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Volume 25 No 2 March/April 1998 Journal Australian Water & Wastewater Association

Editorial Board FR Bishop, Chairman B N Anderson, G Cawston, M R C hapman P D raayers, W J Dulfer, G A Holder M Muntisov, P Nadebaum,J D Parker A J Priescley, J Rissman

General Editor Margaret Metz AWWA Federal Office (see address below)

Features Editor EA (Bob) Swinton 4 Pleasant View Cres, Wheelers Hill Vic 3150 T el/Fax (03) 9560 4752

CONTENTS

Branch Correspondents ACT - Ian Bergman Tel (06) 248 3133 Fax (06) 248 3806 N ew South Wales - Mitchell Laginestra Tel (02) 9412 9974 Fax (02) 9412 9676 Northern Territory - Bill Bean Tel (08) 8924 7201 Fax (08) 8941 0703

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

MY

POINT

OF

VIEW

Queensland - Tom Belgrove

WAMPs, Not Wimps! ...................... ... ... ... ... ......................... ... ....................... .. 3

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

J Simpson

South Australia - Angela Colliver

~

Tel (08) 8227 1111 Fax (08) 8227 1100

Tasmania - Ed Kleywegt Tel (036) 238 2841 fax (036) 234 7109

Victoria - Mike Muntisov Tel (03) 9600 1100 Fax (03) 9600 1300 Western Australia - Jane Oliver Tel (08) 9380 7454 Fax (08) 9388 1908

·, How Safe is Bottled Water? .... .... ........... ..... ... ........................................... 7

RB Thurman, SJ Sterry ·, Use of Water Treatment Sludge .......................... .............. ............. ......... 11

M Ahmed, C D Grant, J M Oades, P Tarrant

Advertising & Administration AWWA Federal Office Advenising: Angela Makris Graphic Design: Elizabeth Wan PO Box 388 Artarmon NSW 2064 Level 2, 44 Hampden Road, Artan11011 T el (02) 94131288 Fax (02) 9413 1047 Email: awwa@inta.net.au

Water (ISSN 0310 · 0367) is published six times per year: January, March, May. July, September, November by

Australian Water & Wastewater Inc AR:BN 054 253 066

Federal President Greg Cawston

Executive Director

WASTEWATER ACTEW Wins AWWA's Prestigious Peter Hughes Water Award ............... 17

C Davis ·, Greywater Recycling in Western Australia .. ... ... .......................... .......... 18

B D evine, B Bowden, ] E Schlafrig, RJ Fimmel 1 9 9 8

Subscriptions Water is sent to all members of AWW A as one of the privileges of membership. Non-members can obtain Water on subscription at an annual subscription rate of S39 (surface mail).

C O N F E R E N, C E

P REV I EW

Waterworld, Wasteworld, Sea World: Queensland's Got the Lot! ... ....... 23 What's New? Ozwater & Ozwaste 98 ..... ............ ............................. ....... .. .... 24 ENVIRONMENT ·,' A Model for Continuous Tracking of Wetland Performance ............. ... 27

J Fabian Creating Sustainable Urban Water Resources ............ ... ... ........................ 31

I Law rence

Chris Davis Australian Water & Wastewater Association assumes no responsibility for opinions or statements of facts expressed by contributors or advertisers and editorials do not necessarily represent the offi cial policy of the organisation. Display and classified advertisements are included as an information service to readers and are reviewed by the Editor before publication to ensure their relevance to the water environment and to the objectives of the Association. All material in Water is copyright and should not be reproduced wholly or in part without the written permission of the Editor.

WATER

BNR3

CONFERENCE

BNR3 Conference Report .. .... .................................. .......................... ... ...... .. 34

R Drury, W G C (Bill) R aper, EA (Bob) Swinton BUSINESS ·, Preventing Backflow Contamination ............................................ .......... 43

RFord Backflow Prevention-What Are We Doing About It? ................. ............. .. 46

R Tucker, J Coghlan DEPARTMENTS International Affiliates .. ... ... ..... .. ........ .... ... ...... ... ... ... ..... ................. ... ... ...... ... 5 From the Bottom of the Well ....... .......................... .. .. .... .......... ...................... 4 New Members .................................... ..................... .... .... ... .......... ...... ... .......... 2 Meetings ......................... .... ..... ..... .. ......... ...... ... ... ... .. ... .................. ................ 48 New Product .............. .................. ................ .... ............... .. ............... .............. 45 OUR COVER: Epistylis spp. , one of the organisms found in biological nutrient removal activated sludge system s. O ur cover picture and the photographs in our B NR3 Conference report on p age 34 were provided courtesy of Dr RJ Seviour, Biotech R esearch Centre, La Trobe University, Bendigo.


WATER

~

HOW SAFE IS BOTJLED WATER? R B Thurman, S J Sterry Abstract Several brands of Australian bottled water were regularly analysed over a sixmonth period for their microbiological and p hysicochemical characteristics . Some brands advertised typical trace mineral content, whi le others merely claimed their product was free of sand, algae, odour and a host of other impurities. Two of the brands were drawn from the same source and had the same mineral content information, but were so ld at diffe rent prices. Differen t batches of the same brand varied widely for nitrates, plate count, pH, salinity and conductivity. W hile all samples were negative fo r E. coli and coliforms, hete rotrophic plate counts were above the recommended guidelines for packaged water. One brand was consi stently acidic, having an ave rage pH of 4.8 which is con siderably below the sugges ted range of 6.5 to 8.5 for Australian drinking water.

Key Words Bo ttled water, water quality

Introduction In 1993 several hundred thousand people became sick and several people died after drinking contaminated drinking water in Milwaukee, Wisconsin (MacKe nzie, et al., 1994). This outbreak ra ised public awareness abou t drinking water quality. As wa ter resources become more and more scarce and as the number and extent of Table 1 Cost per 500 ml Brand

$

1 2 3 4 5 6 7 8 9 10 11 12

0.62 0 .70 0. 71 0 .74 0.75 0 .75 0.75 0.87 0.89 0.92 1.24 1.34

Disti lled water

n/ a

n/a

= not applicable

waterborne o u tbreak s increases, a greater number of people are turning to alternative water sources. The number of brands of bottled water available on sup ermarket sh elves has increased dramatically over the past few years, indicating a rising demand. Currently, a third of th e people in California co nsume bottled water (Allen and Darby, 1994). Bottled water has been called a 'vast con,' as it can cost up to 700 times more than tap water (Brown, 1997). Water labelled 'table water' or 'purified water' may be bottled tap water. In B ri tain tap water is more tigh tly controlled than bottled water and nearly two per cent of bottled water sa mples (over ten million litres) were found to have unacceptable levels of bacteria. LeClerc e t al. (1992) report that bacterial levels may reach 10,000 colo ny- forming units (CFU) per mL in bottled waters (Choice, 1995). Ogan (1992) noted that some bottled waters had pH values ra nging from 3.5-5.9 w ith bacterial cou nts as high as 87,000 per mL. Edberg et al. (1996) concluded that natural aqu eous bacteria isolated from bottled water samples are not associated with virulence. For this reason it has been suggested that future revisions to water legisla tion should not target such microbial populations in bottled water. Instead, the fi nal product sh ould be free of specific pathogens and exogenous contamination. Rogers (1993) states tha t som e European bottled mineral waters may

be required to carry health warning labels citing their lack of suitability fo r drinking by certain groups within a population . Nitrate levels greater than 10 mg/L may cause methhaemoglobin emia in infa nts (TPS, online). Aside from the health aspects and price of bottled water there are environ~ mental concerns that need to be considered. Approximately 600,000 tonnes of plasti c water bottles are disposed in landfills each year. T he fu el required by tru cks and aeroplanes to transport water within and between countries furthe r contributes to environmental pollution.

Methods and Materials Unfortu nately it was impossible to test the water quality of all the selected brands of bottled water throughout the entire study period, as som e were no longer available after a few months. Cost was standa rdised pe r 500 mL volume of water in order to compensate fo r the variety of bottle sizes. Some brands had a pour spout, while others did not. This was not taken into acco unt duri ng price sta ndardisation. Table 1 lists the brands in order of price. Microbiological and Physicochemical Analyses Differe n t brands of Australian bottled water were purchased. at local Victorian supermarkets in Victoria duri ng the study and analysed for E. coli and coliforms (Colisure MPN kits, Millipore, Bedford , MA) , heterotrophic plate co unt (R2A AGAR spread plate,

Table 2 Maximum and minimum values of results from bottled water samples Measu rement

Brand

pH units Nitrates (N0 3¡) mg/l Plate count CFU/ml

12 10 1

Turbidity NTU Sa linity mg/l Conductivity mS/ cm Coliforms MPN/ 100 ml E. coli MPN/ 100 ml

3 11 11 all all

Maximum

Brand Minimum

Overall mea n val ues

Distilled water mean values

Values for Drinki ng Water*

7.29 0.09 not done 0.15 10

6.5-8.5(2) s;5Q(2) !>100(1) s;5(2)

0.03 <1.1 0.00

typica l tap water value 0 .50(3l 0 CFU/ 250ml !1l 0 CFU!2l

9.12

9

4.21

34.67 322,000 0.57

0.19 0.00 0.05

260 0.57

9 6 6 3 3

0 0.01

7.13 11.79 32,269 0.14 90 0.22

<1.1 0 .00

a ll a ll

<1.1 0.00

<1.1 0.00

!>500(2)

* Values listed belong to one of the fol lowing: (1) = Standard S5 for packaged water and packaged ice (2) = NHMRC, Australian Drinking Water Guidelines (3) = TPS P/L, Springwood, Qld: http://www.tps-brisbane.corn.au/-tpsweb/ WATER MARCH/ APR IL 1998

7


WATER 25° C for 5 days, APHA, 1989), salinity and co nductivi ty (LC84, TPS, B risbane, Q LD), turbidity (2100P, HACH , Colorad o, USA) and p H (H I8417, H anna, Tullamarine, VIC) . Nitrates (NO 3-) were determined using the cadmium reduction method on a UNICAM UV-2 spectro- ph otometer (Cambridge, U K) with a HACH )'it (Colorado, U SA , APHA, 1989). T he Australian Standard S5 (1990) for Packaged Water and Packaged Ice uses the plate coun t me tho d as described in AS1095 Microbiological Methods fo r the Dairy Industry, part 4.12. A new method, AS4276 part 3.1, 1995 for Australian D rinking Water, has sup erseded AS 1095. H owever, it does not sp ecify acceptable levels of heterotrophic plate counts. T he culturing techniques for this new method suggest using plate count agar (P CA) and incubating for either three days at 21° C or two days at 35° C. We opted for the method as stated in Standard Methods fo r the Analysis of Water and Wastewater (APHA, 1989) which calls fo r R2A agar and five days incubation at 25° C. A compariso n o f the two methods is briefly mentioned in the R esults section. Statistical Analysis T h e SPSS statistical package was used to analyse the data using AN OVA, box plots and t- tests where appropriate.

Results Particular brands had bette r results for some parame ters t han othe rs, regardless of cost. While the price of bottled water did not correlate w ith overall water quality, to some extent the higher the price, the higher the salinity. No single brand came ou t as being clearly better all round than any other brand (Table 2). Quality Variation Results varied significantly between bran ds of bottled water. Figures 1 and 2 sh ow the interquartile range for pH and nitrates respectively. Brands 1, 2, 7, 10,

11 and 12 had significantly higher mean pH values than brands 4 and 8. Brands 2, 7 and 10 had significa ntly higher means nitrate values than brands 1, 3, 4, 6, 9, 11 and 12. Salini ty and conductivity were significa ntly different between brands 2 , 7, 10, 11 and 12 w hich were high compared with b rands 1, 3, 4, 6, 8 and 9 (see Figure 3). R esults varied w idely between batches of the same brand of bottled water. Brand 2 had a nitrate range between 19.9 and 32.3 mg/L (38% variation). Brand t showed a very wide variatio n between the two samples tested for nitrate. B rand 4 showed a 35% variation in nitrates and a 57% variatio n in total dissolved solids (data not shown). Brand 3 showed an 80% variation between batches fo r total dissolved solids, while brand 9 had a wide variation in pH between batches (data not shown). All samples failed to meet th e standards fo r pla te count as described in Standard S5 (1990) for packaged water. W hile all samples were negative for E. coli and total coliforms and had turbidities of less than 5 NTU as recommended by the U SA guidelines for bottled water (Federal regulations, online), every sample exceeded the 100 CFU/mL fo r standard plate count. The results of a com pari son between R2A agar and PCA have demonstrated that h eterotrophi c plate cou n ts are likely to be at least twice as high on R2A agar as counts do ne on PCA regardless of whether colony coun ts are made on day 3, 5 or 7. Samples tested on PCA at 25° C at 3 days were above the guideli nes . Samples tested on R2A agar and incubated for 5 days had values ranging from a low of O CFU/ mL (brand 11) to a h igh of 322,000 CFU/ mL (brand 9). B rand 6 had the lowest mean plate count at 2,000 C FU/mL. While brand 9 had the single lowest pH at 4.21 units, brand 8 had the lowest mean pH (4.80) and brand 12 h ad the highest p H at 9.12 uni ts. B rand 10 had

the highest mean ni trate level at 29.8 mg/L and brand 9 had the lowest mean nitrate level (0.4 1 mg/L) . T urbidities were fairly consistent among the brands tested, with brand 3 having the high est mean value at 0 .30 NTU. Brand 6 had the lowest mean turbidity value of 0.06 NTU. Brands 3 and 6 had the lowest mean conductivity values of 0.04 mS (milli- Siemens)/cm, while brand 3 had the highest mean conductivity value, 0 .56 mS/cm. Conductivity does not have a performance evaluation acceptance criterion value fo r drinking water (EPA, online), but a typical value is 0. 50 mS/cm (TPS, online) . T he Australian D rinking Water Guidelines (NHMRC, 1996) state that the 1984 W H O guideline maximum valu e fo r total dissolved solids is 1000 mg/L w hich converts to 1.67 mS/cm. M ean salinity was highest in brand 3 at 2 50 mg/L. Brand 3 had the lowest mean salinity at 10 mg/L. T h e highest repo rted magnesi um concentration was in b rand 11 (24 mg/L) and the lowest was in bra nd 3 (0.62 mg/L). Bran d 11 advertised a Ca :M g ratio of 3.25, w hich is above the recommended ratio of 2. O nly brands 3, 6 and 11 and sometimes brand 1 adve rtised the ir water as having a sodium concen tration below the recommended concentrati on of 10 mg/L (data not shown) (G reen and Green, 1994; von Wiesenberger, 1991).

Discussion Microbiological Quality T he quali ty of bottled water is generally be tter than that of rain water regardless of the type of tank in which the water is stored (Thurman, 1995). Even though pathogens or indicators of faecal pollu tion were not isolated from bottled water in this study, the. product is not sterile. As samples tested in this study were ta ken directly from supermarket shelves, we cannot say whether or not any variation from guidelines was due to the source water or occurred

Number of samples analysed N•

- - - - - - --

-

---~

- - --- • ·1 Ill

7

-

-

BRAND

Figure 1 Interquartile ra nge for pH

8

Number of samples analysed

J

10-r-- - - - - --

WATER MARCH/ APRIL 1998

N•

30

1

20

11

12

-

I

......

w

>~ >-

10

z

BRAND 10

J

40r------ - - - - - - - - - - - - -- - - -~

-

1'£!!!11

II

3

ow

Fig ure 2 Int erquartile range for nitrat e

9

10

11

12

ow


WATER sporidium exist in surface waters in by artificial radio-nuclides entering Australia and may lead to contamina- drinking water from medical and industion of drinking water depending upon trial use and wastes. how it is accessed and handled Brand 5 claims that its product is (Thurman et al. , in press). D etailed fresh and clean from the pollution information regarding the source of concerns of the rest o f t he world wate r packaged and sold as bottled because it flows into the processing water is not readily available. It is also plant by a bore from an underground difficult to know w hethe r or not natural spring. T his is an interesting bottlers are using machinery or bottles claim in light of the fact that its mean w hi ch co ntact surface wa te r of nitrate level was 24.5 mg/L. While this unknown quality during the packaging result was not the high est in the study, process. If this occurs, bottled waters it was more than double the mean value cannot be guaranteed to be free of for all bottled waters studied (11.8 pathogens. Another issue relates to the mg/L). Even though nitrates (as NO -) 3 viable-but-not-culturable microorgan- are not considered to be a health hazard isms which may be present but undetectable by current plate count methods. These microorganisms may persist, recover and be able to cause disease in water sa mples w hich have already passed curre nt microbiological guidelines. Methods whi ch do not take for the general p opulation until th eir into accoun t the viable- but-not- cultur- level reaches 50 mg/L, one wonders able microorganisms and which only how protected the source is, considermeasure a portion of the h eterotrophic ing the surrounding landuse involves microorganisms tend to underestimate h eavily fe rtilised agriculture (potato the true microbial population in drink- crops) and free-ranging livestock. ing water (Cohen, 1997). While nitrates can be inhe rent in soil, they can also leach through the soil and Mineral Cont ent Some brands advertised typical trace invade springs or wells. The Australian Drinking Water mineral conten t, while other brands Guidelines (NHMRC, 1996) state that merely claimed that their product was drinking water should be within the free of sand, algae, odour and a host of range of 6.5 to 8.5 pH units. There is other impurities. T wo brands (2 and 10) doubtful harm in drinking water in the were drawn from the same source and range found during this study (4.2 to had the same mineral content informa- 9.1 pH units). H owever, the wide range tion, but were sold at different prices. of values demonstrates the variability of One bottler claims to have a product bottled water products. This in itself free from nuclear pollution, yet offers might be related to the type of source no information on the label detailing water or quality control. This problem that comme nt or indicating in the is further compounded when batches of composition list w hat radionuclide they bottled wate r vary from advertised tested for. Such a claim may be true for values. Wide variations in . results nuclear pollution from point sou rces between batches of the same brand such as nuclear power plants. How- suggest that quality control measures ever, natu ral radioactive isotopes are need to be a larger issue at bottlers and by far the greater co ntrib ution to followed through distribution to the human exposure (NHMRC , 1996). p oint-of-sale. Variations may be related This may occur to seasonal changes in water quali ty through natur- w hich are dep endent upon the source. ally occurr- It is expected that deep sources are less Number of samples analysed ing radioactive likely to show fluctuation in quality Nâ&#x20AC;˘ 3 throughout the year as opp osed to 300, - - - -- - - - - - - -- - -- - - - - -- ~ isotopes which surface waters or shallow sub surface leach into'spring' waters. If the values for analyses adverwater that contised on the label change throughout 200 tacts igneous bed- the year , then labelling should reflect rock. Techno- those changes or the water should be logical enhance- modified to fall into line with the adver~ 100 ment of natural tised analysis. However, if bottlers have z :::; radioactive lev- to modify their product to coincide < els in the soil with the label, then the bottled water is may occur dur- no longer a 'natural' product. 12 o w 10 11 BRAND 1 ing mining and Bottled water should have at least 90 processing of mg/L magnesium, not more than a 2:1 Figure 3 Interquartile range for sal inity mineral sands or ratio of calcium to magnesium, and less during processing or distribution. However, it seems unfortunate that bottled water is often transported in unrefrigerated trucks and sold at ambient tempe ratures. Since natural aqu eous bacteria are able to grow at environmental temperatures an d because low level contaminati on of water with pathogens (which may survive for extended periods of time in water) may occur, this practice increases the chance of creating a health concern. Our results varied w idely from the expected standard for plate count as noted in Standard S5 fo r Packaged Water and Packaged Ice {1990), which states that heterotrophic plate counts must not exceed 100 C FU/mL. The large discrepancy between the standard and our results may in part be due to variations in the type of agar and incubation co ndition s used in this study. However , bottled water samples tested with both R2A agar and PCA had hetero trophic plate cou nts greater than the standard, suggesting that the microbiological quality of bottled waters may be a larger issue than has been previously conside red. Bottled water samples may meet microbiological guidelines for packaged water at the bottling plant, but plate co unts can exceed that level depending upon handling and storage procedures (Cohen, 1997). The question of whether or not high plate counts are important remains fo r the most part unanswered. While Edberg et al. (1996) concluded that plate counts are not likely to be a health issue, one wonders from an aesthetics viewpoint why the product shouldn' t be refrigerated or made sterile to prevent odour and taste problems. From a health standpoint one wonders whether or not the cleaning and handling procedures for the use and reuse of drinking water carboys or for the single use of bottles is good enough to exclude health risks to the consumer. Even though the bottled wa ter samples in this study were not analysed for parasites, Giardia an d Crypto-

(I)

'Clearly the regulations and guidelines need t~ be re-evaluated.'

- ------ - -

WATER MARCH/ APRIL :1.998

9¡


WATER than 10 m g/L so dium (Green and Green, 1994; von W iesenberger, 1991). H owever , magn esi um levels high er than 125 mg/L can have a cathartic and di uretic effect (APHA, 1989). Drinking water deficient in calcium and magnesium has been linked to heart attacks. M ineral ,,vater co ntaining calcium and magnesium has been recomme nded as a possible th erapeutic or pro phylactic age nt in red ucing calcium oxalate kidney sto ne disease (Magnesium , online). Some brands of bottled water did not meet these levels. Brand 11 advertised a C a:Mg ratio of 3.25, which is above th e recommended ratio of 2. Only brand s 3, 6, 11 and

sometimes brand 1 adverti sed t he ir wa ter as having a sodium co ncentration below the recommended concentration of 10 mg/L (data not show n). Three brands ro utinely had sodium levels less than or equal to 10 mg/L. It is interesting to note that Standard 08 for Mineral W ater (Australia and N ew Z ealand Food Authority, 1997), states maximum levels on 17 me tals and contaminants, as well as rad ium and chemi cal OA'Yge n demand. H owever, the Standard does not require bottlers to list th e levels of tho se substan ces. Instead, it requires them to state the levels of bicarbonate, calcium, chloride, magnesium, potassium and sod iu m , none of which are mentioned in the Standard. It see ms u n usual th at consum ers have access to Standard 08 , yet cannot determine w hether or not a particular brand of bottled water conforms to the Standard by reading the label. O ne brand of bottled spring water did no t advertise all of the chemicals required to be listed by the Standard. Providing innovative and Clearly the regulations and guideneed to b e re- evaluated. lines cost effective solutions for Regulations need to be stringently the sustainable adhe red to and suppliers of bottled development of our wate r need to have th eir products region's water resources. tested on a regular basis by reputable laboratories with the results being Recent major projects include: published in scientific, edu cational, • SewerTreatmentFacility health and popular press j ournals. ha ndling63ML/d overfl ow rate, Canberra, ACT Conclusions • Penrith Wastewater Plant, All the brands of bottled wate r teri tary ti ltration treatment studied exceeded the Au stralian fo r 60ML/d, NSW Standard S5 fo r he terotrophic plate • Homebush Bay advanced count (see Methods) . water management and W ide variations betwee n batches o f recycling system, NSW th e same brand suggest that quality • Thorneside BNR plant co ntrol may be an issue for bottlers. Price does not necessarily reflect design and supervision, Qld the quality of bottled water. • Major water supply C laims on bottled water labels may augmentation, Cairns, Q ld no t reflect the quality of the product. • Successful completion of the Torrumbarry Weir on Acknowledgements River Murray, Vic T his project was funded by Aust• Design of water treatment ralian Catholic University Office of plant fo rHami lton, V ic R esearch . • Greater Bun bury land disposal wastewater References study, WA Allen L, Darby J L (l 994) Quality C ontrol • Beeny up Wastewater of Bottled and Vended W ater in C alifornia: A R eview and Comparison to Treatment Plant Tap Water. J Environ. Health, 56: 17-22. upgrade, WA APHA (1989) Standard Methods for the • Water supply system upExam.ination of Water and Wastewater, grade for DaNang, Vietna m 17th Ed. Eds. C lesceri L S, G reenberg A

WATER

Gutteridge Haskins & Davey Pty Ltd Contact any of our regional or local offices throughout Austra lia and South-East As ia. 10

WATER M ARCH/ APR IL 1998

E and T russel R R , Amer. Pub. H ealth Assoc. • Australia and New Zealand Food Authority (1997) Food Standards Code, Standard 08 for Mineral Water. Brown, P (1997) B ottled W ater is 'Vast C on,' Guardian W eekly, October 5.

Ch oice (1995) Bottled Water, Choice February, 37 (2): 6-9.1. Choice (1996) H ow Safe and Affordable is our Drinking Water? Choice September, 6-13. C ohen P (1997) T he Enemy Within, N ew Scientist, 2099: 4. Edberg S C, Gallo P and Kontnick C (1996) Analysis of Virulence C haracter-istics of Bacteria [solaced fro m Bo ttled, Water Cooler and Tap Water. Microbial E cology in Health and Disease, 9: 67- 77. EP A (1997)[On1ine]: http://www .epa.gov/ OGWDW/certlab/lab4t9.html. Federal R egulations (1997) [Online]: http://www. ag.state. ut. us/divisns/regsvcs/ botl 2o.htm. Green M, Green T (1994) T he Good W ater G uide, R osendale Press. National Water Qual.ity Management Strategy (1996) Australian Drinking Water Guidelines, NHMRC , Commonwealth ofAustralia. LeClerc H , Mossel! D A and Savage C (1992) Monitoring N on-carbonated (Still) Min·eral Waters for Aerobic C o lonization, lncem.j. Food Micro-biol., 2:341-347. MacKenzie W R., Hoxie J B, Proctor M E, Gradus M S, Blair K A, Peterson D E (1994) A Massive O utbreak in M ilwaukee of Cryptosporidium Infec tion Transmitted Through the Public W ater Supply, N Engl} Med; 331 :161- 167. Magnesium (J 997)[Online]: http://www. execpc.com/ - magnesum/index.html. N HMR..C (1996) Australian Drinking Water Guidelines, Natio nal W ater Quality Management Strategy, N at. Health M ed. R es. Council. O gan, MT (1992) M icrobiological Quali ty of Bottled Water So ld in Retail Outlets in Nige1ia, J ApplBacteriol. 73 (2):175- 181. R ogers, A (1993) Mineral Waters, Lancet, 342:1 71. Standard S5 (1990) P ackaged W ater and Packaged Ice, Commonwealth o f A ustralia Gazette, N o. P34. Thurman, R B, Faulkner B, Du ncan V, C ramer G and MeikJej oh n M (in press) W ater Quality in Rural Australia, J Appl. Bacterial. , U K. T hu rman R (1995) Evaluatio n of Rainwater Stored in CollectionT anks, A ust. Microbial., 16 (1 ):20-22. T PS, P/ L (1997)[Online]: http://www.tps-b1isbane.eom.au/ - tpsweb/water/nitrate.htm. von Wicsen bcrger A (l 991 ) The Pocket G uide to Bottled Water, Contemporary B ooks, Chicago.

Authors Dr Robert Thurman gained h is P hD in Microbiology at the University of Arizona and is H ead of the D epartment of Science, Maths, Information T echno logy at th e Aust ra lian C at ho lic University, PO Box 650, Ballarat Vic 3353. Dr Thurman has worked exte nsively in the public h ealth domai n, including novel mean s of e nu merating Giai·dia and Cryptosporidium cysts an d oocysts. Sandra Sterry is a T echnology Officer at the Australian C atholic U niversity. She graduated BSc M icrob iology fro m Pe n nsylva nia State University.

(


(

Abstract

Introduction

Because alum sludges from water clarificatio n co n tain al uminium in perceived phytotoxic conce n trations, they are subject to stringent EPA guidelines for handling and di sposal. The objective of the prese nt study was to examine this perceptio n. The magnitude of soluble aluminium in alum sludge was compared with t hat in naturally occurring soils and in acidic soil to which sludge and li me were added . The performance of p lan ts grown in th ese materi als was also compared. In all exp erime nts alum sludge, because of its inherently high pH and buffering capacity, was found to possess minimal solu ble alumi nium by compariso n w ith na turally occurring soils. W hen alum sludge was mixed with an acidic soil oflow buffering capacity, the pH increased into the neu tral-toal kaline range, the bulk d ensity decreased, the infiltration rate increased and plant-available nitrogen and plan~ yield increased. The sludge had one main limitation- its large P- fixing capacity. This generated P deficiencies in plants which necessi tated large applications o f P fertiliser. However, this did not seem to be necessary fo r slow-growing plants.

Filtrati on p lants in Sou th Au stralia produce drinking wa ter by treatin o' raw ' water firom the River Murray and ::, from the ca tchment reservoirs of the Mount Lofty Ranges. T he treatmen t process involves flocculation and filtrati_on of the suspended clays and dissolved organic compounds using aluminium sulpha te (alum), together w ith o ne or more of acrricultural O limesto ne (CaC0 3), ferric c hlo ride, poly-electrolytes, and activated carbon (Le hmann and Palmer, 1995). The flocculated material, commonly known as 'sludge,' is dewa tered either by evaporation from shallow lagoons or by

50 O

40

in water

in CaCl2 [Al]= 1 984 • 1o-O · 56 PH

30

T = 0.861, n=20

[Al] (mg/kgJ 0

10

0

0 3

6

pH

Figure 1 Concentration of alumi nium from alum sludge and nine different Australian soils as a funct ion of pH in water and calcium chloride

using mechanical presses before partial drying in concrete holding bays. At this stage the sludge is regarded as a metal hydroxide waste and has been disposed of as regulated landfi ll. T he justification for this cau tious approach to the disposal of alum sludges is questionable. It appears to centre around the total aluminium conten t in sludges (South Australian Environment Protection Authority, 1996), and disregards the fact that aluminiu m, after all, composes 8% of the Earth's crust and occurs naturally in the environment (McBride, 1994). The amou nt of labile alu minium in alum sludge depends on the pH of the sludge. This va ries with the quantity of lime added to raise pH and precipitate labile (or soluble) species of aluminiu m (Elliot and Dempsey, 1991). Because of the lime added , alum sludges can have a calcium carbonate equivalence of up to 20% (dependino on their alkalinity), and so they have a~ inherent liming value. For this reason, sludges have been used to raise th e pH of agricultural and forest soils in the mid- western United States for 40-50 years (Elliot and Dempsey, 1991; Bugbee and Fri nk , 1985). Alum sludges are elsewhere rou tinely discharged directly into natural waterways with no increase in labile forms of aluminium (Abdullah et al. , 1995). WATER MARCH/A PRIL 1998

11·


WATER 20

r - - - - - - - - - - - - (")--- - ,

15

.

,.• 'i

:;;,,0 -~1. 0

!?.S 0.

.00 1

.01

.1

1 00

10

P (solution) (µg/ml)

Figure 2a Alum sl udge and red-brown earth P-sorption cu rves 0.10

:;;1: 0 -~

~s

r - - - -- - - - - - - - ,

0.0 5

0.

0.00 i - - . ~ ~ ~ ~ ~ ~ ~ ~ ~ . . . . . . , . / .01 . 1 10 100

P (solution) (µg/ml)

Figure 2b Red-brown earth P-sorption curve (expanded scale)

7.5 7.0 NoUmo

pH 6.5 6.0

-

-a-

Lime O 1.81/ha Lime O 3.61/ha

-

Lime@ 7.21/ha

- - -,c,- -

Lime C 14.•tllla

5.5 ~ - ~ - - ~ - - ~~ 0 200 400 600 800 Sludge Appli c ati on Rate (t/h a)

2.5 . - - --

1.5

[Al] (mg/kg)

-

- -- - - - --, --0-- No Ume Lime@ 1.81/ha Lime O 3.61/ha Lime O 7.21/ha Lime O 14.4tlha

1.0

0.0 ' - - - -- - ' -- - - - ' - - - ~- -~ 0 2 00 400 6 00 8 00

Sludge Appli cation

Rate

(t/ha)

Figure 3 pH and concentration of watersoluble alumi nium in 1:5 soil:water extracts as f unct ions of the application rat e of alum sludge or lime to Urrbrae red-brown earth

12

WATER MARCH/APRIL 1998

Alum sludges commonly consist of highly disordered clay minerals plus organic matte r and precipitates of aluminium hydroxides (Bugbee and Frink, 1985; Rengasamy et al. , 1980). The aluminium hydroxides are similar in nature and amount to those comm only present in soils (Lucas et al. , 1994; Ellio t and D empsey, 1991 ; R engasamy et al. , 1980). By comparison with sewage sludges, most alum water treatment sludges are relatively inert w ith respect to biological pathogen s, pesticides and other organic contaminants (Elliot et al. , 1990; Grabarek and Krug, 1987), although the presence of oocyscs from parasites may occasionally present problems . H owever, soluble aluminum has potential toxic effects. For hu ma n consumption, the concen tration of aluminium in drinking water should not exceed 200 µg/litre (Sayer, 1988). In aquatic environ ments, the tolerable concentrations are considerably low er (ANZECC , 1992). Different concentration li mits at different pH values take into account the fact that hydrolysis of aluminium in solu tion is pH -depende nt and that certain hydrolysed species are more harmful to biota than others. While it is generally agreed that informatio n on the various species of aluminium present in soil water can be useful fo r predicting the consequ ences of low pH conditions Qohnson et al. , 1981), there is less concurrence on the methods that should be used to quantify the various species of aluminium. Total aluminium in soil extracts can be determined by atomic abso rption spectroscopy, but this does not differentiate be tween toxic and non-toxic species (Manley et al. , 1987) . Spectropho tom etri c methods, on th e ocher hand, provide better estimates of the species of alu mini um based upon th e rates of reaction between various reagents for different periods of time. T he pyroca techol vi ole t method (Dougan and Wilson, 197 4; Siep et al. , 19 84) is one of th e m ore widely adopted methods to measu re aluminium in wastewater and drinking water (APHA, 1992), and has therefore been adopted in th is study. Early investiga tions o n the land application and water treatment residuals we re co ndu cted in Australia (Rengsamy et al. , 1980). More recently, difficulties in disposing of residuals as landfill or directly to streams or water bodies have led co increased interest in application to soils. W ater treatmen t residuals have been used in silviculture, on croplands and pasture, fo r horticultural crops, in gardens and as mixtures with other materials to produce potting mixtures (Bugbee and Frink, 1985; Elliot and Singer, 1988; Geertesma et

al. , 1994; Lucas et al. , 1994; Skene and Oades, 1995; Skene et al. , 1995 ; O xenford , 1997). These studies generally agree that application of alum sludge at modest rates increases soil pH , improves soil physical properties (e.g. struc tural stability, water-holding capacity, infiltration, bulk density) and plant performance and yield. The only serious problem identified in all studies was P deficiency in plants brought on by the high P-fixing capacity of the sludge, which was found to be overcome by application of P fe rtiliser. T here were ce rtainly no problems fou nd with elevated contents of aluminium in plant tissues in any of the above studies-in all cases, aluminium was lower than in plants grown o n naturally-occurring acidic soils. N evertheless, m uch of the work reported above was condu cted using sludges, soils and climates that differ sign ifica ntly from those found in Australia. It was therefore considered important to assess the applicability of conclusions drawn elsewhere under Australian conditions. If it can be shown chat findings from research con du cted elsew h ere still h old for Australian soil s, the costly and problematic issu e of sludge~ disposal would be solved . T he future demand for this material m.ight even outstrip its supply (Skene and Oades, 1995). A collaborati ve study was therefore cond u cted by the U nive rsity of Adelaide and the South Australian Water Corporation to: • compare the concentration of soluble alumi nium species p rese nt in alum sludge with a range of naturally occur- . ring Australian soils • compare the concentration of soluble aluminium species present in an acidic soil with and without the addition of alum sludge and lime in various proportions • determine the effects of adding alum sludge to soils on the growth of grass.

Materials and Methods Several tonnes of alum sludge from the H appy Valley water filtration plant near Adelaide, South Australia were collected from the concrete holding bay at the dewateri ng plant and transported to t he Waite Agric ultural R esearch Institute to be dried for use in the exp erimen ts. Som e physical and chemical properties w ere measured on the sludge including water retention, infiltration rate, bulk d ensity, particle density, porosities, extractable Fe, Mn, C u, Z n, B, plant-available N, and Psorption characteristi cs. Aluminium in the sludge was compared with that in nine diffe rent soils from across Australia. Samples of 1:5 soil or sludge were shaken for five minutes in distilled

(


WATER water or 0.01 M CaC12 and pH and the water soluble aluminium content of the filtered (0.45 µ m ) supe rnatant was determined. In a laboratory incubation experiment, the sludge was mixed with one of the nine soils (Urrbrae red-brown earth from the Waite Institute) to produce application rates equivalent to 0, 200, 400, 800, and 1600 t ha- 1• Agricultural lime was incorporated into these mixtures at application rates equivalent to 0, 1.8, 3.6, 7.2, and 14.4 t ha- 1. Samples of each of these mixtures were placed in sealed plastic containers and stored eight weeks at 20° C at 80% 'field capacity.' At the end of the incubatio n period , pH and wate r soluble aluminium were measured. In the glasshouse, sludge was mixed with a red-brown earth at the same application rates as above in 10 litre pots, with N -P-K complete fertilise r mixes added as required. Lawn grass was sown in all pots at a rate of237 kg ha- 1 and the pots (4 replica tes) were arranged in a randomised comple te block design and maintained at water contents at or just below 'field capacity' for 12 weeks. Grass was harvested every four weeks. In a field experiment at the Waite Agricultural Research In stitute, sludge w as applied to an acidic red-brown earth in small, replicated (x 4) plots (3 m x 5 m) at rates similar to those used in the glasshouse study. Soil was removed from each plot to a depth of 20 cm and mixed with sludge and N-P-K complete fertilisers in appropriate quantities, then placed back into the plots. R ye grass was sown at an application rate of 200 kg ha- 1, and an automatic sprinkler system was installed for irrigation. After 14 months the fresh and dry weights of grass clippings from each plot were determined. A subsample of the moist clippings was taken fo r tissue nutrient analysis using ICP spectrometry (Zarcinas et al., 1987).

Results and Discussion A strong, negative relationship was found between the pH of the sludge

or soils and the co ncentration of aluminium in solution (see Figure 1). It is of particular importance to note that all the materials having a pH > 6.0 (including the sludge) recorded concentrations of aluminium that were virtually negligible, regardless of w h ether measurements were taken in water or calcium chloride. By comparison w ith the naturally occurring soils, the sludge presents no phytotoxic risks with respect to aluminium. Without the addition oflime, however, several of the low pH soils would present significant problems to agricultural plants (Ritchie, 1989). Various chemical prope rties of the alum sludge are compared with the U rrbrae red-brown earth in T able 1. While the electrical conductivity data indicated the sludge contained a modest concentration of soluble salts, this poses no serious salinity risk (USSL Staff, 1954). Furthermore, the sludge contained at least five times more plantavailable N than the Urrbrae soil. This has also been found for alum sludges in other studies (Skene et al., 1995). While there are fewer diethylene triamine pen taceti c acid (DTP A) extractable micronutrie nts such as B, Fe, Mn and Zn in th e alum sludge relative to the Urrbrae soil, the concentrations are all sufficiently high to accommodate satisfactory plant growth. There was a high concentratio n of total Cu in the sludge relative to that in the Urrbrae soil. Its bioavailability, however, may not necessarily be of concern because th ere is a large quantity of organic matter in the sludge, which may chelate any copper that becomes mobilised w ith time. The bioavailability of copper in alum sludges from reservoirs treated with copper- sulphate is currently under investigation. The significant P-fixing capacity of alum sludges has been confirmed in this study. The magnitude of this compared to the P-fixing capacity of th e Urrbrae red- brown earth is show n in Figures 2a and 26. Considering the optimum soil solution concentration of P to be 0 .2 ppm

MeanTlssueN(%)

(Nishimoto et al. , 1977), the amount of fertiliser P required to achieve this for the alum sludge is inordinately high (11,479 kg P ha- 1) compared to that required for the Urrbrae soil (18.4 kg P ha- 1). Nevertheless, the P bound in oxides and hydroxides of aluminium and iron may become available to slowgrowing plants (e.g. trees in temperate forests) , or in situations w here th e demand for P is relatively small (Grabarek and Krug , 1987) . Many native Au stralian plant species fall into this low-demand, slow- growing category. The addition of various amounts of alum sludge to the acidic Urrbrae red- brown earth caused a significant increase in the pH from the initial 5. 7 up to 7 .5 after the addition of 800 t/ ha (see top of Figure 3). A liming value i~ clearly demonstrated by the slu dge. For example, addition of200 tonnes of sludge per hectare increased th e soil p H by more than a full pH unit, and had a similar effect to the addition of between 1.8 and 3.6 tonnes CaCO 3 per hec tare. This result suppo rts the widely practised (and unregulated) addition of alum sludges as substitutes for lime on agricultural soils in the United States (Che et al., 1988) . As would be expected, the increase in pH caused by the addition of sludge or lime significantly reduced the concentration of aluminium in solution from > 2 mg/kg in the unamended Urrbrae soil down to < 0.5 mg/ kg (see Figure 3). This demo nstrates clearly that the presenc e of aluminium in sludge per se is n o more harmful than that contained in the natural soil environment. The potential phytotoxicity of aluminiu m is thus related more to the conditions controlling t he solubility of aluminium than to the total quantity present in the sludge . • G rass dry matter yields for the glasshouse study generally increased with the sludge application rate (see Figure 4). The N and P concentrations in the grass tissue are shown in Figure 5 as functions of the sludge application

- - -- ~

m Mean Tlssue P (%) 60

so M ean

o,,

M•tu r

M ea n

%

Nutri ent In T issue

Yl e ld (g/pot)

40

Tluue Al

(µg/g)

30 20

10

200

,oo

Sludgt Appllcatlon Rat•

800 (t/ha)

Figure 4 Mean dry matter yield of lawn grass as a function of application rate of alum sludge (mean standard error = 0.55 g/pot )

200

,oo

800

Sludg e Appllc 1Uon R ate (t/ha)

Figure 5 Mean concentration of N and P in lawn grass tissue as a function of application rate of alum sludge (mean standard error for N = 0.087%, and for P = 0.021%)

200

, oo

800

Sludge App11catlon Rate (t/ha)

Figure 6 Mean concent ration of Al in lawn grass tissue as a function of the application rate of alum sl udge (mean standa rd error = 3.5 µg/g) WATER MARCH/APRI L 1 998

13

(


WAT E R rate, sh owing the o/oN increased modestly and the o/oP decreased. This has also been observed by Elliot and Dempsey (1991) and Skene e t al. (1995) . H owever, the P-uptake per pot (data not shown) increased with time, indicating the sludge may be able to supply Pas it ages in contact with soil, a phenomenon also noted by Wood et al. ( 1 984) in a hardwood forest. The concentration of aluminium in the plant tissue decreased presu mably due to th e associated increase in pH and decrease in aluminium solubility w ith sludge application (see Figure 6). Similarly, the co ncentration s of C u and Mn were found to be at optimum levels in the plant tissues and were not influe nced by the rate of sludge application (data not shown). Visual inspection of the field plots at the Waite Institute revealed that germination of the grass seeds was earlier and more uniform, and greener, in th e plots to w hich only sludge was added (i.e. sludge replaced all the soil to a depth of 20 cm). Furthermore, the addition of increasing amounts of sludge to the soil signi ficantly reduced t he dry bulk density as well as the average particle density, and signifi cantly increased total porosity, and infiltration rate (see Table 2). Dry matter yields of lawn grass, the concen tration of N in the grass tissue, and the concentration of available N (nitrate) in the soil all increased signi ficantly at the high er sludge application rates only (see T able 3). Contrary to expectation, the P d eficiency symptom s were not shown for any of the treatments, indicating that the P-fixing capacity of sludge may not be a longterm problem when applied to soils. It is also possible that the relatively high N co ntent of th e sludge was able to compensate for any P limitations.

Conclusions T here is no evidence in the available li terature nor in the studies condu cted h ere to suggest land application of alum sludges poses any enviro nmen tal o r phyt otoxic hazard ,vith resp ec t to aluminium pollution. T he chemis try of aluminium is controlled largely by pH,

Table 1 Chemical properties of alum sludge and Urrbrae red-brown earth Parameter Conductivity (1:5 ratio) (dS m-1)

0 200 400 800 1600 LSD

Bulk density (t m·3 )

Particle density (t m·3 )

1.25 1.21 1.14 1.02 0.80 0.09**

2.56 2.41 2.48 2.44 2.36 nd

Total porosity (%) 51 50 54 58 66 3 **

Available N B Cu Fe Mn Zn

0.05

62.3 0.4 23.0 18.6 27.2 1.6

11.9 1.0 2.8 56.8 50.8 6.0

Acknowledgements T he auth ors gratefull y acknowledge supp ort from the Urban Wate r Research Associa ti on of Australia (Projec t No. WS-69) and the South Australian Water Corporation.

References Abdullah M P, Baba !, Sarmani S, Erdawati (1995) Distribution of Aluminium from Alum Sludge in Water and Sediment. M arine & Freshwater R esearch , Vol. 46, pp. 159-65. ANZECC (1992) Australian Wat~r Qualiry Gu idelines for Fresh and Marine Water. Australia and N ew Zealand Environment and Conservation Council. APH A (1992) Standard M ethods for th e Exam.ination of Water and Waste Water. 18th Edition. Eds A E Greenberg, L S Clcsceri, A D Eaton. American Public H ealth Association. Bugbee G J, Frink C R (1985) Alum Sludge

Table 3 Effect of adding alum sludge at different rates in field plots of Urrbrae red-brown earth on performance of lawn grass

Air-filled porosity (%)

Infiltration rate (mm h·1 )

Sludge applied (t ha·1)

Yield of dry matter (t ha·1 )

23 21 24 25 25 NS

398 331 696 1061 1755 454**

0 200 400 800 1600 LSD

2.00 1.45 1.78 2.30 3.23 0 .74*

LSD = Least significant difference

WATER MARCH/APRIL 1998

1.1

and the alum sludges produced by water filtration plants are all treated with lime specifically to raise the pH to the point where soluble aluminium sp ecies are minimised. In fact, there is less watersoluble aluminium in alum sludge than in many of Australia's commonly occurring acidic soils. For example, if alum sludge were to be applied to land , even on acidic soils which are usually sandy w ith low buffering capacities, it would be likely to increase the soil pH and dec rease the water- soluble aluminium. Even if the application rates were too low to increase pH, it would be a simple matter to add lime to raise th e pH, or to monitor soil pH periodically as is usual in the agric ultural community and add lime if needed. The alum sludge has a number of agro nomically beneficial p rope rties when applied to soil. Firstly, the high level of N in the sludge (presumably from the natural organi c matter in the raw wa ter and the added o rganic polymers) is ca pable of contributing significantly to the nitrogen requirements of crops . Secondly, it is a highly stable and non-dispersive mate ri al w hich when added to soil reduces its bulk density, increases its porosity and wa ter-holding cap ac ity, and also inc reases its infiltrati on rate. The improvement in soil physical properties can only aid in plant growth and the rehabilitation of p oorly structured soils, particularly those of lighter texture. The agronomic results of this study suggest

** significant at P=0.01; NS = not significant at P=0.05; nd = not determined

14

Red-brown earth

Nutrients (mg kg-1)

Table 2 Ef fect of adding alum sludge at different rates in field plots of Urrbrae red-brown earth on soil physical properties Sludge application rate (t ha·1 )

Alum sludge

that the high N content of the sludge may compensate for low P or that the sludge gradually releases some of its P. Conversely, it is also apparent that alum sludge has an enormous potential to sorb P from solution , a subj ect which is currently unde r investigation w ith respect to control of P-triggered algal blooms in fresh inland wa te rs of Australia. Disposing of this valuable resource in municipal landfill sites is unju stified when there are so many possibilities for its practical use and so few disadvantages. So long as the alum sludge has been air dried (thus fixing any soluble aluminium into insoluble oxide and hydroxide fo rms) it should be released for di spersal with out regulation. H owever, becau se there appears to be a negative connotation associated with the term 'sludge,' its u se in reference to water treatment sludges is to be avoided in fu ture. T he confusion with sewage sludges may then be eliminated. The term 'water treatment residual' is a possible alternative which still describes the composition of t he material acc urately, while also distingui shing i t from sewage sludge. Other efforts to increase the public acceptabili ty of this material should also be explored.

Concentration Concentration of of N in plant available N in soil (mg N03 · kg-1 ) (%) 1.37 1.60 1.55 1.78 2.01 0.37 *

5.2 6.2 9.5 7 .7 21.4 6.9**

Concentration of available P in soil (mg kg-1 ) 56.7 42.7 54.2 40.5 38.0 NS

LSD= Least significant difference • = significant at P=0.05; •• = significant at P=0.01: NS = not significant at P=0.05


WATER as a Soil Amendment: Effects on Soil Properties and Plant Grow th , Connecticut Agriculture Experiment Station Bulletin No. 827, 7 pp. Che M D , Logan T J , Traina SJ, Bigham J M (1988) Properties of Water T reatment Lime Sludges and their Effectiveness as Agricultural Limestone Substitutes, journal of the Water Pollution Control Federation , Vol. 60, pp. 674-680. Dougan W K, Wilson A L (1974) The Absorptiometric Determination of Aluminium in Water: A Comparison of Some Chromogenic Reagents and the Development of an Improved Method, Analyst, Vol. 99, pp. 413-430. Elliot HA, D empsey BA (1991 ) Agronomic Effects of Land Application of Water Treatment Sludges, Journal of the American Waterworks Association, Vol. 83, pp. 126-131. Elliot H A, Dempsey BA, Maille P J (1990) Content and Fractionation of H eavy Metals in Water Treatment Sludges, J ournal of Environmental Q uality, Vol. 19, pp. 330-334. Elliot H A, Singer L M (1988) Effect ofWacer T reatm ent Sludge on Growth and Elemental Composition of Tomato (Lycopcrsicon csculcntum) Shoots. Communications in Soil Science and Plant Analysis, Vol. 19, pp. 345-354. Geertsema W S, Knocke W R, Novak J T, Dove D (1994) Long-term Effects of Sludge Application to Land , j ournal of the Amcric,111 ·w aterworks Association, Vol. 86, pp. 64-74. Grabarek R J , Krug E C (1987) Silvicultural Application of Alum Sludge, j ournal of the American W'aterworks Association, Vol. 79, pp. 84-88. Johnson NM, Driscoll CT, Eaton ] S, Likens GE, McD owell W H (1981) Acid Rain, Dissolved Aluminium and Chemical Weathering at the H ubbard Brook Experimental Forrest, New H ampshire. Geochcmica ct Cosmoschcmica Acta, Vol. 45, pp. 1421-1437. Lehmann T C, Palmer N T (1995) Alum Sludge Treatment and Disposal from Happy Valley Water Treatment Plant, Proceedings of the 16th Federal Convention of th e Austra.lian Water and Wastewater Association, Vol. 1995 , pp. 643- 649. Lucas J B, Dillaha T A, Reneau RB , Novak J T, Knocke W R. (1994) Alum Sludge Land Application and its Effect on Plant Growth. j ournal of th e American Watenvorks Association, Vol. 86, pp. 75-83. Manley E P, C hesworch W, Evans LJ (1987) T he Solution Chemistry ofP odzolic Soils from the Eastern Canadian Shield: A Thermodynamic Interpretatio n of the Mineral Phases Concrolling Soluble AJ 3+ and H 4Si0 4 ,joumal ofSoiJ Science, Vol. 38, pp. 39-51. McBride M B (1994) Environmental Chemi st1y of Soj]s, Oxford University Press, N ew York. Nishimoto R K, Fox R L, Parvin PE (1977) Response of Vegetable Crops co Phospho rus Co ncentration in Soi l Solution,journal ofthe American Society of Horticultural Science, Vol. 102, pp. 705- 709.

Oxenford J (1997) Land Application of Alum Residuals, Drinking Water Rese,1rch 7, 4, American Water Works Association Research Foundation, Denver. R.engasamy P , Oades J M, Hancock T W (1980) Improvement of Soil Structure and Plane Growth by Addition of Alum Sludge, Communications in Soil Science & Plant Analysis, Vol. 11 , pp. 533-545. Ritchie G S P (1989) The C hemical Behaviour of Aluminium, Hydrogen and Manganese in Acid Soils in Robson A D (ed.), Soil Acidity & Plant Growth, Academic Press, Sydney, pp. 1-60. SAEPA (1996) Land Application of Alum Sludge from Water Treatment, Environment Protection Authority Technical Bulletin TB No. 12 November 1996, So uth Australian D epartment of Environment and Natural R esources, 2 pp. Sayer I M (1988) International Standards for D rinking Water,j ournal ofthe American Watenvorks A ssociation, Vol. 80, pp. 53- 60. Siep H M , Muller L, Nass A (1984) Aluminiu m Speciation: Comparison of Two Spectrophotom etric Analytical Methods and Observed Concentrations in Some Acidic Aquatic Systems in Southern Noiway, Water A ir & Soil Pollution, Vol. 23, pp. 81-95. Skene T M , Oades J M (1995) Water Treatment Sludge-A Resource, Not A Waste. Water, Vol. May/June 1995, p. 41. Skene T M , Oades J M , KiJmore G (J 995)

Water Treatment Sludge: A Poten tial Plant Growth M edium , Soil Use & Managem ent, Vol. 11 , pp. 29-33. USSL Staff 1954, Diagnosis and Improvement of Saline and Alkali Soils, Agriculture Handbook No. 60. United States D epartment of Agriculture, 160 pp. Wood T , Boiman F H , Voigt G K (1984) Phosphorous C ycling in a Northern Hardwood Forest, Science, Vol. 223, p. 391. Zarcinas B A, Cartwright B, Spouncer L R. (1987) Nitric Acid Digestion and Multielement Analysis of Plane Material by Inductively Coupled Plasma Spectrometry, Communications in Soil Science &Plane Analysis, Vol.18 , pp.1 31-1 46.

Authors Dr Mustaque Ahmed obtained his PhD from the University of Adelaide. H e was employed as a R esearch Office;· on this project an d is now wi th Peatsoils. Dr Cameron Grant is from the Department of Soil Science at the Waite Agricultural Research Institu te, University of Adelaide, Glen Osmond SA 5064. Professor Malcolm Gades is now D ea n of the Facul ty of Agric ultural and Natu ral Resource Sciences at the U niversity of Adelaide. Peter Tarrant is a Systems Management Engin eer with t he South Australian Water Corporation.

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15


WASTEWATER

ACTEW WINS AWWA'S PRESTIGIOUS

PETER HUGHES WATER AWARD C Davis ACT water and power utility ACTEW has won the prestigiou s Peter Hughes Water Award for its innovative approach to technologies for purifying and reu si ng water, especially the CR.ANOS sewage treatment system. The j udging panel, comprising AWW A's Peter H ugh es and Mark Pascoe and NSW Environment Protection Authority's Andrew Bryan t, felt that ACTEW had created an environment in which its staff ca n produce well engineered tech nical solutions to long- sta ndin g problem s. The CR.ANOS plant, a very compact, hi gh-rate system that ca n be produced in a factory and assembled quickly on tiny sites, i s the latest example of the sort oflateral approac h w hi ch ACTEW has adopted to sewage treatment. The trophy for the Award , a Swedish c rystal piece, w ill be presented at a gala dinner in Brisbane on 27 April during the WaterTECH conference. T he Peter Hu ghes W ater Award criteria cal] for a nominee to have made a significant contribu tion to wate r conservation over the last three years and for the wo rk preferably to have poten tial in ternatio nal sig nificance. ACTEW's work in water saving, com m unity consultation, water mining (i.e. extracting and purifying sewage fo r local reuse) and on-site sewage systems has placed the Corporation well in fro nt of other players in this field. An earlier initiative by ACTEW is the sewer mi ning plan t at Southwell Park. Set in a suburban Ca n be rra loca tion , th e Southwe ll Park plant extracts sewage at the rate of 5 L/s from a sewer on- site, treats it to a high standard and then stores it for irrigation o f t he surrounding sports fields. R em otely operated via a telem etry connec tion, the plant i s entirely automated and is lo cated in an anonymous-looking building w hich could be a store room or something equally mundane. O n the household fron t, ACTEW has been busy too , having at least six households around the city fitted w ith a range of on- site sewage sys tems,

operate. The columns ca n be aerobic or anoxic, to provide co n ditions for nitrification or denitrification. The CR.ANOS plant has considerable potential as a highra te compact sewage trea tment system , an esse n tial fea tu re in many applica tions, es pecially high-rise complexes, and industry and em ergency field installations. Because the C R.ANOS plant is modular in construction sections can be fac tory-built, shipped in standard containers and th e n assembled quickly on-site. In w11111i.ng t his Award , ACTEW joins t he CSIRO 's for me r Divisio n of Water R eso urces, Pro f. Jorg Imberger and his team from the Centre fo r Water Research at the U niversity of W es tern Australia and th e Australian Conservatio n Foundation 's water ca mpaigner Tim Fishe r, the other recipients of the Award since its inception in 1992. Of this select gro up , rangmg from comProfesso r Imbe rger postmg toil ets to went o n to win the activa ted sludge coveted Stockholm Water Prize in 1996. system s. Each of these is in the home Pete r Hugh es, of an ACTEW staff who was Fed eral member, so they are Secretary o{ AWW A all monitored an d for several years and well m aintained. became the AssociaD ata gleaned from tion's first Exec utive Director on his inithis sort of work enables ACTEW to tial retirement, laid ma ke good j udge- The CRANOS plant-compact, highmuch of the groundm en ts about the rate, quickly assembled work fo r AWW A's viabili ty of on- site systems. strong pos1t10n today. AWW A's most ACT EW proj ect manager Ke n prestigious award was the refore named Barnett, tantalised by the potential for in his honour in 1992 after his retiresewer mini ng, wanted to shrink the ment from AWWA. Southwell Park plant to fit an even The current win by ACTEW rounds smaller footprint, and conceived the out th e range of Pe ter H ughes Water idea of pressurising an aerobic fluidised Award winners and their achievements. bed system to boost oxygen transfer. ACTEW's CR.ANOS prototype is a This was the genesis of CR.ANOS. The development to watch , along w ith the acronym stands for Compact, R educed other innovations in Canberra's water Air, N i trifying- denitrifying Odo ur system . There are many changes which controlling unit w ith low Solid s are needed to the way the urban water production , and the plant is essentially a cycle is ma naged and ACTEW is series of vertical, pressurised columns in definitely leading the way in finding w hich fluidised sand- ca rrier bed s alternatives. WATER MARCH/ APRIL 1 998

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m Abstract Western Australia is already extensively recycling greywater in country areas and experiencing an increasing demand for usage even in metropolitan Perth. Sources are washing machines, sh ower and bath water. Evaporative air conditioner bleedwater is also used on the garden in country areas. At present greywater recycling is illegal unless Health D epartment, Water Corporation and local government approvals are obtained for 'below ground' use. In some cases Department of Environmental Protection approval is also required. Most of the current applications are illegal. As a water conservation measure, legal greywater recycling is being investigated by: • establishing physical trials under fully controlled conditions • developing guidelines for local government application and administration • trialling the guidelines • simplifying the approval process at local government level with state government support through H ealth Act R egulation modification. The paper describes the process of monitoring the physical trials, developing the guidelines (adapting the Urban Water Research Associati on of Australia (UWRAA) Guidelines from Brisbane), and setting up the trials for the guidelines in Perth. Site t rials operate in Geraldton, Cottesloe, Fremantle, Hovea and Palmyra.

Key Words Greywater, gui delines, recycling, garden watering, laundry waste, sh owers, bowl fl ushing, residential use, demand management, wastewater reuse effects, health risks, sewerage impact

History Opportunities for wastewater reuse in Australia have been identified in previous publications (Sc hlafrig and Anderson, 1992) and reuse has only marginally increased since then. In the early settlement of Wes tern Australia, as i n the othe r colo nies, sewage di sposal was by means of a cesspit, but this was abolished by the H ealth Act in 1911 . The firs t septic tanks were introduced to Wes tern Australia at the turn of the century and in 1927 the H ealth Act was amended to place control of septic tanks under the Public H ealth Department. The first septic tank was a dual-compartment single tank intended to treat only toilet waste. Other household wastewaters were disposed of separately. This had 18

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WASTEWATER

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GREYWATER

RECYCLING IN WESTERN AUSTRALIA B Devine, B Bowden, J E Schlafrig, R J Fimmel

Murdoch University's Martin Anda (right) shows Brian Devine, WA Health Dept, and consultant Bob Flmmel around a Fremantle community garden watered wHh greywater

much to do with the toilet being an outhouse located somewhere at the rear of the property. Greywater is defined as untreated household wastewater w hich has not come in to contact w ith toilet waste (blackwater) . It can be from bath, sh ower, basin , washing machine, laundry tro ugh, kitche n sin k and dishwasher. Currently, for the purpose of Weste rn Australia's reuse plans, kitchen wastewater is conside red excluded but the bleed water from evaporative air coolers is included. Unde r the H ealth (Treatment of Sewage and Disposal of Efiluent and Liquid W aste R egulation s), the requirement is that all on- site wastewater be disposed of underground into systems such as soak wells and leach drains. More recently in Western Australia a view has developed that more use should be made of greywater. Water resources in many country areas outside urban development are scarce

and expensive, and extensive greywater r ecycling is ca rried on ille~ally by separating the greywate r from the blackwater and spreading it on the lawn, flowe rbeds or even vegetable patches. In Perth, w here groundwater is mo re plentiful and of a quality suitable for the garden there is less demand. H owever, in some suburbs of cou ntry towns over 30% of householders are said to reuse greywater to some degree. Extensive use of greywater in gardens was identified as part of the Kalgoorlie Boulder Water Use Efficiency Study (Preferred Options, 1994). There have been numerous requests for approvals for greywater recycling. The ethos to conserve resources is admirable but the health risks vary and the need to establish guidelines is high for both below ground and, to a greater extent, above ground recycling before encouraging formal greywater recycling systems. The opportunity to recycle grey-


WASTEWATER water exists for other parts of Australia and overseas w here scheme- water m ust be conserved. Brisbane City Council, through UWRAA, has recently published Model Guidelines for Domestic Greywa te r Reuse for Australia Oeppeson, 1996). These have been used to develop draft gu idelines for Western Australia. It is hoped that after trialling in a numbe r of municipalities, the feedback will be sufficient to improve these guidelines and impl emen t a formal process encouraging correct use of greywater recycling to ensure water co n serva tion , the m inimisatio n of public health risk and no detriment to the sewer system. Fundamentally, the H ealth D epartment of Western Australia (HDWA) is not averse to innovative methods of greywater recycling and supports the concept on the basis that the system: • does not give rise to a nuisance or health risk • is approved for the purpose and designed for long-term use • environmental risk is considered. In 1995 the then Water Authority of Western Australia in A W ater Supply Strategy for Perth and M andurah to 2021, along with the H ealth D epartment and lo cal governments, listed as one of its commi tments the preparation of guidelines and regulatio ns for reuse of greywater.

Health Implications Greywate r contains microorganism s, e.g. from washing of soiled skin and clothing. A health risk to h umans may exist if it is not disposed of properly . Adequately treated wastewater can b e disposed of above or below ground. H owever, this does not mean that greywater application to the ground su rface is con side red acceptable. Apart from its health risk to humans, further problem s can arise when it pools and becomes stagnant. Breeding of mosquitoes, attraction to other insects and the nuisance fro m odours are all p otential problems. Greywater would have to be treated by disinfection for any above ground disposal. Disposal of greywater below ground is the preferred option. Provided the wastewater is discharged at an adequate depth below the grou nd to preve nt surfa cing this w ill provide adequate protection to public health. The only form of treatment that will be required would be removal of hair, lint, suspended solids , oil, greases, etc.

Effects on Sewerage The benefits of saving potable water are complem ented by having less wastewater to collect, treat and d ispose of for most of each year, i.e. outside the wet period when greywater normally reverts

to sewers and septic systems. Any hou sehold wh ich reuses all its greywater would reduce its wastewater eilluent during sum mer by around sixty per cent. However, any significant problems for sewers due to a sum mer flow reduction m ust also be addressed. Jeppesen (1993) estimates an annual saving in wastewater discharges in Brisbane to be 105 kL per household (normally 356 L/d). Wastewater pumping savings will accrue depending on the sewerage system layout. Perth has an unusually high number of pumping stations, some operating in series, and could reduce energy costs significantly by reu sing greywater outsid e the winter period. Concern with possible sewer problems resu lting from redu ced fl ows co uld be inves tigated in-field in a sim.ilar manner to the site testing that was carried out (in at least three states of Au stralia in 1990) to examine the effects of reduced W C flushing quantities on private and authority sewers laid at minimum gradients. It has been estim ated Oep peson, 1993) that an average B ri sbane hou sehold would redu ce both its an n ual bioc hemical oxyge n d emand (BOD) and suspended solids (SS) output by 10.5 kg. T his assumes greywater BOD and SS co nce ntrations bo th to be 100mg/ L and represents up to 30% of total household load. A reduction in operating costs from treatment plants should follow. Biosolids treatment and disposal must also benefi t in the longer term. Possible reduction i n biosolids byproducts (methane, oil, soil conditioner) may not be significant enough to classify as a loss. Wh ere effluent has to be pumped away some benefit in e nergy saving will occu r. For smaller schemes, especially in summ er , a reduction in effluen t quantity will assist in such matters as visual impact and eutrophication in d isposal areas, river beds etc. Such issues are not so sensitive in winter. H owever, some country town sc hemes reuse all their treated effiuent for irrigation , so greywater reuse would probably not benefit them. For on- site septic tank system users greywater reuse in sununer can be the m eans of extending the life of their soil ab sorption system (soak-well, leach drain, french drai n, ET bed e tc.) through reduction of its load (by 60% hydraulically) for around eighty per cent of each year. It is interesting that for Brisbane w ith 275,000 water- connected households, J eppeson (1994) estimated the dollar savings if all customers were to install greywater reuse systems as: • for potable water saving, $19 m to $31 m per year

• fo r sewerage system saving, $11 m per year (Brisbane assumed to be 98% sewered).

National Guidelines Guidelines for design and operatio n of greywater reuse systems have already been produced in Australia in both the national and local government sphe res. UWRAA, a division of the Water Services Association of Australia (WSAA) published Model Guidelines fo r Domestic Greywater Reuse fo r Au stralia Oeppeson, 1996). The proposed guidelines result, firstly, from a 1993 evaluation of overseas correspondence and literature, with some local greywater ch em ical and microb ial analyses Oeppeson , 1993). Secondly, Oeppeson , 1994), investigated overseas practices in greywater reuse and how they could be applied to Australia. Effiuent application could then be as shown in Figures 1, 2 and 3 . In terest in greywater reuse for water conservation at both federal and state government levels has prompted some local govern men t bodies to offer advice to constitu ents. Examples are from Queensland (Department of Primary Industries, 1992) and N ew South Wales (R ecycled Water Coordination Commi ttee, 1995). Jeppeson and Solley (1995) suggest that th e new 1996 guidelines should be read in conj u nction with the by-laws and regulations of relevant regulatory and/or administrative au thori ties. National implementation of greywater guideli nes, th ough desirable, wo uld need time, experience and edu ca tion with the use of numero u s syst ems befo re a compre he n sive set were adopted. Meanwhile, locally applied rules will hopefully be compatible with current nationally produced guidelines and avoid the tendency for diverse practices to become entrenche d across the nation. It is expected that feedback w ill significantly update the guidelines and that trial implementation is the best way to achieve this. Probably the biggest issue is the local government abili ty to support the approval and rand om inspection process, together with the readiness of existing greywater recyclers to respond and obtain 'official' approval. In time, the WSAA may decide that an update is appropriate. Support is expected from the manufacturers of equipment for greywater recycli ng now that a base guide has b een presented with which they can develop systems in liaison w ith au tho rities.

Trials in Western Australia In Western Australia five trial greywater recycling installations exist. They have been authorised by the HDWA and t he Water Authority, now the WATER MARCH/APRIL 1998

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WASTEWATER Water Corporation of Western Australia C'vJCWA), and are owned and funded either privately o r publicly. They cover diverse conditions with testing in place for operational data. User information is also being gathered. Geraldton A three- year trial is being undertaken at Geraldton. T his trial u ses all laundry and bathroom greywater from a single domestic house at Mt Tarcoola to irrigate ornamental garden areas by sub-

South Fremantle Greywater from two homes in builtup residential Fremantle is passed through a standard septic tank for sedimentation, then distributed subsurface to shrubbery in a public park situated on a corner block ofland. The 1500 litre sedimentation tank meets HDWA septic tank standards and effiuent can be diverted to either of two subsurface fields (see Figure 4). On one arm the effiuent distributes onto an Ecomax-designed bed of red mud (byproduct of bauxitt processing) before takeup by vegetation. The other arm, a sta ndby, distribu tes effluent along a subsoil d rain laid in an organic humus filter bed. Surface and groundwater conditi ons are monitored. The settling tank, when examined in August 1996, had accumulated onJy a 20 to 30 mm sludge layer since startup in M arch 1995. The principal test aspects are: • the effect of septic-tank settling on effluent quality and infi ltration • avoidance of surface ponding • the effect of irrigation of vegetation and the effect on the aquifer.

' ... .1n many count ry areas ... extensive greywater recycling is carried on illegally' surface soak pots. The proj ect was funded jointly in J an uary 1994 by the National Landcare Program and the then Wate r Au tho rity of Western Australia. After scree ning to remove ha ir and li nt, greywater is pumped to fou r distribu tion tanks and gravitates through 10 mm diamater distributors to subsurface soak pots, consisting of up to 30 inverted plastic funnels, th roughout garden areas. System monitor-ing starts with the householder keeping records of the typ es of p rincipal additives, cleaning agents etc, discharged in the greywater. Analyses of the greywaterirrigated garden soil will be carried out for any residual effects on the sandy (with a small clay fraction) subsoil. As a water conservation 1neasure, a small hand basin for toilet use rs discharges to the toilet cistern. The pri ncipal test aspects are: • screening and pumping raw greywater • distribution by low-head gravity reticulation through 10 mm tubing • effect of greywater use on garden soil • feasibility of using handbasin water for toilet fl ushing. Cottesloe In a project in Cottesloe greywater from the kitchen, bath room and laundry of a single suburban home of fou r people is initially treated by a bioMax Model ClO anaerobic/aerobic wastewa ter treatment uni t, modified fo r lower organic loading. Effluent, after chlorine disinfec tion, is pumped to underground D ripmaster drippers fo r irrigation o f garden shrubs and groundcover. T he installation is p rivately owned and operated. The principal test aspects are: • effectiveness of modi fication to the bioMax unit for greywater treatment • effectiveness of D ripmaster irrigation drippers. 20

WATER MARCH/APRIL 1998

Palmyra At Palmyra greywater from the kitchens, bathrooms and laund ries of six aged-couples units situat ed close to Fremantle is biologically treated and disinfected for u se in toilet flushing and garden irrigation. The project, fu nded under the Building B etter Cities Program, co mmenced operation in August 1995 and is owned by W estern Australia's housing authority, Homeswest. An Aquarius biological treatment unit produces a secondary-grade effl ue nt for di sinfection by 30- minute chlorine contact to not exceed the levels of thermo-tolerant colifonn org-anisms in Guidelines for Use of Recla imed Water in Australia (NHMRC/AWRC, 1987). The effluent is stored, then used fo r toilet flushing and irrigation of garden s by m eans of undergound drippers. The gardens are fenced and ornamental only, situated on silica sand with a low clay frac tion . T he principal test aspects are: • flow quantity measuring • sui tability of the aerobic treatment unit for greywater (low orga nic load) treatment • d isinfection effectiveness after chlorination and sto rage • feasibility o f reuse fo r toilet fl ushing and irrigation

Sandy loam mounding with grass, shrubs or ground cover

Scarified base soil \... 25 mm laterals. 2 m spacing, minimum 3 mm holes at 1 m intervals

Aerobic and sandy loam layer

Scarified base and improved soil layer

Figure 1, 2, and 3 Approved filtered effluent app lication methods


WASTEWATER City, has registered strong interest and has been accepted fo r trialling. The soil types include considerable clay and fine sandy silt, very different from the Perth metropolitan soils, but typical of the Goldfields, Pilbara and Kimberley. The comm unity consultation committee for the Kalgoorlie-Boulder Water Efficiency Program, WEAC, expressed a clear wish to participate in the greywater trial and requested co ntinuous updates in progress reporting. H owever, the main issue concerning the EH O of the Kalgoorlie-Boulder City Council was that special arrangements would be required fo r the data recording and retrieval system for inquiries. Part- time assistance would be needed.

Irrigation field secti ons

Sand

/ Plastic membrane

~ 90 mm dia pvc with 10 mm dia holes

Type 1 ('Ecomax' design)

Type 2

100 mm dia perforated Draincoil

Figure 4 So uth Fremantle Greywater Recycling Pi lot Arrangement

• odour, regrowth and staining problems • consumer acceptance. Hovea At H ovea greywater from the bathroom and laun dry of a four- person h ome in th e Perth H ills u ndergoes detenti on in a sedimentatio n tank sim ilar to a septic tank meeting H DW A requirements. Effiuent is distributed to a clayey soil by a subsurface trench disposal system, irrigating a garden of selected sp ecies. The trenc h co m plies with AS 1547-1 994 , Disposal Systems for Effiue nt from D o mestic P remises (see Figure 5). T h e slo t ted drainpi pes, surrou nded by crushed stone, are laid in a parallel grid with a minimum clearance of one metre between them , fed on a non-alternating basis in a garden enviro nme n t. At 21 m onth s since its J an uary 1995 syste m start up the sedimen tatio n ta nk had negligible sludge buildu p and the soakage field fu nctioned well. T he installation is permanent and its principal test aspects are: • set tlement as the sole greywater treatment • effectiveness of the disposal/irrigation field in clay soil/garden environment.

Western Australian Draft Guidelines Work has bee n co mp leted 111 Western Australia o n draft guidelines (guided by the UWRAA model) fo r use by local governments (H ealth D epartment of Western Australia, 1996). It has been recognised that they have a m aj or role to play through environmental health officers (EH Os) placed in each local government. Scope The guidelines offer requirements for design and installatio n o f new domestic greywater reuse system s, as well as modifi cati on s for existing systems. T hey cover: • h and- basin toilets-use of handbasin water fo r flu shing the toilet • primary systems-for direct reuse of un treated greywater from a single living unit • secondary systems-treated greywater

where short-term sto rage m ay be appropriate--includes multiple-occupancy dwellings. Audience T he model docu ment aims to facilitate on-site reuse of greywater, carefully avoiding compromise to public health and the environment now and in the future. Clearly, it targets local governmen t e nvironme n tal health officiers, who may then adapt it if appropriate, but there is excellent value for individuals who need cautious advice p rio r to seeking approval from local or state health autho rities.

Monitoring Setup If, after having received a set of guidelines (on trial), existing 'informal' users or proposers of new greywater systems were to lodge an applica tio n for approval, the EH Os could randomly check how these were complied with. This would include any n eed for modification and exten t of interest. A da tabase would be kep t of all phone, mail, fax, inspections, etc. T his would be in cluded in reports from the municipali ties and fina l reporting by the research team.

Method of Implementation of Guidelines Initially, there will be a need for trialling in diverse soil type areas to acquire data for extension throughou t Western Australia. T his will be followed by fi nalising the draft guideli nes, official lau nching in each area, preparation and distribution of fliers and application forms as a letterbox drop.

Feedback T he mai n drivers for this research are the H DWA and the Water and Rivers Com m.ission as the main in terests are in public health protection and wate r conservation. Feedback from the public would be via the EHOs. Feedback will be encouraged during the trials, bu t, ap art from random checks, the process will be self- regu lating and evaluation of this wi ll be part of the trials.

Trialling the Draft Guidelines

There are three trials planned for 1998 o n three competely different soil types: Financial Support • Bassendean Town, w hich is predomBecause resources are too limited fo r inantly the Perth suburb well known for the trials to be funded withirr existing its sandy soils. It i s sim.ilar to most resources, support could be expected suburbs o n the heavy dune and from the beneficiaries, notionally treatli mestone plain running alongside the ment plant suppliers, WSAA, specific ocean water su pply utilities and the H ealth • Kalamunda Shire , in the Da rling D ep artme n t. It is noted tha t extra R anges, which is qui te different from staff, communication s and promotion Bassendean, having rock at very shallow resources would be required. depth and lateritic character in its t op- soil, as E II Friable E I well as clay/soil soil topping \ in the suburbs m aggregate on the foothills Clay E • Kalgoorliesoil E a Boulder, which N "' because of water 80 mm dia conservation slotted drainpipe awareness and 55 m total length the implementation of the Drain cross-section wo rld's fi rst Waterwise Figure 5 Hovea Greywater Recycli ng Pi lot Arra ngement \

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l_3~0__m~ _J

WATER MARCH/APRIL 1998

2:1.


WASTEWATER Evaluation

With the feedback being logged and 'marketplace penetration' recorded, full evaluation of the trial will be carried out and appropriate recommendations made, including possible Regulation and Act modification. For different soil types, there are expected to be modified performance figures. For this reason, the guidelines will need to address the diversity of geotechnica1 conditions in residential properties throughout Western Australia. When this is compiled from the feedback from trials and extension to other areas, review of Acts and R egulations can be carried ou t and a full program of implementation through local government can commence wi th appropriate seminars and fo ru ms fo r ratepayers as components of the promotion program.

Implementation in Western Australia Changes to some regulations are n ecessary for wider use of greywater in the co1nm unity. An emphasis would be placed o n use, as well as disposal, accou nting for: • avoidance of surface ponding or runoff • control of the type of use and access to irrigated areas • avoidance of conta mination of surface and underground water • prevention of soil d eterioration or nutrient overloading. Some flexible aspects of the laws, p ri marily the health legislation to allow for: • later adjustments based on any further findings of trials • auth orities to accou nt for local conditions. Already a valuable liaiso n exists within the Greywater Recycling Policy Group representing the Western Australian H ealth Department, Water and Rivers Commi ssion, Department of Environment P rotectio n and the Water Corporation, whereby existing trials are monitored and proposals are viewed to assist the autho rising bodies where necessary. Innovation, an essential element for cost-effective systems, will no doubt spring from the private manufacturer and customer (as it has done fo r other household water savers) . A 'central' body representing at least those of the above group must exist for: • monitoring new proposed innovatio ns and existing trials in Western Australia • maintaining a cautious outlook on greywater reuse, realising its potential hazards • keeping constant contact with other 22

WATER MARCH/APRIL 1998

states and leading overseas users of the technology • recommending possible amendments to the regulations • seeing that in administration of the rules the basic intent to protect both the public health and the environment is retained. Not only must householders be given informative guidelines to reduce the chance of poor greywater practices, bu t the industry, which might provide these gui delines, must itself receive proper training. Local governments which participate in water conservation through greywater reuse wi ll want to provide training to both industry and householders, including: • aware ness of the benefits, water saving, n utrient value etc. of greywater use for irrigation • awareness of regulations w hich exist and the principal hazards they are meant to address • operation of systems, especially those serving more than just single dwellings • basic precautions during design and installation such as limiting access to some areas, avoiding cross connections with other fluids, and the selection of sites and soils etc. • sensing and dealing with problems arising due for example to hydraulic overloading, chemical intervention, soil clogging etc. A principle on which training migh t be based is 'simplicity is the key, safety is a necessity.'

Jeppeson B, Solley D (1994) Domestic Greywater Reuse: Overseas Research and its Application to Australia, Urban Water Research Assoc. of Australia, Research Report No. 73, Brisbane City Council. Jeppeson B (1996) Model Guidelines for Domestic Greywater Reuse for Australia, Urban Water Research Association of Australia, Research Report No. 107. Brisbane City Council. Preferred Options (Stuart White) et al. (1994), Blueprint for a Water-EfEcient City-Report of the Kalgoorlie-Boulder Water Use EfEciency Study, Water Authority of WA. Recycled Water Co-ordination Committee, NSW (c.1995), Fact Sheet-Domestic Greywater Reuse. Sch.lafrig J E, Anderson JM, (1992) Strategies for Increasing Recycled Water Usage in Australia, Conference on Wastewater R eduction and Recycling, A WW A, l2-15thJuly 1992, Geelong Vic.

Further Reading

Hartling E (1994) Water Recycling in Los Angeles County. Jelliffe P , Sabburg G, Wolff J (1995) Key Factors in Minimising Water Polhition in Unsewered Areas, AWW A Federal Convention, April 1995, Sydney NSW, Vol 2, pp. 85. Jeppeson B (1994) Greywater R euse, Recycled Water Semi nar Proceedings, 19-20 May 1994, Newcastle, NSW, AWW A/Recycled Water, pp.197-204. Kourik R (1988) Gray Water Use in the L11Jdscape, Matamorph.ic Press, CA, USA. Lechte P, Shipton R , Christova-Boal D, (1995) Installation and Evalllation of Domestic Greywater R.euse in Melbourne, AWWA Fed. Convention, Conclusions April 1995, Sydney NSW, Vol. 2 p. 91. Widespread informal and illegal greywater recycling needs to be adapted Ludwig A (1997) Create an Oasis with Grcywater, PIP, Santa Barbara, CA, USA. in the community interest to guidelines National Capital Planning Authority (1993) which enable the consumer to use the Designing Subdivisions to Save and resource whilst minimising health risks. Ma nage W ater Better Cities P rogram. Trials will enable the development of Southern Cross University (1996) Innovative guidelines and procedu res suitable for Approaches to the On-site Ma!1':lgement use in Western Australia, allowing local of Waste and Water Confe rence Nov., government to host a measure of water Lismore, NSW . conservation, a topic fresh in the minds World Water and Environmental Enginof Western Australian water consumers. eering (1996) Greywater R ecycling: Treatment Techniques and Cost Savings, The environmental benefit must be February 1996, pp. 18-19. considered in order to allow an attrac-

tive return on investment. The water and sewerage provider will benefit more significantly, but this need s to be proven through trialling on a large scale.

References Department of Primary Industries, Q ueensland (1992), Policy Options Paper-The Use ofGreywater. H ealth Department of WA (1996) Draft Guidelines for Domestic Greywater Reuse in W estern Australia, Water and Rivers Commission Project, second draft, July 1996. Jeppeson B (1993) Domestic Greywater Reuse: Preliminary Evalua tion, U rban Water Research Assoc. of Aust., Research R eport No. 60. Brisbane City Council.

Authors John Schlafrlg is Project Manager, Water Conservation in the Water and Rivers Commission, Western Australia, PO Box 6740, H ay Street, Pe rth WA 6892, fax (089) 278 030 1. Brian Devine is Principal Environ me n tal Health Officer and Barry Bowden is Manager, Wastewater Management in the H ealth Department of Western Australia. Bob Flmmel is a Senior Civil Enginee r an d water use effici ency expert in CCD Australia, a company specialising in on-site and overall wastewater systems engineering.

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m

ENVIRONMENT

A MODEL FOR CONTINUOUS TRACKING OF

Abstract T he performance of a wetland in tem1s of stormwater quality improvement is dependent on the design of the wetland, the characteristics of the runoff event and the conditions at the commencement of stormwater inflow. A one-dimensional convection wetland model developed to estimate the influences of different parameters governing wetland processes is presented in this paper. T he model is based on the assumption that water quality improvement is a function of detention time. T o demonstrate the capacity of the model the performance of a wetland under the control of different outlet structures is presented throu gh a hypothetical case study. The study has shown that the type of outlet structure has a vital influence on detention time and that the water and pollutant phases need not have identical detention times.

Key Words D etention time, we tlands, stormwater treatment, outlet structure

Zarriello (1988) has used a methodology similar to that ou tlined in th is paper for detention basin analysis. Solution of differential equations for flow and transport of sediments provides the opportunity for a more detailed stu dy of wetland processes (Walke r, 1995). H oweve r, increased deta il demands more input data and longer computation. Not even these sophisticated methods cope with all pollutan t removal mechanisms. It is likely that different approaches and models will be used for research and design purposes in the future. The most practical methods are based on the idea of detention time, which unfortunately is seldom defined accurately. This paper presents a description of a one-dimensional co nvection wetland model w hi ch, although sim ple, is capable of resolving basic we tland-related problems . To demonstrate the capacity of the model a hypothetical case study has been adopted. This has been simplified in tentio nally to demonstrate some important wetland- related ideas and definitions.

Introduction Wetland performance 1s often estimated on the basis of global parameters like mass deposition/water surface area, length/width ratio etc. The indicators of a particular we tland are compared to typical empirical values. There are very few models in practical use so far. One of the earlier models is the Pond model, which has been used successfully in Canada and the USA. This model was developed for steady state conditio ns (US Environmental Protection Agency, 1987) and modified for dynamic settling conditions (Marshall Macklin Monaghan, 1994).

Pollutant Detention Model Efficiency in terms of reducing pollutant levels in water is considered to be the measure ofwetland performance. It is reflected by the difference of inflow and outflow pollutant mass and by the amount of captured pollu tants. Although sediment quantity analysis provides accurate results, it has th e d isadvantage of being available only after several years of wetland operation. To reach the index of efficiency, the calculations are divided into four stages: • for a given inflow hydrograph and pollu tograph (pollutant concentration

.,

versus time) the pollutant mass inflow and the outflow hydrograph is determined by hydraulic calculations • based on the o.utflow hydrograph, the average potential detention time of each water or poll utan t particle entering the wetland is calculated • the quantity of retained pollutant is calcu lated based on empirical pollutant retention versus detention time fu nction • having calculated the inflow mass and the retained pollutant mass the index of efficiency is determined. The hydrograph transformation in this model is given by solving the water balance equation with a chosen time step for quasi steady conditions. The pollutant mass inflow is then calculated based on the inflow hydrograph and the time-dependent pollutant concentration. Detention time is defined in this model as the time period for i particle (of water or poll utant) to flow from the pond inlet to the pond outlet, given by Martin (1988) . D etention time is in most cases unsteady, determined by the initial and boundary conditions which are unique for each particular runoff event and wetland design. Due to the rapidly cha nging di sc harge du ring a storm event, the velocity of particle motion is also changing. As a result, each particle has its own detention time depending on its variable velocity along its trajectory through the wetland. It is assumed that the actual velocity of the pollutant particles is proportional to the flo w velocity. Due to t he storage function of a wetland the p hysical movement of particles is more closely related to the outlet discharge than to the inlet discharge. The particles which leave the wetland through the outlet must be physically replaced by followWATER M ARCH/APR IL 1998

27


ENVIRONMENT

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Time (hrs)

The Pollutant Retention (PRE)

r o ·- Weir _

t- 2 12

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T t- 182

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t-233

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Figure 1 Function

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Figure 3 Water Levels for Different Outlet St ruct ures

Figure 2 Wetla nd Hydrogra phs

25 ,-----,--,-- - , -- , - - - . - - - - . - - - , 20

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Emission Time (hrs)

Figure 4 Inflow Pollutograph

Figure 5 Distribution of Detention Time During the Event

Figure 6 Wetland Efficiency Variations

ing ones. According to th ese assum ptions the increment of poten tial dete ntion time of each pollu tant particle in a single calculation step is

wetland p ollutant rem oval fu nctions migh t be represe nted by a single independent variable: detention time. The relation betwee n the de tention time and the pollutant re te ntion efficiency (PRE) is treated as a typical 'black box' relation unique for each wetland and pollutant type that need to be calibrated (Figure 1). R egularly updated PRE fu nction s allow accurate performance identification and tracking. The retained pollu tant m ass (dm (t)) in each time step (dt) i s determined by

The meaning of the uppe r expression depends on th e relevant time period defined by the limits of the integrals. If that period involves j ust one (well separated) rainfall runoff event, IE is an event-related index of efficiency. Lifetime index o f efficien cy might be derived similarly. Efficiency i n these terms includes the conti nuously dunging effectiveness of the pollutant de ten tion m ec hanism s of th e wetland (seaso nal and long-term changes) , as well as the appropriateness of the wetland design.

1 dL d t,c,(t) = C v Q OUT(t)/ A(t)

(1)

where Cv L

is the adjusting factor of velocity is the ave rage le ngth of the flow path between the inlet and outlet Q 0 uT(t) is the outlet di scharge A(t) is th e average ac tive cross sec tion area o f the we tland . The active cross- sec tion area is timedependent due to the water level variations duri ng a rain fall ru noff event. Fo rmulati on o f detention tim e by average cross- section (averaging alo ng the flow path ) restricts th e applicability of the method for wetlands with quasi one-dimensional flow, bu t the simplicity of the procedure is m aintained . T his m akes the model suitable for continuous wetland analysis using a sequence of storm events. The wetland retains a certain frac tio n of the pollutant due to its trapping mechanism s, which include ph ysical, ch emical and biological processes chara cteristic to each particular wetland. C ertain p ollutants are affected by more than one pollutan t trapping and treatment functions. M any of these functions are cross- corre lated and signi ficantly inclined to seasonal variations and long-term changes. Seve ral dozen parameters could be listed w hich might have an influence on pollutant trapping functi on s. As time is a common param eter for all types of pollu tant trapping m ech anism s, all 28

WATER MARCH/ APRIL 1998

dm(t) = P R E (tdct)Q 1N(t)C 1N(t) dt

(2)

where

Hypothetical Case Study

Q 1N(t) is the inflow discharge, C 1N(t) is the inflow pollutan t concentration.

A hypo theti cal e vent-related case study foll ows. This has been simplified intentionally to clear up some wetla ndrelated ideas and definitions. The hyp oth etical we tland is 150 111 long and 30 m wide. T he influence of two diffe ren t outlet struc tures (a wide rectangular weir versu s a ri ser) on we tland performance has bee n investigated. A two-burst storm even t beginning at t=120 hours lasting to t=181 hou rs with m ean discharge of 0.034 1113/s and total vo lume of 7551 1113 has bee n simulated. A long in te r- event period with constant base flow of0.01m3/s has been assumed. T he parameters of the outlet structures have bee n matched to give the same maximum water levels that results in equal storage requirement fo r both wetland arrange ments (see Figure 3) . The storage volu m e is 4212 111 3 at maximum water level, 3459 3 1113 at weir crest level and 1848 111 at riser crest level. A case of early flu sh has been simulated as indicated by the pollutograph in Figure 4. The differe nt ou tl et structures

The cumulati ve pollutant mass input and mass re te n tio n is pro vi ded by summing the parti cular ' pollutant packages' in each time step. It is possible to find o ut the wetland efficiency of any moment based on the cumulative p olluta nt mass functions. W etland efficiency is expressed by th e index of efficie ncy (IE) . Several formulations can be found in the literature. Martin (1988) mentions three: eve nt mean conce ntration efficien cy (EMC), regression of loads efficiency (ROL) and summation of loads efficiency (SOL). The autho r suggests avoiding the EMC efficiency as it is suitable for steady state conditions only . [n this work the last fo rmulation based o n summation of load s is adop ted: IE=

m(t) fQ 1N(t)C 1N(t)d t

(3)

t

JQ 1N(t)C 1N(t)d t - fQ ou-r(t)C 0 u i t

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Figure 7 Cumulat ive Pollutant Mass Input and Deposition

p rodu ced diffe rent d etention time graphs. The detention time of each pollutant package is plotted against the em.ission time (time of arrival to the inlet structure). Detention time weigh ted by the PR.E function yields th e g raph of wetland efficiency variations under the influen ce of the current event (see Figure 6). Each pollutant package determined by th e inflow discharge and poll utant concentration faces the corresponding potential dete ntion time and wetland efficiency. To ge t the m ean deten ti on time or the mean effi ciency, th e graphs in Figures 5 and 6 must be fu rthe r weighted by the corresponding masses. As a result of changing detention time and we tland efficiency, a different portion of the pollutant inp ut is retained in each tin1.e step. T he cumulative pollu tant mass inflow and deposition is presented in Figure 7. The graph of deposition for weir and riser control almost cover each other in this particular case. T he reason will be explained later. The cumulative pollutant masses are plotted against the emission time rath er than real time. Consequently, readings for a certain emission time ca n be used to calculate the resultant efficiency of the wetla nd up to the chosen moment. Event Definition Event-based analysis is a com m on approach to wetland performance identification. Knowing the beginning and the exact duration of the event is

inevitable in such cases. T he 'event' is, however, mostly not well defined, not even in a case of long inter- event periods between the following events. In the case presented the beginning of th e event (both for the water and pollutant phase) is well defined with the rise of the inflow discharge and pollutant concentration at t=120 hou rs. Although the end of inflow is the same for both cases, th e tim e of outflow re- establishment is different, using the same criterion for both ou tlet structures of dropping the di sc harge back to 1% above th e base flo w . Similar cri teria in terms of wa ter levels would yield different estimated event completions. The conclusion of water treatmen t (end of inflow+ detention time of the last particle) gives different values as well, (see Table 1). Practi cal cases are even more complicated due to the overlapping of several succeed ing eve nts. Whic h m oment might be considered to be the end of the eve nt? The presen t method gets around the problem by plotting the detention time, coefficient of efficiency and th e cumula ti ve pollutant m ass against the emission time (moment of arrival of each considered particle to th e wetland inlet) that fixes the end of the event for calculation purposes at the end of the inflow, t=181 hours. The difficulties related to the definition of event duration suggest continu ous wetland performance tracking instead of breaking down th e continuous runoff process into single events.

Table 2 Comparison of the characteristic time periods of the wetland Water phase

Weir

Table 3 Mean detention time of pollutant phase

Riser

Pollutant phase

Weir

Riser

Detention time, event period only, 120- 181 hours (hrs)

36.0

28.5

Detention time, event + inter event period , 0-264 hours (hrs)

49.2

38.5

Calculated detention time, event period only (hrs)

48.4

32.6

Detention time formula tdet=V/Q* (hrs)

28.2

15.0

Detention time formula tdet=V/Q* * (hrs)

34.4

34.4

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1.2

5.7

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2.1

10.9

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2.6

19.1

19.7

110.7

Drain time* ** * (hrs)

* Q Is the mean inflow discharge, V is the wetland volume at outlet structure crest level ** Q is the mean inflow discharge, V Is the wetland volume at maximum water level *** From the first peak of the inflow hydrograph to the first peak of the outflow hydrograph **** Time required to drain the wetland from the maximum water level to the crest level of the outlet structure

Detention Time Figure 5 shows the detention time varies significa ntly during a storm event. Before and after the analysed even t the base flow yields different uniform detention times for weir and riser control due to their different crest levels. Both ou tlet structures (especially the weir) affect the detention time of particles that have entered the wetland befo re the cu rrent eve nt. Consequently, the present event i s also influenced by the subsequ ent event (or inter-event ) characteristics. Artificial separation of the sequen ce of flow events into separated ones is not an unambiguous procedu re. This supports the idea of co ntinuou s performance tracking instead of event-related analysis. Each outlet structure has specific characteristics. The ri ser produces .a flatter outflow hydrograph and treats the early portion of the inflow more effectively. Compared to the weir, the riser produces a shorter mean deten tion time due to th e shallow flows through th e we tland. Therefore, ri se rs give be tter results on the first cell of a multicell we tland system or in trea ting early flushes. The detention time recovery of the we ir is fas te r. H e nce it is more effective in treating th e late portion of th e inflow. The weir is more effec tive on less dynamic flow wetlands. The inflow pollu tograph is expected to va ry during a sto rm event. Furthermore, in cases of early or late flu sh it is not in phase with the inflow hydrograph. As a result, th e detention timeof the water phase is diffe rent from the detention time o f the pollutan t phase. The presented method is sensi tive to these parameters, so the results are given separately for the water phase and pollutant phase (see Tables 2 and 3). N one of the time periods presented in T able 2 approxi mates the calculated detention time closely enough. It is important to notice that the detention time formula used for cases othe r than steady state condition s gives unreliable estimates, as both the wetland volume

Table 4 Index of efficiency Weir

Riser

Event period only 120-181 hours(-)

0.736

0.739

Event+ inter-event period, 0-264 hours (-)

0.755

0.753

WATER MARCH/APRIL 1998

29


ENVIRONMENT and the discharge are changing during a storm event. It is important to notice the difference between the mean detention time of the water phase and the pollutant phase. This difference is caused by the uneven pollutant concentration distribution during the runoff event. M oreover, T able 3 shows that treating a runoff event together with its corresponding inter-event periods (t=0 to t=264 hours) results in completely different detention time values. This suggests that the most objective measure of wetland efficiency is its longterm (probably lifetime) performa nce. D espite the significant diffe rences in detention times produced by different outlet structures, th e difference in ultimate wetland perform ance is not as striking in th e presented case (see Table 4). Longer detention times do not produce propo rtional water quality imp roveme nt due to the non-linear character of the retention time-pollutant detention efficien cy relationship (see Figure 1). A smalle r wetland would produce shorter detentio n times which might fall on the steeper portion of the PRE graph. T his would result in mo re significant differences in wetland efficiency.

-

Wetland Comparison The index of efficiency 1s the measure o f ove rall we tland performance. It includes the we tland design and the intensity of pollutant removal mechanisms. Some of the wetlands, even though they work effectively, may reveal poor water qu ality imp rovemen t d ue to overload. For example, a small wetland w ith very active pollutant treatment processes that is loaded by a relatively big catchment may produce a low index of efficiency. The right indicator for wetland co mparison in terms of pollu tant removal mechanisms is the PRE function. A bigger area below the PRE graph (up to certain d ete ntion time limits) means more intensive pollutant detention activity per unit area.

Conclusions W e tland calibration requi res a well sepa rated and properly monitored runoff event. H owever, clear separation of a single ru noff event to exclude the influences of the succeeding events is seldom possible. Not only the events but also the inter-event periods have significant influences on wetland processes. The ultimate measure of

Run Off & Washdown

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90's Solutions by Fox Diversion Systems

Marshall M acklin M onaghan Limited , St0rmceptor Modelling Study, Stormceptor Study Man ual , Marshall Macklin M onaghan Limited , Canada (1994). Martin E H (1988) Effectiveness of an Urban Run off Detention Pon d-Wetland s System, j ournal of Environmental

Engineering, 114 (4): 810-827. Unied States Environmental Protec tion Agency, Methodology for Analysis of Detention Basins for Control of Urban Runoff Quality, Office of Wate r , Washington (1987). Walker D , Sedim entation in Constructed Wetlands, Proceedings from Natio nal Con ference o n Wetlands for Water Quali ty Control ,J am es Cook University, T ownsville (1995) . Zarriello J P, Simu la ted Wate r-Quality C hanges in Detention Basins, Proceedings from Con fere nce o n Design of Urban Runoff Quality Con trols, Potosi, Missou ri (1988).

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wetland performance i s its lifetime efficiency. Current methods for wetland p erformance estimation rely on the detention time of the water phase, in most cases determined inaccurately. Furthermore, uneven inflow pollutant concentration results in different mean deten ti on times for the water and pollutant phases. These might explain the scatter of measured points around the PRE graph . The type of ou tl et structure has significan t influence on the outflow hydrograph and the expected detention time, and should be cho sen according to the particular requirements of the location under consideration. Albeit simple, the outlined wetland model is sensitive to many paramete rs. Owing to its simple structu re it is suitable for event-related analysis, as well for long-term performance tracking.

WATER MARCH/APRIL 1 998

Dr Julius Fabian graduated in Civil Engineering 1982 from the University of Novi Sad, Yugoslavia in 1982 and subseque n tly gained his Master o f T ec hnical Science in Water Engineering (1987) from the University of B elgrade. After obtaining a Ph D D egree in H ydrauli cs (1992), h e worked as a Lec turer of Flui d M echanics and Hydraulic Structures at the U niversity of Novi Sad. Dr Fabian joi ned the research team of the Monash Unive rsity (Caulfi eld Campus) in 1995-1997, w here he was involved in several projects related to flood routing, wetland processes and development of a gross pollutant trap. He is currently in Yugoslavia , at Gradjevinski fak ulte t u Subotici, Kozarac ka 2/a, 24000 Subotica, Yugoslavia, tel. 001 1 381 24 38560, fax 0011 38 1 24 51580, email: fabiani@EUnet.yu.


ENVIRONMENT

CREATING

SUSTAINABLE

URBAN WATER

RESOURCES I Lawrence

In September 1997, I t ravelled to M almo , Sweden to present an AustraJian position at the Sustainable Urban Water R esources for the 21st Century confere nc e organised by th e US Engineering Foundation. This conference examined the effectiveness of current urban sto rmwater pollution co ntrol measures and drew out principles for ac hieving a more effective approach to su stai nable urban water m anagement in the future.

Urban ESD Broad concern was expressed regarding the poorly defined nature of the 'ecologically sustainable development' term , particularly in an urban context. There was a consensus view that a su stainable u rban water management approach would require the adopti on of: • a risk- based approach to sustai nable loading • a more flexible approach to management and regulating only where other approaches are not in place • more effective information provision to stakeholders and radical shifts in perspectives • a more holistic, integrated, stra tegic and proactive planning app roach to replace the current reactionary approach.

Best Management Practices Co ncerns were expressed abou t the way the term 'best management prac tice' is applied. Often the best affordable current practice is followed instead of the best management practice. The re was an acknowledgment that infiltration and on-site deten tion practices were driven more by qua ntity rath er than quality management conside rations. These techniques constituted

a maj or component of European cally provided. This is in conflict with approaches , but were judged as being the principle of 'at- so urce' or dispersedineffective in the USA and UK, based based infiltration approaches. on extensive records of serious failure. The use of swales and under-drain Concerns rega rding the potential for syst em s was promoted by several groundwater rise and associated damp- presenters as the basis for management ness problems were also cited in respect of roadway quantity and quality to these techniques. However, there management. The techniq ue comprises was debate as to whether the failu re of the use of soil to intercept pollutants infiltration techniques and their associ- and the u se of the swale and granular fill ated problems was more a reflection of associated with the u nder-pipe to atteninadequate design and inappropriate uate flo w . appli cation, rather than any fundamenCaution was expressed by a number of participants regarding the long- term tal limitation of the techniqu e. A 'no direct discharge' best manage- su stainability of a nu m be r of best ment practice was promoted by the managemen t practices. It was also noted US as the most effective measure for that best management practices are just ame liorati on of fl ow and pollu tio n one approach to more sustainable urban impacts. This best management practice water management. The top priority requires that all runoff from impervious has to be so urce management. W hile areas is discharged to pervious areas or there was extensive rhetoric regarding in filtration, wi th provision of overflow 'at-source' con trols, the major· manageor subsoil drainage of the pervious areas ment focus appeared to be based on and their con nection to the drainage detention basins, ponds and wetlands, system. It was acknowledged that there and gross pollutant traps. are often co nstraints (space, soils/ geology, groundwate r protection) to Integration of Water Design the application of this approach . A number of landscape architects at Ponds and wetlands were identified the conference referred to the close as the most effective structural control historical association betwee n towns available in respect to inte rception of and water, with the integration of water urban pollutants. Research in the UK, as a key element in planning and archi Canada and Australia points to the need tecture o f the older citi es. Modern for more care in the selection and planning and development has treated design of these systems. water as a threat to urban amenity! The Infiltration and groundwater recharge architects pointed out a need to recover techniques were also widely cited as water as a key feature of urban areas by desirable management measures . Con- integrated planning and design at the cern was expressed regarding the poten- dwelling, residential block, precinct or tial for groundwater po!Jution. This streetscape levels. There was considerable debate on concern pointed to the need for adoption of centralised infiltration and the question of recovery of 'natural' recharge facili ties, for w hi ch pre- waterway values. T he landscape architreatment facilities could be economi- tects promoted the concept of managed WATER MARCH/ APRIL 1998

31


ENVIRONMENT urban landscapes plus restoration o f 'natural systems,' or integration of the civic and natural functions. There was broad recognition of the need for a more integrated planning approac h that includes u rban fo rm , landscape and wa ter system s. Best management practi ces in th e urba n st ormw ate r context include polluti on co ntrol , aesthetic and recreational facilities. The conference identified a clear need to replace th e ' independent stormwater drain' perspective with an 'integrated urban waterways' o ne.

Catchment Management A number of presentations noted the need for adaptability in wa tershed planning, w ith differing approac hes requi red acro ss the various landu se secto rs in and between catchme nts. The development of stormwater ma nageme n t plans in assoc ia tion w ith t he commu nity was seen as a successful means of securing equi table management measures. T he lack of adm.inistrative frameworks to accommodate and impl eme nt managemen t plans represented a serious constraint to th e applica tion of t his approach. T he re was recognition of the importance of participation of commu ni ty, but little in th e way of administrative provision ou tsid e Australia.

Guiding Principles Principles guiding more sustainable u rban wa ter management in the 21st C entury were identified as: • watersh ed or catchment planning and management • participation of all stakeholders in planning, supported by better information • establishment of clear institutional frameworks necessary fo r the implem entatio n of catchment management plan approaches • modification of perceptions about the value of urban storm water • total wate r cycle plan ni ng and management • promotion of opportunities for re use of black, grey and stormwater • better definition of 'sustainability' and b etter information on management measures and their perfom1ance • adoption of risk assessment • adoption of a more adaptive and fle xible approac h to de termining management and regulatory measures • m ore proactive policies and programs rather than reactive responses • redu ction in impervious areas (increase urban de nsities and selection of urban form) • more innova ti ve in tegratio n of stonnwater into urban landscape and planning

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WATER MARCH/ APRI L 1998

• greater focus on source controls • the adoption of a more balanced approach, in which best management practices are just one means of addressing quality problems. A CD of the conferen ce p apers will be available fro m the Enginee ring Foundation in early 1998.

Author Ian Lawrence is the Leader of the Urban Water M anagement Program at the Cooperative R esearch C entre fqr Freshwater Ecology. '-

BOOKS Tables for the Calculation of Friction in Internal Flows HR Wallingford, D H I Barr, Thol113S Telford Services, 1 H eron Q uay, London E14 4]D, ISBN: 0 72 77 2046 5, 45.00 Despite i ts misleading title, this book consists ma inly of tables for the calculati on of flo w velocities and discharges in pipes. These quantities are largely dete rm.ined by pipe friction calculated by the Colebrook-W hite equation or the M anning formula. The book is similar in intent and content, and identical in style, to the two-volume Tables for H ydra ulic D esign ofPipes, Sewers and Channels reviewed in the July/ August 1995 issue of W ater. There is sufficient difference in coverage to make thi s book an in teresting and u seful supplement to the earlier two. What has been added are tables that provide solutions to the Colebrook-White equ ation for a large range of viscosities, useful for hot or cold water or fluids other than water. Also included is a go od deal of introductory material not contai ned in the previous books. Thit clarifies such confusing and confused topics as the alternative uses of diameter hydraulic radiu s in d efi ning the fri ction factor. There is also an emphasis on approximate solutions and an effort to demystify the tables . Missing is the application of th e method to free surface flows , a topic well covered by Volume II of the previous book. Often mentioned is direct numerical solution of th e Colebrook- White equation. With such capacity readily available in a single cell of a spreadsheet, one wonders at the future need for books of tables such as this. No doubt, the authors and p ublisher think about this; in the meantime, th ey have produced another handsome publication. E M Laurenson


Specialist conferences often run a variety of risks from being too specific to attract a sufficient range of papers to the more practical aspect of inadequate registrations. It is a credit to both the importance of t he removal o f nutrients from th e water cycle and the organisation behind the BNR3 Con fe rence held in Brisbane late last year that this confere nce su ffe red from non e of th ese problems. Its success should be j udged as much by the 320 delegates, including 25 high-level international delegates who atte n ded virtually all the sessions, as by the variety and quality of th e papers presented. The welcoming cocktail party on Sunday afternoon was as m uch a chance to meet the delega tes as an introduction to that u nique experience of a 'small Q ueensland afternoon th understo rm,' the powe r and impact of which emphasised the fact that nature cannot be taken lightly w hether in terms of weather, or the environment that the conference will help to protect. The Lord Mayor of Brisbane, the Right H o n ourable Ji m Soorley, opened the conference with a broad-ranging speech that tou ched o n blue-green algae problems, wastewater reuse for irrigation and reforms in the water industry. H e also provided insight into Brisbane City Council's plans fo r upgrading i t's wastewater treatment plants. In ternational keynote speaker George Ekama got down to the basics of BN R w ith a talk on filament bulking and modelling. His complimen t to design er/ 34

WATER M ARCH/APRIL 1998

OVERVIEW RDrury build ers tha t they were brave e nough to p u t so meon e else's money whe re the theorists' mouths were was well accepted by all present. Sim.ilarily, his warning that models can raise more questions than answers did not fall on deaf ears. Australian keynote speaker Ken Lindrea ensured that delegates started the main presentations of the conference on a bright note with an insightful discuss.ion covering a short history of BNR, its multidisciplinary nature, the Internet as a tool and promises of modelling. Ken also looked quickly into the future to rem.ind us that information is nothing without training to turn it into k nowledge plus the experience and wisdom to use it properly. T he trade display located next to the conference consisted of 36 booths representing the water .industry. Compliments must go to the organisations w hich exhibi ted for th eir excellent and informative presentations-more than any delegate could assimilate in the three days available. The selection o f Tom Fenwick, D irecto r General of the D epartment of N atural Resources in Queensland , to open the trade display was an appropriate choice. T om outlined his Department's ru ral Landcare and Catchment Management initiatives, B N R pilot plants and wastewater reuse

strategy. H e also reiterated his D epartment's association with AWWA ove r the yea rs and stressed the importance BNR has in the protecti on of Queensland waterways. T he papers comprised 31 platform and 37 poster presentations, covering a wide variety of top ics. This range of subjects from the heavier scientific dissertations to the more day- to- day operatio nal activities certainly stretched the m inds of delegates and provided a snapshot of BNR in the wastewater industry. However, even dedicated BNR aficionados cannot live by nutrients alone, and the conference dinner provided an enjoyable respite to a heavy schedule. As usual, the Brisbane Exhibition and Co nve ntio n Cent re p rovided excellent service and . certainly would have impressed the interstate and overseas visito rs, as would have t he after dinner speaker who was well known to many of the d elegates. Professor Peter Swannell, Vice Chancellor at the University of Southern Queensla nd , covered topics as dive rse as knickerknocke rs (apparently an old academic saying) to disparaging re marks concerning people who have become known as nutrient removers. The conference ended on the T hursday wi th a well attended day of tech nical tours that demonstrated, in the words of George Ekama, someone putting their money where their mouth was. Plants from the Sunshine Coast and Caboolture to the Gold Coast and Toowoomba were all part of


BNR3 the tours and provided in one day an insight into BNR practice in South- east Q ueensland that could not be gained fro m weeks of scou ring documents. In summary, BNR3 was a success on many levels. It provided new work in the theories of BNR that stimulated considerable di scu ssion from the delega tes, gave n ew ideas on operational

Thi s report must n ecessarily be very limited. It is w ri tten for the benefit of read ers w ho are not so far intimately concerned with biological nutrie nt removal (BNR). In this brief review, edited extracts from the lead pap er for each of th e sessions have been chosen by the conference orga nisers as representative of the flavour of the others in that session. In these extracts some of the original references are printed in order to convey the timelines invo lved, but the reader is also referred to the full documents in the BNR3 Conference P roceedings, available from AWW A Fede ral Office. Six sessions represented the mai n themes of current BNR resea rch and technology: • Microbiology and Biology of BN R Processes • BNR Biosolids Management • Modelling and Simulation • Operational Exp eriences • Optimisation and R etrofitting and • Alternative M ethods Strategies.

CONFERENCE

methodologies and system s and drew pictures of the future of BNR technology. Mixed with all this was the fact that the vast majority of experts and practitioners in the field of BNR in Australia were presen t to consider and, in many cases, argue the points w hich only strengthen ed the focus and objectives of the conference.

Congratulations must go to the organising committee for a well run program and to the delegates and presen ters who, through their dedication to the w astewater industry and BNR specifically, mad e a success of such a specialised and dynamic topic. Definitely a high risk subj ect for any conference but also one that produced high gains.

TECHNICAL PAPERS

However, they confess that the IA WQ Ac tivated Sludge Model 2 cannot yet be routinely applied to the BNR. processes being developed. W hile the model is useful as a structured framework fo r further research, it falls short when it comes to the design and opera ti on of these systems. Ken Lindrea, of Latrobe University, Bendigo (the host of the first Au stralian BNR.1 conference in 1990) was more philosophical, discussing the ways in which the tremendous flood of information on B NR. can be reduced to 'wisdom.' Ken has been involved with BNR for 15 years and ran the unit which did th e pilot plant investigatio n s for t he Bendigo B NR. plant. In his keynote address he managed to cover the value of conferences, the free transfer of technology, the use or abuse of the Interne t, computer modelling and the vital need for an understanding of micro- biology... and the getting of wi sdom.

W G C {Bill) Raper E A {Bob) Swint on The two keynote p apers could not have been more dissimilar. George Ekama, from t he University o f C ape T own, gave a highly technical dissertation on the value and dangers of modelling BNR. processes whic h he de monstrated by the use of a cartoon in w hich a sculptor i s so enamoured of his creation that he ignores the real person. Together with Mark Wentzel of the Water R esearch Group of the University of C ape Town, George Ekama 1s a worldrenowned expone nt of the modelling of activated slu dge dynamics 111 all its forms.

Some Difficulties and Developments in BNR Technology and Modelling G A Ekama, M C Wentzel In the DEPHANOX system nitrification takes place externally to the BNRAS system (Bortone et al. , 1996; Sorm et al. , 1996) and all the influ ent wastewate r is discharged to the anaerobic reactor to maximise BNR.. After the anaerobic reac tor, the sludge mass is separated from the liquid in a settling tank and discharged to the anoxic reactor. The settli ng tank overflow, which has a high ammonia concentration, is passed through a fixed medium system wh ere nitrification takes place. The nitrified outflow from the fixed m edium reacto r is discharged to the anoxic reactor for denitrifica tion. In the anoxic reactor, denitrify-

ing phosp horus accu mulating o rganisms (DPAOs) participate in the denitrification process using th eir internally stored polyhydroxyalkanoates (PHAs) formed in th e anaerobic reactor during volatile fatty acid (VFA) uptake and P release. Therefore, togeth er with the ordinary heterotrophic organism s (OHOs), denitrification by DPAOs w ith P uptake also takes place in the an oxic reactor. From the anoxic reactor the sludge passes to the aerobic reactor to complete the P uptake process (if necessary). B eca u se nitrification is no longer required, the size of the aerobic reactor is governed by the P uptake process,

fo r which a much shorter sludge age and smaller aero bic mass frac tion is required. An extreme fo rm of this scheme would eliminate the aerobic zone altogether except for a small reaeration tank before final settling. Apart from the short sludge age, its large anoxic mass frac tion allows complete de nitrifi cati on w hich am eliorates AA filame n t bulking (Casey et al. , 1994). The improved sludge settle abili ty (SVIs of SO ml/g have been consistently observed, Sorm et al. , 1996) increases the treatme nt capacity of the system by another 40% or so and may offset the cost of the additional settling tank after the anaerobic reactor. WATER MARCH/APRIL 1998

35


BNR3 Anoxic P uptake is sought to be maximised in the system, but this requires a sufficiently high nitrate load on the anoxic reactor. Comparing the aerobic and anoxic/aerobic P uptake biologenhanced phosphorus ically removal (BEPR) behaviour in conventional BNR systems, it seems that the latter is significantly depressed (to 60%) and therefore uses influent RBCOD less efficiently compared with the former. An evaluati on of the results from a D EPHANOX system (Sorm et al., 1996) indicate that this reduced BEPR may also apply to this system. D evelopments in the unde rstanding of the BEPR processes of (i) phosphate accumulating organism (PAO) denitrification and anoxic P uptake, (ii) fermentation

CONFERENCE of influent readily bio-degradable (RB)COD and (iii) anaerobic hydrolysis of slowly biodegradable (SB)COD are evaluated in relation to the IA WQ Activated Sludge Model (ASM) No. 2. At present there seems little point in changing process (ii) above from a transformation one mediated by the O HOs to a growth one mediated by facultative or obligate anaerobes. The rate of process (iii) in ASM No. 2 has no experimental basis and the evidence for the significance of this rate is contradictory. This process in ASM No. 2 needs to be handled with extreme caution because it allows SB COD to become available to the PAOs and therefore has a profound influence on the predicted BEPR. Modelling nitrifying/denitrify-

ing BEPR (NDBEPR) systems is an order of magnitude more complex than modelling ND systems . Current information does not allow a significant improvement to be made to ASM No. 2 t hat would improve its predictive power and reliability. I The p rimary purpose of ASM \.. No. 2 is to provide a structured framework to guide research into BEPR, but should not form the basis fo r design and operation of NDBEPR systems. Information needs to be collated and evalua ted by the IAWQ Activated Sludge Population D ynamics Study Group to revise the filamentous organism bulking and foaming causative co nditi ons categorisation a1!d prepare state-of-the-art scientific and technical reports.

Education, Training and Technology Transfer: Are These the Same as Wisdom, Knowledge and Information Retrieval? K Lindrea In 1994 at BNR2 in Albury we had a session o n technology transfer, w ith widely varying opinions on its usefulness to consultants, operators and stude1tts, which included an examination of the use of computer models as a type of virtual reality. One has only to ask the process engineer, the consultant and the operator at a low -perfomiing plant for their considered opinions to realise how backgrounds and positions colour their answe rs. The question is: Do we make it easy for those w ho are new to the game? At an IAWQ conference in Munich last year I was impressed by the effort to provide novices with a couple of ea rly papers w hic h o utlined fundamental principles, advantages and disadvantages . Unfortunately, this was negated in later pap ers by consultants who did little more than quote efficiency figures at each other whilst keeping details as vague as possible. Conferences are great places to learn, but sometimes you have to ask. If you are too shy in the sessions, approach the speakers afterwards. The wastewater industry so far has been almost completely free in its exchange of information. In BNR we all had a lot to learn, and the gurus were happy to help. However, misconceptions ab ound, particularly at plant level, 36

WATER MARCH/APR IL 1998

where anecdotal evidence is freely passed around, albeit some of it has dubious value. 'Consultantspeak,' full of acronyms, has a limited audience. The Internet is becoming a richer sou rce of information on almost a daily basis. But beware, it contains so much incorrect information, conclusions based on poor data etc based on the desire

of the typer to achieve some illdefined personal goals. There are no referees on the Inte rnet! As edu cators we are drawn to use the Web because of the speed of access to anything one would want to know. But how does one teach the capacity to discriminate, to distinguish the rubbish, the mountains of trash? Wisdom has been replaced by knowledge, which is itself being rep laced by the capacity to retrieve masses of information.

I have called the AS sludge model an 'amplifier' because it encourages both enlightened stu dy practices and thoughtless ones. It can allow the adept to evaluate concepts and to extend the realm of possibilities, or it can be made to prove anything. The latter is slow ly turning tomorrow's practitioners into laptoptoting automatons. People like me w ho are fundamentally optimistic about modelling have to be very careful about how we prepare our students. T he 'ultimate model' is a H oly Grail-just as symbolic and ethereal. The plants we design and operate are driven by bacteria selected by influent character and process conditions. The improvement in our understanding of the processes involved has been derived from a more complete biological view, and we must be prepared to look beyond and prepare to cross the boundaries of our own discipline. There is so much more to be learned. Information is only data, w hich in itself is wor th nothing. Training provides the skills to use that data and convert it into knowledge which allows one to discriminate between the good and the useless. From this springs experience and hopefully the time to develop the wisdom to use it appropriately.


BNR3

CONFERENCE

Session 1. Microbiology and Biology of BNR Processes The lead paper, from the hosts of the conference at Queensland University's Advanced Wastewater Ma nagemen t Centre, describes sophisticated geneprobe techniques to identify the

bacteria supposed to be responsible fo r P-uptake. It has long been believed that Acinetobacter was the prime candidate, with VFA metabolism an essential characteristic of the process. H owever,

both these assumptions began to be questioned in two independent papers Oenkins; Raper) at BNR2. Identification of the microbes and their biochemistry were discussed in this session.

Bio-P and Non-bio-P Bacteria Identification by a Novel Approach PL Bond, J Keller, LL Blackall The use of culture-dependent methods for identifyi ng bacteria from activated slu dge with enhanced biological phosphoru s removal (EBPR) has strongly implicated Acinetobacter with the process. H owever, using fluo rescent in-situ hybridisation (FISH ) probing to analyse m icrobial population s, we have evidence to oppose this widespread belief. We describe the phosphorus (P)- removing performance and microbial population analyses of three different sludges obtained in a laboratory- scale EBPR reactor. Two sludges with extremely high P- removing capabilities we re exami ned. T he P content of these sludges was 8.6% and 12.3% of the MLSS. Identification of bacteria using FISH probing indicated both sludges were dominated by microbes from the beta proteobacteria and high mo lo/o G+C Gram positive bacteria. Acinetobacter could make up only a small

proportion of the cells in these sludges. A sludge with extremely poor P removal was then generated by redu cing the P in the influe nt. Bacteria resembling the G- bacteria became abundant in this sludge and these were identi-

tied using FISH probing. The anaerobic transformations of these sludges correlated well wi th that of the non-EBPR and EBPR biological mode ls respectively, indicating that the 'G- bacteria' in the non-P removing sludge have

the potential to inhibit P- removal in EBPR systems. Further investigations are required to assess this inhibiting potential. There are biological models describing the metabolic pathways ofEBPR and non-EBPR anaerobic transformations. In this study a trend was established between the three sludges with very high, high, and negligible BEPR. As the Premova l capabili ty decreased, PH A accumulation and carbohydrate utilisation increased. T hus it is clear that the details of the proposed metabolic pathways and transport mechanisms require verification, and t he anaerobic transformations of the efficient sludge differed from the EBPR model. Identification ofbio-P and non-bio-P bacteria would enable valuable progression in the acquisition of these details. In full scale EBPR systems it is likely that bacterial populations are a mixture ofbio-P and non- bio-P bacteria.

Session 2. BNR Biosolids Management The role of BEPR processes is to remove P from the liquid p hase and sequester it into the sludge. However, if the sludge is treated by conventional anaerobic stabilisation, the P is released back into the fil trate, w hich is then recycled back to the influen t wastewater.

A vicious cycle. Consequently, BNR sludges are usually not so stabilised. As well, the physical c harac teristics of BNR sludge differ from conventional sludges. The lead paper in this session reviews the state- of-the- art for produ cing marketable products

from these rich but jelly-like sludges. The paper comes from Queensland, w here the greatest number ofBNR plants have been installed. The other two papers in the session dealt with aerobic stabilisation and the !ability of heavy metals in BNR sludges.

Sustainable Management of BNR Biosolids T Kempton, T Cusack Sustainable management of b iosolids includes treatment to produce products w hic h satisfy long- term market requiremen ts. T hese markets include compost fo r horticultural and landscaping industries, application to agricultural lands and site remediation. Products include compost, liquid sludge, slu dge cake, limestabilised biosolids and thermally

dried biosolids. Process selection should therefore be decided after market sustainable markets, requiremen ts and the level of ma rket and public security required have been identified. The major cha rac teristics of BN R sludges w hich affect these criteria are the potential for nutrient release, dewaterability and the need for stabilisation.

Most TKN entering a BNR plant is released by NdeN as N2 gas. H owever P, in the form of polyphosphate, fo rms some 3.5 to 6 % of the dry sludge, is unstable and may be released to the liquid phase in anaerobic or prolonged aerobic condi tions (Rabinowitz, Barnard, 1994), so recycle to the plant must be minimised. BNR sludges have high levels WATER MARCH/ APRI L 1 998

37


BNR3 of intracellular w ater w hich cannot be removed by filtration or centrifuge without disruption of the cell membranes. Consequently, BNR sludges are not normally dewatered beyond 12-15% solids, contrasted to 16- 22% for digested sludges and 30% for undigested primary sludge. Processing costs such as the demand fo r lime for stabilisation and transport costs can therefore be three times that of limestabilised primary sludge. The effect is exacerbated for processes suc h as thermal drying and ATAD. BNR slu dges are odorous, contain signifi cant levels of pathogens and are attractive to vectors, so that stabilisation is essential fo r any beneficial use (see NSW EPA Guidelines). The authors con sider that because of these challenges, the biosolids manage ment strategy needs to be developed prior to or concomitan t with specification of the BNR process itself. It requires a process, a product and a market. Processes include anaerobic digestion, aerobic digestion, lime stabilisation, them1al drying, composting, comp osting with solid waste. In 1996 Sullivan and Oerke determined that lime stabilisation

CONFERENCE was the cheapest process for Grade A stabilisation. Products include liquid biosolids, dewatered cake, compost, lime-amended cake, thermally dried and pelletised biosolids. Markets need to be identifed, along with opportunities and constraints. Transport is obviously a maJor co n straint; application

rates determined by agronomic and contaminant content another. The value of competitive products (municipal compost, aglime, manures, fertilisers) must be assessed. In the authors' view the market for compost is limited, requires stringent pathogen control , and may be oversupplied from m unicipal gree n waste processes. However , there is a large market

in agriculture as a soil ameliorant, though transport ove r longer distances beco mes a dominant factor. Land application of Grade B stabilised dewatered cake is the least-cost option. Site remediation has occasional relevance. The Australian experience with' dewatering processes is t hat gravity drainage decks (GDD) and DAF are the most common, but new plants are turning to GDDs on top of belt fil ters. Stabilisation by anaerobic digestio n is p ractised at a few plants in South-east Queensland, with chemical treatment of the sidestrea m by CO, stripping and lime dosing (e.g.- at Nambour: Cusack et al., 1997). Most of these plants were retrofits of conventional plants already equi pped with anaerobic digesters , and th e sidesteam process is best suited to large plan ts. Aerobic digestion i s more expensive and th e sludge is more difficult to dewater, but it is suitable for small plants. The challenge is to u se the technologies which best suit the ove rall objectives of producing low N and P effluent and biosolids manageme n t at lowest cos t to produce products which meet market requirements.

Session 3. Modelling and Simulation Session 3 co m enced with a paper from another of the world's top BNR research teams, operating from a number of institutes in Delft, the Netherlands. The team has concentrated on a model for P removal calJed th e Delft model, and is developing sophisticated analytical methods for measuring the va rious parameters. Australian authors presented their modelling

and calibration experiences. Modelling has bee n useful in optimising plants at Quakers Hill, Redcliffe (where prefermentation is essential) and St Marys, and for costing the feasibility of nitrificatio n at the massive Easte rn Treatment Plant near Melbourne. In theoretical p apers, Tonkovic reviewed the literature on mechanisms in BEPR; Ridgley dissected

all the chemical parameters necessary for accu rate 111.odelling (a total of 29) ; Lee introduced the con cep t o f axial dispersio n ; Griffiths showed that the IAWQ2 model required recalibration of several default values ro accord with Australian results; and Shama sh owed that none of several models could account fo r denitri fication by PAOs.

Innovative Methods for Sludge Characterisation in Biological Phosphorus Removal Systems D Brdjanovic, M C M van Loosdrecht, C M Hooijmans, T Mino, G J Alaerts, J J Heijnen

The ability of microorganisms to store reserve materials such as poly-hydroxy-alkanoate (PHA), glycogen and poly-phosp hate (poly-P) plays an important role in the process of biological phospho ru s removal (BPR) (Van Loosdrecht et al. , 1997a). BPR from wastewater is based on th e enrichment of activated sludge with P- removing bacteria. The 38

WATER MARCH/APRIL 1998

procedure to achieve a phosphorusremoving bacterial population m an activated slu dge system is exposure of activated sludge to anaerobic and aerobic (or anoxic) conditions. Under anaerobic conditions phosphorus-accumulating bacteria transport volatile fatty acids (VFA, e.g. acetate: Hae) into the cell and subsequ ently convert and store these in the form of

PHA (e.g. poly-hydroiry-butyrate: PHB). The energy fo r this transport and storage is supplied by hydrolysis of intracelJularly stored poly P t o ortho-phosphate which is released from the cell into the liquid. The anaerobic P-re lease is strongly influenced by pH (Sm olders et al., 1994). The redu ction equivalents required for


BNR3 the conversion of acetate to PHB are supplied by conversion of intracellular stored glycogen through the glycolytic pathway to PHB and CO2 (Mino et al., 1987; A run et al. , 1988; Smolders et al., 1994) . This conversion also generates ATP. Under aerobic co nditi ons, the anaerobically stored P HB is used to generate energy for cell growth, poly- P synthesis, and glycogen formation and maintenance , resulting in net uptake of phosphate. Recently, Smolders et al. (1995) developed a metabolic model of the aerobic BPR process using biochemi cal knowledge and the conservation principles o f compou nd s and elemen ts involved. Soon after, Kuba et al. (1996) developed a metabolic model for BPR by denitrifying organisms. T hese two models were combined by Murnleitner et al. (1997) who presented an in tegrated metabolic model for the aerobic and denitrifying BPR processes (the D elft model of BPR). In these models the rates of the metabolic pathways of BPR rely on three internally stored polymers: poly-P , PHB and glycogen. For the purposes of process evaluati on and mathe matical

CONFERENCE

modelling of BPR it is necessary to have an accurate measurement of the storage materials involved, reliable value of the aerobic and anoxic ATP/ NADH2 ratio (e aerobic and e anoxic), and information o n the proportion of bacterial populations in activated sludge important for BPR such as phosphorus accumulating organ-

isms (PAOs), denitrifying phosp ho ru s accu mulati ng organisms (DPAOs) and glycogen accumulating (non-poly-P) orga nisms (GAOs) . T his paper summarises several recently developed techniques and methods for sludge characterisation using ongoing BPR research. For determination of the PHA co n ten t of the biomass, the hydroxyalkanoates are hydrolyzed in propanol/dich.loroethane with

hydrochloric acid. The bioassay for glycogen in BPR systems is based on the stoichiometric coupling between the anaerobic acetate uptake by the activated sludge and the related glycogen consumption. H oweve r, the bioassay is only valid under the assumption that glycogen is exhausted d u e to acetate uptake. The bioassay for the fraction of denitrifying PAOs is based on the fact that DPAOs are active under both aerobic and anoxic conditions, whereas aerobic PAOs are inactive under anoxic conditions. In the bioassay two batch tests are done using the same sludge unde r aerobic and anoxic conditions. For the determination of ATP/ NAD H 2 R atio (e value), see Smolders et al. (1995), Kuba et al. (1996) and Brdjanovic et al. (19976). In well operating BPR plants the fraction ofGAOs in the sludge is probably negligible. H owever, for the purposes of process evaluation and mathematical modelling of BPR it is interesting to know the GAOs/ PAOs ratio in activated sludge. T he method is based on measurement of surplus acetate consumption w ith and without depletion of poly-P pool in the cells in an anaerobic batch test.

Session 4. Operational Experiences Although only six papers could be presented o n the platform, this session was the biggest, with a furthe r fifteen poster papers. A t least seven described operating plants throughout Australia. One interesting paper, Ph osphoru s R e m oval by Accide nt, Carole Park, described a plant designed fo r nitrogen removal w hic h pe rformed reasonably well in

BPR. Ano th er poster, High Performance Biological Nutrient Removal via Prefennen tation, proved that a simple BNR co n figuratio n could reduce P from 40 mg/L to 0.5 mg/L, given effective prefermenta tion. The o ther 17 papers covered a w ide range of topics, from optimising BNR in anoxic zones through control of sludge bulking, to the effects of salt and zinc on

p erformance. T h e lead paper, by Merv Goronszy and co-autho rs from ESI and Caboolture Council, described an upgrade at South Caboolture, using the sys tem that Merv has bee n selling successfully both in the USA and Australia. This system has its origins in t he 'Bathurst Box ,' developed by the NSW Public Works Department.

South Caboolture STP Upgrade-A Dual Basin Sequenced Batch Reactor with Feed Forward Control MC Goronszy, M Pet ers, M Basterfield, R Ash, F Fornasier In May 1996, Caboolture Council awarded a contract for a BNR plant to serve an estimated population of 40,000. The plant was designed and constructed by ESI Pty Ltd, based on the cyclically operated system invented by Goronszy. T hrough simple air-on and-off sequ encing, oxic, anoxic and anaerobic co nditions are

cyclically imposed o n a single activated sludge. Automatic control of the oxygen mass balance is fundamental to the process. T he basic control algori thm contai ns the fu ndamental AOR SOR oxygen relationship w ith a matrix which includes submerge nce, mid-depth dissolved oxygen saturation concentration,

oxyge n transfer efficiency and air flow rate against dissolved oxygen concentration. The measurement of O)rygen utilisation rate at the end of the aeration seqence is a m easure of the 'endogenous' state of the biomass and the availabili ty of carbonaceous material. Incremental adjustments are made to the air WATER MARCH/APRIL 1998

39


BNR3 supply as demanded by the oxygen set points . In some circumstances the respiratio n rate may dec rease markedly, requiring a similar rapid decrease in the supply of air. Such rapid movements may cause limiting of the controls and an end-ofcycle oxygen deficit which would elevate the ammonia concentra-

CONFERENCE tion. A lag period set point and a cycle fill period are used to counter this. A single DO sensor in a fixed position in each tank gives a simple linear approximation of the rate of change of the DO at the end of each cycle. T he dedicated software analyses t he data and controls the rate of oxygen supply

and duration of aeration in each cycle. The procedure requires a 'calibration' of settings and cycle times. Finally, results of less than 1 mg/L P, less t han 1 mg/L ammonia, and less than 2 mg/L nitrate have been achieved, w hich is well within required performance levels.

Session 5. Optimisation and Retrofitting Unlike the sessions on 'greenfield' plants, four of the papers in this session dealt with conversion of existing facilties to BNR. The lead paper, by Brisbane Water engineers, described what might be termed as pilot-plant investigations on two full- scale operating plants, a courageous attack which has paid off. Although neither plant can be said to be a true BNR

system , they both achieve much better nutrient removal than they were ever designed for. Y e rell et al. reported the use of the BIOWIN model (after calibration by pilot plant work) for design of a BNR retrofit to a large trickling filter plant. Morgan et al. reported details and early results from the Selfs Point retrofit (data from which has been recently published

in this journal). C hong e t al. reported variable success wi th re~rofitting three different IDEA plants for P-removal. A team from CSIRO and Melbourne Universi ty outlined the results of nitrification experiments w hqe clinoptilolite was used to concentrate ammonia on the surface of a media and enhance resistance to shock loading.

Optimise What You Have First-Low Cost Upgrading of Plants for Nutrient Removal D Solley, K Barr Brisbane Water has undertaken field trials into low-cost modifications and optimisation to improve the level of nitrogen and phosp horus removal in two of its large WWTPs. Luggage Point has two stages and deals with an estimated population of approximately 1,000,000, with a significant industrial load. It is normally operated as a conventional AS plant w ith tapered aeration, and designed to give full nitrification, although the current licence does not demand nutrient removal. Each stage is independent, so the oppo rtunity was taken to trial va rious operational modes in Stage 2, leaving Stage 1 as a control.

ent could be fed to the central zone. The BIOWIN simulator was used for modelling, and six modes were tria11ed, as detailed in the paper, with various matrixes of aerated (DO set point 2 mg/L) and unaerated (DO set point O mg/L) zones, each t rial lasting some months. The result is that one system halves the TN to less than 10 mg/L and achieves an average P of

Aeration Variation Whereas Stage 1 has cerarruc dome diffusers, Stage 2 was fitted with fine bubble membrane disks which allowed intermittent aeration to be trialled. Although there are no baffles along the aeration tank, the aerators could be operated independently in five zones along the tank. This was achieved by an expenditure of $70,000 for individual actuators for the five air valves, and insertion of DO probes and control systems. Also some primary effiu40

WATER MARCH/APRIL 1 998

4 mg/L. Model1ing indicates that inclusion of a mixed liquor recycle and minor baffling could further reduce TN to less than 7 mg/L. The Gibson Island plant is an oxidation ditch, but fitted with fine bubble diffusers as a more efficient alte rn ative to surface aerators. It has a nominal design

capacity of 150,000 e.p., and was designed to meet a licence of 10 mg/L TN. The plant commenced operation in 1990, was underloaded for three years, yet met the licence limits. In 1993, inflow reached 120% of design loading, includi ng effluen t from a meat renderer. With improved DO co ntrol and the additional carbon source, the process produced 4.5 mg/L TN, consistent with the axiom that 'BNR plants work best at ful1 load.' The BIOWIN simulation package was used to evaluate a nu mber of D O scenarios, as described in the full paper. Apart from a period when trade waste up sets occurred, the TN averaged less than 3 mg/L, with NO3-N less than 1 mg/L. T h e model predicts that w ith the addition of some more diffusers in the unaerated bend, the plant can cope with 150% of design loading at a similar peformance. P removal is also high, reducing 11 to 4 mg/L, e.g. Once when there was a high BOD overload, P was reduced to 2 mg/L. These case studies demonstrate that substantial im provements in N and P removal can sometimes be achieved with mm1mum capital expenditure.


BNR3

CONFERENCE

Session 6. Alternative Methods and Strategies Th.is session was wide-ranging, with seven papers discussing process alternatives, four on wetlands, three on instrumentation and control, and two on chemical polishing. The paper chosen by the organisers for an edited extract ca me from a Canadian team, Rabinowitz and Barnard of R eid Crowther and

Partners Ltd , James Barnard being the researcher fi rst credited with developing BNR at th e National Institute for Water Research in South Africa. Their paper reviews both the wo rld literatu re and operating experience in Canada on the use of primary sludge fermen tation to increase the proportion of

sh ort-chain volatile fatty acids (SCVFAs). Effluent ortho-P levels of 0.1 to 0.2 mg/L were obtained at all three plants from influent levels around 5 mg/L, but at one plant it was noted that SCVFA production was relatively low, suggesting that other beneficial compounds are produced in the prefermenter.

The Use of Primary Sludge Fermentation in Biological Nutrient Removal Processes B Rabinowitz, J L Barnard Primary sludge fermenters are a wastewater treatment plant by W estern Canada at the Kelowna, now routinely incorporated into acid fe rmentation of the primary Westbank and Calgary Bonnythe design of biological nutrien t sludge, attempts were made to broo k Wastewater Treatment removal (BNR) plants that treat develop a primary sludge fe r- Plants has led to these conclusions: low organic strength wastewaters, menter to improve the BNR • primary sludge fermentation plants in temperate climates, and characteristics of the process. The remains a viable method for plants required to achieve effluent first time a side- steam fermenter ensu ring that biological nutrie nt total phosphoru s concentration s was used to produce SCVFAs on- re moval wastewa te r treatment plants are reliably able to meet below 1.0 mg/L. These u nit their effluent limits whe n treating processes have been used in BN R organically weak wastewaters with plants in Ca nada, the U SA , marginal characteristics Europe, South Africa, Australia • the three primary sludge and New Zealand. The principal fe rmenters under investiga tion function of the primary sludge increased the SCVFA concentraferme nter is to anaerobically break tion of the wastewater by between down the complex organic mater4 an d 25 mg/L. T hese values ial in primary sludge to fo rm are comparable with the values sh ort-c hain volatile fat ty acids reported in the literature (SCVFAs), principally acetic and • the SCVFA production in all propionic acids. three primary sludge fermenters The important role played by Ciliate protozoan was sufficien t to ensure that the SCVFAs in the biological excess phosphorus removal mechanism site was at the Kelowna WWTP in plants consiste ntly met the ir was first postulated by Fuhs and British Columbia in the late 1970s. effluent phosphorus and nitrogen There are four principal pri- limits C hen (1975) and was refined in • the SCVFA yield of 0.08 to biochemical models proposed by mary sl udge fermenter co nfigComeau et al. (1986) and Wentzel urations currently in use in BNR 0 .25 kg SCVFA p er kg VSS et al. (1986) . The practical wastewater treatment plants: acti- applied observed at the single benefits of adding an external vated primary tanks, complete mix stage fe rmenter/ thickeners at the so urce of SCVFA was clearly fem1enter, single-stage fermenter- Kelowna and Westbank WWTPs demonstrated at the Secunda thickener, and the 2-stage com- compare favourably with those reported in the literature WWTP in South Africa (Randall plete mix/thickener fermenter. These fo ur configurations were • the SCVFA yield of 0.06 kg et al. , 1992), w here an industrial waste product rich in acetic acid detailed, together with thei r SCVFA per kg of VSS at the 2was fed to a simple anaerobic/ advantages, disadvantages, design stage completely 1n.ixed/thickener aerobic activated sludge process. crite ri a and typical op erating fermenter at the Calgary BonnyAfter addition of the industrial problems by Barnard (1994) and brook WWTP is significa n tly lower than that reported in wastewater, w hich was tru cked Rabinowitz (1994). R ecent ope rating data from the literature for other 2-stage directly to the plant and discharged at a constant rate to the three primary sludge fe rmente rs in fermente rs. However, the plant has excellent nitroanaerobic zone, the gen and phosphorus plant reliably achThe BNR3 Conference Proceedings, comprising 604 pages removal characterieved an effl u ent of excellent platform presentation and poster pap ers, is istics, sugges ting ortho-P concentavailable from AWW A Federal Office, tel. (02) 9413 1288, that beneficial comration well below pounds other than fax (02) 9413 1047 for $75 plus postage. 1.0 mg/L. SCVFAs are proR ecognising that The pictures in dus article are courtesy of Dr R J Seviour, duced 111 the SCVF As can be Biotech R esearch Centre, La Tmbe U1uversity, Bendigo. fe rmenter. generated on- site at WATER MARCH/ APRIL 1998

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m

BUSINESS

PREVENTING BACKFLOW

CONTAMINATION R Ford Abstract Major changes occurring in Australian plumbing regulation bring with them a risk of increasing contamination from cross-connections between potable water supply systems and nonpotable water. Education of the public, tradespeople and utility members together with a cross-connection control program are proposed as an effective method of public health protection. To assist this education program and raise awareness of the problem a national register of backflow incidents 1s required.

Introduction What would you do if you turned on your kitchen tap and the wate r that cam e out was w hi te and smelled strongly of insecticide? The residents of Chattanooga, Tennessee faced this problem on 24 March 1976. The cause was the simple action by an employee of a pest extermination company who immersed a hose into a container of C hlordane concentrate to mix a batch for spraying. Unfortunately the water pressure in the street main was so low that the insecticide was siphoned into the street mains. Chlordane is a sticky material and flushing failed to remove all traces of the chemical from the mains and plumbing of nearby homes. As a result, the Water Company replaced all mains in a threeblock area and all the internal plumbing in 47 houses. The cost was about US$1 million. Fortunately, because of the smell, nobody consumed the contaminated water. What is the risk of a similar event happening in Australia? If examples from the Ballarat Region are representative of other parts of Australia, we have probably been lucky.

Local Examples of Backflow Contamination Eel Factory In 1989, the former Ballarat Water Board took responsibility for water supply to an area serviced by a smaller authority. As part of a due diligence

process, properties were assessed for potential backflow risk. One property considered a high risk for potential cross-connections was an eel processing factory. Part of the operations involve storing large numbers of live eels in tanks. The tank water was recycled by a pump bu t make-up water was added by a direct mains connection to the high pressure side of the pump. There was no backflow protection. Historical laboratory records indicated coliform contamination of the town water su pply in the area in summ er when low pressure complaints were common. It is postulated that at times of high demand, the recirculation pump forced water contaminated with eel faecal matter back into the town water main network. An order was issu ed requiring complete separation of the recirculation system from the town supply. Spot inspections confirm there is now no p hysical connection between the two system s. Cheese Factory A small cheese factory is located in a rural township about 20 kilometres from Ballarat. It is supplied with town water but the pressure is limited due to the absence of suitable hills for an elevated storage. In 1992, microbiological samples were taken from a garden tap in the factory grounds as part of the Water Authority's routine testing program. Very high levels of faecal coliform bacteria were detected. The factory was examined by the Authority's Plumbing Inspectors and a cross-connection was found between a bore in the factory yard and the water supply. The connection had been provided by maintenance staff to enable tankers to be washed down by either high pressure water from the bore or the town supply. The isolating valve had been left open, allowing bore water to enter the factory's water supply. The factory's sanitary arrangements included a septic tank and effiuent disposal field about twenty metres from the bore. The Water Authority required the cross- connection to be removed.

Funeral Parlour Local Plumbing Inspectors received advice from Inspectors employed by a neighbouring authority that they had detected cross- connections in funeral parlours. All funeral directors were interviewed and it was found to be¡ common practice to use an aspirator co nnected to the water supply to remove body fluids from deceased persons. Funeral directors were made aware of the problem and the practice has now ceased. Random inspections are made to ensure new funeral parlour employees do not repeat the practice. Any one of these simple incidents could have had seriou s health consequences and it is suggested they are not uncommon occurrences in any Australian town or city.

Causes of Backflow Backflow can be caused by either backsiphonage or backpressure whereve r there is a physical connection between a potable water system and a non-potable environment. Backsiphonage is the result of a negative or reduced pressure in the supply piping. Typical causes would be a loss of pressure in high areas during summer, from fire fighting op~rations or a burst main. This could result in reversal of flow and contamination of the tow n supply where any physical connection exists with anothe r source of water. Water can be drawn into the system from such simple situations as hoses left in garden ponds or pop-up irrigation sprinkler heads, if the head is submerged in water. Multi-storey buildings are very susceptible to this problem. Backpressure results from a higher pressure in a non-potable system connected to the potable supply. Boiler feed pumps, air conditioning units and pressurised fire fig h ting systems are all common sources of backpressure. A simple but very serious example of backpressure occurred in a country town abattoir where a pump was used to transfer contaminated liquids, which included blood and stomach con tents, WATER MARCH/APRI L 1 998

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BUSINESS to a remote treatment plant. To prime this pump a garden hose had been permanently connected to the pum p casing. W hen the pump started, the pressure w as sufficient to pump con taminated liquid th rough the hose and back into the town supply.

Methods of Protection The National Plumbing and Drainage Code Part 1: Water Supply (Australian Standard 3500.1-1992) classifies cross- connections into three degrees of hazard: • high-any condition w hich has the potential to cause death • medium-any condition which has the potential to endanger h ealth • low-any condition w hich has the potential to constitute a nuisance but not endanger health. T he code requires a backflow prevention device appropriate to the degree of h azard to be provided. For high and medium hazard s only registered testable devices, including a registered air gap, are permitted . For low haza rd co nditions n on-testable devices may be installed . M ost of these devices remain in service for 20 o r 30 years and are expected to operate at any time in the even t of a backflow condition. This can only be relied on where there is regular inspection and testing. Experience from plumbing inspections over the past 20 years has shown that what should be the sim plest and most reliable method o f protection- an air gap or break pressure tank-will often be bypassed as plumbing is changed during building alterations or additional pressure is required . For this reason, the code requires that devices providing protection from medium and high hazard areas are registered and tested at least every 12 months. The code allows such devices to be used only if there is an au thorised maintenance program for device registration and test certification. The device selected is subject to approval by the relevant regulatory agency. To provide qualified persons to maintain these devices, certain T AFE Colleges provide courses and accreditation in backflow testing. The location of a backflow protection device can be arranged to: • provide protection at the water connection to an individual fixture (known as individual backflow protection) . This will isolate the individual fix ture and protect the rest of the internal plumbing of the property • provide protection from specified sections of a building or site (known as zone backflow protection). This w ill isolate a zone or section of the building • provide protection in the property 44

WATER MARCH/ APRIL 1998

service connection at t he p roperty boundary (known as containment backflow protection). This will protect the p ublic supply in the street by containing any contamination within the plumbing of the property. Most states in Australia are moving to separate the regulation of plumbing fro m the water supply function. Traditionally, the approval and regulation of plu mbing work on private property has been the responsibility of the water supply au thority. The removal of this responsibility, the loss of experienced staff, an increasing reliance on self ce rtification and random audits, together with increasing levels of do-ityourself plumbing, has resulted in an increasing risk of contamin ation from backflow and backsiphonage. T o protect the water supplied to their consumers, many water supply authorities are moving to containment protection by installing backflow prevention devices at the p roperty bo undary and leaving individual consumers to deal with the internal plumbing. This involves incorporating dual check valves into all water meter assemblies and assessing properties to determine if a higher degree of protection is required . The Central Highlands R egion Water Au thority requires a reduced pressure zone device on service pipes to car wash ers, laborato ries and its own sewage treatment plants. Water tankers, especially those used for fire fighting, are slowly being fitted with filling pipes that incorporate air gap or reduced pressure zone devices. This is because it is common practice to fill from a hydrant directly through the outlet connection. In rural areas where volunteer crews are used this can be a major h azard because it is in such emergencies that low or even negative pressures can be experienced in the water supply system.

vacuum. In some states this is being replaced by self certification and audit procedures, but the 'do-it-yourself owner who is ignorant of the risk and the growing culture within governments of removing restrictio ns on individuals are problems. As cross- conn ections may lie dormant for many years before conditions occur w hich create a backflow event, it is likely that a property with problem plumbing could be sold several times before the problem is detected. If inj ured persons seek redress, water authorities are likely to be caught up in the legal action. Even the transfer of responsibility may not be sufficient to protect water authorities from legal action. The Victorian State Electricity Commission was found to be n eglig<;nt when a fire caused by the w ires of a private electricity servi ce came into contact on a windy day and it failed to warn the landowner of the risk. A water au thority could be placed in a similar situation if a fault in private plumbing cau sed injury or death. In the area of backflow protection, there is a Standard (AS 3500.1-1994) which sets down technical requireme nts, b u t there is no manual of practice or recognised common practice allocating responsibility for en suring works meet the Standard . There is the refore no way of ensuring that hazard levels are correctly interpreted and the correct works specified or, most importantly with mechanical devices, that the required testing is performed regularly and documented by a qualified tester. At present, the only exp ertise in this area lies w ith water authorities. It is suggested that some fo rm of practice manual setting down responsibilities and an edu cation program of the risks involved is required.

Liability Issues

It is suggested that the areas of responsibili ty can be allocated as follows. The water user has primary responsibility for keeping contaminants out of the p otable water supply system . If a potential cross-connection exists, it is the water user's responsibility to install and arrange testing of approved backflow preventers. The plum bing control agency has the . responsibility for approving technical stan dards, providing interpretation, approving devices, recording results of regular tests and following up on untested devices. The agency also has a responsibility to educate the community on backflow risks. The new plumbing control agency for Victoria, the Plumbing Industry Board , is looking at a proposal to maintain a register of backflow devices

In the present situation it is unclear who is resp onsible for a backflow contamination incident. H owever, in the event of an illness being traced to the water supply, water authorities, their officers and boards of directors may face legal action. To d efend such an action, the individual or corporation would need to demonstrate that it was not their responsibility or, if it was, that they were aware of the risk and caused reasonable action to be taken to prevent such incidents. W ith the current deregulation of plumbing it is difficult to determine clear lines of responsibility for backflow prevention. Water authorities are giving up plumbing regulation bu t are or ought to be aware that this w ill create a

Responsibility

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BUSINESS and follow up untested devices. How ever, until a system is adopted there is no formal register of devices in Victoria. T he water supply authority has the responsibility of protecting the public supply system. This ends at the user's connection at the property boundary. If the authority has required that a backflow preventer be provided at the connection point as a condition of connection, it is the authority's responsibility to ensure it is tested regularly at the user's expense. The tester has a responsibility for correctly maintammg and testing devices and forwarding results to the plumbing control agency. The installer has a responsibility for complying with the relevant plumbing code and advising the owner that where a potential for backflow exists, the co rrec t device must be installed, commissioned and registered (if necessary) with the plumbing control agen cy. D esigner Many industrial and commercial sites have complex pipework tha t is designed by specialist designers. However, as th e primary responsibility rests with the water user, the designer's responsibility should be to advise the owner of the risk , recommend the correct level of protection , and advise of the need for registration of the device (if required under the code) and the need for regular testing and recording.

Control Program Any program to effectively reduce the risk of the public water su pply system becoming contaminated by backflow must: • educate the various stakeholders of the hazards and their responsibilities • en sure backflow devices are correctly installed and regularly inspected and tested • develop a recognised procedure for authoriti es and individuals to follow that will provide reasonable protection for the community • provide a point of contact for people seeking additional information • deal with the large number of existing consumers whose current plumbing constitutes a hazard • provide a mechanism to deal with any change of use of a property that may create a potential cross-connection. The development of a control program would benefit from support of a national body such as the Australian Water and W astewater Asso ciation (AWWA) and the major water authorities. There are well developed programs overseas, especially in the United States, which can serve as a model (American Waterworks Association, 1990). The major difficulty that currently prevents any action is the general lack of aware-

ness by tradespeople and the regulatory agencies of government. Any attempt to raise this issue in Victoria is generally met with a response that the governmen t wishes to deregulate the industry as much as possible and separate regulation from operation. Backflow incidents are curren tly occurring; but there is no coordinated register of incidents. Water agencies pass information of new ri sks and incidents between themselves by an informal network. T he current loss of skilled staff from water authorities with no systematic documentation of backflow incidents leaves no knowledge for the new breed of managers to pick up. The end result is a failure to learn from the mistakes of the past. It is suggested that, as a first step , AWWA set up a special interest group in backflow prevention to provide a register of backflow incidents for the information of water autho rities, regulatory agencies and other professional and trade associations. A second step should be the development by the group of a draft code of practice for backflow prevention for industry comment. Once suffi cient data is gathered, an approach could be made to the state public health agen cies, water au thorities an d councils for assistance in providing education for builders, 'do-it-yourself owners and tradespeople.

Conclusion With th e current changes in plumbing administration the lessons of the past are being lost. People have suffered and even died du e to backflow incidents. W e have been effective in preventing these incidents in the past, but there is no guarantee this level of safety will continue, especially as knowledge is lost to the industry. Public liability and occupational health and safety legislation has the potential to result in criminal charges being laid aga inst property owners, membe rs of water supply authorities and staff. Due diligen ce, as a defence, can be effective only where there are recognised standards and codes of practice. AWW A can play a valuable role in providing information to the industry in this area.

Note If sufficient interest exists, the author is willing to coordinate the establishment of a special interest group.

Reference American Waterworks Association (1990) Manual of Water Supply Practice M14 Recommended Practice for Backflow Prevention & Cross-Connection Control.

Author Bob Ford is Asset Management Manager for the Central Highland s Region Water Authority, having been the Engineer in Chief for the Ballarat Water Board. H e is currently President of the AWWA Victorian Branch. H e can be contacted on tel. (03) 5320 3200, fax (03) 5320 3299 or email: rford@ chw .net. au.

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Fluor Daniel in Victoria has recently awa rded ProMinent Fluid Controls Pty Ltd a contract for the supply and testing of the flocc ulant dosing pumps for the Anaco nda Nickel - Murrin Murrin Project in Western Australia. The pumps chosen for this project were Seepex progressive cavity helical rotor pumps. Two-stage Seep ex pumps were chosen because of the high disc harge pressure (10 bar) involved. The order for twelve flocculant dosing pumps comprised of the Seepex model 10-1 2BN/ 11 04440-303-268 complete with 1 lkW motor, and model 006-12MD/1104440-606-268 complete with 0.55kW motor. Additionally, ProMinent . Fluid Controls will also be supplying two large polymer solution transfer pumps capable of a duty of 125m3/h (at 3 bar). The pumps chosen for this duty were the Seepex model 130- 6LBN/ 110-1420- 303-111 complete w ith 30kW motors. All Seepex progressive cavity pumps are work tested in Gern1any where they are manufactured before being se nt to ProMine nt Fluid Controls Pty Ltd. M otors are fi tted and tested locally by Blakers Pumps Engineers.

For further details on Seepex progressive cavity pumps please contact ProMinent Fluid Controls Pty Ltd in Sydney (02) 9905 9977, Melbourne (03) 9562 9366 or Brisbane (07) 3243 8330. Alternately you may contact Blakers Pumps Engineers in Western Australia. WATER MARCH/APRIL 1998

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BUSINESS

BACKFLOYI PREVENTIONWHAT ARE WE DOING ABOUT IT? R Tucker, J Coghlan Concerns about the type ofbackflow incidents raised in Preventing Backflow Contamination of our Water Supply in this issue of Water have led to the formation of the Backflow Prevention Association of Australia (BPAA), drawing its members from the plumbing and engineering professions and the supply companies. The BP AA was set up in 1996 to foster and promote the safety and protection of potable and non-potable water. An important function of the BPAA is the dissemination of technological an d oth er information to members and the general community. T he Association also encourages and directs research and development work in the area. In 1996 and 1997 the Victorian chapter of the BPAA organised two seminars, both at t he Holmesglen Institute ofTAFE.

Backflow Prevention Overview The fi rst seminar held by the Association was attended by a 90 people and exami ned the backflow protection measures followed by Victorian and American water authorities. Yarra Valley Water spokesperson J ohn Park said new water meters fitted to domestic properties are suitable for low hazard situations as th ey will not pass water in reverse flow. Containment devices are fitted to all new commercial properties and owners are required to enter testing and maintenance agreements. A retrofit program is being implemented to cover high risk properties and a register is bei ng developed for containment devices. Gippsland Water requires backflow prevention devices to be installed on all new properties as per AS3 500 .1 , according to Ken R eid. All high hazard industries are to be surveyed. Large consume rs of water will have new meters fitted with the option of fitting a containment device. Central Highlands Water requires all new domestic water meters to be fitted with dual check valves, Bob Ford told the group. T hese will be replaced every ten years w hen the meter is changed over. A register of all testable devices 46

WATER MARCH/APRIL 1998

Andrew Marciniak, an occupational including air gaps and break tanks has been set up. New properties must have health and safety expert wi th the backflow prevention devices fitted Australian Chamber of Manufactures, as required by AS3500.1. Existing warned that in the case of an accident in connections are bei ng assessed and the workplace the Occupational H ealth owners are required to ensure that any and Safety Act may even result in a charge of manslaughter. risks comply with AS3500.1 The responsibility for hazards in the Steve Morris said South East Water has set up a register fo r containment workplace rests with both the employee devices o nly. Their On Tap newsletter and the employer, who must work is sent to all plumbers in south-eastern together to create a safe workplace. The Victoria. All new jobs must comply Act states that an employer must with the requirements of AS3500.1. provide and maintain a healthy and safe The top 100 water users have been workplace. This applies as much to the targeted and requested to install the water supply that workers d rink as it appropriate hazard- rated containment does to a guard on a machine that an device. So far 80% of users have employee operates. complied. Owners are given a choice to Duty of care depends very much on install a backflow prevention device as the level of control of the employer. If part of an ongoing meter replacement program. The 'a healthy and safe workplace aim is to have containment devices installed on all ... applies as much to the properties in the future and backflow agreement with water supply ... [as to] a guard all owners where devices on a machine.' are installed. Barwon Water requires all new properties to comply with the employer encourages employees to AS3500.1. J eff Wall said a letter had be involved in safety issues and the been sent to high risk industries and a creation of a safe workplace then the register was planned. Backflow agree- du ty of care can be shared, with the ment is sought for new installations and employer and the employee having a duty of care to each other. inspectors are to do training courses. With regard to backflow prevention , Peter Chapman from Wilkins Valves an employer can be held responsible if gave an overview of the American scene, w h ere not all states require someone is injured as a result of a crossdevices to be installed. Devices on fire connection th at the employer knows services cause problems: Arizona does about and fails to rectify. W h en a not require devices on fire services; up request is made to a plumber or backflow tester to test or carry out a to 75% of devices are not installed survey of a premises there is an expectacorrectly; testers are tested every two tion that an expert has been engaged to years; there is a 50% failure rate and do the work. retraining is required. Errol Cadaye of W estday Insurance Brokers advised that backflow testers Legal Responsibilities need professional indemnity insurance The BPAA's second seminar, which as well as the standard public liability was held in O ctober 1997, focused on and workmanship insurance to protect legal responsibilities. More than 60 them if a cross-connection is missed interested people listened to local, while doing a p remises survey and inter state and international speakers someone is injured as a result. T he espousing the benefits of having the client has the right to expect that the correct insurance, following the Work- tester is an expert and competent to do cover rules in the workplace and the the job correctly. If the plumber makes importance of using only approved a mi stake and determines that a hazard is low rather than medium and someone p roducts.

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BUSINESS is injured as a result, who is responsible? Murrey Ellis, a backflow consultant from New Zealand, stressed the importance of being sure that it is safe to turn the water off even when permission has been given, citing his own personal experience to illustrate the point. Having been given permission by the doctor in charge of a hospital to turn the water off, Murrey was proceeding to the contai nment device and almost had the water shut off when the doctor came racing out to stop him-25 patients were connected to dialysis machines! The drains from a reduced pressure zone device (RPZD) must be large enough to take the flow of water that will discharge if the first check valve is severely damaged. He quoted the case of an RPZD that was installed in a sto reroom without a d rain . The plumber completed the job and closed the door. When the storeperson opened the door to test the device he was greeted by a metre- high wall of water. Glen Tai t of Quality Assurance Services (QAS), w hich is owned by Australian Standards and operates as a private company, ou tlined the complex process for approval of the Standard for backflow preven tion devices. Because they are a safety device, they are a very high risk product and therefore have the

highest level of approval issued by job, a page can be printed and faxed to Australian Standards. QAS is develop- the site. He also re-affirmed that his ing a products database for backflow company was nationally committed to valves that will be available through the backflow p revention and posed the the BPAA. The Insurance Council of following questions . Who cares about Australia has advised Insurance backflow? W ho does not care about Companies they are not liable for a claim for damage caused 'the storeperson opened the by a non-approved/certified product. H e quoted a survey door ... greeted a metrefinding that 1 in 10 properties high wall of water.' in New South Wales would lose water pressure some time each year and as a consequence would backfl ow? Why don't all plumbers be subject to back-siphonage. How comply wi th the code? W ho checks on often does this happen in other states? the backflow inside the property? W hy J o hn Coghlan from Holmesglen are only some p lumbers installing hose T A FE emphasised that to carry ou t a connection vacuum breakers on hose backflow survey the most importa nt taps? He stressed that it is imperative fo r factor in the w hole operation is to be the Plumbing Industry Board to set up professio nal, accurate and, above all, and maintain a backflow register to honest. Do not make any assumptions. ensure that the consumer is protected. · Listen to main tenance person nel, but Authors always check things out for yourself The client expects to be accurately Rob Tucker ru ns an engineering and advised. plumbing business, and is the current Tom Oaten, a NSW Water Supply President of the Victorian C hapter of Consultant, entertained the audience the Backflow Preven tion Associatio n of w ith son1e slides of faulty installations Australia, tel. (03) 9555 0522, fax (03) and cross- con nec tions. 9553 2073. John Coghlan, Secretary of John Doig from RMC demonstrated the Association, is a Lecturer in the the advantages of CD-ROM. If a Depa rtment of Pl umbing at th e plu mber requires valve details on the H olm esglen Institu te ofTAFE.

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Profile for australianwater

Water Journal March - April 1998  

Water Journal March - April 1998