wol'itl a11tl Ne111, Elsevier. pp. 749757 Riggert, T. L. 1978. 'The Swan River Esmary: Development, management an d preservation', Swa n R iver Conservation 13oard, Perth , Western Australia .

T hompson, P. A. and Hosja, V. 1996.

'Nutrient limitation of phytoplankton in th e upper Swan l<..iver Estuary, Western Australia', J. lvlar. Fresl,111ar.

Res., 47 , 659-667 .

WATER MARCH 2001

37

CENTRE

FOR

WATER

RESEARCH

Introduction Lak e Pamvotis is a m ode rately-sized shallow lake nestled in the Balkan mountains of north-western Greece (area o f22 km2, average d epth of 4-5 111). (Figure 1). T he lake is ringed by 1500-2000111 mountains that provide a dramatic backdrop for th e sm all bustl ing city o f l oan nina (po pul ation of ca.

100,000) , the regional gove rnm ent and the cultural centre.

The lake does not have a natural surface overflow but rath er, this karstic watershed is riddled with sinkh o les which are probably the source waters for many of the sprin gs in the neighboring river valleys. A man-m ad e d itch and tunn el have co nnected the lake to th e Kalmpas River sin ce 1959.

In 1997, the local auth ori ties commissioned the Centre for Water R esearch to d eve lop m an agem en t strategies to improve the aesth etics and water qua lity of th e lake. Our study was based on: • historical data ana lysis, • seasonal (one-year) and sub-dai ly (one-week) field data acquisition and analysis an d • numerical modelling of the wate r 30 quality. a 1':

Current State

u

t...

I-

Today the lake is eutrophi c with high algal bio mass throughout the year (> 10 (~1g ch la/ L) with summ er blooms in excess of 30 (~1g chla/ L. The local community wants reco mm endations to fu rther improve the water quality, particularly strategies to decrease alga l biomass.

A chrono logy of anthropogenic influences on the lake ecology over the past 40 yea rs is summarised in Table 1.

Period ic measurements o f fi lterable reactive phosphorus (FRP) from the 1970s to the prese nt clearly illustrate the effec ts of external P-loading on th e lake water (see Table 2) . Low FRP during the 1970s atta ined hi gh levels by the ea rly 1980s. The highest levels were m easured in the early 1990s shortly after the cessa ti on of direct sewerage and industrial e ffiu ent o ut falls into th e lake.

C urr e nt p h osphorus leve ls h ave continu ed to dec rease though th ese are still substa ntially greater than the 1970s 38

WATER MARCH 2001

Dcpth (m) ~

2

0

Figure 1. Location of Lake Pamvotis given by * on map.

Bathymetry of Lake Pamvotis with the location of the five seasonal stations, the two inflows, the two outlets (irrigation and outflow) , the meteorology station (x) and t he city of loannina (n).

20 15

10

Month

Figure 2. Average surface , mid-depth and bottom measu rements over the five seasonal stations of (a) temperature, (b) dissolved oxygen, (c) pH, (d) chla, (e) FRP, (f) NH 4 , (g) N0 3 and (h) DIN(=NH4 +N03 ):FRP. The bold line in (b) represents t he saturated dissolved oxygen value and in (h) the dotted line is the 16:1 line.

CENTRE

FOR

WATER

RESEARCH

Table 2 . FRP concentrations (mg P/ L) in Lake Pamvotis f rom the Lab of Analytical Chemistry, University of loannina.

12

Period

Average

Minimum

Maximum

11

1975-1977

0.01

0.01

0.02

10

0.09

0.07

0.12

9

1980 1981-1982

0.15

0.01

0.36

8

1983

0.09

0.04

0.21

7

Mar. 1984

0.04

0.01

0.10

8

May 1984

0 .06

0.04

0.07

5

Sep. 1984

0.25

0.20

0.37

4

Jun. 1991

0.43

0 .12

1.40

Jan. 1992

0.39

0.14

0.58

Apr. 1992

0.12

0.06

0.24

1998-1999

0.07

0.00

0.26

3

these da ta h ave Figure 3. Isopleths of DO at the surface (top figures) and served to validate above the sediments (bottom figures) during the morning of a three- dim e n s i o nal a q ua ti c August 24 (0802-1030) and August 31 (0805-1037) of 1998.

Stations are shown as small black dots. ecologica l m odel d eve lop e d a t CWR. O ur aim inp uts is less th an o n e deca de . O nce the is to be able to reprodu ce th ese observed point o f diminishing returns is attain ed wate r quality patte rns. Next, a onefrom these measures, additional strategies dime nsional ecological model consistin g to in1prove th e water quality o f Lake of a vertica l mi xing m odel DYRESM Pamvotis ca n be implem ented. C onfident Modelling was coupled to an aquatic ec olo gical assess m ent of th ese future strategies will model C AEDYM to m odel 20-yea r Thou gh not discussed in this article, dep e nd upon continu ed researc h into managem ent strategies (T able 3). fie ld m e thod o lo g y a nd num e r ic al Mon thly ave rages o f th ese lo ng0.6 ~ - -- -- - - - - -- - ~ modelling . term simulations clea rly illustrate + + th a t th e ex t e rn a l nu t ri e nt 0.5 reduc tion m easures are the best + + + + 0 0 0 + 0 0 ~ ~ 0 0 O O 0 way to impro ve the n utri ent ~ 0.4 + + a. conditions in the lake (Figure 4).

Ecotech Pty Ltd cri 0.3 Similar red u c tions we re also Wo r/d-C lass Air & Water 1\fo11ilo ring .! <> <> <> <> pred ic te d for th e d isso l ve d ~ 0"" 0.2 t:,. t:,. A t:,. ino rga ni c nit r o g en sp e ci es . <> Q. Suppliers ofthe Americ<tn Si,:m" H ence, th e reco mme ndation at 0 ~ nm,:e of Automatic W11ter Samplers 0.1 the present tin1e is to foc us on & Area Velocity Flmv 1l1eters 0 0 0 0 0 0 0 O c at c hm e nt manag e m e nt .

A A A A A & ~ 0.0 Ho wever, continu ed research JFMAMJ J ASOND into fish sto cking and wate r Month su pply manage me nt options will be consid ered fo r furth e r future Figure 4. FRP monthly equilibrium imp rove m e n ts o n ce t h e concentrati ons in Lake Pamvotis water under ca tch me n t ha s been suita bly baseline and six 20-year scenarios as re habilitated . modelled by the coupled DYRESM-CAEDYM T he respo nse time o f Lake ecological model for Lake Pamvotis. See Table P am vo tis to a decrease in external 3 for explanations of different scenarios.

similar between the surface and nea rsedimen ts.

Substantial hori zontal variations in both the su rface and n ea r-sed iment D O distributions were also captured with our sampl ing strategy . Sedim ent release rate variability is likely la rge purely from va riations in DO w hich were 3-6 m g/L o n August 31 and 4- 7 mg/ L o n August 24.

Water Samplers

•• •• • : !• ••

~ t

,._.. I

Table 3 . Scenarios for lake remediation assessed with DYRESM-CAEDYM simulations over a 25-year duration from 1970-1994.

Scenario#

Scenario Title

Scenario Summary

H

Sewage

Estimate of late 1980s/ early 1990s sewage inputs.

1

Reduce 50%

Reduction of agricultural in puts of N and P by 50%.

Ph . (03) 9894 2399 ll'll'll'. ecotech. com. au

2

Reduce 90%

Reduction of agricultural inputs of N and P by 90%.

3

Increase springs

Increase spring flow by 15%.

4

Reduce sediment s

Decrease sediment fl uxes of NH4 and P04 by 75%.

5

Increase herbivory

Increase the zooplankton grazing rate by 50%.

40

WATER MARCH 2001

Melboume Srd11ev Perth Brisbane

Flow Meters

• •

-'

• Electronic portal opens •

THE

TER IN.

STRY A LLI A NCE NEWS LETTER FO R PEOPLE M AK IN G WAV ES

OZWATER 2001

door to global markets Th e

South

Australian Water

Indust ry

Alliance, the umbrella organisation that showcases the capabi li ti es of compani es in volved in the state's wate r industry has launched a Web Portal as par t of its global marke ting strategy.

• ~ . tto __ , or

-~ -~ - ~

.. -!':"!\.-"':..,

• -7=:,:..r--• mrn,

Descr ibed by Malco lm Col egate, executive director, as "the pe rfect c hann el for tapping into world marke ts," the Portal was offi cially ' logged on ' by the SA Ministe r fo r Governm e nt Ente rprises and Informati on Econo my, Dr Mic hael Armitage.

More than 120 Alliance me mbe rs can now

..

/>,.., __ ... _ __ _ _

_

....,,..,

,-o..-.

!".~-

~

------------------·'

capa bi Iiti es ,

in for med decisions on how to approach a pote ntial project ," Mr Colcgatc said.

products and services through the Portal. It has comprehe nsive public infor mation areas plus e xtC'nsivc me mbe rs only sectio ns which

The Wate r Indust ry Al liance was form ed in

d e monstrate

thci r

special ist

outli ne business opportunities along with th e strategics by which companies operating eithe r inde pende ntly o r in collaboration with othe r s can win contracts interstate and overseas.

"The site, at "'"'"'· 1Vaterindustry.com. au is an industr y initiative that ventures way be yond t he con ventio na l website and di r ectory.

The re's really nothing like it in the Australian wate r industry," said Mr Colegate .

"On one hand the Portal is the publ ic inte rface by whic h pote ntial c ustom e rs globally can instan tly learn al l about the innovative way South Australian based wate r companies do business , what they have to offer to export mar kets a nd how the Alliance itse lf operates to the advan tage of both c usto me rs and me mbers.

On the othe r, it is the tool whic h can be used to give our me mbe rs a compe titi ve edge. It will speed co mmunication between member companies, g ive the m a much needed research facility and enable the m to make fast, but well

1998 as a direct conseque nce of t he outsourcing of water and waste wa te r o pe rations in Adelaide to Uni ted Wate r and the awarding of a Bu ild Own Operate Tra nsfe r contract for wate r t reatm e nt p lants in ru ra l South Australia to Ri ver land Wate r.

• INNOVATIVE TECHNOLOGY An R&D project at th e Universit y of South Australia has result ed in innovative new filter t echnology • PHILIPPINES SUCCESS Valve manufacturer Aqua-gas-AVK has wo n a contract to supply the Baguio wat er project.

These projects brought inte rnational wate r

fo cused on expo r ts. The Alliance came into

• AQUATIC MONITORING A leading AWQC bi ologist discusses the need to monitor th e health of rivers, streams and lakes.

being as an incorporated body after the formation of a water industry cluste r group and is now m aking its p resence felt on t he inte rnational stage.

• SELECTING A NEW IMAGE The story behind the development of a bright new logo for United Utilities.

Recent successes by me mbe r s have includ ed

• SMART SPRINKLERS An adva nced automated sprinkler system uti lising internet t echn olog y w ill dramatica lly reduce t he SA Depart ment of Educat ion's w ater bi lls.

com panies to Ad elaide and established the climate whic h all owed the unique skil ls and capabili ties of local companies to becom e

sales

of

equipment

and

processes

to

Singapore, cotland, Japan , the Middle East and the Phi lippines. SA companies have also been act ive in wate r industry proj ect s Australi a wid e.

Fu rt h er in form at ion:

J\i\alcolm Colcgatc, Execut ive Direc tor, \<Va t cr· Ind ustr y All ia nce 08 8204 1892

Publi sh ed by Th e W at er Industry Al l ia n ce

OUR WEBSITE Contact our website on

w w w .watc rindustry.com.au

Innovative filter technology The Bal een technology evo lved as a result of a fi ve-year Researc h and Developm e nt program tl1at originated fro m the Univer sity of South Australia.

It resulted from an industry need for improved me thods of waste wate r managem e nt , e nhan ced discharge water quality, reduced disposal costs a nd complia nce with inc r easing ly stringe nt environmental regulations.

installati ons

ope r ating

fu ll-time

ac ross

Australian industry since July 1998, handling waste streams from food processor s, w ine manu fac ture r s, a heavy vehi cle washing facility, a soil analysis laboratory, a municipal treatme nt p lant and vari ous ag ri cultur al applicati ons . Refinem e nts in eng ineer ing design during this tim e have led to realisation of a m odular commer cial prototyp e r eady for mass production for export markets.

The soluti on brought to the marke t is an innovative continuo usly sel f- cleaning filt er

Unlike othe r self-cleaning filte rs the Balee n

and separati on technol ogy, capabl e o f r e m ov ing traditi ona lly ' non -filte ra ble' con tamin ants fro m wast e stream s. The

technol ogy can handle ver y high flow rates and a wide range of fluid s and contaminants.

It can separate suspe nded solids from wate r

Balee n technology solves a long-standing industrial and environme ntal proble m - the

as small as three mic rons (three-thousandths of a millim e tr e) and thus provides the "missing link" in the fil tration spectrum fo r

ability to filte r and separate fin e and troublesome contaminants suc h as industrial grit , biodegradable matter, Hbrous mate rial, g rease and oil from wate r-based streams .

Yur i Obst, t he inve ntor o f th e Baleen technology, established Balee n Filte r s Pty Limited in Dece mber 1998 to comme rcialise the techno logy. In April 1999 , the Unive r sity o f South Australia granted an exclusive li cense to Baleen Filte rs for the manu facture, d evelopment and sale

industrial strength wastewater.

and

r e-use

of

scarce

wa te r

resources • recove ry of waste material s or val ue-added by-products for easy disposal or sale • reduced damage to the environm ent and compliance w ith environme ntal regulations • improved per formance over com petitors , and improvements to WWTP design.

The Bal een technology is a financially attractive propositio n to a host of prospecti ve e nd-user s.

A key advantage lies in Baleen 's re latively low capital cost and signifi cantly low ope rating co st s whe n co mpa r ed to co mpetiti ve offe rings. In particular, de mands placed by

includ e: • Re moves

eve r t ightening e nvironm e ntal legislation have forced industry to source new technolog ies in pursuit of simple, reliabl e

suspe nsion • Reduces SS by as much as 90 to I 00% • Co ll ected solid s arc of a sp ad e-able

and

cost

effective

mea ns

to

ac hieve

regulator y compliance.

of the technology.

T he re arc othe r tangible cost be nefit s suc h The Baleen technology has been thoroughly tested in the marketplace w ith ten prototype

dams etc) e nables dir ect savings in land use • recycle

as :

• di splacem ent of settling volumes (tanks ,

Key features o f the BOD,

Bal ee n techno logy

COD

and

TDS

in

consiste ncy • Com pact dim ensions • User friendl y ope ration Visit th e Baleen s tand within the W.1tcr In dustry

Alliance Pa.vilion at Ozwatc r for further information abo ut Balee n filt er systems or phone 08 8239 2533.

Philippines contract success The Australian division of the in te rnational valve manufacturing company AVK has gained a signi hcant breakthrough for its Adelaide based operation after winning a contract to supply valves for a maj o r potable water p roject in the Phi lippines .

Aqua-Gas - AVK Pty Ltd will suppl y up to 500 valves of var ious specificatio ns to stage one of a SA multi -milli o n Baguio water network , which is being fund ed by the Australian Gove rnme nt through Aus-Aid. Valued at mo re t han S 300,000, the valve contract was awarded by the O ve rseas Project Corporation of Victoria, whic h is managing design and construction of the ne w supply network fo r the Philippines city.

Most of t he product will be supplied from Aqua-Gas - AVK's manufacturing facility at

T he contract represents the first signifi cant e xport fo r Aqua- Gas - AVK from South Australia. Its Ade laide operation was

dcvclopn.;cnt plans for fur ther expansion are being exam ined and reviewed.

established in October '98 with assistance from the South Australian Governme nt through the

" The support we have recei ved in South

De partment of Industry and Trade and the South Australian Cenn-e for Manufacturing.

Australia from the Gove rnmen t and pee r organisations has been most e ncourag ing. We have also been able to hire highly capable and

Actual manufacturing comm e nced late in

enthusiastic personnel in Adelaide and as a result arc able to competitively produce to the high quality standards that have made our parent

! 999 and the company is already a lead ing

supplie r of apprO\·ed ' Standards Mark' val ve products to Australian water authorities and industry at large, includ ing mining and minerals processin g.

Initially, the inte rnational company, which is renowned for its high quality standards in produc ts and manufacturing process, had intended that Adelaide become the regional headquarte r s for the Ausn-alian and New Z ealand market sectors.

company an international success," said Trevor Slaughter, Director - Sales and Marketing. " \I've arc pleased with the progress made to date and ar c confide nt of substantial growth over the next few years. As a result , we arc already reviewing our space r equire ments and in te nd to ex p and o ur r ange of locally manufactured product," he said .

T hese recent successes and ge ne ral steady

Fo r furth er in formation on Aquil-Gas - AVK and its produ<.:l range vis it our sta n d w ithin th e \'\ later Indu str y A lli an<.:c Pa vi li o n a t Ozwa tc r 01' cont.tel Trevor

growth in market share has proven t hat thi s

Slaughter on (08) 8159 6 166.

WingHcld Ade laide. The po tential exists for furth er orde r s and these arc e xpected to fo llow as the project moves into its ne xt stage .

decision was well found ed to the point where

2

Aquatic monitoring vital for Industry

Anew image

I

M on itoring the health of ri ver s,

•A united

\ : , Utilities

str eams and la kes sho uld be as impo rtant to in dust ry as the of

United Utilities Australia, part of the global

machin e ry a nd workplace safety,

uti lity scn·iccs company United Utilities

accordi ng to the Australian Water Quality Centre (AWQ C) .

parent organisation , U UA has re tired its

regul ar

m a inte nance

PLC, has a new image. In com m on with its traditio nal blue logo in favo ur of a mode rn

AWQC's Aq uatic

Senior

Bi o logist ,

Eco logy,

Mr

new identity featuring ,·ibrant blues and

Pe ter

g reens.

Sc hultz, said that unex p ected " We fe lt our traditional logo design, while

c hanges to the health of nearby

it scn ·cd us well, was a little too cold and

aquatic systems o fte n provided

corpo rate to appea l to the much wider

compan ies with an ea rly warn ing in

range of audiences the group now ser ves.

proced ures o r eq uipm e nt and co ul d sa,·c s ig nifica nt costs

Many of our custo me r s, par ticu la r ly in the

fur ther d own the track.

company, not a mode rn customer-frie nd ly

sig n

of

a

b reakd o wn

UK , thought that it suggested a city-fac ing 1lloni1.orin9 the c/i.,ersity ancl ahunclance q{ macroim1ertebra1es is an ~ffecti11c way measurin9 the hea/rh ef a waterbo,lj•.

ef

The f1 nan c ial penalty fo r polluting r iver s,

g rou p," said G raham Dooley, manag ing director of United Uti lities Australia.

streams and waterways and any subseque nt clean -up

is

he fty,

while

the

co mpany

"They arc easily sample d , preser ved, stored

responsible ofte n faces a p ublic backlash with

and

a r esul ting negative impac t on its bottom line.

res pond ing

"R egular

m o nito ring

ca n

ofte n

de tect

examined

with

d iffe ren t

differe ntly

to

sp ec ies

particu lar

e nvironme ntal conditions.

"Creating a new id entity is not a decision t hat any business takes lightly, so o ve r a fo ur m onth pe riod the Gro up undertook a huge amount o f r esea rch.

We

ta lked

to

custom e rs, ran 1vorksho ps and canvassed

unex pected changes early e nough to prevent a

" By

macr o in vcrtcb ratc

the views of e mpl oyees, business partners,

major inc ident fro m develo ping. A numbe r of

commu111ty compos1t 1on of an undisturbe d stream o r watcrbody with t hose fro m the

local au thori t ies and oth e r in te rest ed parties.

recent serio us inc idents in South Austra li a co u ld

probab ly have bee n a,·oi dcd

had

adeq uate monitoring been in p lace.

com par ing

the

monitored waters, a m easu re of heal th ca n be made .

Alm ost

forty

diffe re nt

design s

we r e

deve loped using a ra nge of sym bo ls,

In this respect , industry shoul d look at the

Mr Schu ltz said biomo nitoring is applicable to

colours and typefaces. Eventually we took

cost of biom on itoring in the sa me light as the

all in land aquatic syste ms and by monitor ing

seven of these ide nti ties out to research in

ma inte nance of mach ine ry in that it can

at diffe ren t places a long a strea m , the impact

the United Kingdom where most of our

p revent a n unwanted expense furthe r down the line."

of discharge or run-off and recovery rates can

custo me r s arc based to sec how we ll they

be mon itored.

communicated the rig ht m essages .

AWQC is a business unit of SA Water and is

He said AWQC also provides ccotoxicology

Based o n that resea rc h , we re ac hed a

South Australia's premier biomonitoring group.

se n ·iccs, whi c h examine th e effects of

sho rtlist of four and these were u1wci lcd to

It is inte rnationally recognised as a centre of

pollu tan ts o r conta m inants o n an e nt ire ecosystem.

1400 employees at the Group confe re nce in O ctobe r."

excell ence

111

water qual ity,

mo nitoring,

assessment and researc h and recently was the He sai d m any po lluta nts, suc h as hea,-y

According to Graham, who attende d the

m e tals, pesticides or o rganic compounds act

confe re nce,

International Laboratories. It is also the omcial

sync rg istica lly whic h alters the ir toxi cology,

d iscussion, the g reen 'swept' id entity was

independe nt laboratory for the testing of Sydney's water supply.

making it diffic ult to assess the impact a

se lected as it suggested the right balance

parti cu la r

across fou r key factors of customer -focus,

successful tenderer for the pro,·ision of analytica l ser vices for performance benchmarking with

pollu tan t could have o n th e

enviro nment Mr Schultz said biomonitoring provides a direct assessme nt

of an

ecosystem 's

health

based

on

its

c he mi cal

com position alone.

aft e r

mu c h

animated

mod ernity, re liabi li ty and multi -uti li ty.

Fo ll ow ing the conference, som e fina l

by

measuring the living components of a water

Testing the response of a range of plant and

changes were made to the d etail of the logo

body. He said thcAWQC program measures the

macroinvc ,·tebratcs to the po ll ution p rovides

before it was un ve il ed earl ie r this year.

health of a watcrbody by assessing the diversity

a better unde r standing of what impact a

and abundance of mao-oinvcrtebratcs - suc h

part icular po ll ution eco syste m.

creatures as worms, insects and snails. " Macroin vcrtebr ates

arc

an

effective

mon itoring tool as these sm all an imals ar c ver y d iverse and p resent in all aq uat ic systems," he said.

cou ld

have

o n an

"We arc conf1dc nt the new look balances the need for a m o re custome r-friendly symbol with the need for sca le and author ity that go es w ith ope rating key

Fu r the r Informa t io n:

pu bli c ser vices," added Mr Dooley.

M ick Fusco, M;u·kc ting , A\VQC Ph: 08 8259 0252 Fa x: 08 8259 0228

Uni ted Utilities A u str.11ia is ;rn exh ib itor within th e

E-m ilil : m ick.fusco@ saw;itcr.s.1.gov.,1u

\•V.1tcr In d u stry Allia n ce P,, vi li o n at Ozw,Hcr.

3

Phihnac's World First Pipe fittings for Japan Australian pipe systems manufacturer Philmac is the first company in the world to supply Japan w ith specialist plastic water fi ttings for use in connecting Japanese households to t he

world, pa r ticularly in other parts of Asia.

He

the

said

Japanese

water

market

t rad itio na lly used meta l fitt ings and had extremely tough standards that had to be

mains water supply.

overcome be fore any other mate rial would be Philmac r ecently signed a contract potentially

considered.

plastics for wate r s upply is now well

worth SS mill ion a year with major Japanese trading company Kur im oto Ltd, which in turn will supply the fi ttings to Japan's 5000 domestic water supply companies.

It is the first time that Japan has approved the

" In the past, plastic fitti ngs ha\'C been unable to meet these standards and we had to

system

and

follows

significant

development efforts by Philmac in Adelaide.

Mr Cussen said the Kobi ear thquake in 1995

cope with the "cry stringent demands placed

had been the catalyst to the development and

on it before approval was g h·cn," he said . " In add ition to that, Ph il mac design staff had to cope with d iffere nt pipe dimensions used

The contract is a coup for Philmac, and w illingness to meet the specific requi rements of its customer s.

Mr Br uce Cussen, Philmac's Export Manager,

use of plastics in the domestic supply of water in Japan .

"After the ear thquake, authorities found that most of the water systems that fai led were

in Japan. demonstrates the company's ability and

underway in the Japanese markets."

develop a ne w material concept which cou ld

use of p lastic fittings for its domestic water supply

specialist fittings arc required . In the past these have been metal, but innovation in

metal, rat he r than polyethylene," he said.

"Our staff in Adelaide were able to deve lop a patented plastic fitting which exceeded all

"This provided a trigger for the introduction

these standards and enabled plastic fi ttings to

of more polyethylene systems to re p lace the

be a pproved for use by wate r companies in

t raditional

Japan fo r the first time.

conti nued to use metal fi ttings."

metal

pipes,

a lthough

they

sa id the contract was amo ng the most significant c,·cnts in Philmac's history and

"EYcry month about I 00,000 ne w homes arc

would ope n up oppor tunities throughout the

built in Japa n which means up to 500,000

Thermoplastic Excellence W ith a n

aggrcssi\'C

marketing campaign

throughout 2000, it is no wonder that Glynwcd Pipe Systems Australia's "Supcdlo" ABS pipe system is being used on a number of new projects throughout the country.

·11

T he company (a division of Philmac Pry Ltd) is the principal Australian distr ibutor for the Glynwcd Pipe Systems group of com panies, supplying a diver se and fl exible range of products to the water and wastewater industry.

~

Further

in fo rm.ition

abo ut

Ph ilmilc

is .i t

The ABS advantage

I !: • ..,

products

;wa ila blc from the Glynwcd Pipe Systems stand Oz Wa te r, o r by p ho n ing 1800 246 167.

particularly large bo1·c on the system also maxim ises llow velocities, which means further down-the-line sa"ings such as pumping costs.

They arc also easy to work with, and can be cut and joined to suit site conditions. Using solvent cement we lding, the joining process is simple and reliab le -

and there is no need fo r

specialised equipment o r personne l.

G~,n wed's ii BS System at the Bolivar WTP in Sout h ti t1st.ralia.

1\llr Mitchell said ABS pipe was becoming a favoured

alternative

fo r

major

projects

nationally.

Its AB pipe and flttings in particular are winning accolades for their strength and

r igidity at higher temperatures.

d urability in major projects as fo r afi e ld as the

The Marketing Manager for G lynwcd Pipe

Boliva1· Waste WatC'r Treatment Plant in South

ystems Australia, Mr Jason Mitchell , said ABS

Australia and the Lower Molonglo 'Waste Water

pi pe and fittings had significant advantages O\'Cr

Treatment Plant in the ACT

steel and othe r pipe mate rials.

Glynwed Pipe Systems Austral ia supplies a complete range of ABS pipe, fittings and valves from 3/S" to 315mm.

In addition to its extensive range of products, Glynwcd Pipe Systems Australia also provides

Major contractors embracing ABS in their

"ABS is approximately one-sixth the weight of

projects include Transflc ld, Purac, O'Donnell

e qu ivalent steel

G ri ffi n and Aquatcc-Maxcon .

lightweight support systems," he said.

Glynwcd Pipe Systems ABS pipe and fittings

"This means fewe r personnel and less lifting

dosing skids.

manufactured in the UK by Durapipc S&LP arc

equipment arc required, and ABS p ipe is safer to install."

"It's easy to sec why ABS products arc so popular

ABS pipe and fitti ngs arc high ly resistant to

consider the key advantages," Mr Mitche ll said.

particularly corrosion proof and abrasion resistant, with excellent wear properties for a wide range of slurries.

pipe

a nd

re quires on ly

sunlight and do not corrode in weathe r. They do They arc also extreme ly r igid, allowing greater suppo r t distances and AB maintains its

the \'alucd service of pre-fabrication. Customers such as US Filtration enjoy this service utilising Glynwcd's pre-fabricated ABS on their chemical

in \'arious applications, especially whc1.1 you

not need painting or wrapping and arc able to

1:urt h c r in fo rm.1 tion .ibou l Glynwcd Pipe Sys tems Austr.ilia. ABS p rod ucts is ;w,1ilablc from the corup:my's

withstand extre me hot and cold weather. The

st.ind .1 1 Q7.\Vatcr, or by phoning 1800 246 167.

4

Unique disinfection systellls Ultraviolet Techno logy

New contracts for O'Donnell Griffin

of Australasia

Harvey and Baldivis WTPs

Project Manager Laszlo Bachmayc r repo r ts

Ultravio le t ( UV) disinfectio n / stcril iiation

O' Donne ll G riffin has recently com pleted

t hat p ractica l compl etion was achieved o n 12

syste m s in South Australia for more than

commissioning of the Har vey a nd Baldi vis

January 200 1, three weeks a head of sche du le.

20 years . Its units a rc a prove n and un ique

water treatm ent plants south of Perth in

T his was a great result for C raig Ba rber a nd

d esig n and utilise UV light transmittable

Western Austra lia.

( UVT A)

has

Advanced tubing.

bee n

man ufac turing

Flu orop o lymcr

(A FP840)

The wate r or treated e fflue nt

(l iquid) fl o ws through the INSID E of this tubing. The m e rcury vapour ( UY) lamps ar c situated o utside and separate from the

his team on site afte r persistent rain had fr ustrated progress d uring construction.

The design a nd construction of these faci lities for m ed part of the Stirling Har vey Water Supply Sche me which will deli ver 200ML per clay fro m the Har vey Dam to the southe rn suburbs of Pe rth.

fl owing liquid.

This design advantage is important whe n UV treatme nt is used fo r drin king/ cooking water etc, as the re ca n not be any contam ination of the liquid from broke n glass/ quart'. :'. c hips or toxic

T he Har vey site comprised of lime storage, batc hing

and

cl os ing

systems ,

lim e

clarifi cation , c hl orination, acid closing and CO2 dosing. T he 13alcl ivis site at the Perth e ncl of the pipe line has c hlo rination on ly.

me rcury. The c ritical skin temperature of the UV lamp is controlled. to

slip into

an allocated space in the

UV disin fectio n of treated e fflu e nt whe n

pipeli ne carrying the e fflu ent. T he unit will

fl owing through a pipe under pressure can

produced more than a 4 log kill rate.

be

a

headac h e

manufacture rs .

fo r

many

UV

W ith the LI VTA desig n

there is NO N EED to construct a c hanne l or: • Use a vertical up -fl ow /we ir over- fl ow quartz tube type syste m • Use a stainless steel tube type UV uni t w ith e nclosed high p ressure UV la m ps encased in a quartz sleeve.

UV lamps arc located in aluminium lamp racks and arc arranged in ver tical rows outside of paralle l lengths of AFP840 tubing. Witl, the

Mt PleasantWTP

disconnection of a single bayonet plug, an o perator can rem ove each rack from above

O'Donnel l Griffin was awarded a $5 . 5111

throug h access do or s o n

top of each

disinfection unit. Power is provided to tl,c UV

contract fo r the d esign and constr uction of the Mt Pleasant Water Treatment Plant in Septembe r 2000.

lamps by means of very efncicnt clcctTonic ballast~. T he e lectronic ballasts arc e nclosed

The plant utilises the MI EX icon exchange

cabinets,

process foll owed by two separate fi ltrati on

in these d esigns as the co oling o f the UV

e liminating tl,c need for separate ballast panels

streams. The corwcntional stream incor porating

lamp is reliant o n the e fflu e nt fl ow at all

and greatly sim pli fy tl,c installation and

flocculation , settling and media fil tration while

maintenance system .

tl1c second stream is hollow f1brc microf11tration.

The risk of UV lamp 'burn o ut' is very high

times. Hig h-pressure UV lamps have a ver y

within

powde red -coated

steel

short li fe and arc e xpensive to re pl ace. " TERM ! 1ATO R"! desig n UV

Links to a SCA DA system and PLC can be provided with each "TERMINATOR"! unit . A

unit is sup pli ed complete with 4 50 N B A BS

touc h screen is m ounted in tl,c door panel. An

stub flan ge and Table E backing rings ready

optional mode m can be used to monitor or

UVTA's

make on- line changes to a

Constr uction o n site is progressing well and the project is clue for completion in May 200 I.

Shell Harbour and Bombo disinfection faci lities

control system from a remote

O' Donne ll G ri ffin was recently awarded the

site

contract fo r the design and construction of

providing

custom er

immediate

suppor t

and

maintenance.

di sinfection facilities at t he he ll Har bour and 13ombc WWTPs near Wollongong, NSW. The Shell Harbour pl ant wi ll incorporate the

Vis it us at th e \ .Ya1c r Indu str y Al lian ce p;\\' ili on from where we

•

second largest UV d isin fection plan t to be buil t in Australia.

will also demo ns trate h ow d irty, un-di s infcc t c d Wtlt<:r ca n be t urned int o sa fe drin kable wa t e r· u s ing 12 vo lt DC c lcctr i c,11 p o wer fro m a c ar batte ry or any

In anoth e r interstate success O' Donne ll

12 vo lt D C source cg, so lar / wi nd

G riffin has been awarded t he contr act for the

ge n er ators. Furth er infor mati o n

To ny Gardn e r 0 8 8337 0079

Warwick WWTP

prov isio n o f sc ree ning system s and g r it separation systems at the War w ic k WWTP west of Br isbane , Q ueensland .

5

Sniart Sprinklers

Water network siniulation Specialist research and project eng ineering firm Computational Fluid Mechanics (CFM)

The South Australian Education De par tment has bought a new autom ated system that will

is now distri buting HYO -NET, a next

control schools' irrigation through a central

generation water supply network sim ulation and optimisation m odel.

com puter and probably halve its SS million a year water bill. It will eventually control the

HYO -NET is being marketed through CFM's

ir rigation of sports fie lds and green space at some 30 0 school sites .

sister organisation , CREA Australia.

T his state-of-the ar t suite of software, HYO-

ef mine tailings a t the mouth ef King /1.i.,cr

Delta

NET features the fo llowing • Mouse-driven (graphical) input and output routines based on Mi cr oStation; • A full G IS capability, ideal for asset managem ent and which, by virtue of the mo del, is 'live'; • The exact r e presentation o f the total net wor k by two g raphi ca lly and computationally integrated scales, the pipe net wor k (kilometres) and t he plants (metres) ; Unique design opt imi sation routines capable of optimisi ng over any number of

the Olympics site at Ho me bush Bay, Syd ney and the hyd rodyna mics and chemi stry of Tasm ania's Macq uar ie Harbour.

tailings.

2 . This d.iei ls u-:msferre.d

autom;,.tic.tl!y to the M1rcomet 'Industry

The study comprised the fo llowing clements:

(r iver) influences ; • An integrated chemical equilibrium model

Computation Fluid Mechani cs is a lead er in

coastal zones w ith maj or projects including, the Venice Lagoon , Syd ney's d eepwater outfall s, the Barker Inlet coastal wetlands and Coorong lagoons and estuarine channels in South Australia; t idal and fl ood hydraul ics for

•

.!

J .,!

I

.•........., ....,,"'

fo r copper spcciation featu ring the main chemical mechan isms of ad sorption onto hydrous metal ox ides and comp lcxation

· ~9

•\!

"' •O,t

w ith disso lved organic carbon; • Flocculation of hydrous ferric oxide on entering t he higher ionic st re ng th of harbo ur water ; • Sedimentation to th e harbour fl oor; • Predicti o n o f total and toxi c cop per

'4. The listofsitHtob@ 1rr1g~u?d is trnnsmlrtod t0 a high-power ndlo

"''"

.. . and t ht: overall result is co/culat ed water opp/;cations, only applied wh en nec,mory and m,pped if rain faU.s . .

In other words - 'lrrlgotlon drive n by the w eather' Hlct"'Omo t Pty Ltd www.m .k romet .com.::111 I JOO I JO 4.lS

Using data coll ected fro m local weather statio ns, along ,-v ith soil and plant analysis from g iven sites, a r emote controller ident ifies and implem ents optimum watering cycles . As a result, spr inklers w ill not switch on in wet weather - unlike

concen trations througho ut the harbour, assist ing in remediation action and harbour

- or if soil conditions arc such that no

usage.

watering is required.

In form at io n abou t H YO- NET and Compu tat ional Huid Mc<.:hanks is available at th e \•Yat e r Indus try Allinn cc Pavilion al Oz.water o r by contac ting Dr Gany Tong o n

08 8278 l448.

Water level graphs ef some basins in Valle CavalJina net work (' 1"1sca" I, 2 and 4) . /-/)'D- Nf.T gi,•es the opt imised operation plan for all the managed elements (l'a fres and pumps) to dril'e, automaiica/9•, a day ef real plant management with constraints w

n · bln1

•J.0

Se r~r·

Scrver'work1out if and

waters under tidal, wind and fre shwater

bulk systems.

the develo pment of hydrodynami c m odeling and software and its leadi ng edge app lications.

Core wo rk has traditionally been in the

J, The MicrormH 'lnd1mr y

when e;ich site needs imsnlon

opt imising t he design of new networks or the upgrade of existing networks and one for opti mising the day to day operation of

under review by ACTEW AGC.

HOW MICROMET WORKS lO SAVI RC'iOURCf'i, MONFYANO PROllCT THl lNVIRONMfNT

harbour, in a World Heritage area has been seriously affected by r iver -borne copper mine

3D hydrodynami c model • A ful l investigation of highl y str atified coastal

in the north of Italy. In Australia it is cur rently

using weather information and sitc-spccitlc data to make irrigation m ore effici ent.

T he Macquari e Harbour investigation was one of the m ost challeng ing of its type ever undertaken in Australia . T he large natural

load cases simu ltaneous ly and unsur passed on industry standar d tests; • Two optimi sation procedures, one for

T he model is also used by a number of utilities

Designed by Water Industry Alliance member Micromct , the system reduces water use by

,_SUH

::::: - :t===-::.::.:'.. ., ;~

maintain defined water

s.'4--'?t; tr. l •JJ.--~

;"'"" t , . . . ~

:""-------------r

le,,els ranges at reservoirs and pressure at particular points ll'hilc satis/j•inEJ prescribed jloll'S at delivery points.

: ..

·--,1.---~

t 'lr,J/1

j

conventional devices tl1at operate on timers

Smar t use of Internet technology m eans that the company, based in the Adelaide Hills, can offer its unique ser vice Austral iawide and ultimately o ffshor e.

According to managing dir ector Chris Laurie, the Micromet system is becom ing increasingly popu lar with local government.

Eight council s in Adelaide and 18 in Melbourne are alr eady using the system.

T he enor mous potential of the Micromct technology to become a significant Austrnlian export enterprise has recently been recognised by a Feder al Government Auslndustry Research and Development Grant.

A v ideo e xp la ining h ow t he Microm cl system works can b e viewed at th (' Wate r Industry A lliance Pavi lion cha r ing Ozwatc r . 1:ur th c r informa tio n fro m Chris

Laurie, 08 8388 1425.

6

=---

Untted Water

,-DROPL~TS

Building part for the 2 1st c

Winery effluent tre.iment Adelaide-based Chesser Chemicals has introfuccd 'K Clean ' a potassiu1~ based wine indust1,- tank cleaner thar substantially reduces the salinit) ' of win ery effluent!

Gcncrall{,inateirils u£ d for tank deaning arc based on sodium hydroxide and as a result the wastewater created by the cleaning process is rich in sodium ions.

Being potassium ba5cd , 'K Clean ' is fur more environmentally fri endly. Potassium is also an impor tant ingredient in fertiliser and the effluent created by tank cleaning can be reused for the irrigation of wood lots or

With the 1996 awarding of a management, maintenance and operation co ntract in Adelaide, United Water began a partnershi p with the SA Government and SA Water to provid e complete water and wastewater se rvices to the one milli on residents o f Adelaide.

The awarding of this contract was, and still is, the largest and most ambiti ous water outsourcing contract in Australia 's history.

Employing over 400 people, United Water has an expertise and experience in all aspects of the water industry, including operati on and maintenance, asset management as well as design and project management. United Water also has extensive Research and Development exper ience and is involved in many water qual ity improvement p rojects including Cryptosporidium research, taste and odours, CFD modell ing and wastewater reuse.

All of United Water's operatio ns arc backed by resources from its parent co mpanies, Vivendi Water, Thames Water and Brown and Root.

Since United Water began in South Australia, there has been an improvement in the quality o f water and treated effl uent as we ll as lifting ser vice standards and n etwo rk response times. W ith private sector participation, the State Government has achieved a saving of approximately 20% (around S I0 mill ion per

Since commencing operations, United Water has undertaken extensive work to improve the condition of the assets and provide a better water and wastewater ser vice. The resu lts of this work arc now taking affect , with residents in the Papakura area receiving for the first tim e drinking water of an A grade quality.

In April I 999, Ballarat's Central Highlands Water Authority and United Water's parent company Thames Water signed a 25 year agreement to operate the ex isti ng water fac ilities as well as co nstruct and operate two water new flltration plants, providing treated water ser vices for Ballarat and surrounding townships.

Recognising t he im portance of securing a world class operator, T hames Water enlisted the ex pertise and experience of United Water to manage, maintain and ope rate the treatment plants and facilities for the duration

year) to taxpayers.

of the contract .

United Water has been actively seeking and under taking new business opportunities and expanding our operatio nal base, both within Australia and the Asia- Pacific region .

Responsibilities incl ude operating the water fil t ration plants in accordance with stringent water quality perfor mance targets and ensuring storage tanks and basins contain sufficient supply to meet d emand . United Wate r is also responsible for asset maintenance and und er taking asset

In July 1997, United Water became the first private water company to win a franchise agreement in New Zealand, when the Auckland District Council of Papakura o utsourced for 30 years its water distribution and wastewater collection and treatment operations.

Dr Bill Brignal examining water columns m t he Myponga Water Treatment Plant.

management pl ans.

Thro ugh these three outsourcing contracts, United Water is d emonstrati ng many of the advantages of partnerships for publi c and pri vate sector groups. With higher demands and exp ectatio ns o n drinking water and wastewater t reatm ent quality as well as community pressure to keep costs affordable, United Water can provide a tai lo r made sol ution for your community.

vineyards.

A typical examp le of the innovative products developed through the company's extensive commitment to research and development, ' K Clean' offers other user benefits. It is very low foaming, pcneu-atcs faster than competing products and therefore less energy is re9uircd to circulate wash water tlu·oughout the tank and is safer to handle because it creates fewer fumes.

Furt he r infor mation: David Oca l (08) 8260 6575

Broken Hill opts for Adelaide Ultra Pure water technology Water purifi cation technology company Rowatcr, whose PURELLE ultra pw·e bottled water is widely disu·ibutcd in Adelaide, has extended its bottling operations in terstate.

Rowatcr is providing its proprietar y reverse osmosis water u·catmcnt equipment and bottling system to its Broken Hill disti-ibutor, Streamline Distribution Systems, to help that company meet growing demand for the quality, ulu·a pure product.

The Adelaide firm wi ll maintain the equipment being installed in Broken Hill at the premises of Streaml ine Distribution Ser vices and is also providing operational support to ensure quality standard s arc maintained.

The New South Wales Hcaltl1 Department has also confirmed that the Rowatcr treatment and bottling system ful ly complies with all regulatory standards. A major customer is the local hospital, which is using PURELLE bottled water for all drinking supplies after abno rmally high levels of copper were discovered in the new building's water supply.

Further in formation: M ic hael Purza 08 837 1 4588 VVQl.'CI

II IUU;:JI.I

y ,.,_ ... ._. •• .._e

4th Floor, 77 Grenfell Street Adelaide South Australia 5000

l~or fu rth e r information about United Water, conta<.:t United 'Natcr's Busin ess Developmen t Manager M onk Griscti on (08) 830 1 2700 or visit us at st;ind 102 at

Telephone

Ozwntcr 2001.

Email

(08) 8204 1892 (08) 8204 1360 exdir@waterindustry.net.au

Facsimile

For further inform ation about the Water Industry A l liance, contact Malcol m Co legate on (08) 8204 1892

CENTRE

Th e Lake M aracaibo R em ediatio n Study is a maj o r mu lti- disc iplinary study for t h e Pecroleos de Ven ezu ela SA (PDVSA) carri ed out by an in te rnational co n s o rtiu m h ea d e d b y B ec ht e l Inte rnational Systems and includin g the Ce ntre for W ate r R esearch .

Lake Maracaibo is o ne of Ve n ezu ela's m ost important water resources, providing fresh water for ag ri c ultu re and supporting a local fi she ry, and is also the lo ca tio n o f a m aj o r pe tro leum industry. H owever, over the past fe w decades the water quality in the lake has dete rio rated , due pri ma rily to inc reas ing sa lini ty and eu crophication caused by the d redgi ng of naviga tion chann els and th e increas ing indu stria lisatio n and urbanisation o f th e shores o f the Lak e.

Th e o bjectives o f this study are to co mpl e te a co mpreh ensive analysis of the e nviron menta l condition of th e Lake, collect additio nal e nviro nmental data , and develo p analytica l m o delin g cools that al.low th e evaluatio n of alternati ve re m ediatio n strategi es. A basic question posed repeatedly o ve r the years is wh et her re du cin g th e sa lini ty would help re duce nutrie nt levels, increase di ssol ved oxygen con cen tratio ns in th e Lake, and improve the o ve rall e nviro nm ental quality of th e Lake .

C WR has had a maj o r ro le in several o f important aspects of th is project, in clu din g th e planning and participati o n

FOR

WATER

RESEARCH

in th e m ajor fi e ld prog ram to co ll ec t hydrod ynamic and water quality data and the modelling of the Lake usin g the o ned i m e n si o n al h y drod yn a mi c m o d e l DYRESM . T he Ce ntre also provides o ngoin g a d v ice on asp ec ts o f th e consortium's remediation proposals. O cher m embe rs o f th e proj ect team are : Mo fa tc and Nic hols (U SA), the Danish H ydraulic In sti tute (D e nmark), lncoscas (Venezuela) and C CR lnge nie ria (Ven ezuela).

The Lake Maracaibo system La ke M aracaibo, loca ted in wes te rn Ve nezu ela, is the larges t lake in So uth Ame ri ca and a water body o f g reat economic and ecological importance. The Lake M araca ibo area is the largest oil productio n center in Venezuela. T he Lake is about 160 km lon g in the no rth-so uth directi o n and 110 km w ide in th e eastwest direction , and has an area o f about 12,000 km 2 , a maximum depth of30 111 , and a volume o f 300 J 09 111 3 . lt is conn ected w ith the G ul f of Ve n ezue la thro ugh the Strait of Maracaibo and T ablazo Ba y. Several rivers flow into th e Lake drai n ing a watershed of app rox im atel y 89 ,000 km 2, th e largest o f whic h is the R..io Catatu mbo (w hose m o uth and plume is shown above) accounting for close to 60 perce nt of all fresh w ater fl o w into the Lake. Th e m ean fresh water flo w from all rivers drain in g in th e Lake is abou t 40 10 9 111 3 p er yea r or abou t on e

e igh th of the Lake vo lum e. Ri ver flo ws vary also seasonall y be ing at a m ax imum in M ay, and in O ctobe r- Novembe r, and at a mi nimum du ring the J anuary- M arch d ry season. Flo ws also vary fro m year to year. During a 19-year pe ri o d (19761990) fo r w hic h there are system ati c estimates o f th e total river flow into th e Lake, th e monthl y fl o ws vari ed between 0 .3 and 2. 7 tim es the m ea n fl o w fo r tha t pe riod (CGR, 1993). Fresh wate r coming into th e Lake from th e ri vers m ixes with its su rface wa te rs and an eq ual volum e o f wate r leaves the Lake th rough the Strait.

Ti dal action in combinatio n w ith seve ral o th e r fac to rs brings saline water from the G ulf o f Ve ne zu ela into Tablazo Bay and th e Strait of M ara caibo. T he ex tent o f th e salt wedge intrusion entering the system depe nds o n th e combi nation of several facto rs, w hich, besides the tides, in clude the race of fres h wa ter fl o w into th e La ke, w ind di rection and speed , and atm osph eri c pressure dist ribution. In dry years under low river flo w conditio ns, c om b in e d w ith fa vo rable w ind a nd barocropic condition s at the entran ce co the syste111 , the salt wedge can advance to the south end of the Strait o f M aracai bo , and from the re to the botto m o f the Lake.

This process raises th e salinity of the Lake, es pecial ly in the h yp o limni o n , and co ntri butes to its den sity stra ti fi cati on.

Th e e nvironme ntal co nditio n o f the Lake is a fun ctio n o f the combinati o n o f WATER MARCH 2001

41

CENTRE

FOR

WATER

RESEARCH

several natural and anthropogenic factors contributing to its advanced eutrophicatio n state. T he high primary production is th e source oflarge quantiti es o f dead organic matter settling to the bottom of the Lake. Algae, zooplankton and higher forms of aquati c life w hen they die settle at the bottom of the Lake, w h ere they decompose consumin g all available oxygen.

This, in co mbination with the stratification of th e Lake, wh ich prevents oxygen tra nsfer to th e hypo limnion, leads to anox ic conditions below the pycnocline, w hi ch acts as a barrier to verti cal 72 71.8 716 71~ 712 71 708 oxygen transport.

LOnQ•ude("W] T he en vironmental condition of the Lake has also bee n affected Figure 1. Map of Maracaibo system showing Lake by sewage and indu s tri a l Maracaibo, Maracaibo Strait, Tablazo Bay, Zapara discharges, which cause loca lly and Canonera Mouths, and the Gulf of Venezue la. u nsanitary cond i t i ons an d Also indicated are the location of the dredged co ntribute to the n utrient load of shipping lane and Maracaibo City. th e Lake. H owever, the bul k of nu t ri e nts comin g into Lake nutrient loading of the La ke, as we!J as Maracaibo is from the rivers flow ing into various pol lution discharges. the Lake. The nitrogen and phosph o rous The focus of most of the remediation in the river inflows is genera!Jy in particschemes proposed over the last forty years, ulate form. In their particulate forms, from has been the reduction of salt- water river inflows and as organic detritus fron, intrusion into the Lake. Such sc hem es primary production, n utrients enter the ranged from the constructio n of various saline hypolim ni on through sed imenengineered structures designed to block tation. Within th e hypo lim n io n bacteria sa lt-water intrusion by isolating the Lake break down the organic nitrogen and system from the Gulf of Venezuela, to the p hosphorus forming ammo nium and abandonment of th e dredged navigation dissolved reactive phosphorus resp ecti vely. chan nel and retu rn of the system to its The persistent an oxic conditions in the natural condition. Such schem es had two hypolinm ion lead to the den itrifi cation of general goa ls: a) reduce the density stratnitrates and the release of phosphate from th e sedim ents into the water co lumn.

Some of the e n v ironm en tal 11 13 probl ems of the Lake have quite obvious soluti ons, like for example !:10 po int source control and watershed },. management to reduce the of nutrient '8 and BOD load coming into the La ke, and the co ntrol of toxic pollutant discharges into the Lake system.

The poten ti al e n v ironme ntal restoration measures can be ca n be :[10 classified as : J,.

• en gineering opt ion s in vo lvin g C) '8 physical changes in the Lake system through changes in its bathymetry and the construction of special works. Th e main obj ecti ve of the engineering options is to reduce the salin ity of the Lake, an d by redu cing its density stratFigure 2. F-Probe salinity dat a in Lake ification affect water quality.

Maracaibo; a) transect from NW-SE on 24/11/98; b) Transect from NE-SW on • management options that include 24/11/98; c) transect from NW-SE on TE po int so urce control and wa tershed 25/11/98; d) Transect from NE-SW on manageme nt. The m a na ge m e nt optio ns aim primarily at red uci ng the 25/11/98 .

: : i : ---:41

42

WATER MARCH 2001

ification of the Lake, therefore potentially eliminating the anoxic conditions in the hypolimn io n, and b) reduce the salinity of the surface waters enough to allow their use for irrigation. Many of these salinity reductio n schemes proposed over th e years require the construction o f significan t infrastructure.

Hydrodynamic field program One of th e first tasks for CWR was to des ign a field program to provide an understandin g of the major physical processes that affect the water quality of Lake Maracaibo and to provide sufficient data for the ca libratio n and vali datio n of numerical models. Fieldwork was carried out during two separate field campaigns in 1998-99, timed to co rrespond with the wet and dry seasons of the region. PhD student Bernard Laval trave!Jed to Venezuela to deploy the CWR fine-sca le (fprobe) and mi cro-scale (Self-Contained Autonom ous Mi cro-Profiler - SCAMP) conductivity an d temperature profilers.

M easurements made by other members o f the project tea m included current velocities; conductivity and temperature time-series at fixed depths; w ind speed and direction ; and water level. A water quality monitor ing campaign w as conducted at the sam e time as th e hydrodynami c ca mpai gn.

Considerable historica l data ex ists on the flow an d stratification in these various regions, but th ese data m erely suggest a set of dynamics. Th e data were all co llected for a diverse set of programs over nearly a 40-year p eriod and as such form a valuable reso urce, esp eciall y for long term trends of salinity. However, these data are not co herent enou gh , nor were they co!Jcctcd with particu lar hypotheses in mind, to allow detailed dynamical interpretations in any of th e key h ydro d yna mi c pro cesses th at determine the salinity distribution in Lake M aracaibo or to validate the numerical models of these pro cesses.

The fie ld program was thus designed to serve several pu rposes: (a) to provide an understanding of the maj or processes that affe ct th e salinization , stratificatio n and renewal of hypo l imnetic water o f L ake M ara caibo, (b) to provide su fficient data for the calibration and validation o f num eri cal models, and (c) to provide the modeling groups sufficient data on bou ndary and initial co ndi-

CENTRE

FOR

WATER

RESEARCH

tions. Fieldwo rk was carried out durin g two separate field campaigns i n the M aracaibo regio n . T he two ca mpaig ns w here nomina lly ti m ed " to correspo nd with the wee and d1y seasons o f th e region.

T h e fi e ld prog rams focu ssed on [ t h e fo ll o w in g key d y na m ical tl regim es: " " • Tra n sfe r a c ross t h e m o u t h 10 betw een the Gulf of Venezuela and T he Bay ofTab lazo • Formatio n of stratification 111 T h e Bay of T ablazo • H ydrau lic co ntro ls in the Strait of Mara caibo and the in fl u ence of the co nt ra ctio ns and sills Figure 3 . Salinity t ime series for t he 400 day • Pl ungin g of t h e sa lt wat e r calibration simu lation. The DYRESM simul ated unde rflow into Lake M ara caibo profi les are plott ed as solid lines, and the • Form atio n , m a inte nan ce a n d measured profiles as dotted lines. stabil ity o f th e sa lt hypo lim n ion in Lake M aracaibo. a ti da ll y modu lated salin e u nde r0ow T he fie ld data co llected d uri ng t he exte nd ing w eU into M aracaibo Strait, and 1998 / 99 fi eld prngram con fi rmed the (c) a dom e-s haped , sa line hypo limnion fo ll owing hyd rod ynamic fea tu res of t h e and a large-scale anti-clockwise circulation Maracaibo system : (a) a predomi nantl y in Lake M aracaibo . The data also indi cates se m i-d i u rn a l t id e t h ro u g h out t h e a possible inte rn al hyd rau lic co ntrol nea r M araca ibo Strait, and Tablazo Bay w ith Zapara M o ut h . T he field program did not an apparent anti- node in T ablazo Bay, (b) observe an y sali ne unde rflo w south of the

strait and in to the lake during either th e wet or dry season.

Of particu lar importance w as data re late d to the salin ity structure of the Lake. Figure 2 presents the fprob e da ta fo r severa l transec ts across Lake Maraca ibo and clearly shows the presence of the saline hypolim nio n . T he tran sects confi rm the do wnward curvatu re of isopycnals wi th co nsequ ent hig her surface salinity near t he lake centre. The interna l R.ossby radius of deform ati on based o n t h e m easu red stratifi cation w as abo u t 12.5 km, indica ti ng chat rotatio n is im portant in th e in te rnal d ynami cs, w h ich supports the hypothesis cha t the do min g of th e hypo limni o n is predominan tl y d ue to a geostrophic balance with the cyclo nic circulation.

2()

I,.

Modeling To evaluate th e water q uality im pacts of the m any o pti o ns proposed ove r t he years, special comp u ter m odeli ng tools w ere used to predict the expected changes under each option . T he da ta from the field investigatio n w ere used to ca librate and validate t he com pute r m odels. Beca use of

ProMinent

have the right metering pump and instrumentation for any of your chemical dosing appplications.

:.,r. . ., •

!

•

I

,.,

~

:-:

+- Our Beta range features reproducible metering accuracy set

by Quartz locked frequency in 10% increments with maximum capacity ranges from 0.6 to 321/h.

+- Vario & Sigma

).J( ., ~- •I

. ,. ,1,l

1 ,, .

are motor driven pumps which ,l l, \ fl offer a level of control previously only 't ' available with solenoid pumps, control from mA _ _ ___ or pulse sig nal.

I

.,.,:· ,rl ~~. .,

1:

~r,

Newly released hi-tech Gamma / L range.

Accessories include flow failure monitors.

1' The motor driven Meta, Makro and Orlita range are renowned for their reliabi lity Capacities up to 100,000 1/h and pressures to 380 bar

Litres/hr displayed.

..C a, C ·-~ C ..a. ®

ProMinent Spectra progressive either block

Instrumentation for feed forward PID control. Measuri of pH, free & total chlorine, OR 0 3, Cl0 2 and conductivity ProMinent Fluid Controls Email: sales@prominentltuid.com.au

Web: www.proml

HeadOffice: Ph (02)94500995 OLD Office: Ph: (07) 3243 8330 VIC Office: Ph: (03) 9562 9366

Distributors WA: Ph: (08)94589555 TAS:

Ph: (03) 6244 7575

WATER MARCH 2001

43

CENTRE

FOR

WATER

RESEARCH

cie ncs, against field data from Nove mber 1998 to March 1999 .

Figure 3 compares the " fie ld data sa linity pro files wi t h the DYR ES M 20 "' simulation fo r the 1997-98 calibra ti o n p e ri o d . Th e simulated salt stratificatio n is considered acceptable given IQ the pote ntial erro rs in the simulated inflow data and the assumption of on e-d im ens i o n al i t y . Th e mo d el re pro duc es t h e vert ical 0 G O O D O O o S 10 o s 10 D S 10 0 5 10 0 S 10 O S 10 iJ 5 10 O S 10 salinity struc ture well over ai,yStmgill a-,s~ oq..(mQILI a:tt.ill'l'IOl'Ll my5(Motl-l ..,,-5imot-l oW)l5i-,-.:,ll.] thi s p e ri o d , with t h e Figure 4. Dissolved oxygen profiles for the 400-day exceptio n of the profile in calibration simulation. The DYRESM simulated N o v e mb e r 199 7 . The profiles are plotted as solid lines , and the measured differe nce in the simu lated profiles as dotted lines. and ob se r ve d sali n ity structu re in N ovember 1997 the different time- and space-scales of the cou ld be possibly due to th e phase differprocesses affecting e nvironmental quality e nces in the estim ated saline underfl ow in the Lak e and th e computational du e to th e lack of adequate data to define requirements for their proper simu lation, the boundary and forcin g cond iti ons in a combination of three- and one-dimenth e Gu lf of Venezuela. Th ese errors are sio nal models was used. CWR was reflec ted in the DYR.ESM outpu t. Th e responsi bl e for th e o ne-dim e nsiona l sa linit y profi les mea sur e d o n 19 wate r quality modellin g of the lake using Nove mbe r 1997 suggest that a major DYR.ESM-WQ. DYRESM- WQ was inflow of saline wa ter may have occurred used to mod el th e main body of Lake sometime before that date, ca usi ng an Maracaibo, with the so uthe rn end of the increase in the sa linity of the hypol imnion Strait formin g the north ern boundary of to approximately I O psu at that ti me. Such the model domain. The model was an event is not shown in the three-dimencalibrated against available data for the sional model output used to provide the perio d Au gust 1997 - September 1998. bo undary conditio ns fo r th e DYRESM It was then va lidated using data fro m the simulati ons. p eriod Novem ber 1998 - March 1999.

Calibration o f the wa te r quali ty The calibrated and validated model was module o fDYR.ESM-WQ is an ite ra tive used to assess the lo ng-term ( 10 to 20 process and was initiated fro m previously years) effects caused by changes in the used values of the water quality paramexchange fl ow in the Strait and c hanges eters from tropi cal lakes. Th e processes to the nutri e nt loadin gs, and to perfo rm that required ca libration were: a sensiti vity analysis.

• sedim ent release rates fo r nitrogen an d DYR.ESM- WQ was initially calibrated phosphorous again st avai labl e field data for th e pe riod • bioc he mical reaction rates for n itrifiAu gust 1997 - Septe mbe r 1998. Since cation an d deni trification DYRESM is o n e- dim e n sion a l th e • sedim ent oxygen de mand coefficie nt properties in each layer of DYRESM• phyto plankto n param e te rs and rate WQ represe nt basin-wide h ori zo ntal coeffi cients ave rages. For th e pu rposes of calibratio n • chlo rophyll-a induced light attenuation and va lidation of th e mod e l, th e coefficient DYRESM-WQ output was co mpared D espite so me differences be tween the with data from a statio n located near the va lu es of observed water quality variables centre o f Lake Maraca ibo. Initiall y th e and th ose simulated by th e calibrated model was run without the wate r quality mod e l, DYRE SM-WQ app ea rs to m odules (i. e., as DYR.ESM only) to re produ ce th e impo r ta nt n utr ie nt simulate the o bserved te mpe rature and dynami cs suffi cie ntly w ell to allow an salinity stratification., and then it was run assessment o f scenarios based on hydrau lic with the wa ter quality modules (i. e. works and/ or managem ent options on the DYR.ESM-WQ) to fi x the rate coeffiwater quality in Lake M ara caibo . cie nts for th e b iogeochemi cal processes.

After the ca libration the model was As an example of the water q ua lity validated , witho ut changes to any coeffisimulatio ns, Figure 4 sho ws the dissolved )0

~~

44

WATER MARCH 2001

oxygen profi les generated by DYR.ESMWQ compa re fa vorably with the fie ld observatio ns in relatio n to magnitude and vertical d istribu tion . T he hypolim nio n remains anoxic throughout the simulation profiles, bu t 0l\.')'gen is shown to penetrate to the bo tto m in the field data coll ected in March I998. It is important to no te that the field data shows no distu rba nce to the salt stratifica ti on d uring M arch '1998 perio d and hence the m echa nism by w h ic h t he hypoli m n io n b eca m e oxyge nated is not clear. It is possible that the dissolved oxyge n is bro ught into the Lake in the saline u nderflow. In the present DYRESM- WQ simulations it was assum ed that the d isso lved o xygen concentration o f the saline u nderflow is negligible and so th e model may underes timate the oxygen flu x from th is so urce. H owever, it is expec ted that the oxygen demand of the hypo limn io n and the sedim e nts will q u ick ly consu m e any oxygen bro ught in by the u nderfl ow comin g into the Lake fro m the Gu lf of Ve nezu eln.

The ca li bra tio n an d validatio n sim ulations confi rm that the salini ry stratifica tion is a maj or in fl uence o n th e oxygen and nu trie nt dynam ics . Th e stratifi catio n redu ces vertical flu xes across the halocl ine so tha t the hypoli m ni o n re mains anox ic fo r the du ration o f the simulatio n and nutrie nt concentratio ns (N H 4 and P0 4) increase slightly befo re reac hing a steady state . H owever, the nu trient and c hlorophylJ-a co ncentrations in the su rface layer rema in relatively constant.

Evaluation of options Th e Lake M aracai bo system co ntains roughly $2 billion of port and petroleu mrelated transport infrastru cture develo ped over th e past 50 yea rs. Th e costs of the evaluated options range from ve1y low fo r the case of maintain ing the existing channel to very high , of the o rder of$2.5 bi llion , fo r the case o f allowin g the navigation channel to silt in and relocating all maj or fac ilities. T he costs conside red were th ose associated w ith the various proposed hydraulic works as well as those associated w ith infrastru cture relocati on an d developm ent , and excl ude those fo r dom estic and industrial poi nt source con tro l, w hich sho u ld supplement any option.

T wo remediation options were selected for in-depth modeli ng analysis: a) to maintain th e existi ng c hanne l as is today, and b) le t th e navigation channel to silt in to retu rn the syste m to its bathyme try prior to dredging w hi ch would requ ire relocatio n o f all major po rts wi th in the Lake . Bo th o ptio ns are accompan ied by

CENTRE a program fo r the con trol of all do m estic and industri al point pollutio n sources and t he development of water ma nagement plan for the reductio n of nutrients and o ther po llutio n loading coming to the Lake. These two o ptions bracket the range of potential water quality c hanges short of sea ling off th e Lake from all m arin e influ ence. T he first optio n - m aintaining th e prese nt na viga tio n chann el configuration in combination w ith poll utio n source co ntro l m easures - has a locall y positive water quality impact and serves to provide a base lin e fo r oth er analyses as well as answe1ing policy-related q uestions.

The option of re turning to the pred redging bathymetry, in co mbi nation with the im pl e m entation of a watershed m anagement program and poll u tion so urce control m easures produces the g reatest positive c hanges in water quality .

T he assessm ent of the relative contribution of th e closure of the navigation chann el and a watershed m anagem ent program to wate r qual ity cha nges in the Lake is still in progress.

FOR

WATER

RESEARCH

At the time of w riting, modeling evaluation co ntin u es. P re li mina ry res u lts indicate that control of direct point source d isc harges by itself wi ll not have a major e ffec t on the eutroph icatio n of the Lake.

P o int so urce control is th o ug h essenti al for improving water qual ity lo ca lly and fo r protecting publi c health. M ore significant improvem ents can come in fro m the implem entation of a lo ng-term watershed managemen t plan, aim ed at redu cin g th e nutri en t and pollu tant loadings from the ri ve rs d isc h a rgin g into t he Lake .

Considering that the system see ms to be in a state of d yn am ic eq u ilibrium, m aintain ing the navigation chann el will not lead to increased degradation of water quality. Closing the navigatio n chann e l will even tua lly return the sal inity of t he Lake to its historic levels prio r to the dredging of th e chann el, of about 1.2 ppt. , and wi ll signifi ca ntly redu ce the sa lin ity stratifi ca tion. Weaker de nsity stratification wi ll continue to exist seasonally due

to th e variability of water temperatures.

Th e reduction of salinity stratification will increase dissolved oxygen levels in the Lake , however t he therm al stratifi catio n may still provide eno ugh de nsity gradients during part of t he yea r to prevent the oxyge nation o f th e hypolimnion. T he extent of the impact of the elimination of salinity stratification o n anoxic conditions in th e hypolimnio n is still unde r evaluatio n .

An essential e lement of the solutio n to th e proble m o f anoxic conditions in the hypolimnion is the reduc tion of the o rga nic matter in t he Lake, w h ic h re qu i res redu c tion of t h e p ri m ary productio n (ph ytoplankton , i.e. algae).

T his in tu rn requ ires reduction of the nutrie nts com ing into the Lake, w hich can be achieved primarily th ro ugh control and management of different activi ties in th e watershed and seco ndarily thro u g h trea tm e nt of all wastewater direc tly discharged in the Lake.

Coa sta l & Estu ar ine Data Collection Lake, River & Wetland Monitoring Hydrologic / Hydrographic Services Stormwater & Wastewater Studies Radio Telemetry Systems Flood Warning System s Climate Monitoring

-

-

GREENSPAN

~

T E

C H

N

O

L

O

G

Y

WWW,9(00VlSf'O.Vl,COt'Yl,O.U WATER MARCH 20 01

45

CENTRE

FOR

WATER

RESEARCH

Lake Diagnostic System S Feave r such as the dissolution of th e m etals, The Lake Diagnos tic System (LDS) iron and manganese, are highly correis a uni que diagnostic system developed lated to deep water dissolved oxygen at the Centre for Water R esearch concentrati ons and ca n be in ferred in (CWR ), which is designed to assist in this way. At prese n t, lo ng-term the management oflakes and reservoirs. continuous measuremen ts of dissolved The LDS consists of a lake station , oxygen at depth are limited by the w hich continuously m easures the water short li fe of available DO sensors, so column temperature profil e, wind this can be a useful alternative to speed and wind direction at the centre co ntinuous direct measureme nt. of th e lake (see Figure 1).

W here the lake is experiencing This data is transmitted in real prolonged stra tification , the water time, v ia te le m etry, to a sh o re quality in a lake has been shown to be m anageme n t stat ion runnin g the successfull y influenced by instalJing an LAKEMON software . Using this data, artificial destratification system suc h as the LAKEMON software is able to a bubble plum e gen erator or a series monitor the lake stratification and, using of mixing pumps. Coupled with the the Lake Number concept (see below), LOS, the performance of th e destratdetermine the extent to which the lake ifier can be assessed. T he degre e of as a w ho le will mix in response to the mixing induced by these destratifiwin d forcing. Th e lake stratification and cation systems may be m onitored by degree of mixing directly influence the Figure 1 . A new LOS depl oyed in Victoria the LDS and continuously adjusted in water quality. In particular, in the lake 's Reservoir, Western Australi a. order to achieve maximum effi cie ncy deepe r waters, prolon ged strati ficat ion of operation and to countera ct the can lead to poor water quality, w here seasona l stratification. the wind. For LN less than a critical value, anox ic conditions lead to e nhan ced the wind destabilising forces are sufficient release of meta ls and nutrients. H.ence, As well as being successfully applied as to cau se acti ve mixing w ith in the lake, m o nitorin g of the stratifi cation and a tool for the management of reservoir rapidly tran sferring oxygen to depth. By mixin g activity in the la ke is an important water quality, CWR have also used the contrast, for LN larger tha n the critical part of managing the wa ter quality.

LDS exte nsively for intensive process va lue, wind forces are only sufficient to understanding experim ents, where high The LDS continuously records the mix the near smi1ce layers and, in general, resolution temperature measurements temperature profil e, w h ich indicates the do not impact on the deeper parts of the (0.001°C) and fast sa mpling (eg. 5 secs for position of the seasonal therm oclin e and water body. U nde r these strongly stratthe activity of seasona l internal wave 40 thermistors) have been critical to ified cond itions oxygen is depleted by measu ring high frequency internal wave climate. This provides an understanding biological and chemical OJs.')'gen demands. activity. H ence, the LDS is designed to of the physical processes occurrin g and Once calibrated using historical field data, va luable informatio n about the positi on both provide this high - res olution inforLAKEMON uses the magnitude o f the of the thermocline in relatio n to the water mation and also provide a robust system Lake Number and the time since the offtake position and, hence, the quality for long-term reservoir management. T he initial mixing event to model the dissolved of this water. The continuous temperature most significant recent development to the oxygen conce ntrations at depth in real profile available also provides accurate upnew LDS has been the development of ti me. Other water quality parameters, to-date information on suitable depths for a single cable th ermistor chain, w hi ch ha s pro vid ed easier water quali ty sampling (see Figure 2). handlin g a nd improved Victori a Reservoir - Contour of Thermi stors #1 to 26 durability. T he LDS is c urrently In add ition to mo nitoring (' C) ava ilabl e w ith a r ange o f 20 the stratificati on and mixing additi onal sensors, including a activity, if hi storical water 19 m eteo rolo g ica l sta t io n a n d quality data is available for the 18 cond u ctivi t y se n so rs. It is lake, LAKEMON is able to planned to also have dissolved in fer the water quality at depth 17 oxygen measu rement available in in the lake. LAKEMON uses the next six mo n ths. T h e the Lake Number (LN) and 16 simple empirical relationships to LAKEMON software will soo n 15 b e a we b -base d syste m, model the concentrations of dissolved oxygen and metal providin g cont rol and data 14 ions, suc h as manga nese and display via th e web browser.

13 iron. The LN characterises the There are plans for the new LDS 288.5 289 289.5 290 290.5 291 291.5 292 strength of the mixing activi ty to be available commercially Time (Julian Day) and is the ratio of the stabilising fr om Precision M easurern.ent Figure 2. Temperat ure data acquired by a new LOS force of th e stratifi catio n to the En gineering, m Ca lifornia, in dominant desta bilising fo rce of deployed in Victoria Reservo ir, Western Aust ra lia.

2001.

46

WATER MARCH 2001

J~J,w ~ ?JC.. JJ !l.ll[o/Fr8I~Jl::"l~ ',:_., ---~,--'TT'--------.-..._ Progressive cavity A, mps capable of handling most proce s pumP.ing needs, especially unger dema ililg c0ncf~iti_o_ ns_o_f....,.._""""...,.. rasion, sludqr s and igh viscosity.

~.n1 J~j~

C

_ruJ}

Low speed, ·n shaft grinder, suitable for raw sewage, screening and digested sludge.

No bottom seals ~nq bearings, built-in trash trap and pu!I back cutter cartridge.

D]s ~J'3~IJ

;.\F!... iilrwa

A range of dynamic self cleaning Screens designed for today's sew__age systems.

Mixed flow pumps for large volumes at low to medium heads for waste ater and sewage containing solid or fibrous matter and for sludges.

lVli:..t<=l't:.lQ t·

EkoIIJ~{ J~JU~~ Submersible mixers for blending, disso1v·ng and suspension of solids m municipal and industrial treatment plants.

J

Two sizes of high speed centrifugal Macerators suitable for raw sewage applications.

,!;i.rHl3J' ? B!-l'.B~.;;~J ?.!.lmµ S·lBllon:;:; Complete 'one-stop' packaged pump station ideal for remote cottages, houses and small office developments.

J

J~Jul.i'~Ji0.i' ? .!.JJJJµ .F'.m;J~:oJ,fja The system of finely macerating and pumping raw sewage from collection points to discharge into main sewers or treatment plant.

J

}Jyµ-&>.111L! Submersible bottom mounted mixers for stirring activated sludge, particularly in square and round tanks.

~J@.©°'M

~ ytefo.lIJJ Ft1~ Self-aspirating submersible aerators for waste water and water treatment in municipal and industrial plants.

J

Mono Pumps (Australia) Pty Ltd Melbourne Sydney Brisbane

Perth COST-EFFECTIVE PUMPING

Adelaide Darwin Hobart Auckland

03 9580 5211 02 9521 5611 07 3350 4582 08 9479 0444 08 8447 8333 08 8984 3099 03 6249 8704 +64 9829 0333

Monot 0

<(

A Halliburton Company

a

WATER

METALS IN DRINKING WATER IN NEW HOUSING ESTATES G Rajaratnam, C Winder and M An Abstract The 1netals Pb, Cu, Cd, Z n, Mn, and Al, were m easu red in drink ing water in fairly new houses in the Sydney metropolitan area. At the supply points, the levels of all m e tals measured were be low Australian Drinking Water Guidelines (ADWG). In the houses, of the first-flus h samples, m etal levels exceeded the ADWG leve ls, up to 60%.

Metal levels decreased as flush times increased. In fu lly-flushed water, the levels of all metals were well be low ADWG. Avoidance of meta l conta min ants to public health is discussed.

Key words: drinking water, health , metals, Pb.

Introduction Excess or deficiency of some essential m etals can damage human health, and non-essentia l meta ls suc h as lead (Pb) can be tox ic at even very low co ncentrations (ADWG, 1996). Reported health effects have included various cance rs, adverse reprodu ctive o utco mes, cardiovascular disease and neurological disease (Ca lderon, 2000). Fo r example, it has been reported that an analysis of Beethoven 's hair indicated t hat he suffere d from Pb poisoning, probably from th e loca l gro u ndwater. One of major sources of human exposure to hig h metal levels is drinking water (Matte and Jacobs, 2000).

The metal contaminants reac h d rinking water supplies from va rio us sources, such as natural geologica l formations, drinking water distribution materials and th e drinki ng water treatm e nt process e tc.

(Ca ld ero n, 2000).

High lead levels can be present due to leach ing from brass fittings, bro nze fittings, tin / lead solder (usually in th e ratio of 50:50 or 60:40), goosenecks, gaskets, possibly tubing made from recycl ed copper and drinking-wate r founta ins .

Cadmium (Cd) may occur in drinking water as a result ofi mpwities in galvanised pipes o r brass valves, or by leaching from solders, water heaters, water coolers, and taps. Copper (Cu) occurs in drink ing water through corrosion of copper pipes and hea te rs (and occasio nally copper sulfate is used to con trol algae in waterstorage tanks). Zi nc (Zn) can contaminate

48

WATER MARCH 2001

drinking water through severa l pathways, such as from galvanised pipes, brass valves, fittings, and Cu alloys. M anga nese (Mn) may be present from impurities in the plumbing systems and polluted ground water (N H MRC and A R.MC/ ANZ, 1996) .

Very few studies on m etal contaminants in drinking wate r have bee n published in Australia (G ulson et al, 1997).

The purpose of the present study was to investigate concentrations of Pb and other m etals in Sydney's drinking water; to identify contamination sources; and to ascertain whether m etals in drinking water in new ho useholds in Sydney constitute a risk to public health.

Methods 95 houses less t han 18 mon ths o ld

were samp led in 10 suburbs in Sydney.

Control samples of the water su pply before delivery to houses were coll ected from Sydney Water su ppl y po ints and main towers in Beacon Hill, Epping, Baulkham Hill s, Castle Hi ll, and Glenmo re Park.

Three samp les from each house were collected, and the procedure fo llowed Vegesna and McAnal ly (1995), ie.

Sample 1 - first-flush water 125 mL; sample 2 - post-first-flush next I 000 mL; sample 3 - fully-flushed wa ter 125 111 L of water take n after 2 minutes of flush ing .. T he sam ples were analysed for a va ri ety of m etals: Pb, C u, Mn, C u , Cd, and Al, by a Hewlett Packard HP 4500 Ind uctive ly Coupled Pla sma-Mass Spectromete r.

SPECIALISING IN ENVIRONMENTAL SERVICES

E -

ENVIRONMENTALGROUP

Water Supply & Treatment

NATIONALLY

Water Quality Management Management Systems & Compliance Auditing Water Resources Development, Hydrology, Irrigation & Drainage Wastewater Collection, Treatment & Reuse Environmental AudiVSite Investigations Contamination Assessment & Remediation Hazardous/Industrial Waste Management Solid Waste Management Environmental Impact Statements Environmental Management Planning & System Development

Emissions Testing & Air Quality Monitoring

fJ:eg i5 consulting Australia Offices throughout Australia and South East Asia

Website: www.egisconsult.com.au

Neville Ward, Ron Edwards & Dr Peter Nadebaum (03) 9272 6666 NEWCASTLE

Ian Gregson (02) 4929 3255 NSW

David Russell, Dr Ian Garrard (02) 9412 9999 QLD

Stephen Trainor, George Khouri & Brad Steele (07) 3233 1611 VIC

Don Vincent, Dr Jeff Bazelmans, Mike Juleff, Dr Wayne Drew (03) 9272 6666 WA

Paul Turner (08) 9220 9300 SA

Paul Lindon (08) 8271 2322

WATER

Results and Discussion Control samples

All co ntrol sa mples from Syd ney water storage tan ks had metals below ADWG levels. The levels of Pb, Cd and Cu in m ost samples were well below the detection limi t of !CP-MS, while th e levels of Zn, Al an d Mn were detectable but sign ificantly be.l ow ADWG levels. An estimated positive CC P P (Calciu m Carbonate Precipi tation Potential) value indicated that the source waters were not undu ly corrosive to water treatment plan t equ ipment and reticulatio n system s.

Metal levels in household samples

Sign ificant differences of meta ls levels were found between sample types. Pb and Zn concen trati o ns were significantl y differen t between the three ty pes of sa mples (P <0.001). Mu ltiple-comparison tests showed that Pb and Zn levels in firstflus h water were sign ifica ntl y higher than eith e r post-first-fl ush or fully- flushed sa mples (P <0.05), and that Pb and Zn leve ls in post-first-flush samples were significantl y hi gher tha n in fu ll y-flushed samples (P <0 .05). Sixty pe rce nt of first£lush sa mples, 24% of post- first-flush water sampl es, and 4% of full y-flushed sam pl es had Pb levels above the ADWG gu idelin e limit of 10 µg/ L. Simila r results were foun d fo r C u , Mn , Al, and C d. T we lve percent of firs t- flush samples were abo ve the AOWG value for C u (1000 µg/L); 18% of post-first-flush samples were above the ADWG value for C u and; and in fu ll y-fl us hed sa mples 3% were above the ADWG va lue for C u .

The low metal levels in supply n.:servoirs suggests that the sou rce of m etals contaminants in drinking water arc house ho ld plumbi ng systems rathe r than supply points or storage tanks. T he findin gs that first-flush samples contain the highest concentrations of metals and levels decrease as £lush ti mes in crease were genera Uy in agreement w ith the literature (Lee et al, 1989; Levin, 1986). Lead leachi ng from pipes, brass fittings, bronze fittin gs, tin/ lead solder, goosen ecks, and gaskets has bee n iden tified as the main so urce of lead con taminant in drinking water (Lee et al, 1989, Levin, 1986) .

More and more co mmun ities are concerned about health risks posed by lead and oth er metals co ntamination in their d rin king water. T h e prese n t stu dy indicates that even though Sydney water supply has no t bee n th e source of m etals contam inants and various guidelin es are impl em ented by regulatory authorities to ensure supply of safe drinking water for the public, health risks are still high due to drin king water being contaminated by

m etals, particularly lead, in fairly new housing. H owever, such health risks can be effectively minimi sed by various measures. Adoption of preventive health behaviours is one of su ch m easures . O ld practices, ie. flush ing household water sup plies for several minutes after pro longed standing, can effectively reduce metal con taminatio n levels well below ADWG va lu es . T o avoid wastage o f water, the flushing water can be co Uected and used fo r wateri ng plants, or for bathing, washin g dishes and clothes, or showering. Mass media , pamphlets mailed di rec tl y to re sid e n ts, int erpe rso n al channels may all be ways to get information across.

Acknowledgments We than k Professor B rian L G ulso n (Macq uari e Un iversity); Sydney Water Qual ity Group staff; Dr John M Ferris, and Mr David Hill (A N STO); and the num erous householders who were wi lling to participate in th is resea rch.

References A11strnlim1 Dri11ki11g Water C11ideli11es (1996), NI-IMRC and ARMCANZ, Can berra.

Calderon R. L (2000). T he epidemiology of che mical contaminants of drinking water. food & Che111irnl Ti,xicology. 38:S 13-S20.

Gulson B L,James M, Gibli n AM, Sheehan A, and Mitch ell P ( I 997). Maintenance of elevated lead levels in drink ing water from occasional use and potential impact on blood leads in ch ildren. Sci Toi. Euvir. 205: 271-275.

Lee R G, Decker WC, and Collins D W (1989).

Lead at the T ap: Sources and Cont rol. Jo11r A WWA 81:7:52-62 .

Levin R. (1986). ls.educing Lead in drinking water. A Benefit analysis. EPA-230-09-86019.

Matte T D and Jacobs D E (2000). I-lousing and health - c urrent issues and implications for research and programs. Jo11mal of Urbai,

rlealt/,-811/leti11 ef 11,e Neu, York Arade111y ~( Medici11e. 77( 1):7-25.

Vegesna S R and McAnally S A (1995).

Corrosion indices as a method of corrosion measurement and a systems operating tool.

J. E11viro11. Sci. Health A30 3 , 583-605 .

The Authors Dr Geetha Raj aratnam (email: g r a@ansto.gov.a u ) is w i th the Environment Division, Australian Nuclear Science and T echnology O rganisation, Priva te Mail Bag 1, Menai, NSW 2234 and collaborates with Dr. Chris Winder at the School of Safety Science, University of NSW. M in An is currentl y with the Env i ronmenta l a nd Ana l ytical Labo ratories, C harles Sturt University, Wagga Wagga.

WATER MARCH 2001

49

m

WATER

WATER CONDITIONING AND STABILITY ASSESSMENT: AN INTRODUCTION P Gebbie Abstract Currently there is no requirement under the Australian Drinking W ater Guidelines to produ ce a stable water w hich is not potentially corrosive to water treatment plant equipment and reticulation systems. This paper disc usses the concept of w ater stability, d esc ribes various indices available to ga uge the corrosivity o f a water, and m etho ds o f calculation. An approach is also outlined w hereby the stability of a ,Nater can be d e termin ed fo ll ow ing a pa rtic ular treatment regime and how it can then be conditioned to make it less aggressive .

Examining different treatm ent and conditioning options for a typi ca l w ater illustrate th ese concepts.

Key Words: Corrosivity, Water Stability, W ater C onditioning, Langelier Ind ex, CCPP

Introduction At present there is no requirement in the Australian Drinkin g Water Guidelin es to produce a stable water - i.e. one that is neither scale-fo rming or corrosive other than having a pH in the range 6.5 to 8.5 (ADWG 1996). H owever, ma ny surfac e waters require a c hemi cal co agulant such as alum for effective treatment and disinfection using chlorine.

Som e waters can then becom e aggressive, leadin g to possible deterio ratio n of equipment, pip elines and reticulation system s, so post- treatment conditio ning 1s necessa ry.

Water Chemistry As far as co rros ivity issu es are concerned, th e most impo rtant water quality param eters are: • alka linity • pH • calcium • total dissolved solids (TDS).

Th e c o nce ntrat i on o f v ario u s constitu ents in a water can be expressed in one o f tw o ways: • as the ion (or "as is"), e .g. 8 mg/L calci um (C a) as calcium, or 50

WATER MARCH 2001

• as calcium carbonate, e.g. 8 m g/L Ca becomes 20 m g/ L Ca "as calcium carbonate" (CaC O 3) . (purely an historical conceit. Ed) T o con vert from one fo rm to the other, the conversio n factors listed in T able 1 are used . T he chemical for mula, formula we ights and equi valen t weights of these constituen ts are also listed.

Positively charged io ns are called "catio ns" (e .g. calcium ion or c a++) and negati vely charged ions, "anio ns" (e.g. bicarbo nate or H C O 3 -) . T he sum of the concentration of cations expressed as m g/L C aCO 3 should also equal the sum of the anions, thus giving a balanced water analysis.

Having such an analysis, th e fo llowing can then be investigated: • the stability of the wa ter; • the impact that chemical addition as part of th e treatment process can have o n water quality (e.g. alum and chlorine), and • the pH of the water fo llowing chemical add itions.

T able 2 is a list of chemicals corrunonly used in water treatment processes, giving th e chemical fo rmula , formula w eight, equivalent weight and the factor to

con vert to equivalen t weight as C aCO 3.

T his table w ill be used wh en optio ns for con ditionin g a water to make it stable and no n-corrosive are considered.

A Typical Example As an exa mple of how to apply conditioning, consider a typical w ater suppl y: the W aranga C hannel at R ochester, Victo ria, w ith the analysis listed in Table 3. From this analysis the following can be co ncluded: • the sum of the cations is not equal to the sum of the anions: 84.9 v 82.7 mg/ L CaCO 3 . H owever, in practice a water analysis is considered balanced if the (sum of cations/sum of anions is within + or 5%. In this case it is +2.7%, so it is acceptable, • the alkalini ty of the water is 15 .0 m g/L as CaCO 3, which is relatively low, suggesting this water will require supplem e ntal alkali additi o n for effe cti ve trea tment w hen using alum , • th e total hardn ess of the wate r ([Ca]+ (Mg]) is 34.1 m g/L C aCO3 and may be described as being a soft water, and • from the conductivity (E C) of the w ater, the TDS is 115 mg/ L , using the common conve rsion factor of 0.64.

Table 1. Chemical Formula, Formula Weight, Equiva lent Weight and Factors to Convert Concentration from "AS IS" to "CaC0 3 " for Common Cations and Anions Ion

Chemical Formula

Formula Weight

Equivalent Weight

As CaCO3 Multiply by

Aluminium

Al +++

27.0

9.0

5.56

Ammoni um

18.0

18.0

2.78

Calcium

NH4+ ca++

40.1

20.1

2.50

Ferric Iron

Fe+++

55.9

18.6

2.69

Ferrous Iron

Fe++

55.9

28.0

1.79

Magnesium

Mg++

24.3

12.2

4.12

Sodi um

Na+

23.0

23.0

2.18

Potassium

K+

39.1

39.1

1.28

Hydrogen

H+

1.0

1.0

50.0

Bicarbonate

HC0 3· C03··

61.0

61.0

0.82

Carbonate

60.0

30.0

1.67

Chloride

Cl·

35.5

35.5

1.41

Hydroxide

OH·

17.0

17.0

2.94

Sulphate

S04··

96 .1

48.1

1.04

WATER

Table 2. Chemical Formula , Formula Weights, Equ ivalent Weights and Factors to Convert Concentration from "AS IS " to "CaC0 3 " for Common Chemicals Used in Wat er Treatment Processes Chemical Formula

Chemical

Al 2(S04l3.

18H20 NH3 CaC03 Ca(OHb cao CO2 FeCl3.

6H 20 Fe 2(S04)J FeS04.

7H20 HCI Na 2C03 NaO H NaHC03 H2S04

Alum (Aluminium Sulphate ) Ammonia Calcium Carbonate Lime (Calcium Hydroxide) Qu icklime (Calcium Oxide) Carbon Dioxide Fe rric Chloride Ferric Su lphate Ferrous Su lphate Hydrochloric Acid Soda Ash (Sodium Carbonate) Caustic Soda (Sod ium Hydroxide) Sodium Bicarbonate Sulphuric Acid

Formula We ight

Equlvalent Weight

As CaC03 Multiply by

666.1

111.0

0.45

17.0 100.1 74.1 56.1 44.0 270.3

17.0 50.0 37.0 28.0 44.0 90.1

2.94 1.00 1.35 1 .78 1.14 0.56

399.9 278.0

66.7 139.0

0.75 0.36

36.5 106.0 40.0 84.0 98.1

36.5 53.0 40.0 84.0 49.0

1.37 0.94 1.25 0.60 1.02

Table 3 . Water Analysis Wa ranga Channel at Rochest er (Unless otherwise noted , a ll analyses in mg/L) As Ion

Calci um Magnesium Sodium Potassium

As CaC03

7.9 3.5 22.0 2.3

Alka linity Chloride Sulphate

19.7 14.4 47.9 2.9

As Ion

As CaC0 3

18.3 45.0 4.0

15 .0 63.5 4 .2 82.7

EC microsiemens/cm 180. True Colour 60 Pt/ Co Units

Table 4. Alkalinity Consumed and Carbon Dioxide Produced per mg chemica l dose Chemical

Alum H2S04 HCI Ca(OHb Na2C0 3 NaOH NaOCI Chlorine (gas)

Alkalinit y, CaC03 per mg Chemical

-0.45 -1.02 -1.37 1.35 0 .94 1.25 0.6 7 -1.41

mg CO2, per mg Chemical

0.40 0.90 1.20 -1.19 -0.41 -1.10 -0.59 1.24

Some Basic Concepts In order to understand what h appens w hen vario us che micals are added to a water and to determine if it then becomes corrosive or stable, it is first necessary to appreciate seve ral important " rules" : 1. Alkalinity is consumed w hen an acid is added to a water. In this instance, an "acid" also includes metal cations. H ence, w h en a coagulant cation is added to a water, say

52

WATER MARCH 2 001

where : pH = pH of the water [ALK] = a lkalinity of the water, mg/L CaC0 3, and [CO 2 ] = carbon dioxide, mg/ Las CO 2 (i.e. "as is") l n the case o f the Waranga C hann el w ater, th e C O 2 level may be computed to be 0 .84 mg/L, "as is".

Water Stability Indices

84.9

PH 7.6

occur w hen various c he micals are added to a water.

Note that w hen an alkali is dosed to a w ater two th ings happ en sim ultaneo usly : • the alkalinity increases, and • carb on dioxide is consu med.

Similarly, w hen an acid or a coagulant is added to a water, simultaneously: • the alkalinity is decreased , and • carbo n diox ide is p roduced.

From T able 4 it is seen that w he n sodium hypochlorite is used for disinfection , the alkali nity of t he wate r w ill increase and CO 2 is consu med, resulting in an increase in the pH of the wate r. This can be important w hen the effec tiveness of disin fec tion at diffe rent pH values is considered .

T he pH o f the dosed w ate r can now be calculated using E quation (1). This imp ortant relationship holds tru e fo r waters w ith a pH of 4.5 to 8.5 at 25°C. pH = log(2.24X10 6 *[ALK]/[C0 2 ]) - (1)

Turbidity 40 NTU

aluminium fro m alum, alkalinity is destroyed. The same is also true when chlorine gas is added for disinfe ction .

2. Alkalinity increases when an alkali is added to a water.

3. C arbon dioxide is produ ced in a w ate r w hen alkalinity is co nsumed. This m eans that w hen alkalinity is used up fo llowing the addition of alum, carbon dioxide is produced .

4 . Carbon dioxide is consumed w hen an alkali is added to a wate r .

5. The pH of a water will decrease w hen carbon dioxide is fo rmed and w ill increase when CO 2 is destroyed.

Knowing the changes that va rious ch emicals m ake to alkalinity and ca rbo n dioxide levels allows the prediction of the pH of a water as a result of different treatm e nt re gim es.

T able 4 gives the changes in alkalinity and carbo n dioxide concentrations that

Whe n a wa ter is neither scale-formj ng nor corrosive, it is sa id to b e stable.

Although a number of indices h ave been developed to gauge water stability, no n e has demonstrated the ability to accurately quantify and predict the corrosivity or aggressiveness of a w ater. At best th ey can only give a probable indication of the pote ntial corrosivity of a w ate r.

Indices that are used to indicate the corrosivity of a w ater supply ca n be divided into three broad groups: • calcium carbonate saturation indices, • indices based on sol ution properties that influe n ce corrosion rates, and • emp iri cal indi ces based o n statistical correla tions develop ed in the fi eld .

In this paper, o nly calcium carbonate saturatio n-based indices are disc ussed .

In considering indices de rived fron, calcium carb o nate c h e mistry , it is im portant to apprec iate that th ey only define the d egree of saturation o f a w ater w ith respect to CaC0 3 and do not necessarily indicate its corrosivity . H ow ever, exp erience has shown that if cond itions encourage the forma tio n of a protective calcium carbonate film , then corros10n w ill ge nerally b e minimized.

The New Generation N-Pumps Cut your down-time and costs.

(j)

How could we possibly improve our N-Pump? After all, the unique self cleaning design of the N-impeller is a tough act to follow. So the New Generation N-Pumps have a host of features to reduce the two things you find toughest in pumping operations: operational costs, and downtime. The Spin Out seal protection system prevents particle damage to seals.

New, improved cooling means the high efficiency motors run at lower temperatures. And the new Plug In seal system means that if you do have to replace a seal, it'll take you just a few minutes. All of which helps put the New Generation N-pumps a cut ahead of the competition in the fight against costs.

Call us for more information on 13 19 14 or visit us at www.flygt.com.au.

The N-techn ique patented by ITT Flygt, features a self cleaning impeller that, together with an integrated relief groove in the pump housing, ensures sustained high hydraulic efficiency and clog resistence.

Flygt ITT Flygt Limited, Australia Offices in Adelaide Brisbane Townsville Mackay Mt Isa Darwin Melbourne Sydney Perth Kalgoorlie

ITT Industries Engineered for life

WATER

(1996) has released a PCbased sp readsheet program base d o n th e Roth b erg, Tam b urini and W i n sor -30 Mod el, w hich allows speedy calcu lation of a number of -20 I corrosivity indices, including CCPP. The spreadsheet also allows -10 calculation of the effects of ('I') various chemical additions to 0 (.) a water. It does not however, 0 (.) give d etail ed inform atio n .J about treated water quality, C) such as provided by th e E 10 approach o utlined 111 this paper. i5 20 Another m ethod of deter< m ining the CCPP value is a graphical procedure involving 30 the use of water conditioning diagrams as originally developed by Caldwell and Lawrence (1953).

These diagrams can also be 50 used to solve a wide range of water treatment and conditioning problems (including 30 10 20 -20 -10 0 lime and lime-soda softening).

LSI = pH - pH5 - (2) Figure 1 is part of a C2 = (ALK-Ca), mg/L CaCO3 pH 5 = 11.2 - log[Ca;] - log[ALK] -(3) Caldwell-Lawrence Diagram Figure 1. Caldwell-Lawrence Wat er Condit ion ing Di agram, for where: drawn fo r water at 25°C with wate r at 25 'C and TDS 4 0 mg/L pH = measured pH of the water a TDS of 40 mg/ L. [Ca;] = calcium concentration, Although a unique C-L The R SI value of a water should be less mg/L (as the ion) Diagram should be used fo r the temperthan 10 to be considered to be stable and [ALK] = alkal inity of the water, mg/L CaC0 3 , ature and TDS of the water in qu estion , non-corrosive. and in practice the infl uence of TDS is not For the R ochester water, the RSI value pH 5 = pH at saturation great and Fi gu re 1 can be used over a may be com puted to be 10.7; again range of conditions withou t serious error.

In practice, a water is considered to be suggesting this water is m ildly corrosive.

To determine the CCPP of a water, potentially aggressive if it has a LSI less Calcium Carbonate Precipitation two parameters are calculated: than -1.5.

Potential (CCPP) is a more reliable water or C2, and • (ALK-Ca) For the Rochester example, this water stability index to use since the parameter has a pH of 7 .6, Ca of 7. 9 mg/ L "as is" • AC IDITY gives a quantitative measure of the calcium and an alkalinity of 15 mg/ L CaCO3 . T he Both of these param eters are expressed carbonate deficit or excess of a water, thus LSI can be calculated to be - 1. 5 . Th is in mg/ L CaCO 3 . giving a more accurate guide as to the water can be characterised as being likely extent of CaCO 3 precipitation.

The approximate acidity of a water may potentially mildly corrosive.

R esearch has also shown the rate of be fo und using Equation (5).

Another related parameter is the Ryznar deposition ofCaCO 3 is second order w ith ACI DITY=[ALK](1+ 4 .245X106*10·PH) -(5) Stability Index (RSI), w hi ch is given by: respect to CCPP, again indicating the where: fundamental importance of this parameter.

- (4) RSI = 2pH 5 - pH ALK = alkalinity of the water, mg/L CaC0 3 , Rossum and M errill (1983) concluded where : pH = pH of the water.

CCPP to be the most appropriate index pH = measured pH of the water to use when assessing CaCO 3 saturation Equation (5) applies for a water at 25°C pH 5 = pH at saturation in a water over a range of pH values. and with a TDS of up to 200 mg/ L. T he measure of the corroOnce th e values of (ALK-Ca) and sivity of a water for differen t Table 5. Corrosivity State of Water for Different AC ID ITY are known, these values are values of CCPP is given in CCPP Val ues plotted on the C-L Diagram to fi nd the Table 5. point of intersection, as shown on Figure Corrosivity State of Water CCPP Value, mg/ L CaC03 Previously, CCPP has 1. By interpolation, the Ca concentration been less frequently applied >0 Sca ling (protective) at saturation can then be read off beca use the longhand calcuo to -5 Passive Th e CCPP value is then found from lation procedure is time5 to -1 0 Mildly Corrosive Equation 6: consuming and quite tedious. < -10 Corros ive (aggressive) -(6) CCPP=([Ca] - [Casatll H owever, the AWWA

Many models and indices are ava ilable that use calcium carbonate chemistry to evaluate water stab ility (Rossum and Merrill 1983).

A commonly used index is the Lan gelier Saturation Index (LSI).

This index provides a measure of the stability of a water with respect to its degree of CaCO 3 saturation.

If a water has a negative LSI value, it is under-saturated w ith respec t to calciu m carbonate and is potentially corrosive .

Conversely, for waters with a positive LSI, a protective layer of calcium carbonate could form, as the water is over-saturated with CaCO3 and the water is scaling.

Saturated water has a LSI of zero.

T he pH at which a water is saturated with CaCO 3 is known as the p H of saturation or pHs. At 25°C and TDS levels less than 500 mg/ L (the case fo r n-iost surface waters), LSI can be calculated from Equations (2) and (3):

54

WATER MARCH 2001

-40

"'

~-

u

WATER

Table 6 . Stability Indices for Rochester Water Compared with Typical Values for Stable Water Stability Index Langelier Satu ration Index

Rochester Water

Acceptable Value

-1 .5

> -1. 5

10.7

< 10

In general, this water can be concluded to be most likely non-corrosive to iro n, steel and AC pipelin es.

Water Conditioning

The water at R ochester bas a true colo ur and turbidity of 60 Pt/Co units and 40 NTU Calcium Carbon ate > -5 · 4.7 Precipitation Pot ential respectively. An alum dose of > 10 10.3 50-60 mg/ L wo uld typically be Aggressiveness Index required for effective treatment in a co nventional WTP. where: T he p H of the water will be depressed [Ca] = calcium concentration of water, to approximately 3 .9 fo ll owing addition mg/ L CaC03 of 50 mg/ L alum , w hich is too lo w for [Casad = calcium concentration at e ffective alum coagu lati o n. The pH saturation , mg/ L CaC03 01ust th erefore be ra ised. Generally_a p H For the Waranga C hann el water: va lue of 6.0 to 6.5 is required , usin g an alkali such as h yd rated lime (calcium • (ALK-Ca) = - 4 .7 mg/ L C aCO 3 . hydroxide), soda ash (sodium carbo nate) • AC !D lTY = 16.6 mg/L C aCO 3 fro m or caustic soda (sodium hydroxide). The Equation (5) . exact p H must be determined usin g jarFrom Figure 1 (Poi nt A), the calci um tes ts in th e laboratory but as first value at saturation , where the (ALK-Ca) approximatio n, a p H of 6.5 is a useful vertical line insec ts with the horizontal guide fo r calculati on purposes.

AC ID ITY lin e, is read off as 25.0 mg/ L, The choice o f alkali used will depend and h ence the C CPP value may b e on: co mputed to b e - 5 .3 mg/ L. • the capital and operating costs associated Th e precise value of CC PP is - 4.7 with eac h chemica l; mg/L, indi cating the water is " passive" • li kely sto rage volumes requi red ; and therefore acceptabl e.

• particular Occupatio nal, H ealth and The graphical m ethod outlined above Safety issu es, and w ill give approx imate so lutions o nly but is still useful in d eriving an es timate o f • D angero us Goods storage requireCCPP valu es. T his method will used later m ents. when water co nditioning is considered.

Gen erally, lim e is used whereve r The Aggressive ness lndex (Al) is use d possible du e to its low cost and the fact for estimatin g the potential for leaching that alkalinity and calcium are both added o f the cem ent m atrix from asbestosto the water. T his is important since [C a] ce ment pipelines and is given by: appears in the computation o f bo th LS] and CCPP: see Equ ations (3) and (6) .

- (7) Al = pH + log([ALK]*[TH ]) Soda ash is not fav oured because of where: high doses required as well as increasing pH = pH of the water the TDS of the treated water considerably.

(ALK] = alkalinit y of the water, mg/ L CaC03, and C austi c soda doses required are very simi la r to those requ ired for lime and the [TH) = total hardness of the water, mg/ L CaC03 capital cost o f the storage and dosing eq uipm ent is lower. Care has to be taken A water wi th an Al value less tha n 10 iflow temperatures are expected since the is likely to b e aggressive to asbestosfreezin g p oint of 46% w/ w ca ustic soda cem ent pip ework and fitt ings. Fo r Al is approximately 7°C, o ften n ecessivalues between 10 to 12, a water is miJdly tating heat tracing o f storage tanks and corrosive and for values > 12, the wate r dosing pipewo rk. It is however, often is protective. These valu es o f Al have used at smaller plants as a matter of convebeen fo u nd to correlate reasonably well with th e release o f asbestos fibres caused nience . by dissolution o f the pipeline cement U sing the Waranga C hannel water as matrix (Single y 1981) . an example, the concepts behi nd water conditio nin g are now dem onstrated.

Fo r Wa ran ga Chan nel water, the Al is 10.3 and so c ou ld be mildly corrosive.

Starting with th e raw water analysis, it is fi rst necessary to calculate the co nseTable 6 su n1marizes th e various water quences o f dosing 50 m g/ L alum. corrosivity indices considered for the Aluminium hydroxide is form ed so there Rochester water c ompared with accepted is no addition of cations to the water. The values for a stable, non-corrosive wa ter.

Ryznar Stability Index

alu m consumes alkalinity and to maintain a balanced water analysis, sulphate will in crease by an equivalent amo unt.

The new water analysis w ill be : • ca tio ns: no chan ge • ani o n s: alkali nity= 15. 0-0.45X 50= -7 .5mg/L N o te that all o f the alkalinity has n ow been consum ed and to ensure the correct pH is achi eved , alkalinity must now be added.

A trial- and-error procedure is now fo llo wed. Assume 12.2 mg/ L lime is added to the water. Both the calcium and alkalinity o f th e water will be increased.

T he new water analysis will be : • catio ns: Ca = 19.7+ 2.5X12.2X40.1/ 74.1 = 36.2 mg/ L CaC0 3 . The factor (40.1/ 7 4.1) gives the mg of calcium added per mg Ca(OH b added as CaC03, from Tables 1 and 2.

• a111011s: alkalinity= 15.0-0.45X50+12.2X1.35= 9.0 mg/ L su lphate = 4.2+0.45X50=26. 7mg/ L CaC03

N ext, the change to the C O 2 level is determ in ed: • Initial CO 2: fro m Equation (1) 7 .6 = log(2.24X106 X15/ C0 2 ) CO 2 = 0 .8 mg/ L as is • CO 2 added from destruction of alkalinity by alum add it ion=50X0.4 = 20.0 mg/ L • CO 2 destroyed by lime addition = -12.2X1.19 = -14.5 mg/ L •

Final CO 2 concentration = 6.3 mg/ L

T he pH of th e water fo ll ow ing chemical addition can now be found fro m Eq uation (1): pH=log(2.24X106 X9.0/ 6.3)=6.5,

This is th e targe t pH for al~1111 co;iglllati o n and so the assumed lime dose is adequate . If th e calculated p H W<\S higher or lower than 6.5, then adjustments to the lime dose assumed w oul d b~ req~1irect , T his water is now aggressive anct if chlo rinated will be quite corrosive rn the reticulation system.

The solution to this potenti al corrosivity problem is water conditioning using post- trea tment alkali additio n. Bpt th e qu estions o f wh ich on e and how !11l1 Ch will be required to conditio n th e wa ter must be answered.

As in itial obj ectives, the conditioned water shou ld have a pH of 7 .5 to 8 .0, a LS I of > - 1.5 and a CC PP value > -~ mg/ L. Further assum e that 1.5 mg/ L chlorine is requi red to disinfect the water and that 6.0 m g/L of lime will be dosed to finall y condition the water to render it stable and suitabl e for supply into the reti culation.

WATER MARCH 2001

55

WATER

Table 7. Water Analysis Waranga Channel at Rochester Following Chemical Conditioning (Unless otherwise noted, all analyses in mg/ L) As Ion

Calcium Magnesium Sodium Potassium

As CaC03

As Ion

As CaC0 3

17.7

44 .3

Alkalinity

18.3

15.0

3 .5

14.4

Chloride

46.5

65.6

22.0

47.9

Sulphate

25.7

26.7

2.3

2.9 109.5

1 07.3

pH 7.5 The TDS of the conditioned water will be 163 mg/L

The same procedure as above is again followed.

Addition of lime wi ll increase the alkalinity and calcium of the water. The new water analysis will be: • cations: Ca=36.2+2.5X6.0X40.1/74 .1 = 44.3 mg/L CaC03

• anions: alkalinit y: 9.0+6.0X1 .35-1.5X1.41= 15.0 mg/L chloride: there will be an increase in the chloride level equivalent to the decrease in alkal in ity due to chlorine addition , i.e.

2.1 mg/L.

The change co the CO 2 level is aga in calc ulated.

•

Initial CO 2 : 6.3 mg/L as is

• CO 2 added from destruction of al kalin ity by chlorine add ition = 1.5X1.24 = 1.9 mg/L • CO 2 destroyed by lime addition = -6.0X1.19 = -7.1 mg/L •

Final CO 2 concentration=1.1 mg/L

The final pH of the co ndition ed water wi ll be: pH = log(2.24X106X15.0/1.1) = 7.5.

Th e condition ed water now has a p H of 7.5 and a LSI of - 1.3, which is satisfactory from a corrosivity standpo int. The CCPP value can also be checked using the graphical method ou tlined earlier.

In this case: • (ALK-Ca) = 15.0-44.3= · 29.3 mg/L CaC03.

• AC IDITY = 17 .0 mg/L CaC0 3 from Equation (6).

From Figure 1 (Point B), the [Ca,, ,] value may be read-off as 48.0 mg/L, and hence:

new TDS of the conditioned water found.

Th e new water analysis is shown in T able 7. Note that Mg, Na and K levels in the raw water all remain unchanged as a consequence of water conditioning with lime.

Th e difference between the sum of cations and the su m of anions is + 2.2 mg/ L, which is the sam e as the original water analysis and hence the calculations are correct.

This procedure can also be repeated using caustic soda and soda ash as alternative alkalis for conditioning.

Table 8 co mpares the three different alkalis using WaterQual, a water treatment and quali ty assessm ent model developed

by Fish er Stewart. Th e differences between the results from WaterQual and the above calculations are du e to the use of more accurate data in the model and co rounding errors.

Note the operating cost differential in using lime compared to caustic soda and soda ash .

The additional advantage in using lime is also apparent: this conditioned water has the lowest CC PP. T he TDS increase associated with using soda ash is also evident: l15 to 195 mg/ L, a 70% rise.

References Australian Drinki ng Water Guidelines (1996), NHMRC and AR.MCANZ, Canberra .

Arnerican Water Works Association (1996), The Rothberg, Tamburini and Winsor Model for Corrosion Control and Process C hernistry, D enver, C olorado, U SA .

Caldwell, D.H. and Lawrence, W .B. (1953), Ill//.

Ell,~ - Chem; 45 , 3, 535-548.

Rossu rn , J. R.. and M e rrill, O.T. (1983), JA WWA, Feb; 95-100.

Singley,J. Edward (1981),JAWWA, N ov; 580.

The Author Peter Gebbie is a Senior Engineer in the Water Industry Group at Fisher Stewart, M elbourne responsible for water and wastewater treatment process and detailed design. Tel: 03 8517 9268. Email: peterg@ fisherstewart.com .a u

Alkali Dosed Parameter

CCPP = (44.3-48.0) = - 3.7 mg/L CaC0 3.

Th e precise va lu e o f CC PP 1s -3.4 mg/ L, suggesting the water is " passive" and has been conditioned to a satisfa ctory level.

The assumed lime dose of 6.0 mg/L used in the calcul ations is therefore su fficient.

The fin al sum of the cations and an ions can also be determin ed and from this, the

Alkali Dose: pre-treatment, mg/L

WATER MARCH 2001

Water stability indices have been reviewed w ith a focus o n the Langelier Saturation Index and Calciu m Carbonate Precipitation Potential.

Methods of calculating these parameters ha ve been outlin ed. An approach to determining the impact that different treatm ent regimes can have on treated water quality and how a treated water can be condition ed to make it less corrosive has also been presented .

The te chniqu es outlined are straightforward and can be readily adapted to a PC-spreadsh eet, providing a useful tool to allow water treatment plant optimisation.

Water stabil ity indices will no doubt be used more freq u ently in the future as the general trend to improve treated water quality and redu ce plant operating costs continues.

Th e methods prese nted in this paper wi ll hop efull y contri bute towards these goals.

Table 8. Comparison of Different Alkalis for Treatment of Rochester Water. Raw Water Quality: true co lour 60 Pt/ Co Units, turbidity 40 NTU, alum dose 50 mg/ L. Disinfection: 1.5 mg/L gaseous chlorine

Coagulation pH

56

Conclusions

Lime

Caustic Soda

Soda Ash

6.5

6.5

6.5

12.4

13.4

25.1

pH of Conditioned Water

7.5

7.5

7.5

Alkal i dose: post-disinfection, mg/ L

5.7

6.1

23.5

LSI of Conditioned Water

-1.3

-1.7

-1.2

CCPP Cond itioned Water, mg/L CaC0 3

-3.4

-5.2

-6.4 195

TDS of Conditioned Water, mg/L "as is"

162

162

Total Alkali Dose, mg/ L

18.1

19.5

48.6

6.5

10.6

21.8

Operating Cost of Alkal i Dosing, $/ML

a

WATER

STABILISATION AND BUFFERING OF WATER: SOME CAUTIONARY ASPECTS R J Turney and P R Nadebaum le has be en common in Austra li a that treatment of water fo r drinking purposes simply invo lves clarifi cation and fil tration and disin fec tion, w ith add ition o f lime aft er treatme nt to raise th e p H co close to neu t ral. Over the last decade, co nsideratio n has been given to the need to "stabil ise" th e w ater; ie, to ensure chat the wate r is not undu ly corrosive to the ce m e nt- lin ed mild steel and ductile iron pipe work w hich is common in Australian water supply distributio n and reticulation syste ms . le is also becoming common to co nsid e r the need to control pH rise in th e re ticu lati o n system , beca use in man y locatio ns in Australia the water is soft and poorly buffe red and subj ec t to very high pH at som e locati o ns.

Th e fa ctors w h ich can affect the achievem ent o f a stable and app ropriate ly buffered supply are o ft en not w eU unde rstood. le is the purpose of chis tec hnical note co indicate som e impo rtant issues.

Stabilisation In order co protect pipework and structures against corrosion it is usual to specify chat there be a positive Calcium Carbo nate Preci pi tation Potentia l (CCP P); typically chis might be + 1 m g/ L. CC PP involves a th eoretical calculatio n based o n ph ysica l chem istry. It is simi lar to th e Lan ge lie r Index, and provides a m easure o f w hethe r wa te r has potenti al to precipitate o r dissolve calc ium carbo nate. A positi ve

value will usually m ean that calcium carbo nate w ill no t dissolve and the refo re concre te structures and the lining o f cem e nt lined pipes w ill be protected against attack. T he stab ili ty of th e w ater is only on e of several factors affecting corrosio n of pipework and stru cwres.

Both th e CC PP and Langelie r Index have impo rta nt limitati o ns w hich need to be recognised: â&#x20AC;˘ T he estimati o n of CC PP (a nd the Langeli er Index) assumes equilibrium conditio ns, and w hile these m easures can provide a n indica tion of th e te ndenc y to corrosio n o r scalin g, they do not provide a m easure o f capac ity o r rate o f corrosio n o r scaling (Lan ge lier, 1936) . Under so m e

WATER MARCH 2001

57

WATER

conditions the processes of precipitation o r dissolution of ca lcium ca rbonate may be inhibited, and the predicted effects may not be observed.

• T he estimation of CCPP is based o n theoretical calculations and o nly takes into account the presence of certain io ns, such as calcium and carbonate species, and salt.

If substances such as phosphates o r organics are present, then the precipitation or dissolution of calcium carbonate may be inhibited. CCPP and the Langelier Index is more likely to be relevant for water which has been treated and has low levels of colo ur and dissolved organics (eg when treated for drinking water purposes).

Where inhibiting effects are suspected , then the Marble T est (Degremont, 199 1, also in the A WW A Standard M ethods) ca n provide a better indication of the stability of the wate r.

• Phosph oro us co mpounds s uc h as orthophosphate and polyphosphate ions ca n severely inhibit calc ium carbonate crystallisation by surface adsorption, with a new molecular layer being form ed which prevents crystal growth. T his adsorption can affect both the depositi on and dissolution cycles by 1 to 2 o rders of magnitude, shifting the solubility product by 1 to 2 orders of magn itude from that estimated. These effects can be seen at low concentrations, eg 0.5 mg/ L T o tal P (van Langerak, 1998).

• Sim.ilarly, organics such as humic acids can be adsorbed onto the calcium carbonate crystal seed sites preventing further growth. These effects ca n be seen at a Dissolved Organ ic C arbon co ncentration of 0 .6 mg/ L in low TDS waters (Sontheimer et al, 1981). T his concentration is often exceeded in drinking water supplies. Similar effects can be seen in high TDS waters such as seawater, w ith low concentratio ns of o rganics such as lipoids and amino acids (which are associated w ith li ving organ ism s and are commo n in natural waters) inhibiting precipitation o r dissolution of calcium carbonate (Suess, 1970).

• O ther ions such as ferri c or magnesium can also affect the rate of prec ipitation and dissoluti on, although th e effects are not as clearly defined. It appears that fenic ions ca n inh ibit the for mation of calcite but not aragonite (ie certain crystalline fo rms of calcium carbon ate) , and reference has also bee n made to magnesium affecting the rate of crystallisation (Stumm , 1981 ).

In practice, the presence of magnesium can be beneficial in reducing the concentrati on of calcium ca rbo nate in treated water (eg from lime soda softening), th rough magnesium hydroxide formed in the process acting as a flocculan t and 58

WATER MARCH 2001

captu1ing fin ely divided calcium carbonate which would o therw ise carry over.

• The crystallisation of calcium carbonate proceeds with time through va rious stages (amorphous precipitate, vaterite, aragonite, and finally to calcite) . The solub ili ty of calcium ca rbonate decreases with ageing, and the calcite form is least soluble . This effect is used to adva ntage in so lids co nta ct clarifi ers for lim e softening, where the recirculation of solids allows the crystallisation time to precede to completion, with improved removal of calciu m carbonate.

These factors have som e important impl ications fo r drinking wate r supplies: • Suppli es which are from protected catchments and are chlorinated but not filtered ca n have relatively high concentrations of organi cs. Often these waters are soft and m ay be predicted to be highly corrosive to cem ent-lined pipes and concrete stru ctures, but it is found in pra ctice that the water is not particularly aggressive. As a general rule of thumb, colo ur levels in the order of 15 - 30 PCU may significa ntly reduce (but not necessari ly eliminate) corrosion, although this is dependent on th e particular water.

• Where a water authority has built up knowledge regardin g the rate of concrete attack for waters w ith relatively high con centrati ons of o rganics, this historical info rmation may no lo nger be relevant if the water is treated. If treatment is carried out, greater care wi ll need to be taken to stabilise the water in order to avoid accel erated attack on pipes and structures. This is particularly the case with soft waters with low alkalinity which are common in Australia.

Buffering Stabi lisa tion should not be confused with control of th e buffer capacity o f water, although the two can be related.

The pH rise that is observed w h en water passes though new cement- lined pi pes occurs because of the dissolution of lime from the cement, and the extent of pH rise is dependent on the buffering capacity of th e water (ie the conce ntration of carbon diox ide and bicarbonate ions whi ch react with the hydroxide ions resulting from the lime). The dissolution of lime may be inhibited if th e water is stabilised such that calcium carbonate fom1s o n the smface of the lime; however, in soft poorly buffered waters, particularly if there is a significant organic content which inhibits precipitatio n, it is often not practical to stabilise the water to the extent that li me disso lution will b e controlled.

Instead, in such situations control o f pH rise may be ac hieved throu gh in creasi ng

the concentratio n of bu fferin g ions (cg b ica rbonate) by the injection of carbon dioxide together with lime.

Note that in creasing the pH of soft wate r by the additi on of lime will increase its stab ility and will reduce its corrosivity, although if th is is accomplished w ithout an increase in bicarbo nate ions, then increasing the stability of the water in this way may resu lt in an increased range of pH in the reticulation system . T hus "stabilisation" of water ca n result in exace rbating pH rise. In fact, reducing pH, for example, by injecting ca rbo n d ioxide an d making the water more aggressive w ill increase the buffer capacity and wi ll redu ce pH rise.

Th e obj ectives fo r buffering and control of pH rise need to be carefu lly though t through . Key issues are: • The p H range in w hic h water is to be maintained; • T he percentage of customer services that are to be maintained within the range, and wheth er there is a maximum pH which is to be comp lied with for all services.

In prac tice th e variation of pH in the distributio n system w ill vary w idely, and will depe nd on the pipe m aterials, thei r age, and the range of water residence ti mes. Often con trol of pH w ill involve sta tistical considerations: w hile increasing the buffer capaci ty of water will reduce the pH rise, leaching of lime w ill still occur as before and there will still be a pH rise, albeit reduced. Note that the control o f pH rise will be most effective where the quantities of lime leached are small (a nd within the buffer capacity), whereas if the quantities are large, then th e buffer capacity may be exceeded and the pH rise will still be high . Because of this, it can be expected that increasing the buffer capacity wi ll reduce the pH , but there w ill still be a varying q uantity of lime leached in the reticulation system (varying with factors such as flow/p ipe surface area) and therefor e th ere will sti ll be a percentage of customer services w here the pH is still h igh relative to the mean pH. As a rule of thumb, in potable water sys tems it is desirable for both the alkalinity and calcium hardness to be at least 35 - 40 mg/ L, preferably 50 m g/ L, to provide for both a positive CCPP and a good buffering capacity. For very soft water this may req uire a substantial chemica l addition, and ma y involve a significant cost in terms of equipment and chemica ls. If the water supply syste m has bee n o pera ted historically w ith low alkalinity and hardness, then increases of this magn itude may be of co ncern to

WATER certain customers, such as industrial users with boilers.

Key Information Requirement s In making decisions regarding stabilisation and buffering, it is important to obtain the key in fo rmation that allows the situation to be analysed. T his information includes: • Asset life in formati on including failure frequency, and particularly informatio n where the asset life is limited through attack o n cement linings of pipework, and asset repair and replacement costs.

• The chemical compositio n of the water and its variation, toge th er w ith pH variation, through the reticulation system.

• The presence of inhibito rs, such as organi cs and phosphate.

• The desired system service objectives, including maximum pH fo r any customer (or pe rce ntage of c ustom e rs), and maximum number of supply interruptions.

Concluding Remarks It ca n be appreciated fr o m this discussio n that determining the optimum stabili ty and buffering conditi ons for potable water supply systems is not always a simple matter. It is important to distinguish the different requ irements for stability and buffering, and w hat eac h is achiev ing.

H igh quality, soft unfiltered suppli es as occur in Australia can be some of the most challenging for determining w here th e optimum operating conditions lie. Because these waters will often have relatively high orga ni c co ntent, they may not be particularly aggressive to co ncrete and cement Linings, and from an asset life perspective it may not be necessary to operate th e

supply with a positi ve CCPP and the substantial chemical add itions that this would require. However, such waters can have a low buffer capacity, and in o rder to avoid a percentage of the customers experiencing high pH conditions, the controlling requireme nt fo r chemical addition may be the need to avoid the most extre me pH co nditions rather than asset li fe.

The key to optimal o peration of water supply syste ms is a good understandin g of the fundamental wate r chenustry, actual operating conditio ns, maintenance requ irements and asset life, and custo mer service requirements.

References Degremont ( 1991) Water Treatment J-/ml{/book, Sixth Edition 1: 36 1 Lavoiser Publishing, Paris Langelier WF (1936) "The analytical control of anti-corrosion water cream,ent",J A WWA 28: 1500 Sontheimer H , Ko lle W, Snoeyink VL (1981) "The siderite model of the fonnation of corrosion resistant scales".JA WWA 73: 572 Stumm W and Morgan JJ ( 1981) Aquatic Chemistry, Second Edition, John W iley &Sons, New York Su ess E (1970) " In terac ti o n o f organic com po unds with calc ium carbo n ate" Ceod1i111(1 et Cosmoschimira Acta 34: 158 - 168. van Langerak, A (1998) Thesis "Control of [{l/ci11111 rnrbo11ate precipitation i11 mwerobic ret1ctors", Wagcningen University, N etherlands

The Authors Bob Turney, now a retired consulta nt specialisin g in minin g and mi neral ex tra cti o n problems, was Mana ging D irector of Boby Water Treatment Pty Ltd. Dr Peter Nadebaum, a chemical engin ee r, is th e Nati o nal M anager, Environmental Management, for Egis Consulting Australia.

BOOK REVIEW E.A.Laws: Aquatic Pollution. An Introductory Text. Third Edition.

ISBN 0-471-34875-9 RRP $205.80 plus po s ta ge $ 11 . Availabl e f rom bookshop@a 1va .as11 .a11. Teleplto11e +61 2 9413 1288 Fax +61 2 9413 1047 This is a comprehensive introductory text presenting a systematic study of pollution in oceans, lakes, streams and underground aquifers: so warns the back-side of this detailed hardcover editi on. The first chapter starts with fundamentals - an excellent approach given that most engineers and many pure scientists la c k the ecological and ecosystem approach which so often informs modern environmental writings.

Food webs, ecosystem stability and photosynthesis give way to an expla-

nation of trophic levels w hich eases the reader gen tly into a first example of aquatic pollution, the very natural event - eutrophication. From here, Laws moves to non point sou rce pollution, sewage pollution, pathogens in natural rivers and toxicology, all points amply illustrated by case studies.

It is clear that the reader is being led through the spectrum of natural to human forms of water pollution to industrial and what could only be termed intentional tampering with the quality of the water through events such as thern1al power production, radioactive c ooling and m i ne wash i n g.

Gro u ndwater poll u t io n a nd acid deposition are also dealt with. Not cheap but worth the money.

TOUGH and economical

PUMPS for

Water Sewage Dosing Sludge

PCM Progressing Cavity Peristaltic Dosing

Svedala Robot Submersible

BBA Self-Priming We specialize in providing and supporting a wide range ofpumps and pumping systems for demanding applications.

PUMPm!BDf1DW

I

AS/ISO 9002 QEC 2977

20 Uralla Road Port Macquarie NSW 2444 Tel: 02 6581 0744 Fax: 02 6581 0790

Email: pumps@nor.com.au Web: www.pumpability.com.au

WATER MARCH 2001

59

WASTEWATER

~

THE COMMISSIONING OF A SMALL STP: A 'SMALL' SUCCESS PR L Mosse Abstract

release o f the Victorian State En v ironm ent A small B iodenitro ™ Protection Po]jcy (SEPP) Sewage T reatmen t Pl ant Wa ters of Victoria , a built on a Design and site had been selec ted Construct contract fai led some 6 km fr o m th e to ac hieve desi gn effluen t to wn fo r th e quality. Water Authority construction o f a lagoon staff undertook to identify system. Due to the cool th e probl em s and find te m perate cli ma te of so lu tio ns to th e problems.

N eer im South , land Bench scale and whole disp osal was d eem ed plant trials were conducted inappropriate. Since a w h ere appropriate. la goo n based syste m The follow ing modificould no t achi eve the cations were made. n e cess ary q u a l ity • Additional feed trucked Figure 1 . Neerim Sth Sewage Treatment Pl ant showing the required by the SEPP for fro m a nearby plant. bioreactors. Only t he left bioreactor is functional. The right bioreactor discharge to a watervvay , • PLC controls m odified is filled with water and can be commissioned in the future.

Gipp s l a n d Wat e r to provide true h ydraul ic decid ed to specify an con trol of sludge age. ac tivated sludge system . large Sewage T reatment Pla nts (STP 's) • D ecan t weir lowering rates adjusted to Th e requ irem ents were packaged as a for nu trient removal and improved prevent flooding of downstream fil ter and D esign & Construct co ntract with the effluent quali ty, the task is no less UV system. upgrade of the larger Warragu l STP (4.2 daunting fo r Water Authorities with small • Sludge wastage established experiML/d ADWF 17,000 EP) to make the STPs. m entally. package attra ctive to more te nderers. A Neerim South (population 490) is a • Dissolved Oxygen set points and B io Denitro™ plant w as designed and small towns hip in the foo thills of the treatment cycle times mod ified to ensure built at the Neerim South site (0.2 M L/d Great D i vidi n g R. a ng e i n anoxic condi tio ns during the deni trifiADWF, 1050 EP). T h e Biodenitro™ Gi ppsland ,Vi c tor ia .

As part of a cation period. process removes nitrogen biolo gically M emorandum of Understanding with the • N itrification stabilised prior to optimiwith al ternating aerobic and anoxic Victorian State Government, a sewerage sation of denitrification. periods in a ditch reactor and relies on reticulatio n and treatment system was • Control of alkalinity established by chemical dosing for phosphorus removal. required fo r th e township. Pri o r to the manual dosin g of bagged lim e.

Th e p l a nt com m e nc ed • Site fo r iron salt dosin g commissio ning in Febru ary shifted.

1998. Figure 1 shows a photograph of th e bioreactors • P h os phorou s r e m ov al 12 achieved by iro n salt dosing and A new sewerage system was lime dosing. constructed under a separate " contract. T his w as completed With attentio n to detail the in Febru ary 1998. Sewage is plant process has been modi fied coll ected from the township su c h that t he p la n t no w and pumped to a rising main compli es with the di scharge via three pump stations. A fina l requirements of the Vi ctorian ,..,_ __, pump statio n d eli vers the State En vironment Po ll ution Jun.el'Aut470d47Deo-tTll'. . . . . . . . . Jun41.,.....~o.o-tl,...... sewage to th e plan t . On Policy and the EPA licence for occasions the raw sewage the site. received at the p lan t is qu ite Introduction septic as a result of coll ecti on Figure 2. Neerim Sth Sewage Treatment Pl ant showing the in th e fi nal p ump station Whil e m any wa t e r bioreactors. Only the left bioreactor is functional. Th e right prior to pu mping. T he £low, bioreactor is filled with water and can be commissioned in Au th orities face the daunting although intermittent, sh ows task of retrofitting or upgrading t he future.

____________________ ....

60

WATER MARCH 2001

Jun,,fl . . . 0a,41Dec,ft

WASTEWATER

Table 1. Design parameters for Neerim South STP. Parameter

Influent (avg)

ADWF (ML/ d)

0.21

PDWF (ML/ d)

0.62

Maximum Flow (ML/ d)

0 .86

80 D5 (mg/ L)

300

Design Effluent

Licence 50%ile

Licence 90%ile

5

10

15 15

Suspended Solids (mg/L)

360

6

10

Total Phosphorus (mg/L)

19

0.3

0.5

1

Total Nitrogen (mg/L)

57

6

10

15

51

0.5

2

5

106 -108

50

200

1000

Ammonia-N (mg/L} Faecal Coliforms (cfu/100ml)

a typical diurnal pattern with the m orning peak arou nd 1000 hrs and a later sm all er peak aro und 1700 hrs.

R esidents of Neerim South were allowed un til 2002 to connect. Of a total of 261 properties, ·116 are curren tl y connected (see Figu re 2). Figu re 2 also shows the total monthly flows to the plant.

Plant Design Th e design para meters fo r the plant are show n in Table 1.

Th e inl et works consists of a raked 10mm c urved bar screen. Screen in gs are passed to a continuous ba g system i n a standard "wheelie" bin. The scree ned influen t is passed to a combin ed grit and grease remova l cha111ber.

T he main plant consists of two 375m3 bi oreactors. O nl y one bioreactor was commiss ioned. Th e othe r remai ns for possible future (agreed) expa nsio n. T he reactor has a sin gle 15.5 kW brush aerator and a sin gle slow speed m ixer. Treated eilluen t is discharged over a m ec hanica l weir with a fixed lowering rate. The final eillu e n t passes through a drum mi croscreen (20 u m mesh size) and then to a UV disi nfection system. Waste sludge (W AS) is pumped into a 15 m 3 settling tank and the settled sup ernatant returned to the hea d of the plant.

Commissioning After so me attempts at co111111issio ning, the contractors fe lt that since th e design load could not be delivered it was unreasonable for G ippsland Water to expect the plant to perform, and requ ested final certificate. This was granted to the co ntractors in May 1999.

Since then Gippsland Water have taken on th e c hall enge of getting this plant to perform and have now been abl e to ach ieve Nitrification and D enitrification and final effiuent concentrations for all parameters within the requirements of the SEPP.

Cycle Design T he PLC co ntrol system provides for some fle xibility in designing cycles. The decision was taken early to run th e plant essen tia ll y in an IDEA mode with fo u r peri ods; aeration (nitri ficat ion (N)), mixing (denit1ification (DN)), settling and decant. In contrast with the stan dard IDEA protocol the Kruger Bio Deni tro process puts the DN phase first. Biowin modell ing for this site co nfirmed that th is was expected to produce an efDue nt w ith a lower Total N .

icantly higher than the su rface of the liquid in the reactor. D uring the discharge pe riod the weir lowers to allow the clarified supernatant to flow over the weir. Since the weir lowers at a set rate, discharge does not occur immediately the wei r starts to lower. Depending on the level of liquid in the reactor, the time to actually co mm e nce discharge va ries.

Durin g the morning peak this amounts to som e 25 m inutes. Consequently the settling time in the cycle was set at around 5 minutes. C learly adequate settling does not occur in this time bu t settl ing co ntinu es to occur durin g the discharge phase w he n the wei r is lowerin g but no final eilluent actually goes over the weir.

T he net result is a settling tim e of between 30 minutes and over 1 hour depending on the tim e of day.

The initial settings for the weir lowering rate frequently led to flood ing of the drum fil ter and by pass of un fi ltered eilluent to the UV system and then to the receiving waterway. The increased turbidi ty of the flood ed effiu ent compromised the operati on of the UV system suc h that th e eillu e nt fa il ed to compl y with the coli form requirements of the li cence. Carefu l obse rvati o n o f the decant throughout the entire cycle and at diffe rent ti mes of the day allowed th e setting of a su itable weir lowering rate (1

Determination of DO Setpoints Because of the low mixed liquor suspended solids (M LSS) and Specific Oxygen Uptake R ate (SO UR), arisin g from the underloaded condition s, use of th e DO contro ls in the no rmal way was not possibl e. A few turns of the rotor caused a rapid increase in DO. T he aim was to operate at arou nd 1.0 to 1.5 mg/I DO during the aeration period. PLC set poi nts were determin ed b y trial and erro r unti l these l eve ls we r e ach ieved. T he upp er DO limit was set at 0.7 m g/L and the lower DO set point at 0.3 mg/L. Th is gave actual DO 's between 2.5 • water supply mg/L and 0.3 mg/L. services

Providing effective water infrastructure management

Determination of the Settling Period and Weir Lowering Rates Discharge of treated eill u ent from the intermitte nt plant occurs via a n adju sta bl e we ir.

Wh en discharge is not occurri ng, the weir is parked at a level signif-

• operations and maintenance • engineering services

WASTEWATER

progr a m to ens ur e have been made to the cycles in an wasting o nly occurred atte mpt to achieve better ni trogen from th e mixed li quor removal. InitiaJly changes were apparently during the aeration made on a trial and error basis w ith little _, 2000 _.,..,...- . p eriod. In t hi s way longterm success.

C) E h y dra ul ic co ntrol o f Analysis of the data for late 1998 and en s lud ge age co uld b e early 1999 (Fig 5) revealed that the plant en _, achieved. did nitrify however the performance was :!: 1500 Since biomass growth inconsistent. Denitrification was co nsisdid occur, albeit at a low te ntly poor. The plant was originally rate, it was decided to commissioned w ith 2 DN/ N periods per 1000 cease wasting and cycle with 6 cycles per day. A chart 10 0 20 30 40 50 60 measure th e actua l recorder was connected to the on line DO Days growth rate, and then probe to allow a continuous record of ca lculate an appropriate reactor DO to be maintained. Analysis of Figure 3. Resu lts of MLSS growth rate trial wasting rate. T he resu lts DO profiles revealed that during the DN of the growth trial are phase there was still a significant DO second lowering each 2 minutes) which present. Because of the low MLSS and show n in Figure 3. did not cause flooding. Once this was low oxygen demand there was insufficient T he growth rate was determined as 17 achi eved the final effluent qu ality time to consume the DO and establish mg MLSS/L/d and a wasting rate of 1.7 improved and coliform limits met. anoxic conditions. The cycles were minutes per four hour cycle was estabtherefore reduced to a sin gle DN/N lished.

During J uly 1999 and August 1999 Supplementary Feeding period p er cycle in late April 1999. This sludge age of this gave a m easured In the early stages of commissio ning, produced some improvement in nitrifiapproximately 120 days. The p lant concern was expressed by the contractor cation. c urrently runs at a sludge age of around that insufficient COD was available to 40 days.

Over the next m o nth or so the DN commission the plant. Consequen tly it period was extended and the N period Figure 4 shows the reactor MLSS over was decided to supplement the plant with reduced. This resulted in som e furth er the entire commissionin g period. The an 8000L tanker load of influent from a improvem ent in both effiuent ammonia double-ended arrow shows the period of n earby STP (COD - 400mg/L, N-NH3 and nitrate levels. However, in J une 1999 the growth trial when wasting was - 18 mg/L, SS - 150 mg/ L). T his supplethere was a rapid deterioration in fi nal stopped to allow determination of an mentary feed was usually added twice appropriate wasting rate. After th e effiuent ammonia. Several cycle time weekly on Tuesday and T h ursday growth trial, a target M LSS of around adjustments were trialed o ver the winter mornings. The feeding was started in J uly 2200 m g/ L w as established reasonably period until in August 1999 it was 1998 and with the exceptio n of the well. The second arrow shows the fi nal decided to carry out so me benc h reactor period August 1999 to mid October sustained addition of iron sa lt (PFS) and trials. These clearly revealed minimal 1999, has been continuous since then. manual addition of lime. The rapid rise oxygen u ptake during the nitrification More recently the fe eding was again in MLSS at this time reflects th is addition period. Further investigation revealed a stopped in mid Febnmy 2000 for a of iron salts and th e increased co ntrilow pH (6. 1 - 6 .5) and low alkalinity ( controlled trial perio d to assess the bution of inorgani c solids to the M LSS. - 70 mg/ L). Although there had been no impact in the plant. The resultant The VSS is still approximately constant. rea l change in these values from the decrease in MLSS is shown clearly in The drop in MLSS that occ urred in previous su mme r and autumn , it was Figure 4 . W het he r this would have March 2000 corresponds to the period in hypothesised that the combination of the caused a deterioration in effluent quality vv h ic h supp lementary feed in g w as p H , alkalini ty and colder w inter te mperw as n o t assessed, however the decision suspended. Since sludge wasting was then atures had resulted in a signifi can t was taken at that stage to reintroduce th e well control.led the results clearly indi cate inhibition of ni t rification . Iron salt th e effe ct of the feeding. supplementary feeding.

Determination of Sludge Wasting ... ......

Nitrogen Removal Rat es Nitrogen removal The plant was o riginally designed to in an intermittent plant achieve sludge wastage by pumping is largely ac hieved by from the reactor for a set number of altering the ae robic mi nutes per time period. Waste sludge (ae rated or Nitrif(WAS) is pumped into a 15 1113 settling ica tion) and anoxic tank and the settled supernatant recu rned (una erated/ mixed or to the head of the plant. Various settings D enitrification) pe rwere trialed between two and four iods. Fi gure 5 shows minutes every 76 minutes but without the effl u ent ammonia , success at maintain ing a co nsta nt MLSS. nitrate and phosphate Under this wasting system, wasting ,..._ __, concen trat ions sin ce cou ld occur from the mixed liquor and ..................

00000000 November 1998. Over at other times from settled bi omass the initial 18 m onths leading to a variable amount of wasted o r so of comm isFigure 4 . Reactor MLSS for the period October 1998 to sludge. To ove rcome th is problem a sioning, many changes April 2000 modification was made to the PLC 2500

. . . .•. .

.~. ......~. . ·

•

_

-.----------------------,

... ...

__________________

~-~---~~-M-~~-~---~ -

62

WATER MARCH 2001

WASTEWATER

in an attempt to be tter matc h the flows into th e plant. Since the n fi nal efflu ent total phosph oro us levels have bee n maintain ed at around 0 .5 m g/ L to 0 .6 m g/L (Fi gure 5).

:r .,

,.,

Number 01 DK N pe,rlods

Conclusion

r9dUcedtrom2to1~ cydo

The N eerim South STP has now complied fully with the EPA require me nts since D ece mbe r 1999.

Thus despite less than favourab le load characteristics and poor initial co mmissioning, it has bee n possible , with su ffi cie nt atte ntion to de tai l, to achieve full lice nce compliance at this small plant.

"

Figure 5. Final effluent ammonia , nitrat e and total phosphate

levels discharged from the Neerim South STP for the period November1998 to March 2000.

dosin g was ceased in late August 1999 (Fig 5) in an attempt to maintain alkalinity and reestablish ni trifi cati o n. Th e spectacular improvement is clearly evident in Figure 5. D enitrification apparentl y deterio rated during the sprin g of 1999 with th e in creased effiu ent nitrate largely reflectin g the more complete nitrification .

From Septe mbe r 1999 to late Nove mbe r 1999, DN and N periods we re progressively tun ed. Laborato ry bench scale experime nts we re used to estimate the minimum time at pea k loads necessary to achie ve full nitrification. T his enabled the N pe ri od to be reduced and the DN peri o d increased. From late Nove mber 1999 the DN period was approx imately 80 minutes and the N perio d approximately 90 minutes. This represe nts a co nsiderabl e shift from th e initial comm issioning times where th e N pe riod was approximately 50% longer than the DN period.

Iro n salt dosing w as reintroduced in D ecembe r 1999. Th ere was no provisio n fo r alkalinity control in the ori ginal design e ve n th o ugh the pl ant was d es igned fo r c hemical P re m oval. T h e plant has bee n manuall y dose d w ith li m e on a daily basis (approx 17 kg pe r day) since Decem ber.

Exce ll e nt amm o n ia and nitrate levels have bee n maintain ed durin g th is phase (Fig 5). C urre ntl y an automated pH co ntrol syste m is being installed at the plant.

Chemical Phosphorus Removal

P o lyme rised Fe rric Sulphate (12% Fe) w as added to th e re turn fro m th e WAS tank in O ctobe r 1998. Initially n o atte mpt w as mad e to dete rn1i ne optimum rates a nd adjustm e n ts were made in an ad hoc fashion . T h e resu ltant P levels in th e final ef£lu e nt sho wed significant variation and did no t co mply with SEPP require me nts. l n Ma y 1999 j ar testing was ca rri ed out and the dosing adjusted. Typi cally iron is dose d at a rate of be tween 30 and 35 mg/ L Fe. Phospho rus re moval improved and ef£lu e nt P was ge ne rall y less th an ·1 m g/ L. When the iron salt d osi ng was stopped in late Au gu st 1999 to reestabli sh nitrificatio n there was a fa irly rapid rise in the efflu e nt phosphate (Figure 5) .

Prio r to recommencin g dosing in D ecemb er 1999 th e dosing site was shifted to th e raw influe nt

Acknowledgements The author wishes to thank the operator Harold Smythe for his assistance during the pe riod of the commissioning, and T ec hni cal Officers Simon Rasmu ssen and !an Barn es for their assistance in the fin al stages o f the commission ing .

Dr J o hn Messe nger and J e nn y Mosse kindl y agreed to criticalJ y review the manuscript.

The Author Dr. Peter Mosse, (mossep@ gippswater.co m .au) is the W ater Trea tment Man age r at Gippsland Water. (P.O. B ox 348 Traralgon Vi c, 3844) .

ipeline Control Services Pipeline Control Services are a dedicated pipeline under pressure tapping and line stopping company established to specifically cater for the government and civil construction industries throughout Australia.

• Under PressureTapping 15mm through to 600mm • Line Stopping Technology for all pipeline application • Line Stopcapacity from I 00mm through to 1500mm • National Sales and Contracting divisions • IO years industry experience So the next time you consider under pressure tapping or perhaps considering a pipeline maintenance contract contact Pipeline Control Services to see how we can improve your customer service while saving you time & money.

Pipeline Control Services PO Box 81 OS Wynnum North Queensland pipecontro lservices@bigpond.com Ph 07 3396 2800

WATER MARCH 2001

63

a

WASTEWATER

NITROGEN REMOVAL: COMPARING TWO OXIDATION DITCH PLANTS Evon Miinch and S Komarowski Abstract This paper compares the performance of two o xidation ditch wa stewate r treatment plants to establish the effec t of d esign and o peratin g parame ters o n nitroge n removal and sludge se ttlin g properties. The two plants that are being compared are Th orneside WWTP (7.5 ML/d design AOWF) and Gibson Island WWTP (45 ML/d des ign ADWF).

Both Thorn eside and Gibson Island WWTP ex hibit very good nitrogen rem oval, w ith typical emue nt total nitrogen con centrations of less than 4 m g/L. Th e m ost stri k ing difference between the two plants is that th e sludge se ttl in g prop erti es at Gibson Island WWTP are mu ch wo rse th an at Thorneside WWTP (indicated by SVI valu es around 150 mL/ g or higher co mpa red to aro u nd I 00 m L/ g at

Thorn eside). T his differen ce is probabl y linked to the prese nce o f an anaerobic plug- flo w selector at Tho rneside and poss ibly the lower C O D / TKN ratio of the raw sewage at Thorneside.

Since the tw o plants have different li cence conditio ns (T horneside WWTP is required to disinfect an d remove ph osphoru s w h e reas Gibso n Island WWPT is no t) and use different methods of sludge disposal, o perating costs are best

Table 1. Comparison of Major Design Features Plant section

Primary treatment

Secondary treatment

Scum removal

Sludge treatment

Unit process

Thorneside

Gibson Island

Raw sewage screen ing

Fine (5 mm) step screen

Fine (3 mm) rotary drum screens

Grit removal

2 aerated rect angular grit chambers

1 aerated rectangu lar narrow grit channel

Primary settling tank

Noneâ&#x20AC;˘

None

Overflow bypass

None

Before "contact tank"

Prefermenter

Activated primary tank (APT)

None

Anaerobic selector

Rectangular, plug-flow reactor

Complete-mix ci rcular "contact tank "

Aeration system

Surface aeration

Fine bubble diffused air

Number of oxidation ditches

1

2

Number of aerobic zones

2

2

Number of anoxic zones

2

2

Number of DO control loops

1

2 per oxidation ditch

Number of final settling tanks

2

6

WAS wasting location

From oxidation ditch

From RAS

RAS flowrate control

Flow-paced off effluent

Constant value

Mixing system

3 vertical shaft surface aerators (2 duty, 1 standby)

3 vertical shaft padd le mixers per ditch

Odour control

Activated carbon for APT

None

RAS screening

Full rotary type screen with 1 2 mm spac ings

None

Phosphorus removal

EBPR + alum

Some EBPR

Chemical dosing systems

Alum, lime (for pH control), ch lorine gas, poly-electrolyte

Poly-electrolyte, sod ium hypochlorite

Scum removal from oxidation ditch

Scum harvester

None (scum harvester to be installed)

Scum removal from final settling tanks

Scum baffle and hopper

Scum baffle and hopper

WAS thickening

None

2 picket fence thickeners

Sludge dewatering

2 belt filter presses (cake - 15% TS)

3 belt fi lter presses (cake - 12% TS)

Sludge disposal

Vermiculture

Landfi ll/ Rehabi lit ation

Chlori ne gas

None

Effluent disinfection

a Whilst the activated primary tank is similar in functionality to a primary settling t ank, it does not remove primary sludge from the process at Thorneside WWTP.

64

WATER MARCH 2001

The Portgible meter with the specifications of a benchtop.

•

2 Year Warranty

•

Resolution - 0.01 NTU on low readings

•

Wide measuring range - 0.01 - 1,100 NTU

•

Automatic calibration using one to four points

•

Complies to ISO 7027 method for determination of turbidity

•

Supplied with four secondary standards and two empty cuvettes

Supporting you all the way ( )

MERCK Lab Business

207 Colchester Rd, Kilsyth Vic. 3137 Tel : (03) 9728 5855 Fax: (03) 9728 1351

Free Call: 1800 335 571 www.merck.com.au

A.C.N.

oos 064 791

WASTEWATER

compared by "operating costs from w here it is channeled to Table 2. Effluent N and P Licence Conditions per megalitre treated w ithou t t h e a n ae ro b i c se le c to r. costs fo r chemi cals and sludge Parameter Limit Type Thorneside Gibson Island Operational results fr om the disposal" . On that basis, the first year o f operatio n are Tot al N (mg/L) Long/short term 50%ile 5/7 .5 10/ 1 5 costs for Gibson Island are 58 pub lished in D e H aas and Maximum 15 30 $ / M L (o r 225 $/tB O D H ertle (1999).

Total P (mg/L) Long/short term 50%ile rem oved) compared to 101 2/3 No limit Th e Gi b son I s l a nd Maximum 6 $/ M L (or 64 2 $ /t B OD WWTP has a nominal design re m oved) fo r Tho rneside, capacity of 150,000 EP and highlighting the influen ce of econom y of processes, they are becom ing a popular disc harges to the B risbane R iver, 8 km solution where stringent nitrogen licen ce scale. from where it flo ws in to M oreton Bay. conditions app ly. One such se nsitive Keywords: O xidation ditch, nitrogen Solley and Barr (1999) have described the discharge environment is the B risbane removal, B NR, SVI, settleability, RAS plant and process optimisation for nitrogen River and M oreton Bay region (Abal et and phosphorus removal. flo e loading, operati ng costs. al. , 1998) . C ou ncils such as Brisbane City As can be see n fro m Tabl e 1, the two and R edland Shire are using oxidation Introduction plants have many design features in ditch plants to achi eve ve ry low levels of T he design of the ox idation ditch mon , bu t T horneside WWTP has a co m efflu e nt n i t r o g e n fr om d o m es t i c process is characterised by a high BOD num ber of additional unit operations (e.g. wastew ater trea tment. loading rate and an endless circulati ng p refermenter, alum dosing fo r phosphorus This paper compares the design and removal , disinfecti on). channel with surface aerators providing operating performance over three years aeration, m ix ing and propulsion of the of two oxidation ditch plants in southeast Licence Requirements liquors around the channel. R emoval of Queensland with a vi ew to establishing T h e e fflue nt li cen ce co n dition s nitrogen in an oxida tion ditch is achieved the effect of design and operating param(Qu ee nsland E PA) fo r n u trients are by alternation between aerobic and eters on nitrogen removal and sludge sho w n in T able 2 . T he lice nce co ndianoxic conditions in the endless channel. settleabili ty. ti ons are co ns ide rab ly tougher fo r The mixed liquor is recirculated by T h o rn es ide WWT P c omp a re d t o Plant Descriptions surface aerators or horizontal mixers . The Gibso n Islan d WWTP, reflec ting the mixed liquo r recycl e flowrate in an The T horneside WWTP is loca ted 30 fact that the Thorn es id e WWTP was oxidation ditch is very high , usually in the km southeast of B risbane and discharges b uil t eight years later than the Gibson order of 100 to 200 :1 (mixed liquor efflue nt to Ti ngalpa C ree k which flo ws Island plant and d ischa rges to a more recycle to influ ent flowrate) . This ma kes into M oreton Bay. In Ap1il 1997, the new s e n s i ti ve r ece i v ing w a t e r bod y . it possible to redu ce the effluent total pla nt with a capacity of 30,000 E P was T ho rn eside WWTP ha s a requ irem en t n itrogen concentra tion to less than 3 commissioned. It is an oxidation ditch co disinfect, w herea s G ibson Island m g/ L fo r almost any wastewater (R andall plant w ith an activated pri ma1y tan k WWTP has not. et al., 1992).

(APT) and an anaero bic plug-flow Since ox idatio n d itch plan ts can selector to enhance biological phosphorus Plant Design and Actual Loads achieve lower effl uen t nitrogen concenremoval. T he primary sludge fro m the The design and actual m easured load trations than many o ther activa ted sludge APT is combined with the APT overflow values fo r Thorneside and Gibson Island WWTPs are given in T able 3. Both plants Table 3. Design and Actual Load Data are operating w ith in 10% of their design ADWF. Thorneside Gibson Island T he raw sewage characteristics fo r Parameter Design Actual Design Actual T ho rneside and Gibson Island W WTP Year commissioned 1997 are given in T able 4. T he measured values 1989 ADWF (ML/ d) for the sewage characteristics are based on 7.5 8.3 45 43 weekly 24- ho ur composite sa m ples. All Total bioreactor volume (ML)" 11 40 .9 analytical results are quoted as ave rage Âą Volume of oxidation ditches (M L) 9.9 40 .1 95% confidence interval (N == number of Volume of selector (ML) 1 .1 0.726 samples) .

Fraction of selector volume to 10 2 Th e design raw sewage cha racteristics total bioreactor (%) for T horneside WWTP were based on Total HRT at ADWF (hours)b 35.2 31.9 21 .8 22.8 daily and weekly 24- hour composite MLSS (mg/ L) 4500C 1980 5000 3850 samples collec ted in early 1994. T he Volumetric BOD loading not specified 0.12 0 .28 0.27 difference betwee n th e raw sewage (kg BOD/ m3/d) d esign and cu rre nt con ce ntr at ions Sludge load ing, or F/M ratio not specified 0 .06 0.06 0. 07 highlights the importance of conducting (kg BOD/kg MLSS/d) a detailed sewage sam pling program to Sludge yield (kg MLSS wasted/ not specified 1 .23 not specified 1 .16 obta in a representative characterisation (kg BOD removed) prior to commencin g plane design .

T he influen t to T horneside WWTP is a This includes the selector (i. e. anaerobic channel for Thorne side and contact tank for Gibson Island WWTP). predominantly fro m domestic so urces.

T he concentrations in the infl uent are b Usi ng tot al bioreactor volume. typical of weak to m ediu m strength c At 90% lo ad and SRT 25 days. do m esti c wastewa ter, except fo r the 66

WATER MARCH 2001

WASTEWATER

Table 4. Raw Sewage Characteristics (Des ign and Actual) Gibson Island

Thornside Parameter

Design

COD (mg/L)

550

Actual•

Design

340 ± 20

not specified

not specified

640 ± 20 (N = 146)

(N = 110)

BOD (mg/ L}

Actualb

250

160 ± 10

260 ± 10 ( N = 147)

( N = 110)

not specified

2.2

not specified

2. 5

TSS (mg/ L)

260

180 ± 10

270

300 ± 10

TKN (mg/ L}

55

COD/ BOD ratio

(N = 149)

(N=110) 55 ± 2

60

30 ± 1

43c ± 5 (N= 5)

not specified

not specified 10d

0 .77

not specified

0 .64

6.2

not specified

13.6

11

9.6 ± 0.4 (N=110)

not specified

12.4 ± 0.4 ( N = 146)

0.02Qd

0.028

not specified

0.019

210

230° ± 9 ( N = 36)

not specified

290 ± 14 ( N = 18)

NH 4-N (mg/ L)

not specified

NH 4-N/ TKN ratio COD/ TKN ratio

47 ± 1 (N = 139)

(N = 110)

TP (mg/ L) TP/ COD ratio Tota l Alkalinity (mg/ L as CaC03 )

(N = 150)

a Averages for Thorneside are for 1 7/ 3 / 98 to 6 / 6/ 00, unless otherwise indicated. b Averages for Gibson Isl and are for 30/ 5 / 97 to 3/ 5/ 00, except for alkalinity which was averaged from 18/ 1/00 to 16/ 5 / 00. c Averages are for 25/ 2/ 93 to 17 / 5 / 94. d As a 50th percenti le. e Averages are for 25/ 2/ 93 to 13 / 6 / 95 and 4/ 6/ 97 to 22/ 10/97.

nitrogen con ce ntrati on wh ich is qui te hi gh . The actual COD / TKN ratio fo r Thorn eside influent is significa ntl y lower than the design value (due to a significan tly lo wer COD value) and is u nfavo urable in terms o f ni tro gen remo val.

Th e Gibso n Island WWTP rece ives sewage from industrial as well as domestic sources. Cu rren tly the main industrial contri butors are foo d, d rink, paper and hide processors which make up 25 to 40% of th e total BO D load to the plant Qune 99 to J une 00 data). The COD / TKN ratio is significantly more fa vo urable fo r ni troge n rem o val at G ibso n Islan d compared to T horneside WWTP. The raw sewage at Gibson Island con tai ns m ore orga ni c nitr oge n t h an at Thorneside, as indi cated by the lower N H 4- N / TKN ratio .

Operating Pa rameters

sum marised in T able 6 an d are discussed belo w.

Figure 1 shows that ammoni a removal is usually very good for both WWTPs, especially during the summer m on ths (effluent amm o nia-N ge nerall y less than 1.0 mg/ L) . During winter, am mon ia Table 5. Current Operating Parameters Parameter

Thorneside

Gibson Island

12 to 14

13 to 15

MLSS (mg/ L)

1980 ± 40 (average for 17 / 3 / 98 to 6 / 6 / 00)

3800 ±60 (d itch 1) 3890 ± 60 (ditch 2) (average for 27 / 5/ 97 to 16/ 5 / 00)

VSS/ MLSS fraction (%)

78 (from data 8 / 4/98 to 3/ 10/ 98)

81

Not measured; calcul ated val ue: 3240 mg/ L

7530 ± 70

105 ± 9 see Figure 4

155 ± 5 see Figu re 4

Sludge age• (days)

RAS-SS (mg/ L) SVI (mL/ g)

C u rrent operational parameters fo r both wastewa ter treatment plants are co mpared in T able 5.

RAS:influent flowrate ratio

Comparison of Nitrogen Removal Performance

pH value in oxidation ditch

T he nitrogen rem oval perform ance of T horneside and Gibso n Island WWTP fo r 19 97 to 2000 is graphed in Figure 1 to Figure 3. Typi cal efflu ent nitrogen co n ce n tratio ns for bo th plants are

brea k- through som etimes occurs, with peaks up to 2.5 mg/ L for T horneside and 7 m g/L for Gibson Island. T he w inter am m onia pea ks in the Gibso n Island effl uent are generally grea ter than fo r Thorneside.

T he reason for this is that th e Gibson Island plant is always operated at th e m inim um possible sludge age in an effort to control filam entous b ulki ng.

W hen the operating temperature suddenly drops, the requ ired increase in sludge age is som etimes not initiated quickly enough.

R ece n tly, a ST IP on-li ne am m o nia analyser has been installed o n the effl uent as another tool to opti mise ni trogen re moval.

T he effl uent NOx concen trations in the Gibson Island effluent (generally < 0.2 m g/ L) are below those in the T horneside effl uent (< 2 mg/ L), see Figure 2. T his is probably due to two factors: • T he anoxic fraction at Gibson Island has be e n o p timised fo r de nitri fi ca tio n (som etimes sacri ficing ni trifi cation); • T he CO D / T l<N rati o in the raw sewage is signi ficantly more favo urable for denitrification at Gibson Island compared to T horneside (see T able 4).

T he effluent organic ni trogen concentratio n at Thorneside WWTP is relati vely constant with an average co ncentration of 1 m g/ L, w hich is typi cal of dom estic so urce efflu ent. T he efllue nt organic nitrogen co ncentra ti o n at Gibson Island varies considera bly (between O and 6.5 mg/L). T h is may be a result of influent organic nitrogen variations from industrial contribu tions.

DO setpoints (mg/ L)

- 140%

100%

0 .7 (end of first aerobic zone)

2.1 (first aerated zone) 1.0 (second aerated zone)

6.9

not measured

Operating temperature

17 to 27' C

20 to 29·c

RAS floe loading (mgCOD/ gVSS in RAS)

96 (VSS % in RAS assumed to equal mixed liquor VSS %)

105

a Sludge age calculation based on MLSS in bioreactor and WAS f lowrate only.

WATER MARCH 2001

67

WASTEWATER

shou ld be perform ed in a • R educing the anoxic volu m e (but this stirred settling cylinder may compromise denitrification perfor(APHA, 1995). This is mance); done at Gibson Isla nd, but Thorneside Gibson Island • Continuous dosing of the R.AS with at Thorneside the SVI is Parameter Oct. 1997 to May 1997 to sodium hypochlorite (approximately l determined in an unstirred June 2000 July 2000 L/rnin.). cyli nder. T he unstirred Ammonia-N, typical < 1.0 < 1.0 The concept of "RAS floe load ing" is m ethod usually produces a Ammonia-N, spikes 2.5 7 .0 sometimes used to design selectors (the highe r settled sludge NO,-N , typical initial contact zone w here raw sewage and < 2.0 < 0 .2 vol ume compared to the return activated sludge are combin ed).

Organic N, typica l 1.0 1.7 st irred method (fo r Patoczka and Eckenfelde r (19 90) Organ ic N, spikes 3.0 6.5 example at Waco! WWTP recommend that a high RAS floe loadin g Total N, typical < 4.0 < 4. 0 in Brisbane , the un stirred should be used in a selector. T he R.AS floe Tota l N, median sludge settleability volume 2.6 2.4 loading is defined as mass flow of COD is about 30% higher than in the raw sewage divided by mass flow t h e st ir r e d s lud ge The total nitrogen (TN) concentraof VSS in the RAS . For Thorneside settleability vol ume). Hen ce, if the ti ons in the eilluent o f both plants are WWTP, this va lu e is 96 m gCOD /gVSS Thorneside operators had used the stirred shown in Figure 3 w hi ch shows that and for Gibson Island it is 105 mg settleability test to determine the SV!, the oxidation ditch plants ca n generally COD/gVSS, and hence it does not values are likely to have been lower. achieve an average eill uent total nitrogen exp lain the diffe r e n ce in settlin g T he activated sludge at the Thorneside concentration of less than 4 mg/L. A behaviour. It may still be beneficial WWTP generally settles significantl y median TN value of 2.6 mg/L was however to increase the RAS floe loading better than the activated sludge at Gibson achieved for Thorneside WWTP over the for Gibson Island by redu cing the RAS Island (SVI below 100 mL/g compared three yea r period (Oct. 1997 to Jun e flowrate. to 150 mL/g and higher at Gibson Isla nd, 2000), and 2 .4 mg/L for Gibson Island Possibl e explanations for the superior see Figure 4).

WWTP (for May 1997 to July 2000). The sludge se ttleabil ity at Thorneside in p erformance of Thorn esid e WWTP is At Thorneside WWTP the SV! has compariso n with Gibson Island WWTP particularly impressive considering its low remained low (approximately 70 111L/g) include : raw sewage COD/TKN ratio. from J uly 1998 until March 2000. Since • The design of Thorneside WWTP March 2000, the SVI values at T horneside Comparison of Sludge includes a plu g-fl ow anaerobic selector, have increased to over 100 mL/g. This Settleability whereas Gibson Island only has a small is attributed to problems with the flow complete-mix "contact tank"; We compared the sludge settl ea bi lity control settings of the RAS pu mps • The higher CO D /TKN ratio in the raw at both WWTPs based on the sludge resul ting in a significant increase in the volu me index (SV I). Standard Methods RAS flowrate (from 160% to 340% of sewage at Gibson Island may provide mor e favourable condi t ions for stipulate that the SVI determination eillu ent flow). The R.AS flowrate control filamentous o rgan isms; was restored in J uly 2000 • Greater enhanced biological phosphorus and the SV! va lues have removal at Thorneside WWTP (data not decreased to around 100 shown) may result in improved sludge mL/g since then . settleability (Schuler et al. , 2000); T he sludge settl eabi lity • D osing of alum at Thorneside WWTP at G ibs on Island WWTP is fo r eilluent phosphorus trimming (plant generally very poor. As does not rely entirely o n EBPR ). About can be seen from Figure 4, 45 L/ML is dosed into the RAS. the SV I value has been Cost Comparison higher than 100 mL/ g since 0 .j....!..b=c!...Jld!..!c"'=,~,L._........_!>=>J!ll!!>,:l!ll\l..!lj.'.,:!.L..............o..nUl!'.l:lb!+'--"--' May 1997 and generally Table 7 com pares th e operating cos ts 1-May-97 I-May-98 l-May-99 30-Apr-OO over 150 mL/g since early for both plants. Since th e Gibson Island 1999. Mi cro biol og ica l WWTP has no requirements to disinfect Figure 1. Effluent Ammonia-N Concentrat ions exami nat i on of t h e or re1nove phosphoru s, its che mica l budget is lower than for Thorneside, activated sludge revealed where chlorine gas is used fo r disinfection that filam entous bu lking and alum for p h osp h orus removal due to the filamentous trimming. During periods of very poor bacteria Type 0092 and sludge settleability, the chemica l costs at T ype 0914 ca uses the poor G ibson Island in crease du e to the usage s l udg e sett l eab ili t y . of poly-electrolyte and so dium Operational m easures used hypochlorite . at Gibson Island to combat When comparing th e operating costs the fi lamentous bulki ng per megalitre treated, the economy of are: 0 .J......!::....!:=~!IJJ...............J.1,---..,c!l~k..l[j.L.....!..U~-¥J....J scale is probably a major fa c tor in I-May-97 l-May-98 1-May-99 30-Apr-00 • Sludge age reduc tion (but explaining the difference (Gibson Island's this may compromise nitriADWF is about six tim es high er than the Figure 2. Effluent NOx-N Concentrations fication pe rformance); ADWF at Thorneside).

Table 6. Typical Effluent Nitrogen Concentrations (all in mg/L)

68

WATER MARCH 2001

WASTEWATER

Conclusions

12

T ho rneside WWTP (7.5 M L/d design ADWF) and Gibson Island WWTP (45 ML/d design A DW F) are examples of oxidatio n ditch p l ants i n sou th east Q u eensla n d that ex hibi t excellent ni troge n re mova l.

T he med ian effiuent tota l nitrogen concentration is 2.6 m g/ L fo r T horneside (Oct. 1997 to June 2000) and 2.4 mg/ L for Gibson Island (May 1997 to Jul y 2000).

T he T horn eside acti vated sludge exhibits good settling properties (SV I below 100 m L/g) whe reas the G ibson Island sludge exh ibits very poor settl ing prop erties (SV I of 150 m L/g and above) .

T his diffe re nce is attribu ted to th e plug- flow anae robic selecto r at T ho rneside and possibl y th e lower raw sewage COD/TKN rati o at that plant.

10

~

8

i=

6

.$

ii E"

4

"' 2 0 1-Mny-97

1-Mny-98

30-Apr-OO

1-May-99

Figure 3. Effluent Total N Concentrations

2SO

..

200

] ISO 100

so

o+----~~~~......~~~~~.......~~~~-'--'+~~......, i-May-97

l-May-98

l-May-99

30-Apr-00

Figure 4. Sludge Volume Index (SVI ) Values

Table 7 . Comparison of Operating Costs Gibson Island

Thornside

98/ 99

99/ 00

The operating costs (without costs fo r chem icals and sludge di sposal) at the G ibson Island WWTP are abo ut half the costs of the Thorneside WWTP per megalitre treated , and about o ne third in terms of per ton of l3 OD rem oved. This dem onstrates the principle of economy of scale.

By co mparing wastewater treatm ent plants tha t e mploy similar processes, we can bench mark these p lan ts and draw ou t advantages and disadva ntages of particular design an d operatio nal details. Th is helps ac hi eve b est ou t co m es fo r lo ca l gove rn m ent's was tew ate r treatm e n t sc hemes.

Acknowledgements We thank W es O' Brien (T ho rneside WWTP operator) fo r his valu able input re lating to o perationa l aspects. We also thank Keith Barr, Graham C hapman, Brad Evans and David Tho mpson for providing expe rt inp u t and o pe rating experie nce with respect to th e G ibson Island WWT P.

References Abal E.G ., H olloway K. M . and D ennison W. C. (I 998) Im e rim Stage 2 Scientific l<.eport, l3risbane l<.iver & Moreton l3ay Wastewater Management Study, l3risbane.

A PH A, WEF (1995) Stn11drml Mcr/,ods )111· 1/,r Exa111i11ntio11 c,f vVater mu/ Wnsre,mtrr, Port City Press, Ualtimore.

D e Haas D. W. and He rtle C. I< . ( 1999) The Perfor ma nce of Two Oxidation D itch Sewage T reatme nt Plants in South-East Queensland . A WW A Regio nal Conference.

R.andall C., l3arnard J. and Stcnsel H. (1992) Design and l<.etrofit of Wastewater Treatment Plants for l:3iolog1cal Nut rrent Re111oval.

Tcchnomic Publishing Co. Inc. Patoczb J. and Eckenfelder W. W. (1990) Performance and design of a selector for b ulking cont rol. Resmrc/1 Jcwmnl Wntcr Pol/111io11 Cc>11tml Frdantio11 62(2), 151 - 159.

Schuler A. J., Jenkins I). and R onen P . (2000) Microbial storage products, bio111ass density, and settl ing properties of enhanced biological phosphorus removal activated sludge. In: First

98/ 99

99/ 00

6.52

7.56

43

43

1090

1060

7088

6833

465

454

45 2

435

85

83

452

361

Total operating costs (1000$/ year)b

553

480

2230

2020

Sludge disposal costs (1000$/ year)

83

98

1062

1018

Total costs for chemicals (1000$/ year)c

118

104

83

91

Specific operating costs with chemicals and sludge disposal ($/ ML)

232

174

142

129

Specific operating costs without chemicals and sludge disposal ($ / ML)

148

101

69

58

World I Vn/c•r Co11,ercss o( 1/,e /11u·mnticmnl Wnter Assorin1io11. Paris, 3-7 July. pp. 131- 138.

Specific operating costs without chemicals and sludge disposal ($/ t BOD removed)d

942

642

269

225

Specific operating costs without chemicals and sludge disposal ($/ t N removed )

2855

1945

1550

1302

Solley D. and l3arr K. ( 1999) Optimise what you have first 1 Low cost upgradi ng of plants for improved nutrient removal. Wnr . Sci. J'ec/1.

39 (6), 127-134.

Flow (Ml/ day) Annual electricity consumption per year (MWh/ year)• Specific electricity consumption (kWh/ Ml) Annual power costs (1000$/ year)

The Authors a For Gibson Island, electricity consumption includes raising the raw sewage at the main wetwell by 15 m. b Does not include the costs of t he sewerage system or M&E maintenance. Includes sludge disposal. c Alum, lime, poly-electrolyte (for the BFPs) and chlorine gas are used at Thorneside; for Gibson Island poly-electrolyte (for the BFPs and for sludge blanket control ) and sodium hypochlorite (for filamentous bul king control) are used. d Effluent BOD for Thorneside is < 4 mg/ L (taken as 2mg/ L). for Gibson Island typically < 5 mg/ L (taken as 2.5 mg/ L).

Dr Elisabeth von Munch is a process design enginee r with Brisbane Water, Pro fess io nal Services - Engin eerin g, PO Box 1434, Brisbane, Q ld 4001. Email: ep8psbw@brisbane .qld.gov.a u. Dr Sonja Komarowski is Ope ratio ns Engineer Sewerage with R edland Water, PO Box 21 , C leve land, Q ld 4 163. E m a il: sonjak@ redl and. qld. gov .au WATER MARCH 2001

69

ENVIRONMENT

II

LEGIONELLA TESTING IN COOLING TOWERS: CLOSING THE GATE WHEN THE HORSE HAS BOLTED? R Bentham Introduction R ecentl y th e Victorian D epartm ent of Human Services Legio11ella Working Party released their recommendations regarding manage ment of health risks associated with coolin g towers. These recom mendations ca me after and partially in response to the recent outbreaks of Legion naires' disease in Vi ctoria (D HS Victoria 2000). This re port did not support the routine (monthly) resting of cooling cower waters for Le,gio11ella. However, th e newly released Australian Standard "Air handling and water system s of buildings - Microbial control. Part 3: P erformance-based maintenance of coolin g water syste ms" which is incorporated in the Building Code, does recommend the routine (mo nthly) testing fo r Legio11ella in co njun cti on with risk mana ge m ent pro g ra m s (A u stra lian Standa rd AS/NZS3666, 2000).

Th e testin g fo r th e prese n ce o f microbial pathogens and prescribed limits fo r these o rga nisms are routine practice in other areas of public and environme ntal health. Howeve r, the case for testing and ac tion directi ves based upo n cu ltu re results fo r Legio11ella m ay not be as clear c ut as it would appear at first glance .

The risks Th e colonisatio n of water systems in the bu ilt en vironm e nt b y Legio11ella spec ies constitutes a risk of Legionnai res' disease to the surro unding populatio n.

This risk is variable depending o n the syste m. Legio nnaires' disease associated w ith cooling cowers has been de monstrated to be spread in aerosol carried over relatively large areas, up to 3 km from the source, affecting a relative ly small percentage of th e exposed popu lation (Brow n et al 1999). This is no doubt related to the large volumes of aerosol bein g em itted from th e cooling cowers be ing carried on prev ailin g win ds.

Alternatively disease associated with spa baths and hot tu bs has typically been contained to much small er areas and has affected a much greater percentage of th e

70

WATER MARCH 2001

exposed population (den Boe r et al 2000, Lu tti chau et al 1998). In th is instance less ae rosol is gene rated but remains co ncentrated around th e sou rce. Though similar to spa pool infections as far as aerosol distributio n is concerned, shower and hot wa ter system-related infectio ns typically in volve much less aerosol generation.

Even the route of infection from th ese so urces has been the subject of co ntroversy (D enis et al ¡J 984 , Yu 2000). Th e inferences fo r mon itoring and maintenan ce of coo ling water systems arc not readily translatable between these di fferent water systems. The relative risk associated with these different sources has never been established or qu antifi ed and assessments would need to treat each of these as separate entiti es . In this pape r Legio11ella contaminati o n in cooling towe rs will be addressed with particular emphasis on the ro le of routi n e sa mp lin g in risk manage me nt.

Action Directives Historically, action directives based o n

Legio11ella conce ntrati ons de tected in cooling cower water have been developed .

The fi rst of these appears to be th e gu idelin es whic h Broadbent and Bubb (1987) developed for th e now defunct Australian Deparm1 ent of H ousing and Construction.

At that time the gu ide lines were imperative due to the need fo r prescriptive limits co control bacte ria and regulate coo lin g tower ma in ten an ce. It wa s in heren t in their promulgation that th ey were based upon a lack o f sc ientific da ta to support their va lidity or relate cultu re results to risk. Subsequ ently attempts to m odify and va lida te these directives ha ve been publ ished (Shelton et al 1994, Mi ller and Kenepp 1993). N ow directives based on Legio11ella culture results have becom e mainstays of regulatory guidelines and legislation (NSW 1991, AS/NZS 3666.3: 2000). Of th ese di rectives few have recommended a frequency of sa m p lin g n ecessary fo r co mpli ance .

(AS/NZS 3666 .3 2000, however, does recommend routine (monthly) testing.

T o date there have been very few reports of th e nature of temporal variation of legion ella coun ts w ithin individual syste ms (Be ntham 2000).

Shelton el al (1994) developed directives based on counts from cool ing to we r s associa t ed w ith o utbr eak s wo rld w id e . Th e s tud y was a comme ndable atte mpt to estab lish data based directives and the results appeared to largely validate the existing directi ves.

However these resu lts shoul d be viewed with some ca ution. The data was collected from multiple syste ms, cultured by mu ltiple laboratori es at vario us poi nts durin g outbreaks. Th e direc tives were d eve loped from sin gle results from multiple systems. T hey did no t ta ke into acco u nt va riati ons within ind ivid ua l syste ms over tim e. Th is data can be considered largely anecdotal as the variati o ns in c ultu re and sampli n g, and b e twee n la boratori es and regu latory authorities worldwide strongly suggests a lack of consistency in the data (Lee et al 2000).

Sampling Frequency Th e fr eque ncy of sa mpling requ ired is an on-going dilemma. Ea rly di rectives su ggested monthl y, quarterl y and 6 m o nthly samplin g d e p e nde n t up o n perceived ri sk to surrounding popu lations (Broadbent and Bubb 1987). Sensitive sites su ch as hosp itals were recomme nded fo r the most frequent (m onthly) sam plin g regimen . T his frequency was also arbitrary, and sc ientifi c reports suggest that as far as freque ncy of testing is concerned "the more yo u loo k th e more yo u find " (Flie rmans 1996). The re was no data availabl e on the variatio n and va riabi]j ty of Legio11ella populations in cooli ng towers over time. It was assumed that the populations were like total hecerotrophic coun ts, and normally distributed over time.

R eports from a field study of Legio11ella in cooling water system s de monstrated that cou nts were not normally distributed (Broadbent et al 1993) and that cou nts could be extremely variable in very short

ENVIRONMENT

time periods (Be ntham and Broadbent 1993). Most recently a statistical analysis of sampling frequen cy from Legio11ellac o l o n is e d coo lin g towers ha s demonstrated that monthly samples are not representative. In most cases the result will not bear any statistica l relation to the c urrent sta tus of the Legio11ella popu lation once it is available after the usual 7- l 0 days cu.lture period (Bentham 2000). These reports ha ve shown that a mo nthly frequency of sa mpling will not provide a representative picture of Legio11ella colonisation and so ca lJ into question the validity of the action directives.

It has been argu ed that mo nthly sa mpli ng is va lid in that it will eventually detec t the presence of the o rga nism in cooli ng water, and so ale rt the ope rator to the need fo r vigilan ce in their maintenance program. H owever, field stu dies have demonstrated colon isation of greater than 65% of cooling towers in any one yea r, and in one instance 99% (83/84) of systems over a four year period (Koide et al 1993, Bentham el al 1992) . It has also been repo rted that on ce a cooling syste m has been colon ised Lel/icmella cannot be eradica ted (Flie rmans 1996). If these data can be relied upo n, then they suggest that the use of cu lture in detecting the presence of Legio11ella in a coo ling syste m is fo r the m ost part superfluous. T he need for vigilance exists aside from c u lture results, as it is most likely that Legio11ella coul d be isolated at some poi nt from almost any cooling towe r in service . T he emphasis should be based upon control of the organism s rather than erad icati on .

Published evid ence suggests that th is ca n be achieved through appropriate design and ma intenan ce (Fliermans 1996) .

Aerosol Dissemination Legio11ella infection is initi ated by inhala tion into the lungs of the bacteria carried in fine water droplets (aerosol) released from the coo ling tower. It should be noted that concentratio ns of bacteria in the bulk water of a syste m ca nnot be re lated to co n centrations leaving the system in aerosol. Properly designed and fitted drift eli minato rs in cooling systems ca n dramatically reduce the release of aerosol, but it can never be totally prevented (AS/NZS3666: 1995).

Enviro nmental variables such as relative humidity, dilution, cloud cover, UV radiation intensity, and wind velocity will all affect the survival and dispersa l of aerosol (Addiss et al 1989, Fliermans 1996). These fac to rs may be a partial explanation of the ten de ncy for disease o utbreaks in the autumn period when climatic conditions better support aerosol

dissemination (Ben tham and Broadbent methods used for culture from cooli ng 1993). The longer a wa ter droplet is water are aggressive and may result in a carried in the air the smaller it becomes significa nt loss in sensitivity (Ta el al 1995, due to evaporatio n , concentratin g its Fliermans 1996) . Legio11ella are co nsidered contents. Droplets may leave the cooling to be fastidious organisms on laboratory syste m at sizes too large to be inhaled and media, and may be out-competed by other e vaporate down to resp irable particl es organisms on the agar plate (Flierma ns wi th their co nten ts concentrated ma ny 1996) . This fastidiousness is most likely times ove r. Du e to the range and related to the ecology of Le~eiimella. These variation of th e facto rs influe ncing this bacteria arc oppo rtu nists rel iant on other phenomenon the concentratio n factor is microbia l species to fulfil their nutritional incalculable. T o compli cate this further requirements. there is no established infective dose fo r A number of o rganisms have been Legio11e/la. It is presum ed that infecti vity isolated that appear to be obligate intrais largely a func tion of the immune status cellular pathogens of amoebae, and cannot of the host combined w ith the exposure be isolated from primary cultures on tim e an d conce ntrations of the organism selective media (Adeleke et al 1996) . Viable (Fliermans 1996).

Legio11ella p11e11mophi/a capable of causing Ecological fac to rs with in the cooling infection have also been reported to be not water syste m w ill also influ en ce the detectable by conventional cul ture fro m dissemination, stab ility and viability o f water samples (Atlas 1999) . The growth Legionella within aerosol. Cyanobacterial of Legio11clla in pure cul ture is an artific ial and algal species are commonly present environmen t fo r the organ ism and in coo ling wate r systems that may therefore li kely t o be i nse n sit ive. enhance the time pe1iod that Legio11ella can Laboratory comparisons between convensurvive in aerosol (Berendt 1981). tional culture and PCR techniques have also demonstrated th is lack in sensitiv ity l t has been shown that Legio11ella may (A tlas 1999). also be carried in amoebic vesicles of respirable size (Berk el al 1998). These T here is a well-established inter- and vesicles may contain many hundreds of intra- species variation in virulence of bacteria, and inhalation of one such vesicle may be su ffi cient to cause disease. It has been postulated that culture of water samples The Urban Water Review 1999/2000 is now avai lable. containing these Providing an overview of the performance of Victoria's ves icles woul d 1 8 urban wa ter utilities, the review reports on : result in a single • financial colony arising on the cu ltur e • service m e dium. T hi s • operational wou ld grossly indicators for wate r and wastewater services. unde restimate the The report covers 5 years of data, provid ing anql~sis of true concentration trends by of organisms in the sam ple (Be rk • Melbourne metropolitan et al 1998).

• non metro polita n urba n > 35000 properties

The Victorian Urban Water Industry in review

Culture Results Th e i ss u es surrounding culture for Legio11ella are also contentiou s. C ultur e techniques for L egio11ella a r e variable, and to some extent species specific (T a et al 1995).

The pretreatment

• non metropol itan urban < 35000 properti es as well as state wide and individual fig ures.

A vital reference book fo r all of those in volved in the industry.

Available from:

Victorian Water Industry Association Suite l, Level 6, 2 Collins Street Melbourne 30000 Ph: (03) 9639 8868 fax: (OJ) 9639 8860 Email: vicwater@vicwater.org.au Price: $77.00 {including GST, postage and packaging within Aust.)

WATER MARCH 2001

71

ENVIRONMENT

.Legio11el/a and even between serogroups and strains (Bosshardt, et al 1997) .

Although I...egio11ella p11e11111op/1ila serogroup 1 accoun ts for the vast maj ority of cooling t o w e r -assoc iated outbr e a k s o f Legionnaires' disease, a number of strains of thjs organjsm and serogroup have never been associated with disease (Bosshardt et al 1997). T he .L.p11e111nophila serogro up 1 Pontiac strain predo minates in cooling tower-associated disease, and even th is strain has aviru lent sub- types (Bosshardt et al 1997). The virulen ce o f an individual strain o r sub- type may also be modulated by environmental conditions (Bosshardt et al 1997 , Byrne and Swa nson 1998) .

Routine culture will n ot differentiate between viru lent and avirulent strains.

So me other serogroups o f L.pne11111ophila and other I...egio11ella species have also been associated with disease, and as such constitute a ri sk (Garcia et al 1993) . T he true significance of a routine culture result from a cooling tower water sample cannot be determined because it ca nno t be re lated to virulence , concentration in aerosol or infecti o us dose of the organism isolated.

T here are notorious variations in cu lture results betwe en laborato ries .

Work prese nted by th e Public H ealth Laborato1y Service (PHLS, Lee et al 2000) demonstrates the extent of these variations through their external quality assura nce program (EQA. ) program . T his study demonstrated wide variations in cultu re res ults from 83 participating laborato ri es throughou t 22 E uropean cou ntri es, with some laboratori es rec ording negative results for sp iked positive Leg io11ella samples. T he study also noted that reco ve ries of no11-L.p11e11111ophila species were poor. D upli cate samp les sent to different accredited laboratories, using the same standard methods might not be consistent.

T hese facto rs dictate that a culture result for any species or strain cannot reliably be equated to a quantifiable risk.

T hey also suggest that a negati ve culture result gives no indication w hether or not the system is co n taminated or even wheth er the sampl e provided co ntains the organisms or not. A positive result at an y point in time indicates that the system is contaminated regardl ess o f subsequent cultu re results, and may ha ve been fo r some tim.e despite previous cu lture results (Flierm an s l 996) .

Cooling Water Populations of Legionella As previ ously stated Legio11ella po pulations in cooling towers may be extrem ely variable over short time periods. Counts 72

WATER MARCH 2001

have been shown to rise by two orders o f m agnitud e w ithin te n m inut es (Ben tham and Broadbent 1993) . It has also been shown that m ean concentrations in cooli ng towers tend to fall in to what ha ve been defined as low- moderate risk catego ries (NSW Health D ept. 1992, Bentham 2000). Standard deviatio ns o f these m ean values indica te that most system s ha ve con centrations in th e high risk category at some point during th e average summer period (Bentham 2000).

T hese vari atio ns are obviously not a produ ct o f the growth rate o f the organism , but relate to system o peration conditio ns.

Many fa ctors affectin g culture results are determin ed by the cooli ng tower des ign and ma intenance. Surface area, volume ratio , system operatio n, water temperatu re , dead- legs in the pip ework, cleanliness, biocide dosage method, and choice ofbi ocide are all factors which determine the tendency for a system to support .Legio11ella growth (B entham and Broadbent 1993). There is a lack of inform atio n in p u blished repo r ts from outbreaks re lating to these criteria.

C onsequently th ese reports give no

ind ication of wheth er the cu lture results represented a transient or ongoing level of contamination. T h ere is eviden ce that rece n t i nterrupti o n s in the system operation have been a common factor co ntributing to the onset of th e majority of o utbreaks (B entham and Broadbent 1993) . C ulture results from sa mples of basin water taken three weeks after turning off a co o lin g t ow er will comm.only return an u ndetec tabl e result (Bentham et al 1992). R e-starting the system after this tim e may produce a signi ficant positive result within minutes.

The point in time at w h ich a sample is taken is critical and the result taken in isolation can easily under-estimate o r o ve r- e stim ate th e assoc iate d ri sk s (Bentham and Broadbent 1993) .

The operating temperature of cool ing towers varies between systems and applica tions and with the seaso ns depending upon climatic co nditions. Th ere is a strong association between water temperature and Legio11ella m ultipli cation in cooling water systems (B entham er al 1992). Systems operating above 20°C are m o re likely to support Legio11ella growth , systems operating at 32-35°C supp ly th e

FILTRATION MEDIA

SAND,GRAVEL,COAL,GARNET MANGANESEGREENSAND Invest in accurately graded, durable media from your complete filter media professionals.

U'e au fttea4d t6 ~

tp14:

• Decades of mineral processing experience.

• • • • • •

Media produced to the A\/-..JWA 8100-89 Standard.

An extensive product range at competitive prices.

Manufacturing in accordance with Quality System AS 3902/ISO 9002 Packaging alternatives to suit any requirement.

Proficient technical assistance and support.

Prompt delivery Australia-wide and Overseas.

So, tap into our extensive experience and helpful service when next you require filter media.

---~-RIVER SANDSr-lir 683 Beenlelgh-Redland Bay Road, Carbrook Qld 4130

INTERNATIONAL: +6173287 6444

~ E E CALL: 008 on 744

FAX: (07) 3287 6445

ENVIRONMENT

optimum temperature for growth of the organism (Fliermans 1996). T he potential for multiplica tion of the organisms in a system at 32-35°C is greater than syste ms operating above or below this range. Th e in fe rences fo r risk drawn from a culture result should take into accoun t the syste m ope ratin g temperature as this dictates to some extent the mu lti plication potential for th e organ isms w ithin the system.

Summary It can be argued that Legio11ella test results provide some criteria fo r regulato1y strategy. The establishment of prescriptive limits can be used to enfo rce pe nalties for ina dequate maintenance regim es, and permit ow ner/ o perators to dem onstrate co mplian ce. T h is is tru e, bu t regulati ons based on th.is sort of data cannot be related to risk and as suc h are not effecti ve preven tative strategies. Compliance with an in val id and unsubstantiated standard will not a mo u nt to a reduced risk. lft hi s is so these regulations will no t be effective in con tro ll ing or redu cing the in cide nce of cooli ng cower associated Legionnaires' disease. Th e unreliability o f th e test m e thods the mse lves unde rmines th e p u rpo se and validity o f su c h prescriptive limits . Comp liance to suc h limits based aro und cultu re resu lts taken at mon thly intervals is likely to engender complacency rather tha n vigila nce.

C rite ria for regulatory po li cy shou ld be based arou nd preventative mainten an ce . T h e d eve lopm e nt and imple men tatio n of Hazard Analysis o f Critical Control Po ints (H ACC P) in th e food industry is a good exa mple of a pre ventative policy based o n clearl y ide ntifiab le risks. Critical control points for coo lin g towe r m ainte nan ce and aerosol disse mjnation are well established.

Th e susceptible popu lation and hi gh- risk populations are also readily identifiabl e .

Suc h co ntrol points co uld be u ti lised to minimise risk fr o m coo lin g towers w ithou t the prior need fo r Legio11ella culture. Once established such strategies could be partially vilidated using Legio11ella cultu re as on e tool within th e ove rall risk ma nagem ent fram ewo rk.

C urre nt opinion stro ngly suggests that Legio11ella co ntrol in cooling towe rs is ach ievabl e (Fliermans l 996). Culture result-based m anage m ent of cooling towe rs has fa iled to prevent outbreaks of Legionna ires' disease, and to some extent absolute prevention can not be expected.

Testi ng cooling water fo r Legionella is not in itself a control strategy bu t may be a n indicato r for the performan ce of an existi ng strategy when co mbin ed w ith a

com prehe nsive managem ent program.

Basing action on culture results will always mean that th e strategy is reactive not proactive . l would strongly suggest that trus sort of strategy is closing the gate once the horse has bolted.

Ref e rences Addiss DG , Davis J P, LaVenture M , Wand PJ , Hutchinson MA , and M c Kinney R.M. ( I 989) Com munity acquired legion naires disease associated w ith a c ooling cower : evidence for lo nger distance transport of Legicmella p11e11111opliila.J J,ifect Dis; 130, 3:55768 Adeleke A, PrucklerJ , !3enson R., R o wbotham T , H alablab M, and Fields BS (1996), E111erg !,!feel Dis 2 ,3: 225-230 Atlas l'l..M ( I 999) Li;~io11elln: from environmental habitats to disease pathology, dete ction and control. E1111iro11111e11t Miffobiol 1, 4: 283-293 Australian / New Zealand Standard AS/ NZS3666.3 (2000) Air handling and water systems of bui ldings - Mic robial control. Part 3: Performance-based maintenance of cooling water syste m s. Sydn ey: Standards Austral ia. !3entham, R.H. !3roadbent, C R., M arwood, LN , M arsh , JM , M cDonald, PJ a nd Lee, PC ( 1992) E cology and Control of L1;eio11ella in C ooling T owers. Australian Construction Ser vices report to th e D e partmen t of Housing and Construct io n. !3e ntham l'l.. H , 13roadbent CR. (1993) A m ode l fo r auwmn o utbrea ks of Legionn aires' disease associated with cooling towers, linked to syste m operation and size. Epide111iol /1!fect 111:287-95. !3entham R. H , Broadbe nt C R. ( 1995) Field trial ofbiocides for control of Le,gio11el/n in cooling to w e rs. C111'1' Miaobiol 30, 3 : 167-72.

Bentham, n... H. (2000). R o utine sampling and th<' control of Li;gio11elln spp. in cooling tower water systellls. C urr Microbiol In Press.

M anuscript No. C M 3219 13erendt l'l..F ( ! 98 I) Influence of blue-green algae (Cyanobacteria) on survival of Legio11l'ila p11e11111op/iiln in aerosols l,ifm li,11111111 32 , 2 :690-692 Berk, S.G ., Ting, R..S. , Turne r, G . W. , and Ashburn, l'l..J. ( 1998) Productio n ofrespirable vesicles containing live Lcgio11el/n p11e111110philn cells by tw o Aca111/ia111oeba spp. Appl E1111iro11 Microbiol 64. I: 279-286 Bosshardt, S.C ., Benson, R.. F., and Fields, B.S . ( 1997) Flagella are a positive predictor for virulence in Legionella. Microb Pathoge11 23; 107- 11 2 !3roadbenr C R., and Bubb CTJ (1987). M easures to control Legionnaires' disease hazards in buildings. T echnical Information T l 178 ME. D epartment o f H ousing and Construction (Australia) .

Brown C M , Nuorci PJ , Breiman RF, Hathcock AL, Fields BS, Lipman HB, Llewellyn GC, H o man J , Cetron M (1999) A community o utbreak of Legionnaires' disease linked to hospital cooling cowers: an epidemio logical m et hod to calculate dose o f exposure. /11temat J Epide111iol 28: 353-359 Byrne B, and Swanson MS (1998) Expression o f L~~io11elln p11e11111ophiln virulence traits in response to growth condi tions. J,ifect /1111111111 66, 7: 3029-3034

D en Boer, J .W et n/. (2000) A large o utbreak of Legionnaires' disease at a D utch flower show.

5th International Conference on Li;~io11elln, Ulm Germany P ap er Abstract 039, September.

Dennis, PJ, w,;ght, AE, Rutter, DA, D eath,JE, and Jon es, BPC (1984) L. p11e11111ophila in ae rosols fro m shower baths . J A ppl Bncreriol 93: 349-353 .

D epartment o f H uman Services, Victoria (2000) Legionnaires' Disease: Manag ing the health risk associated with cooling cowers . Findings and recomm endatio ns of t he Department of Human Se rvices Lc;gio11ella Working Party.

Public H ealth Division , June 2000 Fliermans C B (1996) Ecology of Li;gio11ella: From data co knowled ge with a li ttle wisdom.

Microb Ecol 32: 203-28.

Garcia M , C ampbell I , Tang P , and Krishnan C (1993) Incidence of Legionnaires' D isease and report of Legio11elln sni11t/1e/C11si serogroup I infectio n in Toronto, Canada. In: Barbaree J M, Breiman R.F, Dufour AP (eds) Li;eio11ella: C urre nt status a nd e merging pe rspectives.

Washington DC: Amer ican So c iety for Mic robiology, pp 37-39 Lee, J. V., Surman, S.B., Hall , M., and C uthbert, L. (2000) D evelopme nt of an inte rnatio nal EQA sche m e for the iso lation of L1:eicmelln species from environmental specime ns. 5th Inte rnational C onference on L1:eio11elln, U lm Germany Post er Abstract P77 Septembe r 2000 Luttic hau H R.. , Vinth er C., Uldu m , SA ., M o lle r J., Faber M. , and J ensen JS. ( 1998) An outbreak o f Pontiac-fever among child ren fo llowing use of a whirlpool. C/i11 J,ifrct Dis 26 , 6: 1374- 1378 Miller, R.D. , l(enepp KA ( 1993) l'l..isk assessm e nts for Leg ionnaires' disease based on ro utine surveilbnce of cooling towers for legionellac. In: B arbaree J M , !3reiman l'l..F , D ufour AP (eds) 'Li;~icmelln: Cu rrent status and em erging perspectives.' Washington DC: Am erican Soc iety for Mic robio logy, p 4043.

N ew South Wales H ealth D e partment ( !991 ) Code of P ractice for the co ntro l o f L eg ion n a ires' disease. State H ealth Publication SWR.O 9 1-08 . Syd ney, N ew South Wales.

Shelt on BG, Flanders WO , M orris, GK (1994) Legionnaires' d isease o utbrea ks and c o o ling towers with amplified L~eio11elln concentratio ns. Curr Miffobiol 28 : 359-63.

State of Victoria (2000) Legionnaires' Disease: Managing t he health risk associated with c ooling cowers. G overnme nt l'l..espo nse, J uly 2000 Yu , VL, (2000) . N osocomial legioncllosis. C11rr Opi11 l1ifect Dis. 13, 4 :385-388

The Author Dr Richard Bentham is Lecture r in Public H ealth Microbiology in the Depa rtment of E nviro nme ntal H ealth, Fli nders U niversity, Adelaide. Phon e (08) 8204 5732, e mail Richard.Ben tha m@ flind ers. edu.au WATER MARCH 2001

73

~

BUSINESS

AUSTRALIAN WATER MARKET POLICIES: CURRENT ISSUES AND FUTURE DIRECTIONS H Bjornlund and J McKay Introduction This paper rel ies on past empirical research to raise a nu mber of current issues and future directions related to Au stralian water market policies wh ich lay beyond what is included in the latest generation of water legislati on presently emerging in most states in response to the National Competition Policy (NPC). We believe it is essential to start discussing these issues now since the need for their soluti o ns are so important and escalating so rapidly and the potential environmental, social an d econom ic consequ ences of fai ling to adeq uately and comprehensively resolve them so severe that th ere is no room for co mplacency.

The first part of the paper will put this statem ent into a contemporary policy perspective while the seco nd part w ill discuss som e current and emerging water market issues. T he third part w ill identify elements of the n ext genera tion of water m arket poli ces wh ile the fo rth and fi nal part wi ll discuss som e futu re direc tions for water market policies with in a w ider water managem ent policy framework.

Contemporary policy developments The last decade saw extensive and radical developments within the area of water policy and water management. The Co un cil o f Australian Govern m ents (COAG) took an intense interest in the area in 1994 with the initiation of the COAG Water Reform Age nda (COAG, 1994) . This took place at a time where Austral ian Cooperative Federalism was in a period of reasonable trust between state and fede ral governments as a manifesta tion of New Federalism (Fowler, 1994; Bates, 1995). It also followed a pe1i od with significant develop men ts withjn environmental areas resulti ng in the National Strategy for Ecologica lly Sustainable D evelopm ent (NSESD, Austra lian Gove rnment, 1992) and the Intergovernmental Agreement on the Environment (IGAE) following intern ationa l deve lop m ents res ultin g in AGENDA21 and the Rio Conventi on (Sitatz, 1993).

74

WATER MARCH 2001

These developments ea rly in the decade therefore had sign ifi can t components of both environm enta l and social equity co ncerns and we arc particu larly looking at addressing the conflict between these and more traditional econom ic concerns. The COAG Water R eform Agenda however, ended up under the wi der umbrella of the NCP, w hich was an outcome of economic rationalism gaining mo mentum around the m iddle of the decade. Issues related to ecologically and soc ially sustainable de velopm ent too k the back sea t during th e N C P debate. They were only included in the fin al package of documents due to significant pressure from interest groups in the closin g stages betwee n th e COAG meetings in Danvin in February 1994 and Adelaide in April 1995 (Ra nald , 1995).

To emphas ise the level o f tru st between the signatori es to the NCP package a trivial penalty of S4.2 billion was imposed on states for non -compliance with a totally unrealisti c time sched ule.

At the mid point of the decade it is interesting to note that great effort had been put into federal and state legislation, agreements and fisca l m easures to ensure complian ce with th e NCP. In contrast, no similar efforts were made to ensure compliance with the NSESD and the IGAE clearly show ing the shift in policy fo cus (Dovers, 1997). T his is of particular conce rn sin ce the NCP documents are very weak on these issues and the water policy reforms imbedded in the NCP were not insign ifican t and represented a break with a number o f old paradigms.

Key elements of the reform package were: • introdu ction o f fu ll cost recovery pnces, • privatisation or semi -privatisation of public u tilities, • devoluti o n of the m anagemen t of na tu ral resources and its infrastructure, • use of property rights and m arket based mechanisms; and • removal of governmen t subsidies and cross-subsidies or makjng them transparent Such policy reforms arc consiste nt with a wider intern ational deve lopment

as expressed by a number of major internati onal organ isati o ns such as the UN (Sitarz, 1993), the Wo rld Bank (1993), OEC D ( 1989), FAO (1999) and UNESCO (2000). Water pricing and water ma rkets are two key issues in this package. Th e em e rge nce of this strong interest in pri cing, p roperty rights and m arket-based instruments h as its o ri gin in the fact that the water econo my within man y coun tries suc h as Australia is well and truly into th eir m ature phase. In this phase addi tiona l water supply is limited for both eco no mi c and environ me ntal reaso ns w hil e de ma nd fo r water is in creasing if not esca lating . Failing to continue to m eet this increasing demand will seriously impede further growth. O n the other side of the ledger th e legacy of past water pol icies has ves ted significant volum es of wate r in inefficient and low val ue water use rs compou nd ing en vi ronmental concerns (Bjo rnlund and M cKay, 19986). T o e nsu re co ntinu ed eco n o m ic growt h espec iall y w ithin regio nal and rural areas, w h ere such growth is most needed a rea llocatio n of water resou rces is of fundam ental importance . Fu ll cost recovery prices are seen as a means to e nco urage /fo rce th ese in effi cient low valu e water users to stop irrigatin g whi le water m arkets are seen as an instru men t faci li tating thi s process w hil e offerin g so me compensation to wa ter sellers.

To co mpou nd th e problem s and furth er h igh li ght the need for policy changes the legacy of past water policies also includes significa nt over-alJocations of water (within som e valJeys of NSW up to 1000% (McDonald , 2000)). Th ese over-allocati ons have in the past not presented a sign ificant problem because many Ecense holders have never used their water (sleeper licenses) or only used them partially (dozer licenses) . Th e introdu ction of water markets however has changed this picture as such Ecense holders cashed in the value now attached to th ese assets. Du ring the early stages o f water market operations as much as 58% of all water traded in the G M ID and 69% along the l'tiver Murray in SA were sleeper and

BUSINESS

dozer h censes activating unu sed water (Bjornlund and M cKay, 2000a). To counter this development the MurrayD arlin g Basi n Commission in 1997 moved to place a Cap on water extraction within the Basin to avoid a potential environm ental disaster (MDB C, 1997).

T hese developments resulted in decreasing annual allocations within NSW and Victoria further increasing the demand for reall ocation of water resou rces and in creasing the pressure on water m arkets.

As a result water m arkets with in the GM!D saw 57% of all water pu rchased go to support existing crops (Bj o rnlund and McK ay, 2000a).

The last year of the last century saw a number of importan t reports written about these issues (Australian Academy of Technologica l Sciences and Engineering and the Institute of E ngineers, 1999, Marsden J acobs, 1999 and McGuckian et al, 1999). T he sam e year saw jurisdictions scrambling to produ ce new legislation in fulfillme nt of their obligations under the NCP to avoid the signifi cant finan cial penalties. New So uth Wales introduced their new Water M a nage m ent Bi ll (DLWC, 1999), Queensland its Water (Allocation and Management) Bill (DNR, 1999) an d W estern Australia T he R ights in Water and Irrigation Amendment Bill (Banyard and Kwaymullin a, 2000). South Australi a h ad alread y introdu ced its Water R esources Managemen t Act in 1997.

Water Markets since the 1980s Water markets emerged during the 1980s a nd their use became more widesp read during the 1990s as water market policies were widened and introduced within more States. As irrigation communities beca me m ore fam iliar w ith water m arkets and more co nfide nt w ith their operation and potential benefits water market activities increased significan tly during the decade (Bjornlund and M cKay 1999a; 2000a). Th e authors have carried o ut exte nsive research into the operation and impacts of permanent water markets in South Australia and Victoria.

Early o utcome of this research have been reported in this journal (Bjornlund and M cKay, 1995, 1996 and 1999a) and in more details elsewh ere (Bjornlund and McKay, 1998a,b, 19996, 2000a,b). In brief water markets seem to have achieved a number of its objectives such as moving water to more efficient and higher valu e users with potentially good both economi c and en vironmental o utcom es.

However th e re are also some both environmental and social reservations (Bjornlund and McKay, 2000a,b). We will

not discuss this fu rther here but refer the interested reader to the above references.

Our present proj ect has extended the investigations related to permanent transfers into New South Wales and added the operations and outcom es of temporary markets in Victoria and New South Wales.

Emerging Issues in Water Markets: Cross-sectoral demand In early market operations aL11ost 100% of water tra nsfers were between agricultural users. This is likely to c han ge durin g the next decade or so . Under the MDB Cap all water users have a volumetric license in cludi ng cities and towns. As urban developments continue and existing all ocations beco me inadequate additional urban water supply can only be ga ined from the water market and in reality wi ll ha ve to come out of irrigation. Th is developmen t will for the first tim e generate cross-sectoral demand in water markets. T he earl y success of water markets is accele ratin g this process. As discussed water has moved to m ore effi cie nt and hi gher va lue produ cing irrigators increasing the area of production as we ll as the volume of produce from existing irri gated areas inten sify in g the need for ru ral and regional workers both on farms and in associated processing, packaging, transport and service industries.

This in turn will increase demand from no n-ru ral uses such as resid e ntial , industrial, community and rec reational. As an expression of this development at least one town ship along the River Murray has introduced a developers levy to pay for the purchase of additional wate r to satisfy increased demand fro m new subdivisions.

Emerging issues in Water Markets: Temporary v. permanent markets In both Victoria and New South W ales temporary water trade was introduced before permanent water trade reflectin g community concerns and the fact that the predominant water users in both States have the ability to benefit from annu al water trade. In South Australia both temporary and permanent trade was introduced from the o utset reflecting the fact that almost all irrigators in South Australia are eithe r h ortic ul ture or viticulture and can n ot benefi t from ann ually flu ctuatin g supply.

If policy m a kers a re try ing to encourage a perm anent re-a llocation of water and the associated structural change within irrigation communities, permanent

trade is necessary. Very few irrigators will make investments in more efficient inigation and drainage or pem1anent high val u e crops withou t the long-term secu rity of water. In that sense the introduction of temporary trade mainly served the purpose of gettin g irrigators accustomed to the concept, ga in confidence in its workin gs and open their eyes to its potential benefi ts.

Temporary trade ho wever has its own advantages and place in the process of ac hieving a more effi cient water use.

It allows irrigators to react to chan ges in annual allocations, climatic and m arket changes and chan ges in perso nal circumstances. It allows farmers to sell their water temporaril y w hil e recove rin g from sickness or w hile the land recovers from environm ental degradation w hile still gaining som e incom e . It also allows fa rme rs to retire w hile remaining on the land and gaining inco me from annual sale of the water keeping the in tegrity of the property as an irrigated enterprise for futu re generatio ns or later sale.

Co mp arin g activ ities within the temporary and permanent marke ts in the GM ID in Vi cto ria and the Murray R egion in NSW it beco mes apparent that activities within the temporary markets are muc h higher than within permanent markets. In general temporary markets tends to trade 10 times the vo lume of perm anent markets on an annual basis (Bjornlund and M cKay, 2000a) . A recent report by Marsden J acob (1999) identified significant impediments to permanent trade within man y valleys in NSW and concluded that they as a consequence forgo or postpone significant eco no mi c ga ins.

Some of the reasons for these communities fa vorin g temporary trade were made clear to us durin g a visit to the GMID in Victoria and the Murray R egion ofN SW in April 1999. W e discussed th ese issues with irrigators, their advisors and wa ter authorities. T hree main th emes em erged from these discussio ns: â&#x20AC;˘ Policy uncertainty. At least three maj or uncertainties were identifi ed: 1. the final impact of the MDB Cap; 2. environmental aLlocations and in -steam flow defin itions; and 3. how to deal with the significant levels of over-allocation .

As these issues eventuall y are being resolved annual alloca tions as proportion of water rights will decrease . As a consequence, when an in:igator purchases 1 ML of permanent water right it is uncertain h ow muc h water the irrigator will receive in the future for the price paid.

WATER MARCH 2001

75

BUSINESS

On the other hand when an irrigator purchases 1 ML of temporaty water, 1 ML is exactly what w ill be delivered for the price paid.

• Changing fi n a n cia l s tru c t ures o f farming enterprises (as well as other business enterprises). Many businesses move from a position w here they carry th eir assets o n th e balance shee t to a position w here they lease major assets .

Thi s development is likely to continu e and increase, as irrigated farming becomes more capital intensive. Leasing of water fi ts into this concept and can be designed to follow the timing of leases of major equipme nt depe nding on the water resource and contracts for producti on and sa le of commodit ies. As su ch the arra ngeme nt ful fi lls the requirements of fina ncia l institu tions fin anc ing su ch leases. T he use of leas ing of wate r is also likely to increase as th e right to own th e water is separated from the requirement to own the land on which it is used. Th is has taken place in South Austra lia and is proposed under the new NSW Water 1\lla11age111e111 Act. As a co nsequen ce of this separatio n the fi rst leaseback arrangement has been see n in South Australia. Such lo ng-te rm leases has much the same qualiti es as permanent trade since the lessee re tains the contro l over the water resource for a period long eno ug h to justify long-term investments in effic ient w ater use . The leaseba c k option has th e advantage of converting the irrigators water asset in to cash , w hi ch can be used to finance necessary investm ents to make the farm long-term finan cially viabl e and eco logica lly su stainable .

• Taxation issues. If an irrigator purchases annual water the purc hase price can be written off against annual in come and thus paying around 40% of the purchase price.

When an irrigator sells annua l water the income can be offset against annual expenses, depreciation or carried forward tax losses from previous years. Given th e finan c ial position of ma ny sell ers this m ea ns that they do not have to pay tax on the in come. H owever, if an irrigator p urchases permanent water there is no abili ty to depreciate the purchase cost and fo r sellers the sa les price is fo rmaUy subject to cap ital gains tax.

Elements of the next generation of water market policies To ove rcom e the above im pediments to the wide r use of pe rman ent water markets and at the same time benefit from the emergin g cross-sectoral de mand and its inhere nt w id er spectrum of water use patterns and ri sk positions a nu m ber of further changes need to be made to 'Nater 76

WATER MARCH 2001

market policies. The followin g main areas need to be addressed: • The above me ntioned three unce rtainties must be resolved and its fina l impac t filt er through to end-users. O nce e n vironmental allocations ha ve been defi ned th eir abi lity to be traded must be established as well as the ru les for suc h transfers.

• Tax refo rms are needed to encourage the use of permanent water trade and investments in sustainable water use.

P otential solutions to this issue w ill be di scussed later.

• More soph isticated market instruments such as futures and opti on contracts need to be de velop ed to e nabl e use rs w ith opposite risk exposure and water use patte rns to benefit from such differe nces; • Water rights need to be better defined w ith respect to: 1. Security of supply specified as the probability of receiving the volum etri c en ti cleme nt;

2. Reliability of deli very specifi ed as th e period from ordering to rece iving t he wa ter; 3 . The constraints on trad e; 4. Some indicatio n of the expected quality of the water; 5. The duration of the water righ t e ither indefinite or for a specified period. ln the later case the likelihood of th e w ater right being renewed and the fac tors dete rmining renewal must be stated; • A more efficiently ope rating market.

T his is probabl y the most co mpl ex and important area and requires a numbe r of improve m ents within many different aspects of market operations: 1. Tran sfer processes must be faste r and its outcome more predi ctable, 2. Information on demand, supply and prices in the marke t must be readily and instantaneo usly ava ilable. The emergence of Water Exchanges w ithin th e GMID , M[L and Central Irrigation Trust have provided this for temporary trade w ithin th ese areas; 3. An nual allocations must be announ ced earl y in th e season and changes to such allocations made frequ e ntly at know n interva ls. It must furth er be m ade tra nsparent w hi ch factors impact on the level of allocations suc h as natural precipitati on, evaporation, da m leve ls etc. For each of these factors trigger levels must be identified causing inc reases in annu al all ocatio ns. Con tinuous readings of these factors related to th e trigger levels must be commun icated to irrigators. W ithout su ch in sight irrigators can not make rational buy and sell decisions. It is

important to und e rstand t hat rece nt policy changes have transferred most of the risk managem ent from water authorities to irrigators. In the past, ann ual allocations were made based on water in the storages plus expected inflow duri ng the season and non-use. Today allocations are basically made based on dam levels w ith ve1y littl e alJowance for inflo w du ring the seaso n . Such actual inflow is now used to justify increases in an nual allocations during the season. During the last couple of seasons th ese increases have come after most irrigators cut-o ff date for planting commitme nts. After that date irrigators ca n not benefit fro m additional all ocations u nless they gambl e on them coming. As a result irrigators plant less land and end up wit h excess water.

4. To assist irrigators in making the correct buy an d sell decisions m ore knowl e dge is required about the factors driving water market activities, that is the fa ctors trigge ring buyers and sell ers to act. Thi s could be facto rs such as the level of seasonal a ll ocat io n s, pre c i pitat ion, co mmod ity prices, pri ces of substitute good such as fee d for an ima ls, interest rates, exchange rates and the cut-off daces for growers of different com modities as dis c usse d above. At pr ese nt thi s knowledge is ve,y li m ited and as a consequence uninformed decisions are being made. Once suc h know ledge is known it must be commun icate d to decision makers and information about the position of each facto r mu st be made easily and contin uously ava ilabl e and readi ly compre hensible .

A telephone survey of buyers and sell ers of temporary w ater within the G MID during the 1998/ 99 irrigation season clearly confirmed the first three issues listed above as the m ost important improvements to existing market ope rations.

Future direction in water market policies At this point it is necessary to stop and consider the w id er impli cations of what we have discussed so far. In its ultimate form m ore sophisticated and efficie nt wa ter markets w ill generate a situati on w h ere 100% of wa te r allocated fo r consumptive uses will actually be used eve ry year. The re will be very li ttle unused water left in th e ri ver to cater for enviro nme ntal needs. T he development ou tli ned in this pape r is therefore only ecologically an d socially sustainable within a w ider regulatoty framework protecting environmental and soc ial in terests aga inst pri vate interests rulin g the operatio ns of effi c ien t markets.

BUSINESS

Many economists will argue that market based and regulatory or command and control instruments arc irreconcilable.

Ecological economises however seems to take a diflCrcnt view and state that markets arc excellent servants but poor masters when it comes to protecting biodiversity and ecological sustainability (Young, 1999). However if rcgulaco1y instruments set the ecologically sustainable limits market mechanisms can be an excellent servant to move water around within such limits. In a recent paper we outlined such a regulatory framework (Bjornlund and McKay, 2000c).

Until now we have discussed, acknowledged and promoted the need for increasing the water user's position and rights. When discussing the regulatory framework to protect community interests such as social and environmental concerns we will have to turn our attention to acknowledge, discuss and promote the obligations placed on water users. We were pleased to note that both the Federal Minister for the Environment Senator Hill and the South Australian Minister for Water Resources Mark Brinda! at two recent conferences in Melbourne and Canberra during March '.WOO emphasised this point. Some might argue that promoting both the rights and obligations of water uses amount to a contradiction.

We will however argue that the two things arc complementary and that efficient and progressive irrigators today understand this. This was clearly indicated to us during our recent discussions with irrigators in NSW and Victoria.

The argument for defining such obligations has its roots in the public goods nature of water. Compared to areas such as telecommunication, roads, rails, electricity and mail the water industry employs a significant proportion of the public sector asset base (Industry Commission, 1990). The taxpayers and the wider community therefore have a valid interest in the way this resource is used and a reasonable expectation that the water users use the water in the best interest of the community and not only the individual. Such expectations are environmental, social, cultural and economic in nature. Water should be used efficiently to maximize the economic benefits in form of jobs and export earning, protect ecological systems and the environment to ensure a pleasant living environment and the long-term sustainability of rural communities and culture for present and future generations.

In our recent paper (Bjornlund and IvlcKay, 2000c) we argued that a 'Duty

toward Water' should be defined within each region setting out what it could reasonable be expected that the water resource could produce within locally defined environmental, social and cultural limits. 13ascd on such definitions water users should produce Water Management Plans setting out how each water user intends to fulfill the local 'Duty toward Water'. Such Water Management Plans should also be in accordance with Regional Water Management Plans and the State Water Management Plan setting the overall aims and objective for the states water resources. Based on the Water Management Plans each water user should be given a Water Use Right which is the volume of water that is required for the intended purpose while- maintaining the 'Duty toward Water'. This right should be separate from the existing Water Right, which will not any longer include any right to use the water but only the right to own or hold it. Due to their nature Water Use Rights will have to be property or use specific and will have to be for a defined period of time while the Water Right now can be totally removed from any relationship with land and can effectively be in perpetuity. The failure to fulfill the Duty toward Water after a suitable grace period upon its introduction will result in forfeiture of the Water User Right but not the Water Right.

The Duty toward Water should be revised regularly to ensure that it keeps reflecting the most efficient water use and water re-use technology say every I 0 years, The time horizon for Water Use Rights will have to be much longer like 30 years to ensure the users time enough to justify the necessary investments required to fulfill the Dt1ty toward Water. Water Use Right holders should be under an obligations to fulfill the new Duty toward Water upon renewal of the Water Use Right. Instruments should be in place to encourage water users to adopt the new Duty toward Water when renewed every 10 years by instrument such as those in operations within NSW fisheries (Young, 1995).

The concept of the 'Duty toward Water' will have an inherent requirement of water actually being used. It can not fulfill its duty ifit is unused. The owners of Water Rights will therefore be under a duty or obligation to ensure that the water attached to the rights is being used under a Water Use Right. The failure to fulfill this duty could result in the loss of the Water Right or a forced sale. Such a duty will also eflCctively eliminate the fear that many has that the separation of the right to own from the right to use water

could result in damaging speculation with investors consolidating large volumes of water and forcing prices up by limiting supply.

Such a framework will ensure that owners of Water Rights and Water Use Rights are under an obligation to constantly fulfill the Duty toward Water and thereby ensure the long-term benefits to the wider community. Under such a regime the Federal Government might be encouraged to introduce a number of tax reforms which will facilitate the process.

Such reforms could be: • The introduction of increased or accelerated depreciation on capital investments in accordance with an approved Water Management Plan to ensure fulfillment of the Duty toward Water. Such a system exists for investments under Land Care programs (Young cf al, 1996); • Allowing depreciation of the purchase price on permanent water purchases removing one of the present reasons for preferring temporary trade; • Remove capital gains tax on water sold with the effect that the seller ceases irrigation. This would accelerate the structural adjustment process and case the social pain associated with the introduction of this framework which inevitably will result in some irrigators not being able to fulfill the new Duty toward Water and thereby lose their Water Use Right.

Such tax changes would encourage more efficient water uses and the desperately needed structural adjustment process in two ways. It would assist existing water users in financing: more cflicient water use technology needed to fulfill the Duty toward water. It would also enable buyers to pay higher prices for water thus eliminating the present gap between water market prices and the value of water as part of an irrigated property actively supporting capital investment~ in in·igation infrastructure and plantings (Bjornlund and McKay, 2000b, 1999b).

With the Water Use Rights formally separated from the Water Right trade in Water Rights can take place instantaneously. There will not be any need to evaluate or police such transfers. The issues traditionally considered by the authorities all relates to the Water Use Right and have all been sorted out in the Water Management Plan process and accounted for within the local Duty toward Water.

The only thing the authorities need to monitor is water use, which is already done for billing purposes, and then compare this to the Water Use Right. If the holder of a Water Use Right wants to increase water use a revised Water WATER MARCH 2001

77

BUSINESS

Man agement Plan n eed to be submitted.

This process is separate to any purchase of water right.

Conclusions This paper h as tried to raise a n u mber of policy issu es related to water trading .

F ro m the discussion s it become apparent that water trading can not be seen in isolation from other water po]jcy issues. I t h as to b e d ealt w ith in a h olistic and integrated way to en sure that the outcome refl ec ts th e interests o f th e wide r commu nity. Recent reports h ave clearly indicated th at water n eeds n ot be a lim itation on sustainable growth of water dependent industries an d rural and regional commu nities. The p roviso is that adequate p olicy measures are put in p lace to en su re a re-allocatio n of water resources away from ine ffi cient low value use rs to the e merging sectors o f the economy dem anding addition al w ater. This will also require the r elocation of some water using activities to areas w h ere w ater is more readily ava ilable. T h e use of more efficien t and sophisticated water markets w e re p o inted o ut as majo r i nstru m ents in securing thjs d evelopment. A w ider debate as to w h at constitute an adequate policy fra m ework to ensure an ecologically, socially an d culturally sustainable outcome of this process, w h ich aim is economjc in its fou n dation , is th erefore essential.

References Australian Academy of Technological Sciences and Engineering an d the Institu te of Engineers (1999): Water mid tlie A11stralia11 Eco11 0111y, Australian Academy of Technological Sciences and Engineering, Parkville, Victoria.

Banyard, R. and Kwaymullina , A. (2000): Tradeable Water Rights Implementation in Western Australia. In Vince, A and Main, G. Eds. Co1ifere11ce Pmceedi11gs 1st A 11stml A sia,, Nat11ral R eso11rces Law & Policy Co1ifere11ce (Fows 011 Water). Canberra, March, 162-178.

Bates, G (1995): E1wiro11111e11tal Law i11 A11stralia, 4th Edition, Buttcrwo rths, Adelaide.

Australian Government (1992): Nat11ral Strategy for Ewlogically S11stai1iab/e Develop111e11t. AGP Press, Canberra.

Bjornlund, H. and McKay,]. (1 995) : Can Water Trading Achieve Environmental Goals, Water, 22(5), 31-34.

Bjornlund , H. and M cKay, J . (1 9 96) : Transferable Water Entitlements: Early Lessons from South Australia. Water, 23(5), 39-43 .

Bjornlund, H. and McKay, J. (1998a) : Factors Affecting Water Prices in a Rural Water Market: A South Australian Experience.

Water Reso11rces R esearcl, 34(6), 1563-1570 .

Bjornlund, H . and McKay, J. (1998 6): Overcoming the Introspective Legacy of Tradeable Water Entitlement Policies in South Eastern Australia. In J ust, R. and Netanyahu, S. Eds. Co,,jlict a11d Coopcmtio11 011 Tm11s- Bo1111d11ry vVarer Reso11rces. Kluwer

78

WATER MARCH 20 01

Academi c Publishers, Natural R esource Management and Policy Series, 315-332.

Bjornlund, H . and McKay, J. (1999a): Water Markets: Buyers and Sellers Perception. Water 26(2), 41-45.

Bjornlund, H and McKay, J. (19996): Do Permanent Water Markets Facilitate Farm Adjustment and Structural Change within Irrigation Communities. Rural Society, 9(3), 555-572.

Bj ornlund, H and McKay, J. (2000a) : Water Markets - An Instrument in Achieving a More Sustainable Water Use . In Proceedi,,g fro111 the Xtl, World Water Co,wess, Melbourne, March.

Bjornlund, Hand McKay, ]. (20006) : Do Water markets Promo te a Soc ially Equitable R eallocation of Water? A Case Study of a Rural Water Market in Victoria Australia.

Rivers 7(2), 139-152.

Bjornlund, H. and McKay, ). (2000c): Problems with N C P Water Market Policies in Three Australian States 1995-2000 and Elements of Solutions - 'The Duty toward Water'. ln Vince, A. and Main, G. Eds. Proceedi11gs Fro111 the 1st A 11stralnsim1 Nat11ml Reso11/'Ces Law a11d Policy Confere11ce - Fows 011 l,Vater, Ca nberra, March, 179-188.

COAG (1994): Co1111111{//iq11c on Water reso11rces Policy, Hobart.

DLWC, Department of Land and Water Conservation (1999): A Wl,ite Paper, Sydney.

Davers, S. (1997): ESD and NC P: Parity or Primacy? In Ca rterm M. Ed. P11blic l11 terest i11 the Natio11 al Co 111pe tirio11 Polic y : l111ple111e11tatio11 lsSHes - Getting it Rig/it . Public Sector R..esearch Centre, University of New South Wales, Sydney.

FAO (1999): lsSHe i11 Water Law Refor111. Expert Consultation Pretoria South Africa 3-5 J une 1997, R ome, FAO. Fowler, R (l 994) : New National Directions in Environmental Protection and Conservation.

In Boer, B.; Fowler, R . and Gunningham, N. Eds. E1111iro11111C11tal O111/ook, Law m,d Policy. The Federation Press, Sydney lndusny Commission (1990): Meamri11,(! the Perfom1m1ce of Selected Go11er,1111e11t B11si11ess E111e1prises. lndumy Commission , Canberra.

Marsden Jacob (1999): Water 'fradi11g De11e/op111C11t a,,rl Mo11irori11cg. R eport to the Department of Land and Water Conservation, Marsden Jacob & Associates, Camberwell, Victoria.

McDonald,J.A. (2000): 1000% Over-allocation, democracy can create it, can it also remove it? In Proccedi11gs fro111 rlie Xrh W orld Water Congress, Melbourne, Australia.

McGuckian, R..; Tim C ummins and Associates and R ead Sturgess and Associates (1999): ln'(gatio11 Risk Mm111ge111e1u i11 C,mwt m,d F11t11re vflater Policy E11viro11111e111s. Draft Final R eport to LWRRDC, Canberra.

MDBC, Murray-Darling Basin Commission (1997) : M i11isrerial Co1111cil R eport 011 Diversio11 Cap, Media release, Adelaide 25.7.97.

Natural R esources Queensland (1999): Expos11re Drafl Bill m,d Expla11arory lvlatcrial Water (A llocario11 mid 1\1/m1a_ge111e11t) Bill. Queensland Government, Brisbane.

OECD (1989): Rwewablc Na wral reso11rccsEco110111ic Iure111i11cs for l111pmved !Vla11age111e11t, Paris.

Ranald, P. (1995) : National Competition Policy.

Jo11mal of A11srmlim1 Politiml Ero110111y, 36:1-25.

Sitarz, D . (1993): AGENDA 21: Tli c Eartli

S11111111it Strategy to Save O11r Pla11et. Earth Press, Colorado.

UNESCO (2000): "/7,e design mid i111plc111e11tatio11 strategy of the HELP initiative Young, M. C. (1995): The design of fishing-right systems - the New South Wales experience.

Occa,, and Coastal Management 28(1), 45-61.

Young, M.C. (1999): Water R(gh ts: a11 ecolo,(!ical eco110111ics perspective. Invited paper presented to the Australian Agricultural and R esom ce Economics Society Conference, CS! R.O Division of Wi ldlife and Ecology.

You ng, M. C; Howard, B.; Cunningham, N. ; Grabosky, P. ; McCrone, E.; Elix, J. and Lambert, J. (1996): Rei111b11rsi11g the F11t11re: An Eva/11atio11 ef Motiimtional, Price-Based, PropertyRiglit, all(/ Reg 11/atory foce11tives for the Consenmtion of Biodiversity. Department of the Environment, Spo,t and Tenicories, Canberra.

World Bank (1993): Water R esources Management.

A World Bank Policy Paper, Washington.

World Bank.

Authors Henning Bjornlund is a R esea rch A ss o ciate a nd Jennifer McKay is A ss o c iate Professor, Schoo l of Interna t iona l B u siness, D ivis ion of B usiness and Enterpr ise, University of South Au stralia, Adelaide SA 5001.

J en nifer is Director o f the Water Law an d P o li cy Group w h ich h as members from all over the Univers ity c ondu cti ng research on wate r recycling, corporat isation of water author ities, dam safety, capacity sharing, ESD , an d integrated ca tchment ma n ag e men t . E mai l: J enni ferMcKay@ u nisa.edu.au

water Contributions Wanted The Water journal welcomes the submission of papers equivalent to 3,000- 5,000 words (allowing for graph ics) relatin g to all areas of th e water cycle and water business to b e p ub lished in the journal. Topical stories of up to 2,000 words may also be accepted.

In the first instance, email a draft copy to the Features Editor, Bob Swinton (email bswinton@bigpond .net.au) . Following his assessment of suitability, he w ill table the paper at a monthly J ournal Committee meeting w here, if appropriate, it will be assigned to referees. T h eir com ments will be passed back to the principal author. ff accepted and after any comments have been dealt with, the fin al paper can be em ailed with the text in MS Word but with h igh resolution graphics (300 dpi tiff, j pg or eps files - Zip disks or CD-ROMs can be accepted) in separate files (N. B. graphics embedded in Word files can not be used) .

Hard copy photos and graphics suitable fo r scanning by the publish er can be mailed to 4 Pleasant View C res, W heelers H ill, Vic 3150.