Water Journal November - December 1998

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Volume 25 No 6 November/December 1998 Journal Australian Water & Wastewater Association

Edltorlal Board FR Bishop, Chairman B N Anderson, M R Chapman, P Draayers, W J D ulfer, P Gin, GA Holder, M Muntisov, P Nadebaum , J D Parker, M Pascoe, A J Priestley, ] Rissman, F Roddick, EA Swi nton

[Jl Water is a refereed journal. This symbol indicates that a paper has been refereed. General Editor Margaret Metz, email: mmetz@awwa.asn .au AWWA Federal Office (see postal address below)

Features Editor EA (Bob) Swinton 4 Pleasant View Cres, Wheelers Hill Vic 3150 T el/ Fax (03) 9560 4752 Email: swintonb@c031.aone.net.au

Branch Correspondents

CONTENTS From the Federal President ..... ........ .... .................. ..... ........ .......... ... ...... .... .... 2 From the Executive Director ..... .. ...... .................... .. ......... ..... ..... .... .... ...... ..... . 4

ACT - Ian Bergman Tel (02) 6230 1039 Fax (02) 6230 6265


New South Wales - Mitchell Laginestra T el (02) 9412 9974 Fax (02) 9412 9676

Northern Territory - Mike Lawton T el (08) 8924 6411 Fax (08) 8924 6410

Queensland - Tom Belgrave Tel (08) 8227 1111 Fax (08) 8227 1100

Tasmania - Ed Kleywegt T el (03) 6238 284 1 Fax (036) 234 7 109

Victoria - Mike Muntisov T el (03) 9278 2200 Fax (03) 9600 1300

Western Australia- Jane Oliver Tel (08) 9380 7454 Fax (08) 9388 1908

Advertising & Administration AWWA Federal Office PO Box 388, Artam,on NSW 1570 Level 2, 44 H ampden Road, Artarmon Tel (02) 9413 1288 Fax (02) 9413 1047 Email: info@awwa.asn.au Advertising: Angela Makris Graphic Design: Elizabeth Wan

Water (ISSN 0310 路 0367) is published six times per year: Jan uary, M arch, May, July, September, N ovember by

Australlan Water & Wastewater Association Inc ARBN 054 253 066

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Have We Failed? .. ....... ...... .... ....... .......................... ... .... ............. ................ ...... 3 F Bishop WATER

Tel (07) 3810 7967 Fax (07) 3810 7964

South Australia - Angela Colliver


Tomorrow's Water Scientists ............... .... ... .... ... ........... .... .... .... ....... ... ........... 9 A M akris 路, Early Detection of Outbreaks Of Waterborne Gastroenteritis .... ... ..... 11 A Padiglione, C K Fairley ~ Size Is Important ............. ..... ... .... .. ....................... .. ..... .. .... .... .... ..... .......... 16 G N ewcombe, C Pelekani, C H epplewhite, K N guyen Safe Drinking Water: Are Food Guidelines the Answer? ......... .......... .. 21 D D eere, A Davidson WASTEWATER ~

Trialling the CDS Screening System on Raw Sewage ................ .. ......... 26 NW Swain, RA Jago ~ Health Risks of Medlclnal Residues: More Questions than Answers 30 D Wiesner Dewaterlng and Stablllslng Sludge ..... .... ...... .. ............ .... .. .... ... ................... 33 M Laginestra ENVIRONMENT

[![ Nutrient Release From Sediments: The Effect Of Short-term Anoxla 35 M Ghisalberti

Greg Cawston


Executive Director Chris Davis Au stralian Water & W astewater Association (AWW A) assumes no responsibili ty for opinions or statements of fac ts expressed by contributors or advertisers . Editorials do not necessarily represent official AWW A poli cy. Advertisements are in cluded as an infonnation service to readers and are reviewed before publication to ensure relevan ce to the water environment and obj ectives of AWWA. All material in Water is copyright and should not be reproduced w holly or in part without th e written pennission of the General Editor.

Subscriptions Water is sent to all members of AWW A as one of me privileges of membership. Non-members can obtain Water on subscription at an ann ual subscription rate of$50 (surface mail).


Risk Management Strategies for Recoverable Resources ..... ............. 38 S Davis, A Roche WSAAfacts 1997: A Snapshot of the Australian Urban Water Industry .. 42 T Carpenter DEPARTMENTS


From the Bottom of the Well .. .............. ... ... .... ................. ........ ....... ...... ...... ... 4 International Afflllates ...................................... ...... ...... ....... ...... .... ............... 5 Letter to the Editor ................ .. ... ....... .. .. ..... .. ... ...... ........ .... .... ...... .. ...... ... .. .. .. 10 'Crypto' Crossword ............................... ... ......... .................. .... .. .... .. ........... ... . 10 Meetings .. ............ ........ ....... ..... ... .. ....... ............ ..... .. .. ... ...... .. ..... ... ............. ..... 48 OUR COVER : To enhance product safety the food industry is respo nding to new regulations stipulating the use of quality assurance rather than end product testing. Whilst foodstuffs and drinks, including bottled wa ter, are subj ect to the regulations, drinking water supplies are con sidered very low risk and are exempt. With tighter regulations being called for regarding water supply safety, the food industry experience suggests that a quality assurance approach co uld be the most protective, workable and cost-effec tive response.

Photo courtesy of South East Water





'Factors that contributed to the identification of this outbreak included: Widespread Absenteeism (hospital employees, students and school teachers); Increased Emergency Department attendances for diarrhoea; Citywide shortage of antidiarrhoeal medication. (Nonetheless) .. . the waterborne nature of the outbreak was not identified until at least 2 weeks after the onset of the outbreak.' -CDC assessment of the 1993 Milwaukee outbreak (Kramer et al., 1996) A project co nducted by the Coopera tive Research Centre (CRC) for Water Quality and Treatment reviewed the ability of current surveillance mechanisms to rapidly identify a waterborne outbreak of gastroenteritis and concluded the current mechanisms have low sensitivity with considerable lag periods. The project then aimed to identify if m ore rapid techniques were available and evaluated newer computerised data sources such as ho spital emergency department attendances and processing of faecal specimens by pathology laboratories, the latter appearing to be the most sensitive. .Superimposing the estimated impact of an outbreak over the background of endemic gastroenteritis from all sources demonstrated the difficulty involved. Geographical information may reduce the 'noi se' of endemic gastroenteritis since it could highlight particular water distribution zones. Monitoring of pharmaceutical sales is a possibility for the future, but monitoring absenteeism at schools and workplaces presents major logistical problems.

Key Words Waterborne disease, gastroenteritis, surveillance, n1.onitoring disease

Introduction Drinking water may be associated with very large outbreaks of gastro-

enteritis and in rare instances death (Moore et al., 1993; Aho et al. , 1989; Hayes et al., 1989; Richardson et al., 199 1). MacKenzie et al. (1994) reported that in the highly publicised outbreak in Milwaukee more than one million individuals were exposed over a two-week period to drinking water that was contaminated with Ciyptosporidium , resulting in 400 ,000 cases of gastroenteritis. It is interesting that this large outbreak was identified in part because of a dramatic increase in sales of an ti-di arrhoeal medications . Many waterborne outbreaks are detected due to serendipity rather than active surveillance (Frost, 1996). Earlier identification of waterborne o utbreaks of gastroenteritis should allow earlier intervention and investigation to occur. This would minimise the impact of outbreaks and maximise the lessons to be learnt from them. The ability of current surveillance mechanisms to rapidly detect waterborne outbreaks is unknown but is genera lly felt to be low. A 1988 workshop convened by the Environmental Protection Agency in the United States (USEPA, 1990) recommended the use of computerised data as a long-term goal of surveillance programs. However, regular surveillance of hospital emergency department attendances, absentee rates from schools, pharmaceutical sales and faecal specimens processed is not routine

despite the existence 'of some circumstantial evidence that suggests these data sources may be good indicators of wa terborne disease. For example, in an analysis of the wa ter supply in Milwa ukee Morris (1996) noted a close correlation between rates of gastroenteritis in children and water turbidity in the 16 months before the outbreak. This relationship was strongest for children, a finding that ha s been confirmed by Schwartz et al. (1997) in Philadelphia using data over a longer period and also more sophistica ted statistical methods that took into account other factors such as ambient temperature and rainfall. This occurred despite turbidity levels during the study period being within the range stipulated by the statutory autho ri ties. Whether such a relationship would apply in a city with protected water catchments such as Melbourne is not known. In this paper the current surveillance programs that are in place to detect a waterborne outbreak of gastroenteritis are exarnined, as well as their sensitivity and delays in reporting. Various new data sources that could act as markers of gastroenteritis in the community are then examined.

Background and Methods Current Gastroenteritis Reporting Retrospective data on cases of WATER NOVEMBER/ DECEMBER 1998


WATER gastroenteritis reported to the H ealth Department of Victoria was obtained from computerised records for 1996. This data is collected on the date of onset of symptoms and includes the patient's age and hom e post code, the specific diagno sis if known and the date reported. W e determined the interval between the onset of symptoms and the date the report was received, excluding cases where this interval was recorded as 'O' days, since this was the default code used w hen the date of onset of the di sease was not know n.

Faecal Specimens The daily number of specimens processed by the two largest pathology ¡ companies in M elbourne was obtained for the period 1- 1- 95 to 31- 12-96 inclusive. Because specimens are delivered to both laboratories by dedicated co uriers, the vast maj ority arrive on the day of collection . D emographic details and the nature of tests requested are entered into the central database on arrival, before specimen processing. Information on the number of fa ecal sp ecimen s tes ted in Victoria was derived from M edicare records.

Hospitals Gastt oenteritis rates in children (<17 years) were obtained from computerised records at the Melbourne Royal Children 's Hospital, Monash M edical Centre and Frankston H ospital. As each patient arrives at the emergency department , their demographic data (nam e, date of birth , sex, address , post code and next of kin) is recorded by administra-

tive staff. The . system at the Royal Children 's Hospital (' HAS Sys tem s Australia') then informs the m edical staff that the patient is waiting. After consultation the likely diagno sis is entered into the system by the medical staff. The computer codes the diagnosis u sing a standardise d international coding sys tem, the ' International Classification of Di seases : Version 9' (ICD-9) . The ICD-9 codes that were used to code acute gastroenteritis at this hospital in the study period w ere 9 .1 , 9.2 and 558.9 . This patient managem ent sys tem has now been implemented in most of the public hospital em ergency departments in Au stralia. A similar but more rudimentary system is in operation at Frankston Hospital.

Results Current Gastroenteritis Reporting Only 71 cases of 'presumed food and waterborne illness' were received by the H ealth D epartment ofVictoria in 1996 (Infectious Diseases Unit , 1996). M any cases initially rep orted under thi s category are reclassified once the cause is known. Thi s data (encompassing cases due to a range of organisms such as Blastocystis, Cryptosporidium, E. coli etc.) was not further analysed due to the small numbers. The vast majority of gastroenteritis reports derive fro m laboratory staff w hen they isolate specific organism s. The m edian interval between onset of disease and reporting to the H ealth D epartment fo r cases of Campylobacter and Giardia was 13.8 and 15 .8 days respectively. Even if one excludes the

late reports (those >1 month), the median interval was still greater than ten days for both. These figures are felt by H ealth D epartment officials to be significant underestimates. The date of onset of disease is often not known , and an alternative date such as the date of collec tion of the specimen is u sed instead. In order to estimate the number of reports which might flo w from an outbreak of, say, 20 ,000 , 50,000 or 100 ,000 cases .of gastroenteritis, a numb er of factors w hich interven e between the actual number of cases and the numb er of reports have to be applied. These factors are based mainly on previous experience (see T able 1). Figure 1 reveals the reported incidence of giardiasis for M elbourne during 1996 and shows the expected impacts that large outbreaks of w aterborne giardiasis would have on these background rates. To illu strate how difficult it w ould be to detect such outbreaks, we sup erimpo sed these peaks over the n atural 'n01 se' (see Figure 2).

New Data Sources It is important to no te that the vast maj ority of people with gastroenteritis do not attend a doctor but either stay home or go to a pharmacy to buy something over the counter. Each data source was evaluated as to its utility. However, monitoring of pharmaceutical sales and absenteeism in schools or workplaces would not appear to be simple with current technology. Similarly, real time monitoring of visits to general practitioners would prove

Table 1 Assumptions used in modelling of outbreaks of gastroenteritis Assumption

Evidence from previous waterborne outbreaks

50% of faeca l specimens from people with Giardia are identified as such

see Mandell et al., 1995, p. 2490

0.65% of community gastroenteritis have faeca l specimens taken

8.3% of gastroenteritis cases attend GP (Garthright et al., 1988) No. of GP visits for gastroenteritis Vic/year= 300,000 (Hellard and Fairley, 1997) No. of patients who had faecal specimens examined for parasites Vic/year = 24,500 (Medicare data provided by Health Insurance Commission, Canberra)= 0.678%

85% of community faecal specimens are surveyed

Derived from data supplied by pathology compan ies, Health Insurance Commission (data not shown for commercial reasons)

1% of cases attend emergency department (worst case scenario 0.6%)

Cryptosporidium: 83% attend GP, 5% 'hospitalised': we ll documented outbreak in UK (Outbreak Control Team, 1996); >1% 'hospita lised' in large Mi lwaukee outbreak (Morris et al., 1996) Salmonella: 2.3% 'hospita lised' in US outbreak (Angu lo et al., 1997)

40% of cases are in chi ldren (worst case scenario 35%; best 45%)

43% of cases in children <15 years old in well documented waterborne cryptosporidiosis outbreak in UK (Outbreak Control Team, 1996)

65% of paediatric hospita l attendances attend the monitored hospitals (worst case scenario 60%; best 75%)

65% actua lly attended in 1996

Norma lly distributed over 3 weeks (SD=3 days) 65% of paediatric gastroenteritis cases are coded as such (worst case scenario 60%; best 75%)

Other wel l described cryptosporidiosis outbreaks in the US and UK fit this criterion (Outbreak Control Team, 1996; MacKenzie et al., 1994; Leland et al., 1993) No published data: Emergency department director's consensus that th is is a reasonable and conservative figure





Modelled outbreaks 100,000


50,000 20













1319195 15110/"96 16f l1 /'9G 181 12/9e HW1/97


241319 7





31 /Ml7


Figure 1 Giardiasis in Melbourne, with modelling of anticipated reports from outbreaks 30

Hospitals Gastroenteritis rates in children (<1 7 years) at the major em ergency departments in M elbourne over a 20-month period are presented in Figure 4. W e obtained data from the Royal Children's, W estern (Sunshine campus) and Franks ton Hospitals. T hese three hospitals see 65% of such patients in M elbourne (data not shown). M onash M edical Centre was not included in the analysis since it has been computerised only since the latter half of 1996. Again, we m odelled the expec ted impact of o utbreaks of gastroenteritis m M elbourne of 20, 000 , 50 ,000 and 100 ,000 cases, ass uming a stable background rate of endemic gastroenteritis. It is important to note that the accuracy of the modelling is highly dependent on the assumptions used. Figure 5 shows the outcome w hen a 'worst case' set of assumptions is used . Likewise, Figure 6 shows the outcome w ith m o re ge nerou s ass umptions. These are n o t unrealistic: 75% of hospitals could now be easily monitored by adding in the data from the M o nas h M edical Centre, the o ther m aj or paediatric hospital in M elbourne.

Modelled outbreaks : 100,000






! "

.8E :,




Figure 2 Giard iasis in Melbourne (modell ing superimposed on natural variation) 140

,:, 120 Cl>



Salmonella outbreak in peanut butter reported in media June 20

Modelled outbreaks 100,000











M elbourne . Figure 3 reveals the number of faecal specimens handled on a daily basis throughout 1996. Noteworthy is the large increase in specimens processed in late June, w hich coincides with the release of publicity conce rning a fo od poisoning scare of Salm on ella m peanut butter. (Interestingly, laborato ry staff did not notice an increase in the total number of Salmonella isolated at this time-the outbreak was identified because of the unu sual type of Salmon ella isolated rather than an increas~ in the overall numbers. W e then modelled the expected impac t of outbreaks of gastroenteritis in M elbourne of 20,000 , 50,000 and 100 ,000 cases, assuming a stable background rate of endemic gastroenteritis (see Figure 3) .



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Figure 3 Faecal specimens processed in Melbourne, with modelling of outbreaks of gastroenteriti s

exorbitantly expensive . Two data sources appeared to show the most po tential: emergency department attendance figures and processing of faecal specimen s by pathology laboratories . Each of these shares the attributes of being: • already collec ted on elec tronic databases in real time • a short interval between disease onset and data collection • potentially accessible at low cost.

Accordingly, we obtained data from these two sources and then modelled the expec ted effec t on these data so urces of w aterb orne o utbrea ks of 20,000, 50,000 and 100,000 cases, assuming a stable background rate of endemic gastroenteritis and using the assumptions presented in T able 1.

Faecal Specimens The two largest private laboratories handle around 85 % of the faecal specimens tested by general practitioners in

Discussion M any wa terb orne o utbreaks are detected due to serendipity rather than active surveillance. Earlier identification of wa terborne ou tbreak s of gastroenteriti s should allow earlier intervention and investiga tion. The ability of current surveillance m echanisms to rapidly identify a waterborne outbreak of gastroenteritis is unknow n but is generally believed to be low. W e show it to be associated with considerable lag periods. W e concluded that if large waterbo rne outbreaks were to occur we could not rely on the existing surveillance systems to detect them in a timely fashion . The large numbers of background cases of endemic gastroWATER NOVEMBER/ DECEMBER 1998




that may provide more sensitive and rapid surveillance for w aterborne gastro enteriti s, ye t there is little evidence that the utility of such data sources has been evaluated in a scientifi c manner . Mo st people w ith gastroenteritis stay clea r of doctors. Th ey simply pu t up with their symptoms and a large number will stay home . Moreover, monitoring of absenteeism at schools and workplaces presents major logistical problem s, as would monitoriIJ.g o illness in nursing homes. If people w ith gastroenteritis do take som e action, it is likely to be a visit to the pharmacy. Monitoring of pharmaceutical sales in real time would presently be a nightmare, though this is changing rapidly with new point of sale monitoring equipment currently being trialled in Australian pharmacies . This could well represent an opportunity for surveillance in the near future. Around 10% of people with gastroenteritis w ill visit their GP, b ut real time monitoring of GP attendances wo uld require m assive inves tment . Thi s type of monitoring has been trialled in France, though not specifically for waterborne gastroenteritis.



"'"; 15

Emergency department attendances for gas troenteritis a'nd pro cessing of fa ecal specimens by pathology laboratories currently appear to hold the most promise as surveillance tools for the rapid identifi ca tion of wa terborne outbreaks of gastroenteritis. U sing w hat we believe to be acc urate ass umptions, we feel that monitoring of fa ecal specim ens is the most sensitive m ethod to pick up outbreaks that m ay be missed by the current system and could be a usefu l adjunct to existing surveillance sys tem s. Monitoring of pae diatri c em ergency departments appears to be so m ewhat less se n sitive, but could provide usefu l geographic information and wo uld be relatively easy to obtain at moderate cos t. Further resea rch is required. U ltimately, one could envisage a system co mparing such data sources versus water quality data using geographic information system technology. Such a system could minimise the background 'noise' due to endemic gastroenteritis and highligh t distributions of gastroen teritis in the communi ty that would implica te water as the likely so urce. Technological change m ay soon make other new data sources cost-effective as surveillance tools.



Modelled Outbreaks: 100,000 50,000

40 ~



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Figure 5 Emergency department attenda nces for paed iatri c gastroenteritis in Melbourne, with mode ll ing of outbreaks (wo rst case assumptio ns)


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Figure 6 Emerge ncy department attendances fo r paediatric gastroe nterit is in Me lbourne, wit h mode lli ng of outb reaks (optimistic assumptions)

enteritis make even a very large outbreak difficult to detect. In these circumstances our aim was to identify if more rapid surveillance techniqu es were feasible. N ewer 14


co mputeri se d data sources such as em ergency department attendances for gastroenteritis and processing of faecal specimen s by pathology laboratories have been put forward as alternatives

Acknowledgements This proj ec t was fund ed by the Cooperative R esea rch Ce ntre for W ater Quality & Treatment and Melbourne Water. The authors thank the following people for their assistance

WATER w ith thi s project: Pam Lightbody, Margare t H ellard, Jes sika Willis and Li sa Demos of the Department of · Epidemiology and Preventive M edicine, Monash University; Liz Snash ell of Dorevitch Pathology; Andrew Rothfi eld from Frankston Hospital; Malcolm Eaton of Gribbles Pathology; Chris T etley from HAS Solutions Australia ; Sri Ananthakumar and Geoff Gardner from M elbourne Water ; P eter Barnett at the Royal Children's Hospital; and Garry Ayton from Western Hospital (Sunshine Campus).

References Aho M. et al. (1989) Waterborne O utbreak of Campylobacter Enteritis After Outdoors Infantry Drill in Utti, Finland. Epidem Inf , 103: pp. 133-141. Angulo F et al. (1997) A Communi ty Waterborne Outbreak of Salmonellosis and the Effectiveness of A Boil Water Order. Am J Pub H ealth, 87 (4) : pp. 580-584. Environmental Protection Agency (1990) Workshop on Methods for Investiga tion of Waterborne Disease Outbreaks : Summary of Recommendations, USEP A, Office of Research and D evelopment: Washington , D C. Frost F C and G F, Caldero n R L (1996) Waterborne D isease Surveillance . Journal

~\\C Pl(/~

AWWA: pp. 66-:-75. Garthright WE, Archer D Land KvenbergJ E (1988) Es timates of Incidence and Costs of Intestinal Infectious Diseases in the United States . Public Health R eports, 103 (2): pp. 107-115. H ayes E B et al. (1989) Large Communi ty Outbreak of Cryptosporidiosis Due to Contamination of A Filtered Public Water Supply. New Eng] Med, 320 (2 1): pp . 1372-1376. H ellard M and Fairley C K (1997) Gastroenteritis in Australia: Who, What, Where, and How Much? Aust NZ J. Med, 27: pp. 147-149. Infec tious Diseases Unit (1996) Surveillance of Notifiable Infectio us D iseases in Victoria , Public H ealth D ivision, Victorian Government D epartment of Human Services: M elbourne. Kramer M et al. (1996) Surveillance for Waterborne-disease Outbreaks-United States, 1993-1994. MMWR. 45 (SS-1 ): pp . 1-33. Leland D et al. (1993) A Cryptosporidiosis Outbreak in A Filtered-wa ter Supply. Journal AWWA, 85 (6): pp. 34-42. MacKenzie W et al. (1994) A Massive Outbreak in M ilwa ukee of Cryptosporidium Infection Tra nsmitted Through the Public Water Supply. New Eng ] M ed, 331 (3): pp. 161-167. M andell G L, Bennett J E and D R (Eds.) (1995) Mandell, Douglas and Bennett's Principles and Practice of In fec tiou s Diseases, 4th ed. , C hurchill Livingstone:

Plastic Plumb ing Supp lies Ply ltd .

New York. Moore A C et al. (1993) Surveillance fo r Waterborne Disease Outbreaks: United States, 1991-1 992 . MMWR, 42 (SS-5): pp. 1-22. Morris RD et al. (1996) Temporal Variation in Drinking Water Turbidity and Diagnosed Gastroenteritis in Milwaukee. Am] Pub Hlth , 86 (2) : pp. 237- 39. Outbreak Control Team (1996) Outbreak of Cryptosporidiosis, South and West Devon , August to September 1995, South and West D evo n H ealth Authority: Shinner's Bridge, Dartington, UK. Richardson AJ et al. (19 1) An Outbreak of Waterborne Crytosporidiosis in Swindon and Oxfordshire . Epidemiol. In fect. , 107: pp. 485-495. Schwartz J , Levin R and H K (1997) Drinking Water Tu rbidi ty and Pediatric Hospital Use for Gastrointestinal Illness in Philadelphia. Epidemiology, 8 (6): pp. 615-620.

Authors Dr Alex Padiglione is a lecturer in the Department of Epidemiology and Preventive M edicine, Monash M edical School, Alfred Hospital, Prahran Vic 3181, a partner in the Cooperative R esearch Centre for W ater Quality and Trea tment. Associate Professor Christopher (Kit) Fairley is H ead of the Infectious Disease Epidemiology Unit at Monash Medical School.

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IMPORTANT G Newcombe, C Pelekani, C Hepplewhite, K Nguyen Abstract Natural organic m atter (NOM) present in drinking water sources has been shown to adversely affec t all aspects of water quality and trea tment pro cesses, including disinfec tion , coagulation and flocculation, activated carbon adsorption, and ba cterial regrowth in the distribution sys tem . A knowledge of di stribution can be of great benefit to the understanding and optimisation of these processes. The size of NOM is an important fac tor in the effect ofNOM on water treatment. The resea rch outlined in this paper focuses on the application ofHPSEC in the study of a range of wa ter trea tment processes including chlorination, coagulation and activated ca rb o n adsorption.

Key Words NOM, size exclu sion chromatography, molecular weight, chlorination, coagulation adsorption

Introduction Natural orga nic matter (NO M ) present in drinking wa ter sources has been shown to adversely affec t all aspects of water quality and trea tment pro cesses, including disinfection, coagulation and flocculation , activated carbon adsorption, and bac terial regrowth in the distribution system. Morran et al. (1996) provided som e 16


examples of the adverse effects NOM has on these processes , including: • reacting with coagulants causing slower, less effective flocculation , resulting in increased coagulant demand and coagulant residuals • increasing the disinfectant demand and forming chlorinated disinfection byproducts • acting as an organic food source for microorganisms, resulting in bacterial regrowth in the disrribution system • reducing the capacity of activated carbon for target rrµcropollutants (taste and odour compounds, algal toxins) by compe ting for active sites and blocking pores • redu cing the effectiveness of membrane mi crofiltratio n by irreversible fouling. The size of NOM is an important fac tor in the effect of NOM on water treatm ent. C hadik and Amy (1986) studied the impact of coagulation and adsorption on the molecular weight distributions of several natural waters in th e United States. As a general trend, alum coagulation was fo und to remove higher molecular weight material, while ac tivated carbo n adsorption was observed to remove a broader molecular weight spectrum of material. T his is in agreem ent with the res ults of other studi es (El-Re haili and Weber Jr ., 1987) . The molecular size or weight distribution of NOM can be determined

using ultrafiltration (Amy et al. , 1992) or aqueous gel permeation chromatography (GPC). However, it is important to note that these proced ures are calibrated with comp o unds (e.g. proteins) w hi ch have very different structures from NOM. As a result, these methods can only provide a relative size distribution . It is therefore advantageou s to obtain supporting data from alterna tive size evaluation techniques such as field flow fractionation, vapour pressure osmometry (VPO) , and small angle X-ray scattering (SAXS). High performance size exclusio n chromatography (HPSEC), a molecular separation based on hydrodynamic size, is o ne form of GPC that has been widely used for the analysis of proteins and polymers. HPSE C is based on the ability of molecules to access p ore volume w ithin a porou s gel. Small molecules can access a grea ter fraction of the total pore volume and therefore elute later than larger molecules . The technique was initially developed for purification of biologica l co mp ounds in the pharmaceuti ca l industry, but has been use,d for characterising aq uatic organic matter since the 1970s (Amy et al. , 1992; Amy et al. , 1987; T hurman et al. , 1982; Gloor et al. , 198 1; Miles and Brezonik, 1983) . Recent work by C hin et al. (1994) showed that HPSEC can yield reliable molecular weight distributions of

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Figure 1 Effect of chlorination on NOM along the Ma nnum-Adelaide

Figure 2 HPSEC chromatograms of Hope Val ley UF NOM fractions


NOM without the compli ca tion of significant solute-gel interactions that have plagued the use of thi s techniqu e for accurate and quantitative size analysis ofNOM in the past. HPSEC molecular weight distributions were obtained for a variety of natural waters of different origin, using specific environmental and operating conditions and calibration compounds. Molecular weight di stribution parameters comparable to those obtained using independent measurement techniques such as VPO and SAXS were obtained. The aim of this research was to use HPSEC to elucidate the effect of different water treatment processes on the molecular weight distribution ofNOM from different Australian water sources and to evaluate whether the technique provide s useful information for the optimisation of water treatment plant operations.

Materials and Methods Three natural water sources were used in this study: M yponga reservoir, River Murray, and Hope Valley reservoir. Myponga is located 60 km south of Adelaide and Hope Valley is located 15 km north-east of Adelaide. Raw and treated water were collected from the laboratory of the water treatment plants at Hope Valley and Myponga. River Murray wa ter was collected from Mannum, loca ted 80 km north-east of Adelaide. All samples were filtered through a 0.45 mm cartridge filter and stored in the fridge to minimise biological growth. NOM fractions prepared from the concentration and ultrafiltra tion of Hope Valley reservoir water were also used for the adsorption kinetics and simulated chlorination experiments . The NOM was concentrated using a strong anion exchange resin. The isolation and ultrafiltration (UF) procedure is summarised elsewhere (Newcombe

• d < .8 nm • 8 < d < 2 nm • 20 < d < 50 nm. Th ese regions correspond broadly to primary micropores , secondary micropores and mesopores respectively. These two ac tivated carbons are under consideration for use in suburban and country water treatment plants in South Australia for removal of taste and odour compounds and algal toxins. Adsorption kinetics experiments were perfo rmed with Hope Valley NOM fractions. 1. cJ g of activated carbon was added, with constant stirring, to a 5 L volumetric fla sk containing a solution of 15 mg DOC/L. 20 mL samples were collected at various times and were immediately filtered through a 0.45 mm filter. Five Hope Valley ultrafiltration NOM fractions dilu ted to 10 m g DO C/L were chlorinated with a dose of 20 mg/Las chlorine (Cl 2) . The reaction mixtures were allowed to stand for eight days in sealed bottles in the dark at ambient tempera ture. The chlorinated fractions were quenched with 1 mL of 0.01 M sodium sulphite to neutralise 1

and Drikas, 1996) . HPSEC was performed according to the method of C hin et al. (1994) using a Waters Protein-Pak 125 glycolfunctionalised silica gel column (Waters Corp., Milford , MA, USA) . However, for the adsorp tion kinetics and simulated chlorination experiments a Shodex KW802 .5 silica gel column (Waters Corp. , Milford, MA, USA) was used . UV-254 absorbance was m easured spectrophotometrically with a 1 cm cell. Colour was measured at 456 nm with a 5 cm cell. A platinum-cobalt colour standard of 50 Hazen Units (HU) was used to convert from absorbance to HU. Di ssolved organic carbon (DOC) was determined by the UV/persulphate oxidation m ethod usmg a TOC analyser (Skalar). Two powdered activated carbons (PAC) with different physico-chemical properties were used for the adsorption experiments. Table 1 summarises their physical characteristics. The pore volume is divided qualitatively into three regions , based on pore width (d):

Table 1 Ph ysica l properties of activated carbons Base material

Activation method

BET Surface area (m2/g)

(d <8A)

{8<d < 20A)

(20 < d < 500 A)

Picazine HP







Picatif PCO


Th ermal






Pore vo lume (cm 3/ g)

Table 2 Effect of chlorination on NOM chemical properties Sample


Colour (HU)

DOC (mgL·1 )

SUVA (Lm-1mg-1 )

Specific colour ,( l.HU.mg-1 )

Raw Murray Mannum (post Cl2) Pipeline (2 kms) Tungkillo (30 kms) Anstey Hill (80 kms)

0.122 0 .088 0.085 0.086 0.087

13 4 4 4 4

4.1 4.6

3 .0 1.9

4.4 4 .2 4.2

1.9 2.0 2.1

3.2 1.0 0 .8 0.9 0 .9



WATER 0.06

0 .06

Chlorinated fractions


:I*-\ • ·.. •~




··... t

. .. ...

\ •··.


g 0.02 Q)


"O 0

- - <500 ··· •· ·· 500-3000 ·········· 3K-10K ···<>···· 10K-30K -<>->30K



;"' 0.04

ii!C 0






····- ....... .

• Raw Myponga -










u &






> :::,

""' -0.02 + - - - ~ - - - . - - - ~ - - - . . . - - - ~ - - ~ 6000 4000 2000 0

0 .00 ... . - --+---'l'~-,----,----,....--+-- · ~-.......= ~'=":;:":="~"~""~·!.!"!.!.'!..!"!.µ.I~ 100

Appa rent molecular weight (g/mol as PSS)






Apparent molecular weight (g/mol as PSS)

Figure 3 HPSEC chromatograms of chlorinated Hope Va ll ey UF NOM fractio ns

mg/L of chlori ne residual. Samples were fi ltered through a 0.45 mm filter.

Discussion The Mannum-Adelaide pipeline runs for m ore than 80 km from M annum, o n the River Murray, to the Adelaide Hills. There are several chlorination stations along the pipelin e. T he obj ective was to evaluate the impact of chlorination on the NOM m olecular weight distribution along the pipeline. At the time the survey was conducted only one chlorination station was in operatio n. This was the first chlorination point at Mannum. Samples of raw and chl orinated water were collected at different loca tions along the pipeline. The chlorine do se applied was approximately 4.5 mg/L as C l 2 . Figure 1 illu strates the SEC results for the chlorination survey. T here was a distinct decrease in UV260 detector response after chlorination, as well as a shift towards lower molecular weight compounds. T hese observations indica te that chlorine breaks down larger molec ular weight organic compounds into smaller compounds, and also attacks double bonds and aromatic rings . Table 2 summarises the changes in absorbable UV and colour after chlorination . Specific UV254 absorbance (SUVA: defined as 100 times the absorbance through a 1 cm cell divided by the DOC co ncentration), and specific colour decreased by 37 per cent and 70 per cent respectively. With increased contact time along the pipeline, there were small decreases in both colour and UV-254. A significant increase in DOC (0.5 mg/L) was observed after the initial chlorination. The following DO C so urces we re identified as contributing to th e mcrease : • the release of organic compounds (e .g. extracellular material) from the biofilm present on the distribution pipe 18


Figure 4 SEC of raw and treated Myponga water

wall at the point of chlori nation • the release of organic compounds adsorbed onto particulate matter after chlorination. T he consistent decrease in DOC after chlorination is most likely due to uptake of organic compounds by microorganism s present in the pipe wall biofilm. In addition to the effect of chlorination o n the molec ular weight di stributio n of NOM in the distribution system , its effect on NOM fracti ons w ith different molecular weight distribution s was evalu ated . Figure 2 illustrates the SEC chromatogram s for the five Hope Va ll ey UF fractions before chlori nation. Figure 3 shows the subsequent impact of chlorination. C hlorinati on had a dramatic impac t on both the chemical properti es and molecular weight distribution of all frac tions. T here was a pronounced shift towards lower molecular weights as well as a marked decrease in UV-absorbing NOM. This clea rly indicated that chlorination results in the breakdown of hi gh molec ular weight material to smaller compo und s and also attacks double bonds and aromatics. Furthermore, the molec ular weight distributions of all the frac tions after chlorination were very similar, peaking at approximately 2,000. These results clearl y support the results obtained in the di stribution system, but show the extreme case given the laboratory treatment conditions (20 mg/L C l2 dose for eight days) . These conditions are highly unlikely to be used in conventional treatment practice. Table 3 Chemical properties of raw and t reated Myponga water Sample

DOC (mgl ·1)

UV-2 54

SUVA (Lm·1mg·1)

Raw Treated

11.5 4.3

0.43 0.098

3 .7


M yponga water was used to evaluate the effect of coagulation on NOM molec ular weight characteristics. Thi s water treatment plant uses the fo llowing treatment train: coagulation, flo cculation, dissolved air flotation , sand filtration , and chlorination before storage and distribution. The plant uses alum as the coagulant, and at the time of sampling the alum dose was 75 mg/L. Aluminium residu als in the trea ted wa ter were less than 25 mg/L. Treated wa ter samples were collected directly after sand filtration . R'<lw water samples were not chlorinated. Figure 4 illustrates the HPSEC results obtained for the raw and treated waters. Figure 4 shows a very significant removal of the high molecular weight NOM (> 1000). This is con sistent with other studies w hich have shown that coagulation preferentially rem oves the high molecular weight material. T he changes in UV-254 and DOC are summarised in Table 3. The treatment train effectively removed DO C (63 per cent) and UV-254 (77 per cent). SUVA decreased by 38 per cent. M ost of this is likely to be due to removal of highly colo ured large m olecular weight material by coagulation , rather than the destru ction of aromaticity and double bonds present in NOM . Comparison of serial fractionation HPSE C data (samples not pre-concentrated) with the treated Myponga HPSEC showed that the 500- 1,000 fraction yielded very good agreement (see Figure 5) . This result indicates that it may be possible to model the molecular weight distribution of treated water (from co nventi o nal trea tment processes) w ith a particular UF size fraction. This could be used to optimise treatment strategies for removal of these low molecular weight compounds. One observation is that the peaks of the two chromatograms appear to be slightly skewed. This is a result of the small differenc es in the semi-logarithmic

WATER 0.16



, Treated Myponga 0.8

0. 12


E C:

;,; 0. 10





> ~ 0.08



::, 0.06





• f

O o - 0-

Raw Myponga (UF 500 - 1000 fraction)

2 >"'



0.04 0.02


0 - 0 - 0-

- o- P1cat1f PCO











Time (min)

Apparent molecular weight (g/mol as PSS)

Figure 5


• - P1cazme HP


0.00 0


Norma lised SEC plots for treated Mypo nga and

500 - 1,000 fraction of raw Myponga water

Figure 6 Effect of carbo n adsorbe nt on the adsorption kinetics of 500-3,000 fraction

0.22 0.20 Q) <I)


0 C.



0. 10


0.12 0.10

- •-








'O 0






- o - t= Omin 1t=5min - ,-t=30min t=60min ~ - •- t = 120 min

Q) <I)

- - t =60min t=120min - •- t = 300 min




-o-t=O min 1t =S min - , - t =30min

"' "'::, >


> ::,

0. 18 0.16

t = 300 min

0.08 0.06 0.04 0.02


0.00 -0.02 0






Apparent molecular weight (g/mol as PSS)

Figure 7 SEC of 500-3,000 NOM fraction after Picatif PCO adsorption

mol ecular weight calibrati on curves . Activated carbon is widely used 111 wa ter treatment for the removal of taste and odour compounds , algal toxins, synth e ti c organic contaminants and NOM. For contaminant removal , it is usually applied in powdered form at the head of the plant to maximise co ntact time before removal at the filters. Granular activa ted ca rbon filters are more commonly employed fo r NOM rem oval. Figure 6 illu strates the effect of different carbon adsorbents on the rate of adsorption of the UF 500-3,000 NOM fraction, fo r a PAC dose of200 mg/L. Picazine HP showed rapid adsorption , w hich is a con sequence of the large volume of m es opores w hich permit fas t transport of NOM molecules to adsorption sites (see Table 1). Picatif PCO , however, has negligible mesopore volume but only signifi cant quantities of the smaller primary and seco ndary mi cropores. T he sm aller pores result in a redu ction in the rate of diffusion because of molecular steric hindrance. T herefore, the pore volu me distribution of an activated carbon has a significant impact on the rate of adsorp-






Apparent molecular weight (g/mol as PSS)

Figure 8 SEC of 500 -3,000 NOM fracti on after Picazine HP adsorption

tion of NOM. This has implicati ons in of NOM . In the distrib ution sys tem wa ter treatment operations w here the (source to treatment facility) , disinfeccontact time is often limited. It should tion u sing chlorine resulted in the be noted , however, th at the choice of breakdow n of large NOM compounds activa ted carbon for a particular wa ter to smaller products with a significant trea tment application should not be reduction in UV absorbing NOM and made solely on adsorption kineti cs , but colour. Simu lated chlorination experialso on equilibrium studies and the m ents wi th isolated NOM fractions physical properties of the adsorbent 'Low molecular weight fractions and how they will of NOM are responsible for most impact trea tmen t performan ce . chlorinated by-products of public Figures 7 and 8 show the transient health significance.' change in molecular weight distribution of the NOM. Pica tifP CO showed poor supported these observations, and removal over the entire range of molec- showed that under extreme conditions ular weights. T his is in contrast to the products formed by di sinfec tion Pi cazine HP w hi ch showed significant have similar molecular weight distriburemoval over all molecular sizes . tions regardless of the initial characteristics of the NOM . AJum coagulation was Conclusions sh own to clearly targe t the higher HPSEC is a relatively quick and molecular weight compo,unds. Actisimple me thod for obtaining u se ful vated carbon adsorption showed that m olecu lar weight di stributi ons of NOM removal takes place over the natural organic matter. T he m ethod was range of molecular weights, although show n to be a powerful tool in deter- th is effect depends to a great extent on mining the impact of selected wa ter the pore volume distribution of the treatment processes on the composition adsorbent. WATER NOVEMBER/ DECEMBER 1998


WATER HPSEC supplies valuable information that can be used in the optimisation of various water treatment processes. For example, the low molecular weight fractions of NOM are responsible for most chlorinated disinfection byproducts of public health significance (e.g. trihalomethanes and haloacetic acids). Laboratory-scale tes ting of different treatment processes will allow for development and optimisation of methods which targe t these low molecular weight compounds. The focus of current research has shifted to validati ng the HPSEC technique used in chis study with different column gel materials, as well as more sophi sticated independent molecular weight determination techniqu es, primarily flow field-flow fractionation, in order to obtain estimates of the hydrodynamic size of NOM. This is important from the viewpoint of competition between micropollutants and NOM for adsorption sites on activated carbon where the size of the adsorbates relative to the carbon pore size distribution influences the molecular competition mechanism.

References Amy G L, Sierka RA , BedessemJ, Proce D and Tan L (1992) Mo lecul ar Si ze Di stribution s of Dissolved Organic

Matter,] A WWA , 84 (6), pp 67-75. Amy G L, Collins M R , Kuo C J and King P H (1987) Comparing Gel Permeation Chromatography and Ultrafiltration for th e M olecular W eight Characterization of Aquatic Organic Matter, J A WWA, 79: (1), pp 43-49. Chadik P A and Amy G L (1987) Molecular Weight Effects on THM Control by Coagulation and Adso rption, J Environ Eng, 113: (6), pp 1234-1248. C hjn Y , Aiken G and O 'Loughlin E (1994) Molecular W eight, Polydispersivity, and Spectroscopi c Properti es of Aquatic Humic Substances, Environ Sci Technol, 28, pp 1853-1 858. El-Rehaili A M and Weber Jr W J (1987) Correlation ofHumic Substance Trihalomethane Formation Potential and Adsorption Behavior to Molecular W eight Distribution in Raw and Chemically T reated Waters, Water R es, 21 (5) pp 573-582. Gloor R , Leidner H, Wuhrmann K and Fleischmann T (198 1) Exclusion Chromatography with Carbon Detec tion. A Tool for Further Characterization of Dissolved Organic Carbon, Water R es, 15, pp 457-462 . Miles C J and Brezonik P L (1983) High Performance Size Exclusion Chromatography of Aquatic Humic Substances, J Chrom, 259 , pp 499-503. Morran J Y, Bursill D B, Drikas M and Nguyen H (1996) A New Technique for the Removal of Natural Organic Matter, Proceedings of th e Australian Water and

Wastewa ter Association WaterTECH Conference, 27-28 May 1996, pp 428-432. Newcombe G and Drikas M (1996) Characterization of Natural Organi c Matter from Myponga Reservoir and the Effect on Activated Carbon Adsorption, Proceedings of the Australian Water and Wastewater Association WaterTECH Confez·ence, 27-28 May 1996, pp 442-447. Thurman EM, W ershaw R L, Malcolm R L and Pinckn ey D J (1982) Molecular Size of Aquatic Humic Substances , Org Geochem, 4, pp 27-435.

Authors Gayle Newcombe 1s a Senior Research Scientist at the Australian Water Quality Centre, spending a large proportion of her time supervising CRCWQT projects. She ha s a Master of Applied Science from the University of South Australia. Con Pelekanl is a PhD candidate in Environmental Engineering and Fulbright scholar at the University of Illinois. He works with the CRCWQT when he is visiting Adelaide. Chris Hepplewhite is a PhD student and works at the CRCWQT. Kim Nguyen contributed to this work while she was an Adelaide University summer scholarship student with the CRCWQT.

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WATER .!!1

~ t,




" C: (1)

·u Cf)

"O 0 0



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0 0


,~tf..~·- '',• .... ':· '





.l~.~... ·, .·. ·. <.b' ·".!)j- .... '. ~··· -


From farm to fork, from paddock to plate, from catchment to tapcan the 'space-age' food industry quality assurance system known as 'HACCP' be used to deliver safe drinking water? Abstract The United Nations Food and Agricultural Organisation (FAO) and World H ealth Organisation (WHO) have pu sh ed forwa rd guidelines to ass ure food safety. These guidelines, accepted on both a domestic and international level, stipulate that food producers must implement a Hazard Analysis and Critical Control Point (HACCP) sys tem that focuses on controlling hazards as close to their so urce as pos sible. Whilst drinking water supplies are currently no t subj ect to this approach , incidents of suspected contamination of otherwise compliant drinking water supplj es have led to tough new changes to overseas drinking water regulations. Australia now faces press ure to bring in pathogen control regulations for water, but lessons learnt in the foo d industry point to the failure of using presc riptive end- product testing. They also highlight the djfficulties inherent in setting precise limits on allowable pathogen densities . T he implem entation of HACCP in the water indu stry wo uld not provide a quick fi x . However, once implemented , it

co uld provide the most protective and cost-effec tive means of ass uring the sa fety of drinking water.

Introduction Australian drinking waters mu st co mply w ith National H ealth and M edical R esearch Council (NHMRC , 1987 or 1996) or WHO (1984 or 1993) Guidelines for thermotolerant (faecal) and total colifo rms. However, it is still po ssible for compliant di sinfec ted drinking wa ter to contain densities of pathogens that may be considered undesirable . If new regulations are

brought in to regulate drinking water supplies in terms of pathogen concentration s, they co uld encompass two approaches: • end-product testing or • quality assurance (QA). A brief review of regulations developing overseas provides early warning of w hat could be enacted in Australia. In this paper we consider the interna tionally accepted food safety QA framework, HACCP (pronounced 'hass-up') as a suggested alternative and possible best approach to the production of safe drinking wa ter.

Examples of Legislative Options As a response to the Cryptosporidium and Giardia incident in Sydney, legislative changes are being called for. For example , the N ew South Wales Oppo sitio n leader, Peter Collins, suggestyd the enac tm ent of a safe drinking water bill similar to that introduced in the USA under similar conditions (Hogarth , 1998, US Safe Drinking Water Act Amendments 1996). In the UK new regulations have been propo sed as a response to WATER NOVEMBER/ DECEMBER 1998


WATER recent cryptosporidiosis o utbrea ks. One of these was the Three Valleys W ater Company case, w here a boil wa ter alert affecting 300,000 people was in effect fo r 16 days 111 M arch 1997 (H ealth stream , 1997) . Under a prop ose d amendment to ex1st111g regulations, the W ater Supply (Water Quality) R egulation s 1989 am ended under the W ater Indu stry A ct end-produ ct 1991, testing will be required to measure levels of C ryptosp oridium m water. Water en te rin g supply should no t contain m ore than an average of one oocyst per ten litres . · A ny wa ter autho rity exceeding thi s sta ndard will be subj ect to a fin e. Limitations of End-product Testing In Safety Management A finish ed water cou ld be tested for a suite of pathogens such as: • Campyloba cter • Salmonella • Gia rdia • Cryptosporidium • Norwa lk vi ruses • Rotavi ru ses and/ or an increased range of ind icators such as : • Escherichia coli to indicate possible bacteri al contamination • Clostridium perfringens to ind icate possibl e protozoan and viral contamination • Bacteroides fragilis phage to indicate possibl e human vira l contamination . Regulations could stipu late compl iant densities of these microorganisms which wo uld be included in microbiological monitoring programs. Although this approa ch appeals to common se nse, in practi ce it is not yet workable and even if it were, wou ld be subject to a range of seriou s limitations, some of wh ich could be overcome in future years, such as: • detection methods are too complex and costly for widespread , rout ine application • monitoring methods do not assess infectivity for humans (even pathogens of the same species vary widely in their potentia I i nfectivity) • there is no agreement as to what wou ld constitute an acceptable level of risk or an acceptab le density of pathoge ns/i ndicators in finished water. However, the most significant limitation of end-product testing cannot be overcome even if rapid or rea l-time monitoring methods were deve loped. This is because once unacceptable densities of pathogens are found in an endproduct contamination has already occurred and the system has fail ed. End-produ ct tests provide nothing more than an ' it's already too late ' approach to assuring safety.



Samples will be collected using a drip fee d conce ntrato r that passes 1,000 litres of trea ted water acro ss a sample collecting device over a 22-hour period (leaving two hours to change the device each day) . C ollected samples will be analysed within three days . So far, Cryptosporidium is the only subj ect of this UK regulation , but if other types of outbreaks occur , a precedent has bee n se t that may be expanded. What mu st be understood is that the regulation was no t propo sed based o n sound wa ter quality or public health protection grounds. R ather, the obj ective was to sa tisfy the legal profession by providing info rmati on to aid in defence or prosec ution of a water company in the event of a crypto sporidio sis outbreak or even in the absence of an outbreak. Thi s ca me about after a precedent was se t during the unsuccessful prosecution of the Three Valleys W ater Company where epidemiological evidence was ruled inadmissible. In the USA waterborne outbreaks such as the Milw aukee outbreak in 1993 have led to increasingly stringe nt regulati on s aimed at controlling pathogen levels in drinking wa ter supplies. The Surfa ce Water Trea tment Rule (SWTR) of 1989 has been superseded by the Interim Enhanced SWTR of 1994 combined with a research program to develop a Te rm E nhanced SWTR Lo ng (LT2ESWTR). These rules are at odds with the proposed UK regulation in that they do not regulate according to m aximum fini shed wa ter pathoge n levels. Instead , the USA regulations stipulate wa tershed co ntro ls and/or wa ter treatment m e thod s to en sure minimisa tion and/or removal of high pathogen loadings . The Environment Protectio n Agency justifies this on the foll owing premises: • there is insufficient epidemiological knowledge for setting maximum contaminant levels • methods of detection are not suitable for routine policing • it would be too late to protec t the public from increased health risk if m easuring of contamination was done once water had entered the supply system . It is too early to say w hat form the LT2ESWTR will take, but it seem s likely to be based on a holistic approach in w hich regulations refer to both ca tchment managem ent and trea tment.

A ri sk-based approach might be stipulated that would be specific for each w ater harvesting and supply system. Such an approach has many elem ents common to the HACCP system that is now used fo r minimising pathogen exposure from foodstuffs.

HACCP-A Space Age Approach to Assuring Safety HACCP is an adyanced , internationally accepted safe food ass urance system similar to ISO 9000 and ISO 14000 sen es m anagem ent sys tem s. The approach was originally developed in the 1960s for the design and manu facture of food s for use in space flights. Within two years of the first moon landing, the HACCP system was in commercial use 111 the everyday m anufa cture of consumer foods. During the space program, extensive evaluation was done on the best way of guaranteeing safe fo od . The conclusion was reached that it was essential to have control over the raw m aterials, the process, the environment and the people involved. H azards could then be controlled as early in th e process as possible. It was from this approach that the HACCP co ncept was born. T erms such as 'fa rm to fork ' and ' paddoc k to plate' are used to describe thi holi stic approach. In 1988 , the International C ommission for the Microbiological Sp ecifi ca tions for Food (IC MSF) produ ced its fourth volume covering Seven Principles of HACCP In 1994, the Genera l Agreement on Tariffs and Trade (GATT) specified that food safety systems should be standardised based on the Hazard Analysis Critical Control Point approach (HACCP) or equivalent (Dillon , 1998). HACCP is a risk-based, risk prevention and risk management model that comp rises the following fundamental steps: • conduct analysis of the system • identify the critica l control points • establish target leve ls and crit ica l limits • estab lish a monitoring system • estab lish corrective action • establish verification • establish documentation . The food industry has embraced this approach as a means of pinpointing the likely occurrence of risks to food with in the production process (farm to fork). Water is not only a 'food' ar)d therefore amenable to this type of ana lysis (from catchment to tap), but the key account holders for water authorities are food , beverage and pharmaceutical companies. Al l produce goods to be consumed and therefore require raw materials of the highest quality (including water).

WATER HACCP in food safety and quality. In 1991 , this was followed by the Codex Committee on Food H ygiene, 'Guidelines for the Appli ca tion of the H aza rd Analysis and Critical Control Point (HACCP) Sys tem.' This Codex report was adopted by the 20th Session of the Joint Food and Agriculture Orga nisation of the United N ations (FAO )/WHO Codex Alimentariu s Commission in 1993. Codex initiated a working group to formalise a worldwide approach to th e application of HACCP principles . This approach is · being adopted internationally in the field of food safety. O ve r the next few years, the Au stralian Federal Government, through the Australia N ew Z ealand Food Authority and State H ealth Departments, will be requiring its food producers to implement HACCP systems. M any of our exporters have already done so in response to m arket demand s. A recent special issue of Microbiology Australia, the j ournal of the Au stralian So ciety for Microbiology, was devoted to describing the HACCP approach. This issu e also featured an article by Dr Tony Priestley, Deputy Director of the Cooperative R esearch Centre (CRC) for W ater Quality and Trea tment , o n the activities of the CRC. The article was included beca use of the relevance of safe water as an essential ingredient in most foodstuffs as well as its use in operational activities such as cleaning. Many key account customers of water companies are food m anufacturers. Beca u se the HACCP approach requires understanding and control of hazards in raw materials, these customers will need to know exactly the product they are receiving from their water supplier and will want assuran ce of its safe ty. Even co mpanies supplying apparently innocuous items for the food indu stry such as packaging are implem enting HACCP systems to satisfy the needs of their food manufacturing customers. Thus, a precedent may be set for water suppliers to also have HACCP plans in place. Mu ch of the imp etu s for international application of HACCP ha s come from the food manufacturers them selves . The HACCP framework provides a workable, industry-friendly and cost- effec tive means of protecting public health. The HACCP approach

has not been extended to cover reticulated drinking water supplies . However, as detailed by the Dutch wa ter microbiologist, Dr Arie H avelaar, in 1994, applying HACCP systems to wa ter supply and trea tment pro cesses makes sense . HACCP system s are designed to prevent the end-product becoming contaminated in the first instance. This is achieved through assessment and control of hazards and a focu s on safe operational practices. Indeed , such system s should be so well designed and implemented that end-product testing would only be required during validation . The system would be complete o nce routine end-produ ct tes ting becomes unnecessary. The Au stralian mea t indu stry 1s already using this approach to provide a quality ass ured product. As it is not possible to te st every part of a carcass for microbial co ntamination , HACC P can be used to fill the void between excessive testing and confidence in the safety of the produ ct. Similarly, in wa ter supply system s, it is not economical or feasible for every part of the system to be tested 24 hours a day . It therefore makes sense to identify those areas where most risk is likely to occur and rnitigate those risks.

HACCP in Water Supply Systems The HACCP approach is aimed at controlling hazards as near to their source as possible. In the case of drinking water, since the key microbial pathogens of concern will not grow in those water supplies , the only source of pathogens is faecal material from warm-blooded animals, including humans. Protection of catchments and supply system s and maintenance of trea tment barriers provide the mitigating steps to maintain a safe water supply. HACCP sys tems require detailed evaluation of each step in a process . Monitoring focuses on those factors that can be m eas ured and responded to rapidly, typically electronic devices, such as on-line monitors of temperature, pH , turbidity , particle co unts, net charge, chlorine residu al, flo w and pressure. The integrity of physical barriers such as fe nces and functioning of electrical equipment such as pumps and mixers can also be monitored. To go over a process from 'ca tchment to tap' is a complex task.

Typically it wo uld take aro und a year to develop a HACCP system for a large produ ction process and the system would be subj ect to continuou s improvement over subsequ ent yea rs. External auditing by a H ealth D epartment registered and approved auditor is a prerequi site to certifica tion of a legally valid HACCP system in the food industry. At first sight, it m ~'y appear that wa ter supplies are already managed according to the HACCP approach. For example, ca tchment controls, on-line monitoring, inspec tions and audits all take place . However, these systems often fa ll far short of w hat would be required in a full HAC C P approach . For example, in a HACCP system, it is not enough to simply say that a barrier is in place . To pass a HACCP audit the system would be sc rutinised for co nclu sive evidence that: • the barrier is effec tive w hen working properly • monitoring would pick up fai lure of the barrier • failure of the barrier wo uld be detected in good time for correc tive action to be taken • corrective action would be effective in protecting the end-produ ct. HACCP system s are detailed and system-specific, so a detailed description of a generic HACCP system for a wa ter supply is no t given in this paper. Havelaar (1994) gives a good overview. To give an impression of w hat is involved, w e consider one of the many critical param eters that wo uld need to be continuou sly monitored as part of a HACCP system : • the pH of the wa ter. pH would have to be mea sured co ntinuou sly at a number of locations such as in tanks used for coagulation and disinfection processes. To pass a HACC P audit, the wa ter supplier would need to demonstrate that: • the wa ter at the location of the pH meter was truly representative of water in the rest of the tank. Evidence would need to be derived from validation exe rcises involving modelling of tank mixing and tracer studies or from placing numerous pH m eters at variou s positions and showing that readirtgs were concordant over time and space. If they were not, the tank w ould need to be redesigned and/or multiple pH metres located aro und the redesigned tank • the pH meter was accurate. Evidence WATER NOVEMBER/ DECEMBER 1998


WATER of pH m eter calibration agai1llst an accepted standa rd and system reliability between calibrations would need to be shown • pH meter failure would no t compromise the system. There would need to be a system to detec t pH m eter failure and/or backup pH meters • the actio n limit w here pH is corrected and the critical limit where the system would be taken off line HACCP and Due Diligence

Acknowledging that compliance guidelines may not necessari ly guarantee the quality of the finished water is an important part of HACCP. Using the HACCP · approach to effectively go beyond compliance presents a win to not only the consumer in terms of safer drinking water, but also the water supply authority in establishing due diligence and credibility. To illustrate this, parallels can be drawn with th e ISO 14000 system of environmenta l management standards. The standards direct organisations towards more responsible environmental strategies through targeting and meeting specific goa ls. They provide for policy formulation on environmental management systems including consid eration of the legis lative requirements and information on significant environmental impacts as wel l as specifying continual improvement, i. e. go in g beyond compl iance (Rondi nelli and Vastag, 1996). 'Due diligence ' effect ively means preventing reasonably foreseeable harm. In environmental terms it requires that not only is a system in place to ensure comp liance with environmental legislation , but that the syste m is being fo llowed by means of rigorous supervision and monitoring. The elements of the ISO 14000 environmental management system are encompassed by the fol lowing core princip les set out for establis hing due di li ge nce (Queensland Department of Heritage, 1994): • need for a pollution prevention system • establishment of a pollution prevention system • operation of a pollution prevention syst em • people with ultimate responsibility to receive reports • those with ulti mate responsibility to know the environmental standards • those with ultimate responsibility to know the environm ental laws and • those with ultimate responsibility to dea l personal ly with systems failures. These elements also mirror those set out for HACCP, i.e. the identification and mitigation of possible hazard events. If an organisation ca n demonstrate that it has indeed gone beyond compl iance and that it has a HACCP system in place, it would go a long way towards establishing a due diligence defence (Davison , 1998).



wo uld n eed to be stated. Eviden ce would need to be given using theoretical and/or empirical studies that the pH range covered within the critical limits was truly acceptable. T his example illu strates that fo r every step in the process, some quite detailed development and validation exercises would need to be perfo rmed by the water supplier and reco rded in an auditable form. It is also important to note that the fac tors monitored mu st be of use in taking corrective ac tions. Therefore if the results of a m easurement will n ot be reported until th e water is already in the supply system, a measurement point further upstream o r som e other measurement system must be used instead. T hese measurements act as 'rapid response fac tors,' allowing corrective actions to be taken to prevent contaminated wa ter ever reac hing the customer's tap. If pathogen s them selves were measured, thi s wo uld need to happen far enough upstream of a treatment barrier to allow the result to be acted upon . For example, high pathoge n loadings could be responded to with treatment enhancement or rej ection of the source water.

HACCPlnthe Australian Water Industry Au stralia's biggest water utility, Sydney Water, is alrea dy embarking on risk- based catchment-totap wa ter quality strategies that have som e elem ents in common with HACCP . These strategies focus on the fu ll range of risks w hich could impact on drinking water quality . Alth ough this is not currently a requirem ent of regulations, it is a valid m eans of demonstrating du e diligence. Eleva ting this to a true HACCP system fo r the pathogen contamination components, including validation, verifica tion and auditing, would represe nt the m os t cost-effective means of ass uring drinking water safety. The lesson s learnt by the foo d indu stry wo uld suggest that if regulations are required rega rding pathogen levels in drinking water, the HA CCP approach would make the most sen se 111 tenns of public health and give the best valu e as a cos t-effec tive system.

References Davison A D (1998) Contaminated Sights?: A Look at Legislation fo r th e Pollll ted Environment. M aster in Environmental and Local Governme nt Law D issertation.

M acqu arie University, Sydney. DETR (Department of the Enviro nment, T ransport and the R egions) (1998) Preve nting Cryptosp oridillm Ge tting Into P ublic Dri nking Water Supplies. Public Consultation Paper. Dillon M (1998) Veri fy ing Food Safety System s in T he the 1990s. QL1ality M agazine 7, 23-28. H avelaar AH (1994) Applica tion ofHA CCP to Drinking ·wa er Supply. Food Control, 5, 145-152. H ealrh stream (1997) New le tter of the Cooperative R esearch Centre for Wa ter Q uality and Treatment. Issue 5. H oga rth M (1998) Water Alert As R eadings Skyrocket. Th e Sydney M orning H erald 28 August 1998, p 2. Microbiology A llstralia (1997), 18, Issue 5. Na tio nal H ealth and Medical Research Council/ Agricultu re and R esource M anagement Council of Australia and N ew Zealand (1996) Allstralian Drinking W ater Gllideiines. N ational H ealth and M edical Research Co un cil/Australian Wa ter Reso urces Co uncil (1987) A llstralian D rinking W ater GL1idelin es. Queensland D epartment of Environment and H eritage (1994) En vironm ental Protection A ct 1994 (Qld) Due Diligence Guidelines. Policy Coordin ation Section, Q ueensland D epartment of Environment and H eritage. Rondinelli D A and Vastag G (1996) Internatio nal Enviro nmental Standa rds and Corpo rate Policies: An Framewo rk. Cali forn ia In tegra tive M anagement R eview 39 , 106-122. United States E nviro nmental P ro tecti on Agency (1989) Safe D rinking Water Act. W orld H ealth Organisation Gllidelines fo r Drinking Water Q L1ality (1984) World H ealth O rganisation. World H eal th Organisa tion GL1idelin es for Drinking Wa ter Q L1ality (1993) W orld H ealth O rga nisatio n.

Acknowledgements T he authors w ish to thank Alison Parr of AWT Enviro nmental Science and T ecpnology fo r supply of the graphics printed in this paper.

Authors Dr Daniel Deere is Se nio r W ater Quality Microbiologist at South East W ater, 20 Corporate Drive, M oorabbin Vic 3189. H e gained his PhD in aqu atic microbiology fro m the Institute of Fres hwa ter Ecology/University of ' Liverpool, UK. Dr Annette Davison is Seni or C onsultant at AWT Environment , Science and T echnology, 51 H ermitage R oad, W est R yde N SW 2114. She gained her PhD in bioremediation from M acquarie University, Sydney.

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N W Swain, R A Jago Abstract Co ntinu ous defl ective separati o n (CDS) technology is a new separa ti on technology based on indirect screening. It has led to non-blinding, non-mechanical screening devices that have proven very successful in removing gross pollu tants from stormwa ter. Potential uses could extend to screening of sewer overflows and raw sewage. This paper reports the results of the operation of a pilot facili ty operati ng on raw sewage. A CDS stormwater unit Figure 1 was installed in the M ornington Sewage Treatment Plant in Victoria and fed with up to 36 1/s by a submersible pump from the raw sewage ch annel prior to the conventional bar screens. Initial tests determined that, based on stormwater experience, the design was not adequate to ensure non-blinding operation in sewage. As a res ult, the unit geometry was n1.odified and a number of screen types were trialled. Non-blinding operation was achieved in the range of 420 to 1100 mm aperture screens. In the pilot plant, screenings were removed batc hwi se at a maximum concentra tion of 10% by volume. In qu asi-continuou s trials (du e to supply limitations), run times of72 hours were achieved without operator intervention. There was some fouling on the outside of the screen , limited to aro und 10%. Fouling was reduced to some extent by plastic-coating the expanded metal mesh screens. This work shows the potential of the CDS technology for use in the treatment of sewer overflows, w here it offers the benefits of minimal screen fo uling, absence of moving parts and tota l capture of all gross solids. A unit capable of screening sewer overflows up to 86 M l/d would have a below-ground footprint of approximately 7 x 7 m and 26

devices . Bo th preliminary trea tment of raw sewage at a sewage treatment plant and treatmen t of sewer overfl ows are potential applications. This potential led CDS Technologies in -optional coopera tion with South East Oil Retention Water to trial a pilot Baffle wastewater screening unit at the Mornington Sewage Treat-ment Plant. The scope of the program was limited to determining Catchment Sump fund am er;tal opera ting para m eters, eval-u ating different screens, characterising the performance of Schematic of a CDS unit suitable screens and assessing cost in the order of $350,000 installed. the performance of the system over It also has potential for screening of extended periods. This paper presents raw sewage at trea tment plants and the results of test work to date. compares well with existing technology on the basis of simplicity of operation, CDS Technology low maintena nce and screenmgs CDS technology allows screening of capture efficiency. solids from liquids at high flowra tes without blinding of the screen. A CDS Key Words unit consists of an approximately cylinScreening, treatment, was tewa ter, drical tank with specially shaped inlet sewage, sewer overflo w and outlet channels to lead the water smoothly to and from the unit (see Introduction Figure 1). A cylindrical screen is located Continu ous deflective separation inside this tank and the influent is intro(CDS) units are non-blinding screening du ced tangentially to the inside of the devices which remove gross pollutants screen , forming a continuously rotating from stormwa ter. They have been body of water, while water that has installed in more than 70 locations in passed through the screen flows alo ng Australia, New Zealand and the United the outside in the opposite direction to States to protect public wa terways from thi s rotation. The region inside the degradation by litter, vege tation and screen is known as the separation silts. Clients have been attracted by this chamber and trapped solids either float non-mechanical, low maintenance on the top of the fluid there or settle alterna tive to traditio nal stormwater below this chamber into a collection scree ning devices beca use of the sump . perceived advantages of zero energy The non-blinding n; ture of the demand and the high flowrates trea ted. sys tem is achi eve d beca u se indirec t A logical extension of C DS technol- rather than direc t scree nmg 1s ogy is to the screening of wastewa ter employed. T he water rotating inside the w here its non-blinding operation and screen tends to continually wash solids low maintenance requirements could away from the screen , overcoming any offer advantages over current screening tendency for them to be pinned by the


WASTEWATER water flowing throu gh it. In direc t screening devices such as bar screens, the pa ssing water pin s solid s onto the screen and they must be mechanically removed. Further details of the mechani sm and applications of CDS technology have been presented elsewhere by Jago (1997) and Wong (1997) .

Pilot CDS Wastewater Screening Facility With the cooperation of So uth East W ater, a pilot CDS wastewa ter sc reening fac ility was se t up at the Mornington Sewage Trea tm ent Plant, w hich treats an average flow of 127 1/s (1 1 Mid). A CDS unit with a design throughput of 36 1/s (3 .1 Mid) was installed in the plant inlet room. Figure 2 shows the pilot faci lity. Several modifications to the standard storm water design were incorporated into the unit to account for the anti cipated requirem ents of Figure 2 Pi lot-sca le screening fac ility at Mornington sewage and to provide the Treatment Plant flexibility required in a develGiven that most of the screens used opmental program. R emovable screen cages with diameters and heights of9 15 had apertures with irregular shapes, a mm were provided to allow convenient n ominal size co rresponding to the testing of different screen types. A lid minimum opening is used to describe was installed on top of the separation the screen. Most of the screens used chamber in case of overflows but in were made from expanded metal mesh normal operation the fluid level was with diamond- shap ed apertures in below the top of the unit. A short wh ich the long axis is typically 2.5 times conical section was provided below the greater than the short axis. In this paper sep-aration chamber to allow collection the screen is referred to by its short axis and removal of screenings through a (SWO). For example, one expanded pneumatically actuated knife gate valve. metal m esh screen used had a long axis A submersible variable-speed pump of 1200 mm and a short axis of 600 mm with a capacity of 36 1/s was placed in but is referred to as a 600 mm screen. the open inlet channel ahead of the The term 'blinding' is used in the conventional bar screens to supply raw paper to denote a situation w here there sewage to the 200 nm1 diameter influis a buildup of material on the w hole ent pipe and an ultrasonic flowme ter sc reen that bloc ks all the apertures was installed to measure the influ ent and prevents flow. The general term flowrate. Both the 200 mm diameter 'fouling' refers to partial blinding where eilluent pipe for screened sewage and there is a buildup of material on part of the 50 mm diameter underflow pipe for the screenings were directed back along the screen that does not significantly the inlet channel downstream of the reduce the flow. 'S tapling' denotes a pump. Sample ports were installed type of fouling where long, fibrou s in the influ ent and eilluent pipes. A material such as hair , string or paper mesh straining 's ock ' wa s fitted to fibres wrap around and through screen collect screenings from the underfl ow apertures. pipe when required for surveying or Fundamental Operating weighing. The development program to date Parameters has involved determining fundamental A plas tic- coated expanded m etal operating parameters, evaluating differ- mesh screen with a nominal scree n ent screens, characterising the perfor- aperture of 600 mm was installed into mance of suitable screens and assessing the CDS unit. Blinding of the screen in scree n performance over extended the initial tests indicated that the design based on stormwater experience was periods.

not adequate to ensure nonblinding operation in sewage. The unit geometry was accordingly modified, with the result that non-blinding operation was achieved over six hours at a flow rate of36 l/s. N ext, an approach to removing screenings via the underflow valve and 50 mm pipe was developed. If screenings are not removed, rotation of the fluid ¡n the separation chamber is retarded until it eventually stops. In this situation the unit becomes plugged with screenings and the fluid level in the separa tion chamber rises above the top of the unit. It was determined that the maximum load of screenings that cou ld be maintained within the unit was approximately 10% by volume. To maintain the load below this level, a minimum underflow rate of 0.2 1/s was typically required for the 600 mm screen operating at 36 1/s. However, th e minimum co ntinuou s underflow rate Sewage achievable was 6 1/s, due to the requirements of a large outlet (50 mm) and' the need for an adeq uate transport velocity (> lm/ s). Opening the underflow valve se t up a vortex in the centre of the unit that was useful for removing floating material, but ca used blinding of the screen if operated for more than five minutes. It beca m e appare nt , therefo re, that the screenings had to be removed batchwise, so the underflow valve was operated intermittently under the control of a timer. The frequency of the removal of underflow depends on the scree n aperture and the influ ent flowrate, although it may also vary with the time of day, season and nature of th e influent.

Screen Evaluation Fifteen different screens were trialled to study the effec t of aperture size and form and th e influ ence of surface coa tings . Aperture sizes ranged from 0 .25 mm to 20 mm and their forms included diamonds (ex-panded metal mesh), circles (perforated plate) and rectangles (wedge wire). Some screens were tested with and w itho ut a polyester coa ting. After each test the unit was drained through th<, underflow line and the expo se d sc reen was inspected for fo uling. T here appeared to be an optimum aperture size for non-blinding operation in raw sewage. Screens coarser than 1.1 mm were prone to severe stapling by large fibrou s material, as has also



WASTEWATER Extended Operation

Table 1 Data co llected in six-hour characterisation tests Short way opening (mm)

Aperture area

1100 790 600 580 420

2.2 0.49 0.51 5.9 0.22

Screen type

(mm 2 ) XM-P PP-P XM-P WW-P XM-P 9



Screenings collection rate (l/m3)

Suspended solidsinfluent (mg/I)

Suspended solidseffluent (mg/I)

27 27 27 24 0.76

0.33 0.49 0.46 0 .23 269

259 292 247 280 224

241 268 234 257 17

XM-P = Expanded metal mesh with polyester coating PP-P = Perforated metal plate with polyester coating WW-P = Wedgewire screen with po lyester coating

been observed fo r rotary screen s (D avis, 1987). A 250 mm sc ree n quickly becam e stapled with fine fi bres and could not be made to operate successfully. Screens with apertures between 420 and 1100 mm were used successfully and these were further evaluated in the characterisa tion trials. M easurable reduction in fo uling was achieved for some of the expanded mesh screens by applying a polyester coating. It is thought that the coating fills in the apices of the diamond-shaped apertures as well as smoo thing over edges burred from the punching process, so preventing fibres fro m catching at these sites . This thesis was supported by the observa tio n that plastic coating did not affect the operation of a wedgewire screen w hich has no such burr or notches on which fibres can catch. C leaning of blinded screen s with apertures below 11 00 mm was easily accomplished by gentle hosing dow n of the screen with plant water. If the screen had been allowed to dry, cleaning would take lo nger w hile the material was moistened. In the case of scree n s w ith apertures large r than 11 00 111111 , removal of fo uling was much more difficult. Hosing with plant wa ter was not effective in removing hair , strings or rags that had become entwined in the apertures. H and bru shing and high pressure hot water w ere required to clean these screens .

Performance Characterisation of Potential Screens Once the preliminary survey of screens was completed , five screens that showed minimal fouling were chosen for more detailed performance evaluation . T able 1 presents the performance data obtained in the six-hour tests. T ests w ere commenced at approximately the sam e time each day in order to ensure as consistent an influent as possible. The targe t flow rate was 27 1/s, but in the case of the 420 mm and 580 mm screens non-blinding operation could only b e m aintained at 28


flow rates of 9 and 24 1/s respectively. For eac h run , four sampl es of the influent and efflu ent were taken to determine an average suspended solids reduction. Underflow was discharged into a m esh 'sock' every 30 minutes and the volume of screenings determined. At the end of the test the unit was drained and the screen inspected . Bo th the screenings collection rate and suspended solid s reductio n are indica tions of the performance of the screens. The screenings collection rate increased as the aperture area decreased. Suspended solids rem oval similarly improved with increasing aperture fin en ess, with the 420 mm sc ree n rem oving the highest prop ortion of suspended solids at 17% , compared to 5-8% for the o ther scree ns wi th apertures between 580 and 11 00 mm. The scree nings predominantly consisted of paper but also rags, tampons , sanitary napkins, cotton buds, hair and food scraps. Grits and mi scellaneo us household item s were present. One indication of performance was the condition of the screen at the end of each test. With the exception of the 580 mm wedgewire screen , the inside surfaces of the screens were completely clea n. The wedgewire screen , however, was fouled with fibrous material near the inlet that covered approximately 5% of the screen. The outside surfaces of all sc reen s had fo uling w hi ch cove red about 5- 15% of the screen area. It appeared as if paper fibres had lodged on the ba ck side of the screen , w here presumably the lower fluid velocities in the o utlet channel were not sufficient to rem ove them . The 790 mm perforated plate showed the least amount of fouling on the back of the screen and is perhaps the most promising option. The 420 mm screen sh owed the grea test fouling and given that it operated at only 9 1/s shows the limitation s of the finer screen s. Since it was unknow n from these sixhour tes ts whether the fouling had reached steady state or was continually growing, extended trials were undertaken.

Extended trials of promi sing scree ns comm enced. Initially it was (%) sought to demon strate screen viability for 72 7 hours of continuou s oper8 5 ation, w hich is taken as 8 the maximum duration of a sewer overflow event. During these extended trials, the C D S unit operates quasi-continuously, as continuo us operation cannot be maintained owing to the nature of the influent hydrograph at the sewage trea tment plant. Whenever flow th ro ugh at the plant was insufficient, the pump stopped but the unit remained full. At the end of each trial the unit was drained and the screen inspected . Trials using the 1100 mm screen indi ca ted that the unit could be operated for at least three days without operator intervention . As in the sixhour tests, there was some fouling on the outside of the screen but thi s was limited to around 10% of the screen. Further tests will be condu cted over even longer periods of time and with different screens. It is also intended to relocate the facility to a plant w hich provides a continuo'us, uninterrupted flow. This will allow the unit to operate unattended for periods of one month o r m ore to dem onstrate the reliabili ty and robustness of the technology in this application . In all tests to date no fouling of the screen by fa ts or oils has occ urred , althou gh sm all qu antiti es of fatty material have been observed in the top of the outlet channel after extended opera tio n. However , there is a low content of these po tentially difficult materials in the raw sewage trea ted at Mornington Sewage Treatment Plant and it may be necessary to test the unit in sewage containing higher levels of fats and oils. D espite this, the successful operation of a CDS unit trea ting the washdown fro m butter pro du cti o n gives a good indica tion that fats and oils will no t impair the non-blinding nature of the technology.

Reduction in suspended solids

Potential Uses for CDS Wastewater Screening Units Sewer Overflows The present work has demonstra ted the potential of C DS Âľnits to trea t sewer overflows in real time without the necessity fo r storage before later treatment. A compact, non-mechanical and non-blinding device that removes gross solids down to particle sizes of ca. 500 mm at high flow rates would be a

WASTEWATER significant step forward in the treatment of sewe r overflo ws . W hen treating sewer overflows, the underflow from the C D S unit wo uld be fed bac k into the sewer downstream and trea ted in the usual way at the sewage trea tment plant, w hile the screened efilu en t could be discharged to the receiving waters. A C DS unit capable of handling a sewer overflow of up to 86 Mld has an undergro und foo tprint of approxim ately 7 x 7 m. T he influent can flow through the unit u nder gravity if the available head is greater than 0.4 m . T he underflow (approx . 1% of the infl uent) would need to be pumped fro m the unit back into the sewer, so that pump , valves and associated control equipment m ust be added to complete the installation. W ater sprays wo uld be required to clean the screen at the end of the overflow event. The to tal installed cost of such a uni t is of the order of $350 ,000, assuming that no difficult gro und co nditions are encountered . For higher di scharges, either a larger unit may be installed or the unit may be replicated . While real time screening of sewer overfl ows to ca. 500 mm is a considerable step forwa rd , it is nevertheless cosm etic in that only a minor proportion of the harmful pollu tants are removed. Screening such m aterial to less than 100 mm would considerably increase the am ount of solids rem oved , although for a signifi cant red uction in BO D , C OD , oil & grease, heavy metals and pathogens it is necessary to ac hi eve as high a reduction in to tal suspended solids as possible. R esearch is currently being directed towards developing an enhanced C D S unit to ac hieve this goal.


of solids larger than 6 mm rem oved from the inflow ,' the p ropo rtion o f trace r sticks, plas tic strips and condom s cap tu red, and o bserva tio n of the presence of large identifiable solids in the disc harge. According to the criteria used by T hom as et al ., the performance of a C D S unit w ould m atch , if not exceed , the perfo rmance of all equipm ent evaluated by these authors. The no n-mechanical basis of a C D S unit m ay o ffer advantages ove r existing m echanical screeni ng devices, especially with regard to m aintenance costs.

C D S T ec h nologies expresses its appreciation for the support of South East W ater and fo r the cooperation of the staff o f M orningto n Sewage Treatment Plant.

References Davis C (1987) Inlet Works: Where Are T hey Going?, 12th Federal Convention AWWA, Adelaide, Marc h 23-27 , pp 371-378. N ew Screening Jago RA (1997) C DS : Technology for the Environment, W ater, 24 , 1, pp 47- 49., T homas D K, Brown S J , Harrington D W (1989) Screening at Marine O utfall Works, Jnl In st. Water & En vironmen tal M anagem ent, 3, D ecember, pp 533-547. Wong T H F (1997) Continuous D eflective Its M ec hanism and Separa ti o n: Applications, WEFTEC '97, 2, Water Environment Federation, pp 703-714.

Conclusions C D S screening technology, p rove n as an effective device for scree ning stormwa ter , has n ow been d em o nstrated as a viable technology fo r screening wastewater. A pilot facility has been established w here high rate screening w itho ut blinding was ac hieved using 420 to 1100 mm screens. Further pilo t plant testing will assess the po tential of the technology fo r trea ti ng sewer overflows and for preliminary trea tment of raw sewage. The advantages of the technology in these applications include red uced sc ree n foul ing, no m oving parts, zero energy input and 100% cap ture of all gross solids down to the ape rture size of the screen .

Authors Nicholas Swain is Sen ior R esearch E ngineer at C D S T echnologies, 1140 N epean H wy, M ornington Vic 3931. H e has a bac kground in chem ical engineering and process development. Dr Richard Jago is R esearch and D evelopment M anager at C D S T echnologies. H e is an applied scientist w ith experience in C SIRO and industry.

SPECIALISING IN ENVIRONMENTAL SERVICES ...,. Environmental AudiVSite Investigations

Application to Primary Screening

...,. Contamination Assessment & Remediation

A C DS unit has been dem onstrated as a non- m echanical , 100% effec tive d evice fo r sc ree ning raw sew age betwee n n ominal particle sizes of 420 an d 1100 mm . Such a unit could be combined with washing and dewa tering equipment to gen era te screenings suitable for di spo sal, b u t if sc ree ning to sizes coarser than 11 00 mm were required , the washing and dewatering step could be used to rem ove fine m aterial, leaving the coarser fraction . The fa ct that the unit is 100% effective in capturing gro ss solid s w ould eliminate the frequent fou ling of downstream equipment w ith rags etc. T hom as et al. (1989) evaluated a range of screening equipment at va rious sites and fo und that the m ost effective screens (C ontrashear, Ro tos trainer, 'D ' Screen , Bracket C up) were based on ro tating screens o r bru shes. The perfo rmance of these screen s was assessed in three ways : the proporti on

...,. Environmental Risk Assessment ...,. Hazardous/Industrial Waste Management ...,. Solid Waste Management ...,. Information Management ...,. Environmental Impact Statements ...,. Environmental Management Planning & System Development








'In the United States, eflluent discharges from municipal wastewater treatment plants are responsible for the presence of detectable quantities ofhuman and animal medications and their metabolites in surface water, groundwater, and even drinking water.' -So warns Tara Hun, writing in the prestigious journal of the Water Environment Federation. But is there evidence to warrant these concerns, or is the topic akin to a storm in the proverbial toilet bowl? This paper examines the presence of pharmaceuticals in wastewater and the risk posed by potentially active residual chemicals and raises questions for future policies in wastewater management. Questions for the Water Industry What happens to drugs in the wastewa ter stream? To an extent their fate may depend on the form or formulation in w hich they enter the system. Most people seem to ass ume that tablets, capsules or mixtures are abso rb ed , m etaboli se d and excre ted from the body in a proc ess w hi ch renders them inert and no longer chemically ac tive . The fac t is that, except for the most simple medica tions such as glucose syrup, many pharmace uti cal agents will be voided fro m the body substantially unchanged. In addition , many of today's tablets were specially designed to achieve a delayed release as the medication passes through the digestive tract or for release in the lower bowel, e.g. tho se for trea ting Crohn's disease, chronic ulceration of the lower bowel. Some tablets will dissolve only at a designated pH following contact with gastric peptides, e.g. treatm ents for 30


pepti c ulcers, or as a result of bile acid and enzym e ac tion , e.g. antibiotics w hich are deactiva ted by stomach acids. As a result of illness or age, in many patients medicines will pass through the gastric tract without loss of their protective coatings, e.g. slow K for potassium replacement. In others , the form of medication will not suit the patient and the substance will be excreted largely unchanged , e.g. some types of iron tablets. In each of these instances the ac tive drug prese nt in excre ta will behave chemically in a similar manner to that of the original prescribed and administered medicine . When thi s active residual is added to the unu sed, excess or out-of-date drugs being flush ed down the sink or toilet by patients , pharmacists and ho spital staff, the end result is that pharmacologically active residues in wastewater are likely to be approaching or exceeding current minimum detection limits. However, this po ssibility ha s not been given much express1011 until more recently as

concerns about health ri sks have come to greater prominence as a result of problem s with contamination of drinking water intended for public consumption. R ather, the assumption is made that, once administered to the pati ent or washed away, a prescribed drug will dissolve in time and any ac tive principle will be dilu ted into inconsequ ence . W hat impact do toxic substa nces such as anti-cancer drugs and antibiotic residu es have on bacteria in wastewater treatment pro cesses? And to w hat extent can the aerobic and anaero bic bac teria detoxify these complex compounds? A risk-averse approach and the precautionary principle would suggest that it is somewhat disingen uous to simply assume there is no need for concern without first examining the nature of the problem of medicinal residues . Can it be assumed that the dilution pro cess itself is suffi cient sa feguard against potential impact on the environment? If received in a large 'bolus' by

WASTEWATER the wastewater co llec tion sys tem, a mass of tablets may clump together a'nd form a solid 'cake' w hich is impervious to the turbulence of water and debris. In a congealed form, thi s 'cake' would be captured by pre-treatment filters as it enters the effluent stream to the treatment plant. If the outer tablet cover is breached , the exposed active principle inside may attach to or become adsorbed onto vege tative matter or particles similar to those encountered in the human or animal gut. It is highly likely that the active m edicinal principles w ill be complex molecules w hich have multiple potential ' docking' sites wi th hydrophilic or hydrophobic junctions at w hi ch thi s linkage can occur. ¡ The press ure on water resources mea ns that increasingly, governments of the future will need to address the risks and impacts of potable and non-potable reuse on the wider environment. In both instances, issues such as pharmaceuti cal residues and their ecotoxicity need to be addressed.

Problem Residuals For those in the science community and the health professions, the persistence of residues of pharmaceuticals in the environment poses problems for the following reasons (H alling- Sorensen et al. , 1998) . T here is mounting evidence of an increased resistance of pathogenic bacteria to co ntrol using traditional antibiotic therapi es. This phenomenon has been attributed to indi scriminate and careless use of antibiotics by the m edical professio n , the practices of hospital staff w here attention to hygiene assists developing resistant strains, and poor compliance by patients w ho fai l to fo llow instru ctions abo ut do se and duration of treatments. There are also concerns about the use of antibiotics and hormones in th e animal feedlot industry, particularly w here they are used as growth promoters and to minimise disease spread among closely confined animals. There are already many documented cases of antibiotic failure in patients in the USA and Europe , believed to have resulted from normal foodstuffs. R esidues of antibiotics such as iveractin , avo parcin and o:,.,.rytetracycline u sed in ve terinary medi cine have bioaccumulated in animal tissue before slaughter. Environmental health scientists are quietly collecting and collating data on a number of so-called endocrinedisrupting agents occurring naturally as phytoestroge ns or as residues and contaminants, such as DDE and DDT (USEPA, 1995-1998). Of particular interest to the USEPA are environmental contaminants that act as agoni sts or

antagonis ts w ithin the gonadal o r thyroidal systems, ¡ th us impairing the produ cti on of sperm and impairing normal development and reprodu ction. R esearch is being undertaken both in the laboratory and in the field using m odel orga ni sms drawn from these rep resentative phyla (Clark et al. , 1998). Other resea rch ers 111 th e natural sciences have reported a decline in fertility and sperm counts among frogs (Tylor, 1997) and some fi sh species (Chri sten , 1998) . They too have foc used the blame on oestroge nic substances w hich appear to be present in increasing am ounts in the environment. Synth eti c and natural hormones such as oral contraceptives and HRT harm.o ne replacement therapy are being prescribed for and used by increasing nu mbers of women. T hese substances are only partially metabolised in the body and are excreted still in an ac tive form. The residu es of these steroids cannot be assumed to have nil impact on bacteria and other aq uatic life forms present in the effluent and receiving waters. Anti-tumour age nts and antibiotics are designed to kill living cells. These substances are highly cytotoxic , frequently low in solubility and are often excreted largely unchanged from the pati ent's body. Their fate in the wastewater stream is unknown . Careless disposal of unused, re turned and o ut-of-date pharmaceuticals into the wastewater stream, while unapproved, does occur. Education targeted towards health professions and the publi c should detail appropriate procedures for disposal of these potentially toxic hazardous wastes.

Quantifying the Problem To quanti fy the problem of pharmaceuticals entering the system , a first step would be to survey the ra nge, numbers and volumes of dru gs being prescribed and dispense d , mmu s the drugs returned or disposed of. That information would need to be grouped on the basis of medication type and categorised into medication types with a known impact on other non-human species e.g. steroid hormones, antibiotics and anti-ca ncer drugs, those excre ted largely unchanged, those excreting an active metabolite etc. T his may appear an unwi eldy, inacc urate and errorprone approach . Nonetheless, in the absence of more se nsitive detection technology, it should yield information concerning the scope of the problem and fill the present void. D etection of residues by chemical profiling of the consti tuents is ano ther technique to identify those present in detectable amounts in any given sample

of wastewa ter. Thi s is not cheap research. Once a drug's stereochemical signature is known, spec troscopy or high performance chromatograp hy should be able to confirm its presence .

Whither the Water Industry? W h ether or no t the public (and the media) are ready to accept the issue of potable reuse, non-potable reuse is a reality, both in dual systems and for small-scale use in irriga ting parkland s and recreation fi elds. A~ well , stabili sed sludge is already being used in agriculture, pasture and on foo d crops. There is a possibility that medicinal residues are contained in that sludge, although no-one has thought to look for them. Pharmacologically active agents of all types including those used as pesticides etc. shou ld not be treated carelessly . The medical profession is beginning to see the folly of its cavalier attitude to penicillin and the tetracyclines w hich no longer provide a barrier against ma ny hitherto vulnerable organisms . Antitumour agents are toxic substances and are not simple dissoluble chemicals. Bioindicator species are the natural guardians and wa tch-dogs that herald a changin g scenario-they detect miniscule changes beyond the sensitivity of human instruments. Warnings about tiny changes in the level of oestrogens in the environment suggest a direct impact o n species ferti li ty and reprodu cti on (Christen , 1998). Given that it is possible to detect and quantify medicinal residues in the wastewater stream , is removal a practical option , even if possible? M any drugs are complex structurally and have a high molecular weight e.g. analogues of natural peptides (pro tein constituents). It has been suggested that membrane technology, ultrafiltrati on and reverse osmosis would probably successfull y entrap these compounds. Additional costs would be involved. But are these technologies likely to prove effec tive? According to those working in the industry, pharmaceuticals do not behave as normal physically inert and predictable entities . They are not supposed to, and their behaviour cannot be guessed at under the conditions enco untere d in the effluent process. It has been suggested that activated ca rbon , alrea dy used in wastewater treatment and for removal of di sinfection by-products, co uld serve as an effective adsorbent. Again, a further cost impost arises. ' The use of an adap ted culture specifically intended to targe t residual pharmace uticals in the wastewater trea tment process that is introdu ced during the early stages of wastewa ter trea tment has been proposed as a means WATER NOVEMBER/ DECEMBER 1998




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WASTEWATER of lowering the total end cost of the steps proposed above (van Leeuwen , 1997). While this proposal would offer a partial solution , it may not be realistic at present. As an example, anti-cancer drugs represent a myriad of different agents of multiple structure s and chemical properties designed to evade attack by aberrant cells of the tumour or to undermine its biochemical processes in a highly selective fas hion. The intent is to achieve these aims wi thout being detected and voided "by the body's own immune defences. To seek to further design bacteria capable of selectively inhibiting, antagonising or neutralising these instruments of modern biological warfare would dema nd skills akin to those employe d in sophi stica ted defence weapons design. A cheaper alternative may be ozone. While ozone is a powerful oxidising agent , the presumed byprod ucts of oxidised medicinal residues need to be proven as inert. Until we know w hat we are dealing w ith , lo oking for 'solutions' is perhaps a little premature.

References Hun T, NewsWatch: Studies Indicate T hat Drugs in Wa ter May Come from Effluent D isc harge, J Water E n vironmen t & Technology, July 19,98, 10 (7), 17-22 . H alli ng-Sorensen B , Nors Nielsen S, Lanzky PF , Ingersiev H C, H olten Lutzheft , J ergensen SE, Occurrence, Fa te and Effects of Phan11aceutical Substances in the Environment: A Review. Chem osphere, 1998, 36 (2) : 357-393. US Enviro nmental Protection Age ncy (USEPA) fil es (1995-1998) concerning the effects of low level exposure to chemi cals such as pesticides DDT & DDE, natural and synthetic oestrogens on a range of amphibians, fish and aquatic invertebrate species: salamanders, frogs. C lark EJ , Norri s DO and Jones RE (1998) Interaction s of Go nadal Steroids and Pesticides (DDT, DDE) O n Go naduct Growth of Larval T iger Salamanders, Ambystoma tigrinum. General and Comparative Endocrinology, 109: 94-105 . Dr Micha el Tylor, Zoology D epartment, Adelaide University. Australian Museum lecture seiies: Frogs Lec ture, 1997 . C hristen K, Endocrine-Disrupters: Human Estrogen Co uld Be Ca using Adverse Effects in Fish,] Water En vironment and Technology, July 1998, 10 (7), 22-23 . Hans va n Leeuwen, Vice D ea n, School of Civil Engineering, University of New England , Anrudale NSW (pers. comm., 1997),

Author Dr Diane Wiesner is an Environmental Consultant . She has a PhD and MSc in environmental health, a BSc with first-class honours in pharmacology and a graduate diploma in human nutrition.


By now everyone in the water industry mu st know that sludge is known by a new , 'appropriate' word , a name with enhanced community appeal, no slimy undertones and US EPA approval'biosolids.' The w hole idea is to encourage the use rather than disposal of the solids by-product of sewage trea tm ent. The connotations of thi s wonderfu lly descriptive label are of an organic substance that contains nutrients and beneficial biological solids, aids in soil structure and so on. The term 'sludge' is still used, but typically to describe raw or unstabilised material/ muck. In New South Wales there are environm ental guidelines for the use and disposal of biosolids. Produced by the Environment Protection Authority, these guidelines iden tify classifications fo r bi osolids based on stabilisation and contaminant threshold levels. T he idea is to provide ade quate protection to the environment and health w hile providing practical avenues for use of the biosolids .

Stabilisation Stabilisation is the trea tmen t of sludge to produ ce a stable product (one that won't putrefy) and reduce pathogens. Processes include anaerobic digestion , hea t drying and lime treatm ent. The contaminants specified in the guidelines include heavy m etals such as zinc, chromium and mercury and pesticides such as DDT, lindane and chlordane.

Once stabilisa tion and contaminant levels are identified , specific uses are given in the guidelines as permissible. These range from applica tion of biosolids to home lawns and garden s (highest stabilisation grade and most stringent contaminant grade) through urban landscaping, agriculture, forestry, land rehabilitation and finally to landfill for sludge that is unsuitable for use because it does not m eet the classification criteria set out in the guidelines. Compared to secondary plants, primary sewage treatment plants such as the ones at Cronulla and Malabar w hich use anaerobic digestion to stabilise the sludge more easily m eet the volatile solids reduction criteria specified in the gu idelines, according to Sydney Water's Ian Finney. Ian spoke at a recent seminar held by AWWA's N ew South Wales Branch to examine how current operational practices meet the guidelines. The guidelines specify a VS reduction of 38% fo r anaerobic digestion to meet the stabili sa tion grade B. Secondary activated sludge plants have difficulty with this becau se of the already low VS content of the waste biological sludge. Other tests done by Sydney Water indicated that the specific o>-.'Ygen uptake rate of sludges had no correlation to odour intensity. Composting is one of the m ethods capable of meeting the highest stabilisation grade, Grade A. Robert Nichol of Australian Native Landscapes (ANL) o utlined the company's experience with

composting at its 65 acre Badgery's Creek site. D ewatered sludge-usually anaerobically digested ¡ but also some waste BNR sludge-is combined with green waste obtained from NSW W aste Service in a ratio of about 1 :3. The addition of other materials means there should be a dilution of sludge-based contaminants, w hich should help achieve a higher contaminant grade. ANL has been careful not to allow any storage of sludge, so it is bulked as soon as it arrives. Windrows are set out (about 4 m wide at the base and 2 m high) and a Scarab turner is used to m echanically turn the piles to ensure aerobic conditions are maintained . Essentially it is a ten-week cycle, with testing beginning seriously after six weeks (there are several random spot samples taken throu ghout the windrow). T he guidelines specify that composting should remain at 55° C for five days, but in practice the pile rem ains above this temperature for about four weeks . However, if this criterion is not met the pile is turned and left for another week before testing. At Week 8 the pile is checked for contaminants (the guidelines outline tes ting requirements). Currently there are numerous trials being undertaken in agricultural and mine rehabilitation applications. The market is considered to have a big potential for the vineyard, orchard and cut flower industries. M elissa Salt of L V R awlinson and Associates, who covered the ability of WATER NOVEMBER/ DECEMBER 1998



(40, 50 and 60% lime on a dry solids basis). All dosage rates met the pH criteria. It was found that only the 60% dosage rate m et vira l and bac terial standards (helminths proved to be more difficult to correlate).

Veal talked about an effective method of dewatering sludge that has not yet been commercially developed. It also produces a sludge cake-spadeable, but inedible-which opens up many avenues of disposal for the sludge produ ct. For (oop s! -'bio solids') example, for compo sting, dewatered sludge is definitely required. Avenues for disposal of liquid sludge are certainly more limited-surface spraying and sub-surface injection of agricultural and silvicultural applications are the only ones which spring to..mind. Dr Veal' s investigation with CS IRO and the CRC for Wastewater Treatment involves a process called electrodewatering , w hich ha s been show n to achi eve solids content in the final cake of over 40%-significa ntly higher than that achieved by co nventional filter press/centrifuge dewatering. This typically achieves solids concentrations of 15 to 25% . The process is really an extension of the filter belt press but involves application of an electric field during cake compression. The mechanism of dewatering occurs when particles (which are usually nega tively charged) move towards the anode, and there is movement of water associated with dissolved ion migration. A bench scale system was set up which showed , at pressures •of 10 bar, that a cake solids concentration of over 40% was achievable (compared to less than 20 with no elec tric field applied, and at the same pressure) . A pilot scale (single roll) filter press was then built and used in a series of trials. This was tested at Quakers Hill Sewage Treatmetn Plant and results were actually improved over the pilot scale. The results showed that dewaterability was increased with the number of passes for electro-dewatering-30% solids was achieved with two passes of the unit and over 40% solids with three passes (whereas straight dewatering, even with increasing the passes, only achieved about 18% solids). Power consumption was also looked at with the aim of achieving 1000 kWh/ tonne d. s. A significant potential advantage of this method is considered to be the heating effect as electrical resistance increases-temperature can reach greater than 70° C, so som e pasteurisation may be possible. The next step s forward include continuing the investiga tion and commerci,alisation of the technology . Any takers?



B ecau se dewatering reduces the volume of the sludge, there is less transportation required , with sub sequ ent lower costs. At another AWWA NSW Branch seminar CS IRO's Dr Chris

Mitchell Laglnestra is a Senior Pro cess Engineer with CMPS&F Environmental, Sydney, Level 1, 67 Albert Ave, C hatswood NSW 2067 and President of the AWWA NSW Branch.

The anaerobic digester at Bondi Sewage Treatment Plant

Sydney Water's liquid sludge Injection vehicle In action

CSIRO's electro-dewaterlng pilot plant unit

the lime stabilisation process to m ee t the guidelines, spoke about a study involving 'straight' lime stabili sation (not patented processes N-Viro or RDP) of primary sludge. For stabilisa tion gra des A and B , pH mu st be maintained above 12 for tv,o hours. For stabili sa tion grade A , viruses, helminth eggs and bac teria (E. coli, faecal coliforms and Salmonellae) also need to be co nsidered and these were studied in a series of trials involving measurement and testing at varying lime dosage rates 34


ENVIRONMENT Thi s paper won the 1997 Undergra duate Wa ter Prize and Gold M edal promo ted by the W es tern Au stralian Branch of A WWA. The proj ec t was co mpleted as the final year proj ect for the D egree ofBSc/BE (Environmental Engineering) at the University of W estern Australia.


Abstract A total of 56 core samples from the bed of the Swan River estuary were studied under aero bi c and anaerobic conditions and the rate of release of nutrients w as compared with the partid e size distribution and organic content of the sediments. Whilst sediment release of pho sphoru s is enh anced under anaero bic conditions, to tal nitrogen release rem ains unaffected, though its speciation is altered. Contrary to the traditional limnological view, the results indica te that an increase in organic content translates to a decrease in sediment oxygen demand simply because the m ean pore space (and hence the rate of o>..'Ygen diffusion into the sediment) decreases . However, as diffusion of oxygen into the sediment appea rs to limit the rate of benthic minerali sa tion , recently deposited organics in the uppermo_st layer of the sediment are the most rapidly degraded. The oxygen demand of Swan River sediments decreases with distance from the river mouth due to the high flu x of organic matter to the sediment in the lower reaches. Fi ck 's Law is a valid m ea n s of es timating nutri ent release from se diments provided that tortuosity effects are acco unted for and the O>..'Ygen conditions are favo urable for the release of that nutrient. This study has, in addition, derived corrections for unfavourable oxygen conditions. Consequ ently, sediment nutrient release from Swan River sediments can be accurately predicted under all conditions.

Introduction The Swan River es tu ary is surrounded by the residential, commercial and indu strial areas of Perth . It is highly modified from its natural state and has recently been described as eutrophic. Phytoplankton blooms have been reported in the Swan River estu ary since European settlement but have become significantly worse over recent years, especially in the reaches upstream of the Causeway. R ece nt studies indica te that in unu sual co nditions, internal nutrient regeneration (as distinct from external nutri ent loading) ca n support algal

FROM SEDIMENTS THE EFFECT OF SHORT-TERM ANOXIA M Ghisalberti blooms. The Swan-Canning sys tem receives and retains a high sediment and phosphoru s loading from rural ca tchments. As noted in o ther estuaries, it is reasonable to expec t that high release of phosphorus from sediments would stimulate self-sustaining phytoplankton bloom cycles . Low levels of dissolved o>..'Ygen in a wa terbody have been found to enhance nutrient release from sediments. In the Swan River, dissolved oxygen depletion occurs under density stratification , especially in the upper reaches of the es tuary. Given the importance of sedim en ts in regulating phyto plankton productivity, the co nditions under w hich nutrient release occurs and the m agnitude of this release were investigated. The objectives of this proj ect were to: • measure the sediment oxygen demand (SOD) of Swan River sedim ents-a fund am ental parameter in predicting the onset of anoxia-and derive an empirical relationship with

Figure 1 Representation of the experimental configuration of anaerobic cores

sediment parameters • exa mine the effec t of di ssolved oxygen co nce ntration on nutrient release from Swan River sediments • investigate the applicability of Fick's Law to nutrient release from sediments (since mol ecular diffusion is the basic control m echanism for nutrient release from sediments) • devise a numerical model.

Method Intact sediment cores were taken from the Swan River es tuary on 5 February 1997. Fifty-six sediment cores were taken from seven sites in the Swan River, each site representing a unique bathymetric zone. Within each site there were four sampling locations and two sediment cores were taken from each. The inta ct sediment profile and overlying water were kept in the sediment corer and monitored in the laboratory over three weeks. One core from each sampling loca tion was driven anaerobic by sealing it at both ends and allow ing the natural oxygen demand of the sedim ents and water column to deoxygenate the water. Anaerobic cores with low O>..'Ygen dern.ands were sparged w ith nitrogen . Figure 1 depicts the experimental configuration. The other core from each sampling loca tion was kept aero bic by leaving it unsealed , allowing re-aeration by the atmosphere . Artificial aeration (provided by aquarium bubblers) was employed for aerobic cores with oxygen depletion. After filtration of the water overlying WATER NOVEMBER/ DECEMBER 1998



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Figure 2 Comparison of aerobic and anaerobic re lease of ammonium from samples cores

.the cores , sediment oxygen demand (in anaerobic cores before nitrogen sparging) and nutrient release (all cores) were monitored daily by examining respectively changes in oxygen and n utrient concentrations in the water column. Nutrient release was calculated by fitting a least squares regression line to the cumulative nutrient release data for each core (see Figure 2). The slope of this line was equivalent to the nutrient release in milligrams per day. This valu e was then divided by the surface area of the sediments in each core to yield the rate of nutrient release in mg. m-2 .d-1 . For all aerobic cores, the regression analysis comm ence d on D ay 2 and ended once a constant rate of nutrient release was observed. For anaerobic cores, the regression analysis was limited to periods during which the conditions were sufficiently anoxic. When examining the release of nitrogen nutrients, the regression analysis was limited to p eriods in w hich the dissolved oxygen level was below 0.3 mgL-1 . This is the oxygen level that corresponds to the cessation of nitrification and the comm encem ent of denitrifica tion. Similarly, when examining the release of pho sphate, the regression an alysis commenced after a dissolved




Figure 3 Importance of dissolved oxygen co nce ntration on sed iment nutri ent release

(from a depth of 1 cm) from all aerobic sediment cores.


Figure 2 compares the rate of ammonium release from an aerobic core with that of the anaerobic core taken from the same location. The organic matter content of the sediments ranged from <1 % to 21.0% and exhibited n o discernible trend along the estuary. A strong correlation (r2 = 0.72) was found between the o rganic content and particle size of Swa n River sediments-orga nically enriched sediments are, in ge neral , fin er. This clear correlation between organic content and particle size fo r Swan River sediments has a critical impact on both the correlation of SOD w ith sediment parameters and the observed nutrient effiu xes. Contrary to expectation , organically enriched sediments were found to have the lowest SOD . As diffu sion of oxygen into sedim ents is res tricted by the average pore space, relatively no nporous (i.e. organically enriched) sedim ents permit minimal rates of m,')'gen diffu sion. Therefore , it appears that the rate of benthic mineralisation is limited by the rate of diffu sio n of oxygen into the sediments (the precursor to its con••• sediment nutrient release sumption in the sedifrom Swan River sediments can m ents) , not by the level of organic matter. That be accurately predicted under all is, organic matter in the collected sediments conditions.' appears to be far in excess of the maximum oxygen concentration of 0.1 mgL-1 was rate of degradation permitted by the reac hed, as this is the prevalent oxygen level of available oxygen. An increase in concentration for the reductive dissolu- organic content translates to a decrease tion of iron (III) oxides in the sediment, in sediment oxygen demand simply because the m ean pore space (and hence to w hich phosphate readily adsorb s. At the completion of the experiment the rate of oxygen diffusion into the (Day 15) each intac t sediment core was sediment) decreases. This is contrary to recovered and the organic m atter the traditional limnological view-that content and particle size distribution of proporti onality between organic were later determined for each core. A content and oxygen demand. As diffu sion of oxyge n into the sample of porewater was also extracted 36


sediment appears to limit the ra te of benthic mineralisation , organics lying in the uppermost layer of the sediment are the most rapidly degraded. Therefore, it is the recently deposited organic matter that undergoes immediate remineralisation . The flu x of organic m atter to the sediment provides a clear indication of the levels of organic matter that can be expec ted in the upper strata of the sediment (i.e. that which can be readily degraded). Consequently, a large flu x of organic matter to the sediments implies a high sediment OA')'gen demand . The strongest correlation of sedim ent oxyge n dem ahd was observed with the location of the sediment along the river, w ith maximum valu es observed at the river mouth. Therefore, it would appear that the organic flux to the sediments decreases with distance from the river mouth. Although summer algal blooms occur in the upp er reach es of the estuary, the mean velocity through the narrow channels of the upper reaches ( - 0 .1 ms- 1) is much greater than that in the main basin during the flood and ebb tides . Con sequ ently, phytoplankton within approximately 4 km of the main ba sin can be advected into the main basin during one tidal cycle. For algal blooms further up stream, the net movem ent of surface water dow nstream during the tidally dominated summer period causes suspended phytoplankton to slowly approach the main basinonce within 4 km, the phytoplankton can be advected into this depositional zone during a single ebb tide. During the transition from ebb to flood tide, the residence time of phytoplankton in the main basin is large enou gh for a comparatively high proportion to se ttle out, constituting organic flux to the sediment . The high velocities in the upper reaches mean that there are few zones of phytoplankton deposition, observable by the lower sediment oxygen demand in these reg10ns. Dissolved oxygen concentration is a

ENVIRONMENT fundamentally important param eter . in predicting nutrient release from Swan River sediments. While sediment release of nitrogen is independent of the oxygen conditions (p >0 .99), phosphorus release increases by 120% under anaerobic conditions (p = 0.01) du e to the reductive dissolution of adsorptive iron (III) oxides in the upper stra ta of the sediment (see Figure 3). Nitrogen release is independent of oxygen conditions since nitrification , an obligately aerobic process, simply converts one nitrogen nutrient to another- there is no n et los s of nitrogen fro m the sediment. Under 'favourable' oxygen conditions , nutrient release from sediments can be deemed to be governed by Fick's Law of diffu sion along a concentra tion gradi ent from the porewa ter (high nutrient concentration) to the overlyi ng water (low nutrient co ncentration) i. e.:


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"'-<!>D _11ci ' 11z

= - <j>D . C;, porewater -C;, overlying water I


the overlying wa ter. Fick's Law does not account for indirectness in the flu x of a diffusing species. Under ' unfavo urable' oxygen conditions, corrections (other than for tortuosity) must be made , quantifying the effect of redox conditions in the upper strata of the sediments . For the aero bic release of amm onium , this correction (for nitrification) was deemed to be approximately constant . However, for the aerobic release of phosphate, the correction is linked to the frac tion of th e se diments compose d of (highly adsorp tive) iro n oxides, w hich can be es timated from the charac teristic particle size. Pho sphate and ammonium concentrations in the porewater of th e sediments are proportional to sediment O)..-ygen demand (which is a se nsitive indicator of the rate ofbenthic reminerali sa ti on), as expec ted . As nutrien t release from the sediment is governed by Fick's Law, the parameterisation of nutrient concentrations in sediment porewa ter is cru cial for numerica l modelling. Su spected gro undwater intru sion , observable by anomalo usly low co n centrations of nutrients in sediment porewater in certain zones of the river, reduces predictive capability.

Conclusion The O)..")'gen demand of Swan River sediments decreases with distance from the river mouth du e to the high flux of organic matter to the sediment in the lower reaches. Whilst sediment release of phosphorus is enhanced under anaerobic conditions, total nitrogen release remains unaffected, though its speciatio n is altered. Fick's Law is a valid m ea n s of es timating nutrient " release from sediments provided that tortu osity effects are accounted for and that the oxygen conditions are favourable for the release of that nutrient. This study ha s, in addition, derived a means of correc ting for unfavo urable oxygen conditi ons. Consequently, sediment nutrient release from Swan River sediments can be accura tely predicted under all conditions.

Author Marco Ghisalbertl recently completed his final honours year in the Department of Enviro nmental Engineering at the University of Western Australia and plans to take up postgraduate studies at the Ma ssac hu se tts Institute of Technology.

where F.1 = flu x (of species I) from sediment

into overlying water (gm-2 s- 1)

<j> = sediment porosity D = diffu sion coefficient of species I ' (m2s-1) C.I = concentration of species I (gm- 3)

z = depth of sediment (m); Nb z = 0.01 min this case, since porewater samples were extracted from a depth of 1 cm into the sediment. 'Favourable' m..-ygen conditions are deemed to be those w here the release of the nutrient is not restricted by redox conditions in the upper strata of the sediments. An example is the release of nitrate under aerobic co nditionsunder anaerobic conditions its release is restricted by the lack of nitrification, a process that results in the formation of nitrate. For the coarsest sediments, the observed flu x was approximately equal to that expected by Fick's Law. However, for comparatively uniform sediments, Fick's Law overestimates the observed flu x by up to 40% . This discrepancy is deemed to be due to tortuosity effects-that is , the winding path that is required in uniform sediments for a nutrient to diffuse into

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RISK MANAGEMENT STRATEGIES FOR RECOVERABLE RESOURCES S Davis, A Roche Introduction This paper examines som e of the legal risks that can be associated with waste reuse activities including wastewa ter re u se and comp os ting, puts forwa rd so me prac ti ca l legal ri sk managem ent strategies design ed to minimise or eliminate those risks and discusses the types of programs companies should consider to manage legal exposure and protec t themselves from liability.

Legal Liability Legal liabili ty for waste reuse activities can arise in two circumstances: • w here a party has suffered loss or injury either personally o r to their property from using or being exposed to a waste. reuse product, e.g. som eone w ho ea ts fo od that was fertilised or irrigated with a waste reuse product and sub sequently contracts an illness as a result of pathogens from the waste reuse produ ct • w here there is direct liability under a statute that specifically controls waste reuse options. M ost States have legislation and/ or guidelines relating to wastewater reuse, fertilisers and the handling of orga nic wastes. Even

examination of the bottle, w hich was opaque. In his judgment, Lord Atkin established the ' neighbour' principle, w hich says that a plaintiff has a right to claim damages if s/he can establish that the defendant's ac tion am ounted to negligence. A party w ho has been affected by a waste reuse produ ct and wishes to make a claim of negligence mu st establish three elements: • that the defendant owed a duty of care to them. The existence of a du ty depends on the relationship between the manufac turer or supplier of the waste reuse product and the party w ho suffered the injury . However , in general, manufac turers or produ cers of waste reuse products will owe a duty of care to parties w ho they can reasonably foresee may suffer some damage if the produ ct is defective in any way • that the du ty of care owed to that party has been breached • that the breach of the du ty has caused the damage .

Law of Contract

Increasingly, as dealings in waste reuse products become more sophistica ted, contracts to supply them in larger qu antiti es will also 'Consumers can seek redress for loss become more complex. caused by a defective waste reuse Accordingly, the second main area of po tential product under the law of tort for liability is in the law of contract. negligence ... ' Apart from the more though guidelines lack strict legislative obvious conditions in a contract such as force, regulatory authorities will often the quantity, am o unt , pnce and refer to them to interpret more general paym ent, an astute purchaser would obligations. draft the contract to include obligations as to: Negligence • the cla ssifi cation of the produ ct C onsumers can seek redress for loss either as compost, soil conditioner, ca u se d by a defec tive was te reuse mulch or manure • the physical and chemical requireproduct under the law of tort for negligence or economic loss . Tortious liabil- ments of the product- for example, a ity for products was established in the requirem ent that all the materials fully historic English case of Donohue and comply with Au stralian Standard 4454Stevenson ([1932] ALL ERepl ) w hich 1997-Composts, Soil C onditioners involved an action by a w oman who had and Mulches suffered illness and shock after drinking • the prohibition of toxins above a bottle of ginger beer which contained certain levels including indemnities for a semi-decomposed snail. It was found any damage caused by the failure of the that the presence of the snail could not product to meet the specified criteria. If a product fails to meet the criteria have been discovered by an external 38


set out in the contract, the supplier could be exposed to an action on the basis of breach of con trac t.

Product Liability Laws T h e Trade Practices A ct 1974 (Cwth) w hich is in fo rce in all Au stralian States and T erritories and variou s State Fair Trading Acts provide for con sumer protection and rem edies in relation to product liability for goods and services w hich would include waste reuse produ cts. In particular, The Trade Prac ti ces Act implies ce rtain 11011excludable conditions and warranties in all con sumer contracts and impo ses liability on manu fac turers direc t to con sumers in ce rtain circumstan ces even though the consumer may have acquired the goods from a third party. For the purpo ses of the Trade Practices Act a cons umer is a person w ho has acquired goods either at a price of up to A$40 ,000 or of a kind ordinarily acquired for personal , domestic or household use or consumption. The conditions or warranties implied by the Trade Practices Act in consumer contracts cannot be excluded , restricted or modified verbally, in w riting or by implication . Any term of a contract w hich purports to exclude, restrict or modify these implied condition s o r warranties will be considered void by a court oflaw . T he major so urce of potential liability for producers, manufacturers and suppliers of waste reuse products is under the defective product provision s in Part VA of the Trade Practices Act. Whilst to date no case has been brought to court under this section of the Act, it is likely that its stringent requirements have resulted in numerou s out of court se ttlements as manufacturers realise the difficulty of defending an action on this ground . The mo st important provision in Part VA is the definition of 'defective goods' . Under the Trade Practices Act, waste reuse products are' defective if they are not as safe as people are generally entitled to expec t from these products. In determining w hether waste reuse products are defective for the purposes of the Act, a number of fa ctors need to be considered.

BUSINESS If someon e suffers loss or injmy as a result of a wa ste reuse produ ct wh1ch they claim is defective, the onu s will shift to the manufacturer to establish that the produ ct is not defective o r to rely on one of the set defences . Under Section 75AK of the Trade Pra cti ces Act the manufa cturer can escape liabili ty if it can prove that: • the alleged defec t did not exi st w hen the goods left the m anu fac turer's control • the only reason the produ ct was defective was because it complied with a mand ato ry stand ard • th e defec t co uld not have bee n discovered in light of the state of scien-

The Ten Commandments of Waste Reuse Risk Management


Board and Management Commitment


Risk Identification and Assessment

A legal risk management program requires the commitment of senior management and the board to ensuring comp liance and managing an organisation's lega l risks. The co urts regularly refer to organisations that have established a 'comp liance culture .' This is surprisi ngly easy to determine and involves co mpliance with legislation and adoption of safe risk management practices.

Once a company has committed to estab lishing a legal risk management program for its wast e reuse operations, the f irst step is to id entify the key legal risks and exposures. This is best done usi ng a ri sk assessment methodo logy. Th e usual approach is to: • identify potential exposures associated with the waste reuse operati ons • assess the nature and extent of the risks as they a rise in rea Iity • develop management strat egies to handle the risks. Idea lly, management of the risk should be approached by trying first to eliminate it altogether. If that ca nnot be done, th e next option is to engin eer out the risk t hrough process improvements. If that is not possible or leaves some residual risks, t he exposure of third parties to t he risk needs to be co ntrol led . This may involve a range of measures from warn ings and labels to th e supply of protective equipment.


Legal Requirements

Th e third element is to determine the lega l requireme nts applyi ng to the operation s. These may re late to operating the wast e reuse business on a particu lar site, in cl uding odour and planning controls , t hrough to labelling and product standards. In New South Wales last year the

tific and technical knowledge at the time the goods were manufactured.

Legislative Liability As well as actions fo r defective waste reu se produ cts, there are increasing direc t and indirect legislative controls over waste reuse operations. Direct legislative controls are those w hich impose specific requirements on operators of waste re use activiti es, e.g. planning and Environment Protection Authority controls such as the fer tiliser legislation in each State, the Livestock Disease Control Act in Vi ctori a for the use of raw sewage and the vari ous legislation preventing the reuse of grey-

Environmental Planning and Assessment Amendment (Composting and Other Matters) Regulation 1996 was passed , making composting and other organ ic waste facil iti es designated developments for t he purposes of t he Environmental Planning and Assessment Act 1979 (NSW). Similarly, in other jurisdictions, companies shou ld ensure that their waste reuse operations are authorised and licensed under the releva nt plan ning sc heme if required by environm enta l aut horiti es. Ongoing operations must comply with all relevant acts, regulations and guidelines. As this area becomes more popular it is li ke ly that the amount of co ntrolling legislation will grow acco rdi ngly. Waste reuse operators need to have a system in place to identify al l app li cable legislation as it comes into force .


Industry Standards

Th e next stage is t o determ in e th e relevant industry standards and best practice in the particular waste reuse areas concerned. The courts have held on numerous occasions (e.g. EPA v. Ampol ) that establi shed ind ustry practices and standards are re leva nt factors in determ ining whether or not co mpan ies have acted with due diligence in a particular area. Accordingly, any legal risk management program should retain existing references to Australian Standards for compost and soi l and incl ude th e fo llowing: • (a) AS 4351. 7/ 1996 Biodegradabi lity Organic Compounds in an Aqueous Medium Determination by SemiContinuous Activated Sludge Method (SCAS) • (b) AS 203 1.1 Se lection of Containers and Prese rvatio n of Water Samples • (c) EPA 1990 Guidel in es for Waste Water Irrigation • (d) EPA publication 441 A Guide to the Sampling and Analysis of Water and Waste Water • (e) EPA Best Practice Environmenta l Ma nagement Guidelines for Use of Biosolids (these guid el ines are due to be released in early 1999).

wa ter. This area ca n also include wider liability under mainstream environmental laws if waste reuse options result in breaches of prohibitio ns on odo urs extending beyond a bo unda1y, in the case of wa ter pollution or in the event of failure to obtain licences for operations. Indirect legislative controls appear in the form of guidelines, codes of practice issued by government departments and Australian standards. T hese can include: • the draft Victorian Bio-solids Guidelines (part of the Best PJ actice Seri es) • the draft N ational W ater Qu ali ty M anagem ent Stra tegy G uidelines on R eclaimed W ater • the new Compost Standards AS 4454

Even though these standards are not legislation , legal effect can arise either by incorporation by reference or as de facto requirements. Th ere is an in creasing trend in legislation to inco rporate by refere nce existing Australian standards and to req uire compl iance . For examp le, the Dangerous Goods (Storage and Handling) Regulations 1989 (Vic ) adopt more than twenty Austra li an standards and parties subj ect to th e Act must comp ly with those st anda rd s. In particular, Regulation 600 requires people storing class 3.1 and 3.2 dangerous goods to comply with AS 1940. Non-comp lia nce with th at standard is therefore a breach of the regulation and co uld lead to prosec utio n. It is co nce ivable that future legislation on co mpost will incorporate comp liance with AS 4454 and AS 4419. Courts often have regard to Australi an sta nd ards , gu idel in es and codes of pra cti ce which operate as de facto requirement s in determ ining whether companies and individuals have discharged their legal obligations. For example, in the area of health and safety, employers are under an obligation to provide a safe workplace. Various standa rd s and codes of practice exist to assist employees to wo rk safe ly with plant or mach inery. Courts often refer to these standards and codes to determine whether companies have complied with their obligation to provide a safe workplace. Un less a company can est ab lish that it has ado pted its own OH&S po licy, the releva nt code of practice or standard will be accepted as the means of ensuring a safe workplace in relation to that plant or equ ipm ent, and non-comp liance will expose a compa ny to prosec ution . Similarly, if a co mpany winds up in co urt defendi ng an action brought und er Part VA of the Trade Practices Act, evid ence may be introduced to estab lish that a waste reuse product, for example a compost product, was defective by estab lishi ng th at it fai led to comp ly with releva nt Austral ian standards on compost and thereby was manufactured in ignorance of best practice. Conversely, a company may be able to WATER NOVEMBER/DECEMBER 1 998


BUSINESS management program for producers , manufacturers and suppliers of waste reuse products. Such a program can: • significantly reduce an organisation's legal exposure • pron10te due diligence and responsibility for environmental management • establi sh a 'defence' even if liability does arise under statute or at common law (e.g. negligence , contract, health and safety or environmental laws). Such a defence may be based in statute or consist of an argument at common law that an organisation acted reasonably in all the circumstances or, in a worst case scenario, act in mitigation of a penalty to be imposed by a court.


establish a defence by establishing that it manufactured the product in accordance with a standard and that the defect only arose because of compliance with that standard. In relation to a negligence action , non-co mpliance may be introduced as evidence of a breach of the duty of care.

introduced. Registers can be a good training tool if they contain explanations of the roles and accountabilities of staff in the legal compliance and risk management system .


Compliance System


Delegatlon of Responslblllty

Once the compliance system has been established, an organisation needs to clearly assign internal accountabi lity for comp li ance with the newly developed procedures and guidel in es.

Interna l reviews of comp li ance with legislation (and best practice, relevant Australian standards and guide lines) should be conducted twice-yearly. A checklist can be useful for this purpose. Depending on the size of the operation or how well internal processes com ply, a company may want to track the results more closely, e.g. on a month ly basis . To protect senior management and the board from information overload, it is important to develop risk measures that can be tracked over time . Invariably, the measures selected must be capable of recording the key performance drivers. A role must be created for someo ne to co llect the data each month and funnel it up to the senior layers of the organisation. For example, in a case where it is decided to measure critical pathogen levels and a test reveals pathogen levels in excess of ordinary parameters, this information will need to be reported to the nominated person in the organisation who can then pass it on or make a judgement as to whether corrective action is necessary. Even the most expertly designed compl iance systems count for nothing if sen ior management and the board do not use the info rmation provided. The board must ensure that corrective measures are taken where appropriate and that additional monitoring occurs to ensure that legal exposures are properly addressed . From a due di ligence perspective, it is critical that the company is seen to be responsive to issues which arise in the course of the waste reuse operations.

obtaining re levant insurance. In an id ea l world , responsibility would be entirely passed on to customers or suppliers and full indemnities in relation to any loss or damage which results from the waste reuse products wou ld be obtained . However, this is not always commercially acceptable in the marketplace and is often contrary to impli ed warra nties and guarantees under th e Trad e Practices Act and relevant State legislation . For large contracts, risk and responsibi lity should be transferred wherever possible to customers. Where it .is important for a third party to handle, store or treat the waste reuse product in a particular manner in order to ensure its safety or suitability for use, th is should also be built into the contract and audited by the manufacturer as part of a proper contract management program . Although changes to the Trade Practices Act in 1992 potentially made it easier for plaintiffs to bring actions against manufacturers, the Austra lian insurance indu stry, largely due to th e abse nce of litigation, has not made any rating adjustment. The necessity for product liability and product recall insurance should be evaluated. If product liability insurance is obtained , it is important that the exclusions do not render the policy ineffectual in practice . For examp le, many po li cies exclude claim s arisi ng out of instructions for use or storage of the product, wh ich is particularly relevant for some waste reuse products and li ke ly to be the cause of the actio n in the first place.



and AS 4419. Although these guidelines and standards have no legislative force, they can become de facto laws.

Managing Legal Exposure Producers, manufacturers and suppliers of waste reuse produ cts need to implement an effec tive legal ri sk management program that is not so complex that it consumes excessive time or money and that do es not require a team of lawyers once the approach is understood and the releva nt advice has been obtained. Set out below are the T en Commandments of an effective legal risk

Having determined the lega l requirements and industry standards, a company needs to estab lish a compliance system to ensure that its day-to-day operations comp ly with the relevant contro ls. Compliance systems must be tailored to suit the company's competitive position, size, type of activities and wallet. A compliance system can take many forms . Some companies prefer computerbased compliance systems, wh ile others develop standard operating procedures, manuals, and quality and aud it checklists at vario us stages in the process. Whatever system is se lected as su itab le, the company must at a minimum ensure that its products and operations comply with applicable legal requirements and industry standards . For example, one element of the compliance system is to ensure that labelling complies with the Australian standard and with basic product liabi lity principles. This area has also been subject to the attention of the Austral ian Standards organisation. Largely at the request of the ACCC, the new Austra lian Standard on Legal Compliance Programs AS3806:1998 was released early th is year.


Once the roles and responsibilities are defined, the responsible people shou ld be trained so that they understand their roles and the reason that the system has been




Internal Controls and Reporting

Risk Transfer

Where possible, lega l risks arising from the operations should be transferred to a th ird party. Two obvious examples are in relation to contracts with customers and

Thi s paper outlines the various legal exposures which may be faced in waste reu se activities and how to establish an effective legal risk management program to manage that exposure. It covers a broad range of iss ues in a short compass and the authors wo uld be happy to answer more specifi c questions.

Authors Stephen Davis and Adrienne Roche are environmental lawyers wi th

Malle so ns Step hen Jaqu es Environmental Law Gro up , 525 Collins Street, Melbourne Vi c 3000.


External Review

Once a legal risk management program has been set up it is advisable to have the program reviewed externally by consu ltants. This wi ll pick up any errors that may be overlooked as a resu lt of 'the company ' marking its own homework. ' Some co mpanies rotate consu ltants from year to year using a range of environmental , tech nical , legal and risk/ insurance auditors, whi le others put together a small team from different disciplines.



WATER INDUSTRY T Carpenter Thi s paper is a summary prepared by E A S (Bob) Swinton of the main enginee ring co ntent of WSAAfa cts 1997. The complete 120-page report, w hich includes a fin ancial reporting component, is available from the Water Services Association of Australia, 469 Latrobe Street, M elbourne Vic 3000.

Introduction The Water Services Association of Au stralia (WSAA) is the peak body of the Australian urban water industry. Its 18 full m embers and nine associate members provide water and wastewater services to more than 12.5 million Au stralians and m any of Australia's largest industrial and commercial enterprises. The organisation was formed in 1995 to provide a forum for debate on issues of importance to the urban water industry and a focal point for communic.ating the industry's views to the public. Informed decision-making on issues of ownership , industry structure, competition policy and effective regulation requires accurate analysis of performance across the industry. WSA.Atacts 97 provides an authoritative and audited so urce of perform an ce information through th e active participation of WSAA members. It summarises and compares six years of performance data and costs in the Australian urban water industry to 1996-97 . T hough direct comparison is fraught with difficulty because of the wide range of confounding factors, the trends are more reliable.

The Changing Water Industry 1s 42

The Australian urban water indu stry an era of fundamental and rapid



reform. Co mp etitive pressures are increasing and the indu stry is now becoming part of the internatio nal market for wa ter services. Stru ctural refo rms are clarifying acco untabilities by separating policy, regulato ry and commercial or operational functions. This is providing urban wa ter bu sinesses with clear commercial goals of customer service, w hile safeguarding public health and achieving environmental compliance in a sound bu siness operation, free of other confli cting objectives. The regulatory roles traditionally performed by urban water businesses have either been abolished or are being tran sferred to appropriate regulatory bodies . Economic regulators are being set up to oversee the performance of the industry to protec t customer interests and regulate water prices . H ealth and environmental regulators are coming under pressure to be more accountable for the cos t-effectiveness of their decisions and the consequ ential impacts on water prices.

Cost Drivers An understanding of factors driving the costs of urban wa ter businesses is vital to a valid interpretation of performance stati stics. Differences in the cost drivers between individual bu sinesses makes comparison of different water businesses a complex exercise, particularly for international comparisons. The most reliable indicators are the trends in performance over time for a given business so that the confounding fa ctors or differences in cost drivers are h eld constant. Long-term , consistent performance data are therefore a vital resource . The large climati c variability in

Australia is a major cost driver, requiring large storage reservoirs to maintain wa ter supplies during recurring droughts. The report includes a detailed discussion on the clear link between El Nino and the Southern Oscillation Index and Australia 's rainfall and runoff. Rainfall in 1996-97 was significantly lower than average for all centres except Canberra, D arwin , ¡ N ewcas tle and P erth. The drier conditions led to high er water co n sumption in mo st centres, which had significant effects on water storages, o perating cos ts and revenues . Pipe and sewer breakages were also increased in clay soil areas. Models are being developed by other agencies to forecast streamflows longterm, from SO I and other data.

Statistics T able 1 shows the populations served in 1996-97 by participating businesses and the number of water and wastewater service connections. The 18 full members service a total population of 12.55 million with water services and 11. 9 million with wastewater services. The table illustrates the dominance of residential services in the wa ter industry. Some 90% of water connections and 91 % of sewe r connections supply residential hou seholds. The non-residential component is composed of indu strial , commercial , municipal and other supplies. It should be no ted that the W ater Corporation of W es tern Australia, Power and W ater Auth6 rity of the Northern T erritory and South Au stralian Water are all Statewide organisations and the information provided in WSAAfacts is for their m etropolitan services only, i. e. Perth, Darwin, Alice Springs and Adelaide.

BUSINESS Water Use Interpretation of water use statistics requires information on climate, principally temperature and rainfall. A large table in the report summarises the average maximum and mimmum temperatures together with annual and mean annual rainfall for the centres of operation for participating bu sinesses . Adelaide (SA W ater) is the driest centre with a m ean annual rainfall of 45 3 mm and D arw in (Power and Water Authori ty) the wettest with 1,691 mm, thou gh confined to a two to three month 'we t' season . Pricing reforms and demand management initiatives achieved a reduction of 19% in water use per property between 1990-9 1 and 1995-96, but the impa ct of more severe w eather conditions in 1996-97 led to a return to 1994-95 levels. In 1996-97 an average of 41 8 kL per property was supplied compared to the 1995-96 average of 398 kL. It should be no ted that because the calculation is based on raw data for total water input to the sys tem it also includes unaccounted for water such as system losses. Hou sehold water consumption per property is lower, typically in the range of 25 0 to 300 kL/household . Figure 1 shows the trend in water use per prop erty for the six years to 1996-97. A decreasing trend is evident despite the w ea ther-driven increase in 1996-97, giving confiden ce that reforms to water pricing policies and demand manage m ent program s are having the desired effe ct in driving the effi cient use of water. Table 2 summarises data derived by M elbourne Water on household consumption patterns, with estimates of possible savings from efficient appliances. Wastewater Collection In 1996-97 an average of 287 kL per property was collected compared to the 1995-96 average of285 kL. It should be noted that because the calculation is based on total wastewater input to treatm ent plants , it also includes infiltration to sewers such as during storrns or through illegal stormwater connections. Hou sehold wastewater output is lower than the data provided, as this includes non-household discharges . Apart from an initial drop in trend between 199 1-92 and 1993-9 4, the volume of wa stewater collected per property has remained stable. A new statistic included in 1996-97 is the volume of licensed trade waste collec ted. Service Performance Interpretation of the performance measures mu st consider the different service levels, regulatory prescriptio ns

Figure 1 Trend in water use 1996-97 Table 1 Water and wastewater connectio ns 1996-97 Population

118 99 327 55 51 243

3,489 85 1,084 1,400

1,307 23 442 518

3,81 5




1,511 12,551


Barwon Water

Brisbane Water Central Gippsland Water Central Highlands Water

City West Water Cotiban Water Gold Coast Water Hobart Water1

Hunter Water Corporation Melbourne Water Corporation Melbourne Consolidated' Power and Water Authority' SA Water

South East Water Limited Sydney Water Corporation Water Corporation Yarra Valley Water Totals Note: 3

NonTotal Population Tota l NonProperties Household Properties Household

308 212 812 133 111 578 120 357 185 469

ACTEW Corporation

Storm Water


Water Water Business


170 74 187


9 28 6 5 41 7 13

195 812 119 93 578 106 357

11 3 91 318 47 40 241 43 168

6 26 4 4 40 4 12





155 4

3,489 82


1,01 3 1,400

1,240 28 420 481 1,491 448 518 4 ,620

140 2 37


73 191 81 41 554

3,784 1,120

1,511 11 ,906





Hecta res


57 1,284


61 7

3TT 246




87, 511


166 52 36


Hobart Water is a wholesale supplier to eight local council retailers. Melbourne Consolidated is the sum of City West Water, South East Water Limited and Yarra Valley Water. Power & Water Authority only provide one water supply master meter for a block of flats/units, whereas each property within a block of units or flats is counted as a wastewater service, therefore the number of wastewater services Is in excess of the number of water services

Table 2 Household cons umption patterns and efficient appliance savings Domestic Consumption Domestic Appliance or Annual Coosumption Percentage of average per average hOusehold annual domestic , Component Task kl;/year consumption % , Kitchen




Garden Total

Dish washing




Possible savings with water efficient appliances










48 .6





Washing Machine













Outdoor Use

Notes: 1Figures taken from internal Melbourne Water Corporation study on household consumption

(e.g. water quality and eillu ent discharge standards) and operating environments (physical and structural) within which each water business operates. It should be noted that these differences affect cro ss-business analysis. The trend (time- series) data are most important. Water Supply There is still a variety of standards and guidelines used by State regulatory authorities for m easuring quality fo r the various businesses. Most are based on the 1996 National H ealth and M edical R esearch Co uncil (NHMRC) Australian Drinking W ater Guidelines . Others are based on the 1980 NHMRC Guidelines or World H ealth Organisa-

tion (WHO) Guidelines , having regard to particular charac teristics such as the degree of protection of the water supply catchments . With respec t to bacteriological quality, all the major businesses comply more than 99% of the time , but some country supplies are less reliable. There is a wider va riation in physico-chemical quality: the major authorities ranging from 95 to 99 .8%, but country authorities dropping to as low as 70% (mainly turbidity). Regardless of the generally high level of compliance, the industry is continuing to invest substantial research and capital sums for water quality protection. WATER NOVEMBER/ DECEMBER 1998


BUSINESS Table 3 Proportion of popu lation connected to wastewater se rvices . Water Business ACTEW Corporation

'!, of Population Connected

¾ of Sewage




Table 4 Average annua l bil l, $

Level of Treatment Primary



100.00% 100.00% 100.00% 100.00% 1.00% Brisbane Wate1 100.00% 99.00% Central Gippsland Wate1 99.50% 90.00% 9.50% Central Highlands Wate, 100.00% 12.00% 88.00% City West Wate, 100.00% 100.00% Caliban Wate1 100.00% 40.00% 60.00% 100.00% Gold Coast Wate, 87.00% 13.00% Hunter Water Corporation 100.00% 52.00% 48.00% 100.00% Melbourne Water Corporation 1 NA 100.00% Power and Water Authorit) 67.00o/, 79.69% 92.00% 25.00% SAWate, 95.02% 100.00% 100.00% 100.00% South East Water Limited 100.00% 92.86% Sydney Water Corporation 95.92% 100.00% 4.00% 83.00% 13.00% Water Corporation 80.43% 100.00% 42.00% 58.00% Yarra Valley Wate, 94.87% 100.00% 100.00% Note: Melbourne Water provides wholesale bulk treatment to City West Water, South East Water L1m1ted and Yarra Valley Water and does not directly service a Population. Barwon Wate1


100.00% 91 .92% 96.64% 84.24% 78.43% 99.18% 76.79% 98.82% 93.58%

The 'Level of Treatment' show in this figure is NOT a perfomiance measurer. It is only provided to give appropriate background data to other table. In partirular, it assists in explaining variatk>ns in wastewater operating and total costs. Fig 8.4 demonstrates compliance with regulatory standards.

Wastewater Table 3 lists the proportion of populations connected and the level of treatment provided. Most participating businesses achieve better than 95% compliance with efiluent discharge standards over the range of the plants they op erate. A n ew indicator, the number of wastewater treatment plants that were compliant with their licences at all times, has been included . Additional refinem ent to quantify plant failures is being done to reflect the duration and magnitude of the fai lure to comply. Over the whole industry, 35,785 ML or 2. 7% of trea ted effluent and 54,140 ML or 4.1 % of raw efiluent is reused/recycled. The main constraints to increasing effluent reuse/recycling continue to be the relatively high cost of transporting treated efiluent and the limited market for second quality water. The raw efiluent reuse/recycling statistic recognises the dual benefits of treat-

subj ect to strict health and environmental regulation. R egardless of this, 4 7% of biosolids were reused/recycled in 1996-97.

Customer Service A set of performance indicators for customer service has been developed for 1996-97 based on those collected by the UK w ater indu stry regulator , OFWAT. While some differen ces in customer behaviour exist between the countries, such as whether customers use the telephone or w rite letters to m ake enquiries, figures should be relatively comparable. There was a wide range of response times to cu stomer complaints. The ability of the average customer to access comparative performance data will be fundam ental to the ultimate destiny of the current reform processes.

Water Supply R eporting on service standards for water has been upgraded by the adoption of three 'indicators' from the elec tricity ' ... there may be an increase indu stry of interruption durations frequencies, in burst/choke rates in the although and the different industries are not directly foreseeable future.' comparable given the fundamental differences in the respecment processes such as pasture irrigative industry's delivery assets (e.g. tion at M elbourne W ater's W estern overhead wires compared with underTreatment Plant. While this is part of ground pipes). the treatment process, it also has the A series of tables in the report shows benefit of being input to agricultural how many properties had an interrupproduction. tion to their water supply as a rate per Biosolids are a by-product of waste- thousand properties (per annum) and wa ter treatment. Acro ss Australia , the average duration of the interruption 203, 000 tonnes of dry solids were (in hours) . They are difficult indica tors produc ed in wastewater treatment to analyse and are dependent on: plants. Most solids were stored at the • asset reliability treatment plant site or used as a soil • location of isolation valves used for conditioner on agricultural land. Reuse repair of biosolids is a function of economic • distortion by individual large main viability, plant location and the avail- failure events that can interrupt supply ability of potential customers and is to thousands of properties at once. 44


ACTEW Barwon Brisbane Centra l Gippsland Balla rat CWWL (Mel) Co liban Water Gold Coast Hunter Water Power & Water (NT) SA Water SEWL (Me l) Sydney Water Water Corp (W A) YVWL (Mel)



303 225 308 161 258 239 251 274 230 402 261 222 248 264 257

376 209 189 256 238 308 280 345 218 254 298 334 269 356 366

A final table was calculated by multiplying the number of properties with an interruption by the average duration of those interruptions and then dividing the result by the total numb er of properties supplied by the business. Comparison of the results for the water industry indicate the differences in interruption duration targets specified in licences for individual businesses. A highlight of the figures was the large increase in the number of interruptions in the M elbourne area due to the significantly drier weather leading to asset failures, yet the duration of interruptions was stable or reduced. Wastewater R eporting on service standards for wastewater has also been upgraded by the adoption of three 'indicators' from the electricity industry. Tables in the report show how many properties had an interruption to their wastewater service as a rate per thousand properties per annum, the average duration of the interruption and a final amalgam of the two indicators calculated by multiplying the number of properties with an interruption by the average duration of those interruptions and then dividing the result by the total number of properties supplied by the business . The percentage of wastewater chokes cleared within five hours ranged from 94% to 100%, with an exception w here an eight-hour response time is set by the authority. It should be noted that unlike water supply interruptions , a choke in the wastewater system does not necessarily result in a disruption of service to the customer.

Pricing The widely varying tariff structures for domestic customers are shown in a large table in the report . Indu stry reforms to water pricing stru ctures are base d on a tariff compri sing two

BUSINESS components: • a fixed charge reflecting the cost ·of service prov1s10n • a . variable charge based on the volume of water purchased. Substantial progress is being made towards the goal of en suring that customers receive clear price signals for the cost of increased consumption . Across all participating businesses it is es timated that some 50% of water reve nu e is now raise d from u sage charges. The information in Table 4 show ing the average annual bill per domestic customer has been abstracted from a fuller table . The average change from 1995-96 to 1996-97 is plus 0.6% nominal, but rriinus 0.6% in real dollars.

Table 5 Asset utilisation ratios for water supp ly Water Supply Asaot Utilisation Rlltioo Water Business ACTEW Corporation


Unaccounted for Water A table in the report provides an estimate of the unaccounted for water in water supply systems downstream of

3.50 2.07

2.06 1.68

0.69 0.45




2.62 2.92 0.31 2.81 3.57 6.94 1.48 6.84

1.89 1.45 2.30 1.73 2.20 1.48 2.18

0.45 0.59 0.95 0.76 0.86 0.00

Brisbane Water Central Glppsland Water Central Hlghlands Water

City West Water ' ColibanWater Gold Coast Water Hobart Water 1 Hunter Water Corporation Melbourne Water Corporation Power and Water Authority

SAWater 1 South East QLD Water Board South East Water Limited 1


Sydney Water Corporation

Water Corporation '

4.05 3.14

Yarra Valley Water r



1.46 1.89


1. Hobart Water and SA Water derive signif icant wate r from direct river pum ping (60% for Hobart Water) and t herefore


require much less storage capacity tha n other busi nesses. 2 . See Melbou rne Water figure fo r storage volu me to an nua l cons umptio n ratio for City West Water, South East Wate r

and Yarra Val ley Water. 3 . Water Corporation derives significant water from groundwater sources and therefore req uires less storage ca pacity than other businesses. 4. Peak system delivery capaci ty is on ly an estimate of the maximum day load the system can deliver and as such the ratios sho uld be treated wi th caution.

Infrastructure Asset P~rformance The relationship between the lives of mains, the nature of their deterioration and the growth profile of the urban service networks strongly suggests that there may be an increase in burst/ choke rates in the foreseeable future. However, it is most unlikely that this will translate into a corresponding increase in the need for mains rehabilitation or replacement since it w ill be primarily sourced from a greater numb er of mains moving into the period of their life cycle that exhibits an increase (albeit at a low level) of aging fa ults. The challenge to the water businesses is to m anage service both to avoid premature replacement of water and sewer mains and signifi cant disruption to the cu stomer. For the retail bu sinesses, this m ay be achi eved through a focus on the duration of outages as much as their number. Climatic changes can lead to soil movement and asset failure due to: • changes in watertable/soil moisture content • f~ost heave and clay shrinkage • loss of anchorage/support. A business w hose predominant soil type is sand will , all else being equal, have a much more stable failure rate than one whose predominant soil type is expansive clay. For example, the significantly increased failure rates for C ity West Water and Yarra Valley W ater in 1996-97 are due to the dry weather. Tables in the report compare water main breaks per 100 km of main and sewer main breaks/chokes per 100 km main from 199 1-92 to 1996-97 .

Storage Volumt to Annual Consumptlon Peak Day to Average Day Consumption Peak Day to Peak System Oellvlf)' Capacity

45 0.000


0 0 0


400 ,000 35 0,000 300 ,00 0


.., :t::


250,00 0




200 ,000

w u

150.00 0


100,00 0




i t}

! ,g,

















aRetieutetio n


oBu lk

a Unalloceited

Figure 2 Water su pply capital expend iture forecast to 2001-02

800,000 700 ,000




500 ,000

::, :t::

,, C

Q. 0

.. 0



300,0 00



ws, ...... 0





















,So ~








• T,e•tm ent

Figure 3 Wastewater cap ital expenditure forecast to 2001-02

bulk water meters at dam outlet works. It includes allowance for: • leakage • theft and illegal connections

• illegal use of unmetered customer fire services • fire fighting (street hydrants) • under-registration of customer meters WA.TER NOVEMBER/ DECEMBER 1998


BUSINESS Table 6 Asset utilisation ratios for wastewater Water Business

Wastewater Asset Utilisation Ratios Peak Day to Average Day Load

ACTEW Corporation Barwon Wate, Brisbane Water 1

Peak Day to Peak System Load Capacity

1.65 1.94 1.06

1.33 0.91



Centra l Gippsland Wate, Central Highlands Wale,

City West Water



Co liban Wale, Gold Coast Wate ,



2.64 2.93

0.65 0.93

Hunter Water Corporation Melbourne Water Corporation Power and Water Authority SAWate1

South East Water Limited



Sydney Water Corporation ' Water Corporation : Yarra Valley Water



Wastewater System Infiltration A table providing an estimate of infiltration into wastewater systems upstream of trea tment plants includes allowance for: • stormwater infiltration • illegal co nnections of stormwater pipes • groundwater infiltration. Most businesses range from 8-12% but Brisbane and Hunter Water are outliers at ca. 25%. Asset Use T ables 5 and 6 provide asset utilisation ratios for wa ter supply and wastewa ter respectively and demonstrate the significant reso urces required to deliver an acceptable service to the customer. The high ratios are a reflection of the highly variable nature of both wa ter available for harvesting and customer usage patterns. Storage volume to annual consumption provides an indi catio n of th e drought security available at the curre nt year's annu al dem and . The valu e indicates the number of years of available supply assuming no inflow. Peak to average day consumption provides a measure of the va riability of daily cu stomer demand over the year. Peak day to peak system delivery capacity is a measure of the capacity of the supply system to meet the peak day that occurred during the year. A value of less than one indi ca tes demand did not ·exceed the capacity of the respecWATER NOVEMBER/ DECEMBER 1998

0.77 na

Peak system Load Capaaty 1s only an estimate of the maximum day load the system can receive and as such the ratios should be treated with caution. It is also dependant on treatm ent plant capacity an d is not applicable for City West Water, South East Water Limited and Yarra Valley Water (see Melbourne Water figure for Melbou rne).

• errors in system meters. Evaporation from bulk sto rage dams up stream of the outlet works is no t included and bu siness estimates made for usage by unmetered services have been subtracted. Unaccounted for water ranges from 8% for the relatively small network of ACTEW to 28% for Gippsland, but most are close to the average of 16%, with an overall downward trend .


1.00 2.68

tive system to supply water at the required pressure or treat wastewater discharges. A value of greater than one indica tes augmentation is required. Capital Expenditure The capital investment made by the indu stry over th e last six years has decreased from a maximum of $1,220 million in 1992-93 to $899 million in 1996-97 . The split of expenditure between new works, renewal/ replacement and subdivider developm ent for the 1996-97 financial year for each of the businesses is also summarised. In total , new works con sumed $482 million , renewals $197 million, development $178 million , and others $40 million. Figures 2 and 3 forecast capital expe nditu res to 200 1-02 fo r wate r supply and wastewa ter systems. T hey provide an insight into the overall level of expenditure and the main factors driving industry investment. These two figures show a trend toward increasing capital investment, particularly for wastewa ter treatment, to meet higher environmental di scharge standards. They also illustrate the scale of the marketplace for innovation and improvements in capital efficiency and provide a framework within w hich to discuss the impact of capital.

Financial Performance Summary The full report includes 35 pages of financial statistics and comparisons. In summary, they show that the Australian urban water indu stry continu ed to make significant progress in 1996-97 . Financial performance imgroved, w hile major enhancements in safeguarding publi c h ealth and protecting the environment were achieved in a year w hen real average residential wate r prices decreased. Financial highlights for 1996-97 include: • an improvem ent in the economic

BUSINESS real rate of return from 3.8% 111 1995-96 to 4 .3% in 1996-97 • increased dividends to governments as shareholders • a decrease in average real residential water prices of0.6% • a real increas e in revenu e per property of 3.0% as a res ult of the combined impact of abnormally dry conditions (and hence increased customer demand) and a continued shift to user pays pnc111g • continu ation of the underlying improve m ent 111 operating cos ts reflec ted by the real decrease of 3.75% in the operating cost per property for wastewater services . Operating cos t per prop erty for combined wa ter and wastewa ter services increased by 0.4% . N ew maj or water treatment plants for improvement in drinking wa ter quality and the ab normally dry conditions were significant contributing factors, along with the effects of the El N ino event.

Research WSAA inherited a portfolio of 75 research projects from UWRAA w hich has now been brought under WSAA as the research divi sion . Calling for expressions of interes t from th e research community and selecting interesting propo sals developed the portfolio of proj ec ts. Completion of 34 of the inherited proj ects ha s reduced the portfolio to 41 proj ects atJune 1997 . Th e research covers a wide range of topics from phosphoru s in detergents, reducing costs through evaluating alternative overseas water treatm ent and supply practices, disinfection of wastewater effluent, to ammonia removal from treated sewage using zeolite. T his research is making a valuable contribution to the knowledge base of the Australian urban water indu stry. The report fini shes with a comprehen sive li st of the N ational Water Quality Management Strategy Documents and the 140 WSAA publica tions, including the UWRAA reports.

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+ Municipa l W astew ater

Carol Innes-Brow n of Sydney Water and Annie Lau fron1 the Wa ter Corporation of W es tern Au strali a assisted with th e detailed work so necessary in thi s survey.

+ Water Rec lamat ion Systems + Industrial Coo li ng W ater + Aquacu lture and Marine Life

Tom Carpenter is Proj ec t Director

with the Water Services Association of Australia , principally involve d with industry performance and regulatory issues, and Proj ec t Director for the WSAAfa cts report. Previously he was with M elbourne W ater, in strategic infrastructure planning and operations engineering management.





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