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ISSN 0310- 0367

I

Official Journal of the

Wf.iiih1!M~fWi3iE~I•) mi i:f.!M i=i iW-i-i•XeJ rn i c,1~ 1

IVol. 12, No. 2, June 1985-$2.50 I


FEDERAL PRESIDENT R. Lloyd , G.H. & 0. , GPO Box 668, Bris ban e 4001 .

FEDERAL SECRETARY F. J . Ca rte r, Box A232 P.O. Syd ney Sth ., 2001 .

FEDERAL TREASURER J . D. Moll oy, Cl- M.M.B.W . 625 Lt . Col lins St. , Mel bourne, 3000.

BRANCH SECRETARIES Canbe rra, A.C.T. Dr. L. A. Nagy , 8 Belconnen Wa y, Page, A.C.T. 26 14. (062 54 1222)

New South Wales C. Davis, G.H . & D. PIL, P.O. Box 39 , Railway Square 2000 (02 690 7070)

Vi c to ri a J. Park, S.R.W.S.C. Water Trai ni ng Ce nt re, P.O . Bo x 409, Werr ibee, 3030. (741 5844)

water

Official Journal AUSTRALIAN WATER AND WASTEWATER ASSOCIATION

Vol. 12, No. 2, June 1985

CONTENTS Viewpoint-Chas Wilkes, Organising Chairman, Convention '85 ..... . ............ . ........ .. . . . . .

5

Association News, Views and Comments ...... . ................ . .

6

International Association on Water Pollution Research and Control-News . . ........ .. ........ .. ...... . .

9

Biological Nutrient Removal in South Africa-Dr Michael Flynn Award 1985 -D. W. Osborn and H. A. Nicholls ..................... . ... . .

10

Ammonia Control and Effluent Polishing by Parrots Feather in an Aquatic Treatment System -P. M. Nuttall, R. I. Kerr and J. D. Scholes

17

Convention 'BS-Report ............ . ............. . . . . . . . . . ... .

21

Convention 'BS-Manufacturers Exhibition. Water Tech '85 . .. . ..... .

30

Geelong Ocean Outfall Project. Upgrading of Existing Wastewater Disposal Facilities at Black Rock -D. D. McLearie and D. S. Barkley . .. . . . . .... .. . .. ...,, ....... .

36

Water Treatment-Changing Perspectives -N. D. Johnstone and R. F. Goode .. .. ...... . . .. . . . ... ..... .

41

Conferences-Courses- Technical Interests . . . . . . . . . . . . . . . . . . . . .

45

Plant-Equipment-People . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

46

Book Reviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

47

Quee nsland D. Mackay, P.O. Bo x 412, We st End 4101. (07 44 3766)

So uth Au stralia A. Glatz, State Water Laboratories, E. & W .S. Pri va te Mail Bag , Salisbu ry, 5108. (259 0319)

West ern Au stralia P. Jac k, Govt. Chem . Labs 30 Plain St. 6000

Tasmania G. Nolan, G.P.0 . Box 78A Hobart, 700 1. (002 28 0234)

North ern Territo ry G. Clark, P.O. Box 37283 Winn el lie, N .T. 5789.

EDITORIAL & SUBSCRIPTION CORRESPONDENCE G. A. Go ffin , 7 Mossman Dr., Eag lemont 3084 03 459 4346

COVER PICTURE Work on the shallow conduit section of the Melbourne and Metropolitan Board 's Western Trunk Sewer being built by the Board to replace the existing Main Outfall which has been in operation since Melbourne 's sewerage system was inaugurated in 1897. The new sewer will extend from Brooklyn Pumping Station to the Board 's Farm at Werribee, a distance of 22.6 km . The upstream section of 15.3 km, is 4.4 m diameter in tunnel at an average depth of 30 m, and will discharge to a pumping station with eight massive pumps, at Hoppers Crossing. From the station, 7.3 km of 4.5 m diameter shallow conduit will carry the sewerage to Werribee Farm . It is anticipated that the project will be completed by 1993 at an estimated cost of $266 million. Cover pic ture -

donated by Melbourn e and Metrop olitan Board of Works.

The statements made or op inions expressed in 'Water ' do not necess arily reflect the views of the Austra lian Water and Wa stewater Asso ciation, its Coun cil or committees.

WA TER June, 1985

1


Biological Nutrient Removal in South Africa D. W. Osborn and H. A. Nicholls

DR MICHAEL FLYNN AWARD PAPER 1985 AWWA CONVENTION SUMMARY Initial disappointing performance of multireactor single sludge biological nutrient removing plants led to extensive investigations to ascertain reasons. Composition of sewage appears to be a key factor and if suitable substrate is not available for utilisation by polyphosphate storing organisms in the anaerobic zone, this must br created by fac ult ative bacteria using fermentat ion pathways in this zone, or exterior to the process in primary clarifiers or acid phase anaerobic digesters. Experimental work lead ing to these conclusions is described and details of its successfu l application to two 150 MLl d plants are given. Progress in the mathematical modelling of the process is recorded.

1. INTRODUCTION Biological nutrient removal systems were born in South Africa when Barnard (1974) published the results of his pilot plant experiments carried out at the National Institute for Water Research of the South African Council for Scientific and Industrial Research. This single sludge, multi-reactor process for the simu ltaneous removal of phosphates and nitrogen became known as the Phoredox process in South Africa and the Bardenpho or modified Bardenpho process in the United States of America. The city of Johannesburg, situated in the centre of the cou ntry's business and industrial area, realising that rapid eutrophication of nearby impoundments was taking place, decided to pioneer the application of this new technology into its 150 MLl d Goudkoppies plant, which was commissioned in 1978. This was followed soon afterwards with a similar plant at its Northern Works. Subsequently a number of smaller plants were constructed elsew here and today there are above 30 such plants in operation . Unfortunately, many of these plants were unable to consistently meet the I mg P I L orthophosphate standard introduced in 1980 to selected catchments . Strict implementation of

Mr D. Osborn is Ch ief Scientific Officer of the City Health Laboratories and Mr H . Nicho lls is a Senior Professional Officer of that organisation in Johannesburg, South Africa. The Dr Michael Flynn A ward is made biennially to the author(s) of the paper adjudged the best presented to the Association's Federal Convention. Judging is by a panel appointed for the purpose. The 1985 meeting, held in Melbourne, April 28 ro May 2, was the Association's 11th Federal and 1st Inrernational Convention. IO

WATER June, 1985

the law was delayed until August I 1985 and this led to an intensive programme to understand the basic principles underlying the process. The Water Research Commission, an autonomous body drawing its financial resources from a small levy on a ll water used in the Republic, acted as co-ordinator and often financial sponsor to the research programme. In stitutions involved included universities, research organisations, consulting engineers and some of the larger municipalities. Most of the investigations on large-scale plants were carried out at the Johannesburg Northern and Goudkoppies Works.

2. MATHEMATICAL MODELLING Researchers at the University of Cape Town (UCT), under the leadership of Professor G. v. R. Marais, have been engaged in modelling the activated sludge process since 1969 with the objective of obtaining a basic understa nding of the kinetics of the process for cost effective design and operation of works. Fifteen years later the research group are now in possession of what is probably the most sophisticated model in existence. Its concepts and applications are explicitly described in a Water Research Commission publication. Unlike many other model s, the UCT version is based on COD as a measure of the carbonaceous energy input to the system and this in turn, has led to the necessi ty of defining COD in terms of various fractions as indicated in Fig. I. The total nitrogen input has been fractionalised in the same manner. The magnitude of these fractions becomes particularly significant when considering the requirements for the biological removal of phosphorus. In general, it has been shown that this model can be used to pred ict the COD, TKN, NI NH. , NI NO , concentra tions, oxygen requirements and the mass of MLSS

D. W. Osborn

H. A. Nicholls

Nicholls (1984) applied the model to the 5-stage Phoredox systems operated at the Northern and Goudkoppies Works. D 0 levels were maintained at 2-3 mgl L and under these conditions phosphorus removal was minimal but good correlation was achieved between predicted and measured nitrogen values. UCT researchers are currently attempting to refine the model to include phosphorus removal and to a ll ow for the in situ generation of readil y assimilab le COD (RACOD) . In the absen ce of knowledge on the precise biochemical pathways involved, a parametric model for excess phosphorus removal was developed from observed data on experimental processes operated under a wide range of conditions: ' (i) Influent COD concentration: 250-800 mgl L (ii) Readil y biodegradable COD concentration: 70-220 mgl L (or 0.12-0.27 of total) (iii) Influent TKN I COD ratio : 0.09-0.14 mg Nl mg COD (iv) Sludge age: 13- 15 days (v) Temperature: 12-20°C The results of thi s work have been reported by Siebritz et al ( 1983) and by Wentzel"er al (1984), the latter authors presenting a kinetic

Unbiod egradab le particulate Unbiodegradab:e solub le

........................... ........................... : : : : : : : : : : : : : : .: ------. .......... ..::....:..:..:..:..:.:...:..:..:•~.:.• ............... ........................... .............................. . .........................

Readily assim il ab le Slowly biodegradable

Figure 1. Fractional division of COD of influent raw sewage.

produced per day. It has been tested against most of the activated sludge variations under steady and cyc li c loading at various temperatures.

model describing the phosphorus release process under anaerobic conditions and also experimental data showing that uptake of phosphorus is critically dependent on release


in the anaerobic zone (Fig. 2). The accuracy of the model is reflected in Fig. 3. General conclusions arrived at during the derivation of these models include:

can be tolerated in the anaerobic zone if the minimum residual RACOD is to be maintained . Siebritz et al (l 983) has shown that if

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deleterious effects on nitrification, COD removal, sludge settlt!iability and denitrification were observed. At the Johannesburg Northern Works a different approach has been adopted . In this instance, the thrust has been towards modification of the influent sewage characteristics to increase the RACOD content, either by recycling liquor from an acid phase sludge digester or by elutriating fermentation products from raw sludge accummulated in primary clarifiers. It is also proposed to convert one 50 ML/ d Phoredox system to a threestage unit having no secondary anoxic zone and a compartmentalised anaerobic zone of doub le the previous size and containing a selector unit. The results obtained with some of these modifications will be commented upon later in this presentation .

70

MEASUREO P RELEASE CagP/1)

TOTAL P RELEASE CagP / I i.nfl

4. MICROBIOLOGICAL ASPECTS Figure 2. Total P Release versus Total P Uptake. (I) Excess P removal is directly related to the amount of RACOD in the form of fermentation products present in the influent or generated under anaerobic conditions and increases as this amount increases. (2) Considering the compounds likely to be present in the influent sewage, acetic acid appears to cause a faster release of. P under anaerobic conditions than other acids such as butyric, propionic, etc. The work of Arvin et al ( 1984) also confirms these observations . Design engineers should therefore strive to provide facilities that promote maximum production of acetates in the system. (3) The greater the fraction of the total sludge in the anaerobic reactor, the greater the potential to remove phosphorus, providing always that nitrification can be maintained. (4) Nitrates in the anaerobic zone are detrimental to P removal.

3. CONTROL OF NITRATES In single sludge nutrient removing ac- · tivated sludge plants the presence of nitrates in sludge recycled to the anaerobic reactor presents problems as follows: (I) In the anaerobic zone the presence of nitrates is likely to create an environment in which some facultative anaerobes are able to metabolise substrate along oxidative pathways rather than fermentative pathways which give rise to the carbon sources preferred by Acinetobacter spp. (2) Furthermore, for every 1 mg N/ L as nitrate entering the anaerobic zone 8.6 mg/ L of RACOD will be used up (Siebritz et al, 1983). Note also that for every I mg/ L oxygen entering this zone, e.g. from Archemedian Recycle pumps, 3 mg/ L of RACOD will be removed (Marias et al, 1976). From these figures it is easy to deduce that very little nitrate can

Figure

3.

Predicted P Release measured P release.

versus

be tolerated in the anaerobic zone if the minimum residual RACOD is to be maintained. Siebritz et al ( 1983) has shown that if the TKN/ COD ratio of the influent sewage is greater than 0.08 at 12-14°C, complete denitrification in a Phoredox system is unlikely. This severely restricts its application to most municipal wastewaters where this ratio is generally in the range 0.07 to 0 . 11 . To protect the anaerobic zone from nitrate present in the final clarifier underflow, they suggested a new UCT process in which this recycle as well as the mixed liquor recycle discharge to the anoxic reactor and an extra recycle is introduced from the anoxic zone to the anaerobic zone. In this modification it is necessary to constantly control the volume of MLSS recycled to the · anoxic zone if the nitrate concentration in the anoxic zone is to be maintained near zero. It is claimed that this process can handle a TKN/ COD ratio of up to 0.14 at 12-14°C. To overcome this difficulty and produce a better settling sludge, a further anoxic zone was interposed between the anoxic zone in the UCT process and the anaerobic zone . This necessitated recycles between the interposed anoxic zone to the anaerobic zone and between the two anoxic zones themselves. These improvements to facilitate easier operation were however, at a cost, as this process could now only handle a TKN/ COD ratio of0.11. The apparent complexity of the UCT processes has not been conducive to their large-scale adoption in South Africa and has led to other process modifications being considered. Gerber et al (1984) have carried out pilot plant experiments with sewage having a TKN / COD ratio of 0.10 with anaerobic retention times from 6-24 h . Up to 15 mg P / L removal could be achieved with effluent values in the region 0.2 mg P / L being recorded . No

The operation of many successful nutrient removal plants has been associated with the presence of large numbers of Acinetobacter spp, which are strict aerobes capable of storing phosphorus as poly P. These bacteria often clump together in grape-like clusters, as shown by Buchan (1981) and depicted in Fig. 4(a) . Transmission electron microscope (TEM) pictures of aerobic activated sludge, Fig. 4(b), show .the electron-dense poly Pinclusions as being present in a limited number of large balls, which are easily ripped out in the preparation of thin sections, whilst Fig. 4(c) shows the presence of a number of smaller inclusions. These bacteria are usually in coccoid form but also present in rod and chain form (Buchan, 1981); Lawson et al, 1980). Under anaerobic conditions and in the presence of RACOD, poly P appears to be partially hydrolysed and exported through the cell wall. Marais et al, (1983) have postulated that strict , aerobes such as Acinetobacter calcoaceticus are able to survive temporary anaerobiasis and under such conditions, also have the capability of absorbing, complexing and storing the lower fatty acids within the organism . The energy required for this process is obtained from the hydrolysis of the stored poly P chains, which results in the discharge of orthophosphate to the surrounding liquid. On entering the aerobic zone, organisms such as Acinetobacter can use the sequestered substrate for growth and for replenishment of the depleted poly P pool. In aerobic conditions, Acinetobacter, with its built-in source of food, does not have to compete for available substrate with other aerobes and in this way has a distinct advantage over other organisms. The enhanced growth capability of Acinetobacter spp is therefore highly dependent on the availability of suitable substrate in the anaerobic zone, which is of such composition that it will pass directly through the cytoplasmic membrane. Marias et al (1983) have further hypothesized that facultative aerobes entering the anaerobic zone, also make use of that portion of RACOD which WATER June, 1985

11


Figure 4. Electron microscope pictures of Acinetobacter spp (Bar = lµm) may be in the for m of sugars to obtain energy via fer menta tion pathways, producing lower fatty acids as byproducts. An importa nt sym biotic relationship mu st therefore be present to ensure excess phosphorus uptake by poly P accumulating organisms such as Acineto-

bacter. Support for this co ncept is provided by Brodisch (1984) who showed that adequate numbers of Acine/obacler were not a lways a guarantee for good phosphorus removal. However, when Aeromonas punctata which is ab le to produce acetate as one of its major fermentation end products, is present in large numbers, phosphorus removal increases dramati call y. C loete et al (1 984) fo und that Acinetobacter were present in numbers exceed ing 106 / cm ' throughout a ll zones of the Joh a nnesburg Northern Works, with higher numbers occurring in the aero bic zo ne . Relative numbers of Acinelobacler were fo und to be independent of whet her or not phosphate removal was being achieved. N umbers of Acinetobacter was estima ted using a fluorescent antibody technique, but were though t to never occur in sufficient numbers to be solely responsible for removing a ll the phosphorus present. Lotter ( I 984) in further support of the role of the a naerobic reactor as a fermentat ion basin, carried out assays on the sl ud ge drawn from t he a naero bi c zones of vario us Johannesburg Works and demon strated t hat the enzymes responsible for forma tion of th e lower molecular weight fatty acids were present. Plants achieving good phosphorus removal had activ iti es a n order of magnitude higher

th an those that were not. Gerber et al ( 1984) noted that Mg" and K' appeared to be li berated a long wit h phosphorus when the latter was released under a naerobic conditi o ns, but a lso made the interest ing observation t hat sulphat e co ncentrations increased in the anaerobic zone a nd appeared to be large ly reabsorbed in the anoxic zo ne.

5. FULL-SCALE PLANT EXPERIMENTS TO MODIFY INFLUENT SEWAGE COMPOSITION From the research work desc ribed above, it becomes ev ident that th e successful operatio n of biological nutrient removal plants is criticall y dependent on the amo unt and nature of the RACO D present in the influen t sewage. Modification of influent cha racterist ics has been adopted as a means of improving and stabili sing the performance of two Johannesburg Works.

5.1 Addition of Septic Sewage When tities of fac tory Works, remova l

septic sewage con ta ining large quanhigh-strength effl uent from a yeast was di verted to the Go udkoppi es a n improvement in phosphorus took place, as shown in Table I:

5.2 Addition of Acid Fermented Raw Sludge Raw sludge from the primary clarifiers a t the Northern Works was removed to a cold anaerobic diges ter operating in th e acid phase

TABLE I. EFFECT OF SEPTIC SEWAGE ADDITION ON EFFLUENT Q UALITY Goudkoppies Works

Arit hmetic mean• Stand ard deviation• Geometric mean•

Influent to reactor

No Sep tic Sewage Added o-P

N IN H

N I NO,

T-p

o- P

NIN H

N I NO ,

I. II 0. 72 0.93

0.89 0.74 0.48

1.33 2.1 0 0.13

4.51 2.94 2.9 1

0.66 0.42 0.58

0.36 0.35 0.27

0.39 0.97 0.01

1.60 2.16 0.54

COD

BOD

TK N

T -P

COD

BOD

TKN

T-P

340

170

39

5.9

600

260

38

7.3

• Approximate ly 1000 samples taken at 4 h intervals -

12

WATER June, /985

Septic Sewage Added

T-p

result s in mg/ L.

with a three day sludge age. A portion of the rou ghly settled contents was a dded to the anaerobic zone over a period of 4 h every day . The results as depicted in Fig. 5(b), from which it will be nqted that excellent removals of N and P (up to 16 mg P/ L) were obtained . H owever , with the la pse of time , volat ile fatty acid product ion started to fall off a nd the ex perim ent was d iscontinued. It is proposed to repea t the exper im ent using two a lt ernately fed batch diges ters which will be heated and operated a t a longer sludge age a nd complete ly emptied at each withdrawa l.

5.3 Recylcle of Primary Clarifier Sludge to Influent Sewage At the Northern Works, raw sludge has been a llowed to accumulate in the primary clarifiers from where it is parti a ll y recycled to the influent sewage. Aj the sa me time, a 400Jo hydra ulic overload was imposed on the tanks to encourage th e wash-out of biodegradable co ll oidal and particulate matter into the biological reactor. The results are depicted in Table 2:

6. DISCUSSION AND CONCLUSIONS (a) Thi s presentation, a nd so me of the points that follow, have been orientated around multi- stage nutrient removing processes. Kerd achi et al (l 983) have shown that similar anaerobic/ anox ic/ aerobic co nditions can be achieved in a single bas in plant in which mechani cal aerators ca n be switched on/ off in a predetermined pa ttern. Kerdachi et al (l 984) have also sugges ted that P released under anaerobic conditions is partially precipitated as a colloidal in so luble complex of Fe, Ca and PO,. (b) Fermentation products mu st be present in the influent or generated in the plant to ensure good P removal. (c) P erform a nce of p lants ex hibiting poor P removal can be improved by add ing fermentation products produced eith er by elutriation from raw sludge in primary


mg !e

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Figure 5 . Aci d sludge additi o n to the 5-stage Johannesb urg North ern Wo rks.

clari fie rs or by the anaerobic acid phase (i) Artifi cial modificati on of sewage comdigestion of raw sludge . Both procedures position appears to permit the plant designer to operate outs ide so me of the require to be optim ised . (d) T he prese nce of increased particulate matsuggested criteria offered by Marias et al ter from overloaded primary clari fiers ap( I 983) fo r good P removal. pears to improve nitrogen remova l in th e second anox ic zone. (e), An important , but as yet uncontrolla ble, REFERENCES relati onship appea rs to ex ist between ARV IN, E ., and KR ISTENSEN , G. H. ( 1984) . bacteri a using fer mentative pathways in Exchange of organics, phosphate and cations the anaerobic zo ne and aerob ic po ly P acbetween sludge and water in bio logical cumulat ing orga nisms that can ass imilate phosphorus and nitrogen removal processes. a nd store these products under a naerobic IAWPRC Seminar, Paris. condi tions. BA RNARD , J. L. (1 974). Cut P and N without (f) A ny operati ons likely to introduce elecchemicals. Water and Wastes Engineering, II, tro n accepto rs, e .g. oxyge n or ni trates in33-36. to the a naerobic zone are de leterious to P BARNARD, J. L. (1984). Activated primary tank s for phosphate removal. Water S.A., 10, (3), removal. 121-126. (g) Nuisa nce scums appea r to be associated BROD ISCH , K. E. U. ( 1983) . Interaction of difwith long sludge ages in nutrient remov ing fe rent groups of micro-organisms in biological activated slud ge sys tems and the use of removal. IAWPRC Seminar, Paris. a naerobic selectors to co nt rol high SVI's, BUCHAN, L. ( 198 1). T he locatio n and nat ure of require fur ther investigati on . acc umulated phosphorus in seven sludges from (h) T he tec hnique demonstrated by Cloete et ac ti vated sludge plant s which exhibited al (I 984) for the ident ificat ion and phosphorus removal. Water S.A., 7, (2), 54-60. CLOETE , T. E., STEYN, P. L., and BUCH AN , L. enum eration of speci fi c bacteria deserves (1984). An auto-ecological stud y of Acinetobacwider applicat ion and critica l eva lu ati on tor in act ivated sludge. IAW PRC Semi nar, as it may assist in defin ing th e exact Paris. mechanism o f P remova l. TA BLE 2 . EFFECT OF ELUTRI ATING FERMENTATION PRODUCTS FROM PRIMARY CLA RIFIERS Northern Wo rks

Feed

COD mgl L TK N mgl L NI NH, mgl L N I NO, mglL Total P mglL Ort ho P mglL

550 52 33 15 8.4

Anaerobic

Primary Anoxic

Primary Aerobic

Second Anoxic

Second Aerobic

Effluenr 81•

10 0. 1

5.8 0.3

1.7 4.9

4.4

1. 8 3.0

10

6.5

1.0

0.7

0.5

1.5

1.9 2.8 I.9• 0.4

• So lids car ryove r. Th e above result s reflec t average data obtai ned over a lim ited pe riod of several wee ks but substan tia te t he belier that th is sim ple modificat io n to no rma l ope ra ting procedures ca n bring about a co nsiderable improveme nt in nutrie nt removal. Prior to 1his innovatio n , effluent ort hophosp ha1e leve ls at thi s work s averaged 3.9 mg o-P/ L. Barnard (1984) ha s also demonstrated similar imp rovements to the Baviaanspoort Work s in Pretoria.

GERB ER, A., and W INTE R, C. T . (1 984) . T he in flue nce of extended anaerob ic retent ion ti me on the performance of Phorodex nutrient removal plants. IA WPRC Conference, Amsterdam. KE RDACHI, D . A ., and ROBERTS, M. R. (1983). Fu ll-scale phosphate re moval experiences in the Umhlatuzana Works at differe nt sludge ages. Wat. Sci. Tech., 15, 26 1-28 1. KERDACHI, D. A . and ROBERTS , M. R. (1984). Phosphate removal at Pinetown 's Umhlatuzana P lant. A cinetobacrer and ferrous ions in anaerobic zones. IAWPR Seminar, Paris, Poster Paper No. 9. LAWSON, E. N., and TON H AZY, N. E. (1980). Cha nges in morp hology and phos phate up take patterns of Acine,tobacter calcoaceticus. Water S.A., 6, (3), 105- 112. LOTTER, L. H . (1984). The role of bacterial phosphate metabolism in enhanced phosphorus removal from the activated sludge process. IAWPRC Seminar, Paris. MAR IAS, G . v. R., and EKAMA , G. A . ( 1976). T he activated sludge process, Part I , steady state behaviour. Water S.A., 2, (4), 163-200. MA RI AS, G . v. R., LOEWENTHAL , R. E., and SIEBR ITZ, I. P . ( 1983). Observat ions supporting phosphate re moval by biological excess uptake - A review. Wat. Sci. Tech., 15, 15-41. NICHOLLS, H . A . (1982). Applicat io n of the Marais-Ekama acti vated sludge model to large plants . Wat. Sci. Tech., 14, 58 1-597. SIEBR ITZ, I. P ., EKAMA, G. A. and MAR I AS, G. v. R. (1983). A parametric model for biological excess phosphorus removal. War. Sci. Tech., 15, 127-152. WATER RESEARCH COMM ISS ION (1984) . Theory, design and operation of nutrient remova l ac ti vated sludge processes. (Obtainable from the Water Research Commission, P .0 . Box 824, Pretoria, 000 I, Repub lic of South Africa.) WENTZEL , M . C., DOLD, P. L. , EKAMA, G. A . , and MARIAS, G. v. R. (1984) . Kinetics of biological phosphorus removal. IA WPRC Sem inar, Paris.

WATER June, /985

13


Ammonia Control and Effluent Polishing by Parrots Feather in an Aquatic Treatment System P. M. Nuttall, R. I. Kerr and J. D. Scholes SUMMARY The hydrophyte Parrot s Feather, cultivated as float ing mats in three flow-through wastewater treatment systems, was assessed for its ability to renovate secondary treated effluent. Efficient removal of ammonia-nitrogen (68%), total nitrogen (29%), suspended solids (65%) and biochemica l oxygen demand (44%) occurred over the three year study in an aerated , canopy covered lagoo n. Influent phytoplankton was also reduced by 98%. The main crop of plants was more important in providing substrate for bacterial nitrifiers than for nitrogen removal through uptake and harvesting. However, without harvesting there was a decline in the nitrogen uptake by the aquatic plants. Phytoplank ton removal, macro invertebrate bioconcentration and fi sh culture did not represent a permanent sink for nutrients.

P. M. Nuttall

R. I. Kerr

J. D. Scholes

aquatic plants

D

aquatic plants • aeration • bioweb

D

aquatic plants • aeration • bioweb • greenhouse

0

1. INTRODUCTION The cultivation and harvest of algae, aquatic plants and animals at wastewater treatment si tes has attracted increasing interest in recent years as a method of removing substantial quantities of macronutrients and generally upgrading water quality of effluents prior to di scharge to a watercourse. Although considerab le attention has been given to the development of this idea in other countries (Tourbier and Pierson, 1976; Serfling and Alsten, 1979; Duffer, 1982; Kawasaki et al, 1982; Hejkal et al, (1983) there have been few studies to assess the use of aquaculture for wastewater treatment under Australian condi tions. Mitchell (1978) and Finlayson and Mitchell (1982) have shown a potential for using aquatic plants to treat rural waste in Australia. Finlayson et al (1982) found that the exot ic hydrophyte, water fern grown in tanks was capable of removing various nitrogen compou nds from sewage effluent under a wide range of climatic condi tions. Other st udies have reported an ability of the emergent aquatic plants cumbungi, reed and clubrush to treat animal wastes (Finlayson, I 983; Fin layson and Chick, 1982) where nut rient remova l appeared to be the result of fi ltering and settling out of material rather than plant uptake. Smith et al (1983) showed that parrots feather growing in wastewater ponds resulted in a substa ntial reduction of effluent total nitrogen, even though much of the nitrogen loss cou ld not be accounted for in the harvested biomass.

2. PURPOSE AND SCOPE OF INVESTIGATION The followng paper presents the results of a three year st ud y cultivating the aquatic plant Myriophyllum aquaticum as flo ating mats in three different treatment systems to assess its abi lity to remove nitrogen compounds from seco ndary treated wastewater and generally improve effluent water quality. The effects of different treatment strategies on water quality we re measured and the potential of the treatment system to provide all -year round, consistent wastewater treatment considered. The importance of microflora and fauna in the system was also monitored, and the aquaculture of go ld en perch, carp and freshwater crayfish ca rried out in the discharg~ from the treatment system.

3. DESCRIPTION OF TREATMENT SYSTEM The project consisted of three, clay-lined lagoons each 100 m long, 7 m wide and 1 m deep (Fig . l) based on previous designs by Serfling Mr Peter Nuttall is Research Biologist with the Field Operations Section of the . Dandenong Valley Authority, Victoria. Mr Robert Kerr is Research Officer with the Environment Section of the Authonty. Mr John Scholes is Executive Engineer (Environmental and Scientific) Head of Environmental Section of the Authority.

Figure 1. Arrangement of the lagoons. and Alsten (1979). A continuous flow of secondary treated effluent from a 5 ha wastewater stabilisation pond (Dandenong-Springvale Water Board treatment plant) was regulated to eacfi of the lagoo ns (Table 1). The wastewater in the lagoons was gently mixed by curtains of bubb les released from air tubes placed transversely across the lagoons at 1. 2 m intervals and positioned 20 cm above the sediments. Air was supplied from a blower at a volume 'tif 0.75 cu. m/ min to each of the lagoons 2 and 3. Fluoroscein dye tests conducted on the lagoons during 1981 revealed actual retention periods of 44 h in lagoons 2 and 3 a nd 7 h in lagoon l. Reduced retention in lagoon l was probably the result of flow stratification in the absence of physical mixing. Artificial substrate for microbial attachment within the water column was provided by bioweb wh ich consisted of buoya nt , polypropylene fabric (Leno) attached to steel reinforcing mesh. Lengths of fabric (0.2 x 1.4 m) were folded and attached to the mesh at 0.2 m centres by means of netting fasteners. The mesh was laid in the lagoons over the airlines prior to filling with wastewater. Approximately 2000 m' of artificial subst rate were provided to each of lagoons 2 and 3. Each lagoon was innocu lated with pieces of the aquatic plant M . aquaticum at a density of 10 wet kg/ m' which grew rapidly to form a floating mat covering the surface of the lagoons. A double-skin, polythene canopy was mounted the length of lagoon 3 with the intention of reducing plant stress from winter frost and wind action (Fig . 2). The canopy was 100 m long, and 12 m wide with a 2 m head clearance on the side of lagoon 3 permitt ing access and work space. Co ntinuou s running , low-cost fans maintained turgor between the two polythene layers which was necessary to provide temperature insulation and strengthen the canopy in an exposed situation.

OPERA TING AND MONITORING During the period of study May 1981-October 1983, a number of changes were made to the air supply, flow rate and artificial bioweb in attempts to aid microbial nitrification and denitrification of infl uent WATER June, 1985

17


ammonia-n itrogen in the lagoons. These changes are listed in Table I. Weekly water samples were taken of t he influent to and discharge from each lagoon over the stud y period and when not analysed immediately were preserved by fr eezing. Analyses were normally ca rried out on unfiltered samp les for biochemical oxygen demand (5 day), suspended so lids, pH , disso lved oxgen and water temperature. Air temperatures (max-min) within the canopy over lagoon 3 were also co llected. P hytop lankton content of infl uent to and discharge from lagoon 3 was also monitored.

Figure 2. Section across lagoon 3.

Nutrient ana lyses of influent water to a nd discharges from the three lagoons for total Kjeldah l nitrogen, ammonia-n itrogen and nitratenitrogen was done accord ing to the method set out by Berg and Abd ull ah ( 1977). Harvesting of the float ing mat of plants in lagoon 3 took place twice by cutting alternative strips 4 m wide across the width of the lagoon and removing with a rake. The remaining alternate strips we re spread out to provide regrowth to the cleared sections . C ropping of patc hes of unhealth y plants took place in lagoons 2 and 3 on a regu lar basis during 1982-83 . P lant growth was mon itored from J une , 1981, until June, 1982, using 20 cm long cut pieces of actively growing tips of M. aquaticum transplanted to one metre square wire enclosures within each of th e TABLE 1: CHANGES TO THE WASTEWATER FLOW, AIR SUPPLY AND BIOWEB , 1981-82 Lagoon I

Lagoon 2

Lagoo n 3

May 81-Feb 82 Wastewater fl ow 5130 L/h No airlines Floating mac roph yte

May 81-June 82 Wastewater fl ow 5 130 L/h 80 airlines Air suppl y 0.75 cu.m / min Floating macrophyte

May 8 1-Nov 82 Wastewater fl ow 5130 L/h 84 airlines Air supp ly 0. 75 cu.m / min Floating macrop hyte

cover

cover

Artifi cial plastic bioweb

Artificial plastic bioweb Po lyt hene canopy

2 Dec 82-Sept 83 Wastewater flow 2565 L/h Air supp ly reduced to 0.65 cu.m/ min Floating black plastic cover to first third of lagoon

2 Dec 82-Apr 83 Wastewater flow changes to 2565 L/h , 3045 L/h , 4000 L/h a nd 5130 L/h

cover

2 Dec 82-Feb 83 Wastewater flow 2565 L/h Depth reduced to 0.6 m 4 Airlines put in to give 0.2 cu.m / mi n Floating b lack plastic cover to first third of lagoon 3 Mar 83-Sept 83 Furt her 6 airlines pu t in

18

WATER June, 1985

May 83-June 83 \Vastewater flow 5140 L/h 4 Jul 83-0ct 83 Wastewater fl ow 2565 L/ h Air suppl y to last 1/4 of lagoo n stopped

three lagoons (Fig . I) . An initial ba tch of 200 plants was put into each enclosure, fo llowed by batches of 100 plants in sy_pseq uent trials. Twenty plants were harvested at each samplin g date from each of the three enclosures, placed in plastic trays and returned to the lab oratory where attached algae and small anima ls were removed by washing with a ge ntle spray. Excess moisture was removed by draini ng, the plants weighed and oven dr ied at 95 °C for 36-48 hours and reweighed. The resulting dried materia l was ground to a fine powder and retained for subsequent n utr ient analys is according to the meth od set out by Berg a nd Abd ullah (1977). Performance of the bioweb was assessed by exam ination of test pieces of fabric mounted on I m long frame s and immersed in lagoons I, 2 and 3 for a period of 12 months (June 198 1- 1982). Initial observations within the first month fo llowed by a fina l observation at the end of the year were made of growths on fabric by micro-organ isms. Colonisation of the sediments by small animals was moni tored , ith fi ve metal trays (260 X 340 mm) containing coarse stone chippings placed at 20 cm intervals on the bed of lagoon 3 in O ctober , 1982. The trays were retrieved after 3 mbnt hs, retu rned to the laboratory and the animals counted and id entified. The washed ch ipp ings were returned to the trays and t he trays replaced in lagoon 3 for a furt her three repeat tria ls over the period January-September, 1983. Downstream dri ft is a behavioural phenomenon whereby small animals reposition themselves in running water by being carr ied in the current. Dai ly collections of drift were made from the influent to and di sc harge from lagoon 3 over a 3 mont h per iod in 1983 . Samples , ere returned to the laboratory fo r identification and counting. Fi nally, to determine whether fi sh and crayfi sh mi ght be cu ltured in the treated effluent and contribute to wastewater improvement, populations of golden perch (Macquaria ambigua), goldfish (Carassius aura/us) and yabb ies (Cherax distructor) were grown in separate ponds receiving the discharge from lagoon 3.

5. RESULTS 5.1 Lagoon influent and effluent water quality The ability of the three lagoons to treat influent wastewater is compared in Table 2. Over the study peri od, the aerated, canopy-covered lagoon was more efficient than the two other lagoons in removal of influent ammonia-n itrogen (67 .90Jo) , total nitrogen (28.8 0Jo ), suspended solids (650Jo ) and biochemical oxygen demand (44. 1OJo). Water temperatures of wastewater d ischa rged from lagoons I and 2 were up to 3°C lower than from lagoon 3. Max imum air temperatures within the canopy were on average l6 °C higher than o utside temperatures . Throughout the year, the reduction in percentage oxygen saturation was less in lagoon 3 (14.00Jo) t han in lagoons l and 2 (21.80Jo and 33.40Jo respectively). Nitrification took place in all lagoons, with a percentage conversion of ammonia-nitrogen of 5.3, 12.5 and 60 .3 in lagoons I , 2 and 3 respectively. During thi s period , infl uent pH to lagoon 3 was lowered from an average 7 .5 to 6.8 in the discharge, partly as a result of the release of hydrogen ions from the nitrification process , and to 7.2 in lagoons I and 2. Following plant harvesting in lagoon 3 and plant cropping in lagoons I and 2 there was an increase in the suspended solids and ammonia-nitrogen concentratio n in the effluent of th e lagoon from which plants had been removed .

5.2 Air change effect and oxygen consumption Following changes to t he air supply because of short-term interruptions for maintenance to the air hoses or alterations in the distribution of air to portions of the lagoons, th ere was a substantia l increase in the TKN concentration in t he effluent of the lagoon in wh ich air was red uced, and a sub stantial decrease in the TKN concentratio n when the supply of a ir was increased. The da il y amount of oxygen co nsumed per litre of flow through lagoo n 3 was calculated from analyses of BOD , d isso lved oxygen and nitrogen species. A smoothed plot against time using the technique of employing the preced ing and subsequent result of each point and plotting the median of the t hree is given in Fig . 3. It was calcu lated that the optimum flow rate in thi s treatment system wou ld be 3500 L/h wh ich wou ld utilize approximately 200 g oxygen/ day to full y nitrify the influent in just under three days.


5.3 Phytoplankton removal plant growth The mean total of phytoplankton units in influent samples over the period May 1981 - July 1983 was 5200 units/ mL. Twelve algal blooms over this period gave a mean total of 10 500 units/ mL with a maximum of 28 800 units/ mL, whereas the discharge from lagoon 3 for the same period was a mean 53 units/ mL. Mean percentage removal of phytoplankton by lagoon 3 over the study period was 98%. Phytoplankton removal in lagoo n 3 was probably effected by the restriction of light penetration to the wastewater caused by the mat of TABU. 2. EFFICIENCY OF THE THREE LAGOONS TO TREAT INFLUENT WASTEWATER 1981-83

(1, 2, 3, 4

= modes of operation)

Item

Lagoon I

Lagoon 2

Lagoon 3

Percentage nitrification of influent ammonia to nitrate

1 2 3

I 2

2

Percentage removal of influent suspended solids

P.ercentage removal of influent biochemical oxygen demand

Percentage reduction of influent saturated oxygen

Percentage removal of influent total nitrogen

'QI

a.

--o' _J

VI

E

CJ'\

E C

.Q +-

a. E

ii!C

80

7.0 18.0

4

33.0 80.0 54.0 74.0

1 2 3 4.

68.0 60.0 62.5 69.3 23 .8 75.6 12.5 69.3

I 2 3

- 5.3 5.9 47.9

2

30.4 26.1

2 3

14.3 26.7 47.0

2

14.2 60.0

I 2 3 4

2 3

48.4 19.4 - 2.4

2

14.3 23.8

23.8 2 - 40.5 3 2.3 4 - 31.0

2 3

6.4 23.0 34.0

I 2

10.0 27.0

2

11 .6 35.5

Percentage removal of influent ammonia

0 4.0 12.0

2

8.0 12.5 45.2

2 3 4

19.0 36.0 24.0 36.0

I 2 3 4

42.9 85 .0 62.4 81. I

floating plants and by the polythene canopy. The growth rate of aquatic plants was greater in th~canopy covered lagoon 3 during winter and spring (daily mean increase = 0.07 g dry wt per plant) than in the two outside lagoons. Plant growth rates were similar in the canopy covered lagoon 3 and lagoon 2 .luring sumn:ier (daily mean increase = 0.18 g dry wt per plant) . Plant growth rates were lowest in lagoon I throughout most of the study period. Also, analysis of test pieces of plants grown in wire enclosures showed that for each trial there was an overall increase with time in the mean percentage content of nitrogen of aquatic plants. Nutrient uptake ~y plants occurred with highest values of 0.21 g/m' nitrogen per day m lagoon I , 0.83 g/ m' in lagoon 2 and 0.54 g/ m' in lagoon 3. These results were obtained in summer samples from lagoon 2 and 3 ' and spring samples from lagoon I. This contrasted with analyses of plant material collected from the main crop of lagoon 3 harvested on two separate occasions during 1981. The mean daily nitrogen accumu lation by main crop plants was 0.20 g/ m 2 (May-July) and 0.27 g/ m' (Aug-Oct).

5.4 Colonisation of polypropylene fabric (bioweb) Accumulated populations of microscopic organisms and bacterial slimes on the bioweb were unstable and were easily dislodged with agitation of the water column. However, after 12 months immersion b!ological growths (aufwuch) had accumulated over test pieces of b10web m all three lagoons. the upper 30 cm of test pieces had been co lonised by green algae (Euglenophyta, Chlorophyta and Chrysophyta), zoo fl agellates, ciliates and sessile rotifers. Below this zone bacterial slimes, sulphur bacteria (Beggiatoa sp. and Thiothrix sp .) and fungi predominated. An underwater inspection of the bioweb throughout lagoons 2 and 3 found that accumulated material had caused much of the bioweb to sink. This was particularly the case in lagoon 2 where unharvested plant detritus had dropped down on to the fabric . This contrasted with aufwuch accumulation on the aquatic plants . During summer, particularly within lagoon 3, epiphytic and filamentous algae, bacteria and detritus on aquatic plant roots and stem was heavy enough to drag down and submerge aerial shoots .

5.5 Colonisation of trays and drift sampling Sediments in lagoon 3 supported large numbers of animals of few species. Macroinvertebrate benthos on the tray substrates were typical

R.T 1- 8 days flow 5100 litres/ hr. Air reduced in last quarter RT 3-.6 days flow Air stopped in 2565 litres / hr. last quarter All air to first half Air returned to last third

RT 3-1 days flow 3045 litres /hr. -r RT=2¡3 days flow 4000 litres /hr R.T=1-8 days flow 5130 litres/ hr. RT: 3-6 days flow 2565 litres/ hr. Air stopped last quarter Air returred to

r¡t quarter

0

u

C QI CJ'\ >, )(

0

1981

r

1982

30 mgms 02 consurred per litre per day

55 mgms O, per litre per day = complete nitrification

1983

~

40 mgms 0i per NHrN increase in litre per day

lagoon discharge denitrification trials

Figure 3. Daily oxygen consumption per litre of flow through lagoon 3. WATER June, 1985

19


mediately (Foree et al, 1971) with further, low-level release up to years of a fauna! community living under conditions of organic enrichment later. In this treatment system ph ytoplankton re~va l co ntributed and deposition. Twenty species were identifed from samples of which aquatic worms (Oligochaeta), fly larvae (Chironomidae) and leeches littl e, if any, to nitrogen remo va l occurring in lagoon 3. Macroinvertebrate bioconcentration of nutrients and insect emer(Erpobdellidae) were dominant groups in excess of 2000 in- . dividual/ m'. Changes in the spatial distribution of species composigence from aquatic larvae carrying contaminants out of the system did not contr ibute substant ially to the treatment efficiency. Fly larvae and tion and abundance occurred a long the length of lagoon 3. Species diversity increased from O (inlet) to 9 (outlet) in lagoon 3. aquatic worms probably co ntribut ed to oxygen depletion through bioturbation. This, with the decomposition of plant detritus, Influent invertebrate drift differed from drift coll ected from the phytoplankton and zooplankton, and the biochemical oxygen demand lagoon 3 discharge. High numbers of zooplankton (Cladocera and of influent wastewater competed with microbial nitrifiers for available Copepoda), fly larvae and pupae (Chironomidae) and mosquito laroxygen. vae dominated influent drift , but were absent in the discharge from lagoon 3. Damselfy larvae (lschnura heterosticta), water boatman (Notonectidae and Corixidae), aquatic worms (Oligochaeta) and adu lt CONCLUSIONS aquatic beetles (Dytiscidae) dominated drift from lagoon 3. The aerated, canopy-covered lagoon with a cover of the flo a ting hydrop hyte parrots feather substa ntiall y reduced ammon ia-nitrogen 5.6 Aquaculture of fish and crayfish concentrations (68%) and removed total nitroge n concentrations (29%) over a period of three years. Effluent phytoplankton content, Low numbers of fish survived. 4% of golden perch (Macquaria amSS levels and BOD were also substantially reduced. bigua) and 53% of goldfish (Carassius aura/us) su rvived over the Regular harvest ing of the aquatic plants was not req uired to ensure study period. Most fi sh mort a lities occurred within 3-4 weeks of efficient am mo nia-nitrogen removal. Harvesting was necessary to stocking and were probably due to handling stress (Hume-pers. commaintain the vigo ur of the aquatic plants a nd obtain useful munication). Freshwater crayfish (Cherax destructor) survived and macronutrient assimilat ion and removal, although plant harvesting bred up to 4 generations in the final effluent. was offset by less nitrification of influent ammonia-nitrogen . A lthough some differences were recorded in water quality between A canopy cover to th e lagoon was useful in promoting plant growt h ¡ the discharge from lagoon 3 and from the aq uaculture ponds, the difand nutrient assimilation during winter a nd spring. ferences were more likely a result of denitrification and ponding rather than bioconcentration of contaminants by fish. ACKNOWLEDGEMENTS

6. DISCUSSION The Dandenong-Springvale Water Board treatment plant discharges 38 ML/ day secondary treated effluent containing and average 30 mg/ L ammonia-nitrogen a nd 50 mg/ L total nitrogen. Over the three yea r stud y, the canopy-covered lagoon 3 was the most efficient at removing total nitrogen (28.8%) and in the conversion of ammonia-nitrogen (67 .9%). The optimum influent flow rate for lagoon efficiency was found to be 3500 L/ h. This represented a removal rate of 1.2 kg total nitgroge n per day and co nvers ion rate of 1.7 kg ammonia-nitrogen per day. To obtain 90% removal of total nitrogen from the treatment plant effl uent, 1583 canopy-covered ponds with a total surface area of 110 ha would be required. Simi larly, for the conversion of ammonianitrogen, 47 ha wo uld be required. This necessarily implies all-year round, con sistent removal abi lity by t he lagoons. Where sufficient oxygen was available and where nitrifying bacteria were present in the system, ammonia-nitrogen converted to nitrite and nitrate by microb ia l nitrification. Following increased retention in lagoon 3, microbial conversion of influent ammonia-nitrogen reached 98%, while total nitrogen removal lay in the range 4-46%. Submerged parts of the aquatic plant M. aquaticum acted as a substrate to microbial growth important in the nitrification of influent ammonia-nitrogen. Co ncurrent studies on the lagoons by Hobson (1982) found that populations capab le of nitrifying were present within the lagoons in sufficient numbers but with a particularly active population present on the aquatic plant roots. Foll owing plant harvesti ng in lagoon 3 and plant cropping in lagoon s I and 2 there was an increase in the suspend ed so lid s, total nitrogen and ammo nia-nitrogen concentration in lagoon effluents. This was probably a result of decreased microbial activity caused by the removal of nitrifiers with the harvested plants and dislodgement of aufwuch into the e ffluent. . Nutrient uptake by the main crop of p lants did not co ntribute to substa nti a l nitrogen removal in the lagoons. Analyses of harvested plant material indicated that the macronutrients had not been efficiently assimilated by the aquatic plants, perhaps because of the long interval between harvest in g dates, but a lso beca use of the initia l planting density of 10 wet kg/ m'. Nevertheless, growth trials and nutrient analysis of cut pieces of M. aquaticum within the lagoons indicated that a harvesting regime in which half of the main crop was removed every 16 days would give a mean dai ly removal rate of 0.8 5 g/ m' nitrogen. This would be offset by reduced nitrification following plant harvesting. The reduction of influent phytoplankton did not represent a permanent sink for nitrogen . Ruptured algae ca n release up to 40% of accumulated macronutrients back into th e water co lumn a lmost im 20 WATER June, 1985

The aut hors wish to thank P. Condina, G. Mortimer, S. Seymour, R . Stan nells and R. Step henson of the Dandenong Valley Authority, for their assistance throughout the study. Funding was provided by the Australian Water Resources Council (project number 80/ 139) and the Springva le a nd Noble Park Sewerage Authority, the Dandenong Sewerage Authority and the Dandenong Vall ey Authority.

REFERENCES Berg, B. R. and ABDULLAH, M. I. (1977). An automatic method for the determination of ammonia in seawater. Water Res. 2, 637-638 . DUFFER, W. R. (1982). Assessment of aquaculture for reclamation of wastewater. ln 'Water Reuse' ed. E. J. Middlebrooks Ann. Abor. Scien ce Publ. Inc. ' FINLAYSON, C. M . (1983). Use of aquatic plants to treat wastewater in irrigation areas of Australia. Proc. Tenth Fed. Conv. A WWA, Sydney, pp . 25/ 1-10. FINLAYSON, C. M. and CHI CK, A. J. (198j). Testing the potential of aquatic plants to treat abattoir effluent. Water Res. 17, 415-422. FINLAYSON, C. M., FARRELL, T. P. and GR lFFlTHS, D. J. (1982). Treatment of sewage effluent using the water fern salvin ia. Technical Report No. 37, Water Res. Foundation Australia. FINLAYSON, C. M. and MITCHELL, D. S. (1982). Treatment of rural wastewaters in .Australia with aquatic plants. Der Tropenlandwirt. 83 Oct. D, 155- 165. FOREE, E. G., JEWELL, W. J. and McCARTHY, P. L. (1971) . The extent of nitrogen and phosphorus regeneration from decomposing algae. ln 'Advances in Water Pollution Research 3', 1-27. Pergamon Press . HEJKAL, T. W., GERBA, C. P., HENDERSON , S. and FREEZE, M. (1983). Bacteriological, virological and chemical evaluation of a wastewateraquaculture system. Water Res. 17, 1749-1755. HOBSON, M. J. (1982). A study of nitrification and denitrification in lagoons receiving treated effluent. B.S. Hons. Thesis, School of Microbiology, Univ. Melbourne, pp. 48. KAWASAK I, L. Y., TARIFENO-S ILVA, E., TU, 0. P., GORDON, M. S. and CHAPMAN, D. J . ( 1982). Aquacu ltural approaches to recycling of dissolved nutrients in secondarily treated domestic wastewaters - I. Nutrient uptake and release by artificial food chains. Water Res. 16, 37-50. MITCHELL, 0. S. (1978). The potential for wastewater treatment by aquatic plants in Australia. Water 5, Sept. 15- 17. SERFLING, S. A. and ALSTEN, C. (1979). An int egrated, contro lled environment aquaculture lagoon process for secondary or advanced wastewater treatment. In 'Performance and Upgrading of Wastewater Stabilisation Ponds' ed . E. J . Middlebrooks, U.S. Environ. Protec. Agency 600/a/79-011, pp . 124-145. SMITH, N. A., JANSSEN , J . and RIPP INGALE, R. J. (1983). Tertiary Treatment of wastewater using aquatic plants. Proc. Tenth Fed. Conv. A WWA, Sydney, pp. 27/ 1-9. TOURBIER, J . and PIERSON, R. W. (1976) . 'Biologica l Control of Water Pollution'. Philadelphia, Univ. Penn. Press.

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CONVENTION '85-- MELBOURNE THE CONVENTION This co nvention was an inn ovation in combining the Associations Biennial Confere nce, ou r Eleventh Convention, with international sponsorship through the Water Pollution Control Federation - our First In ternationa l Co nven ti on. Whilst the joint title can sound cumbersome, it marks a most significant step in the developing story of the A WW A . The Convention timing, April/ May, placed it well and truly in the so uthern autumn, normally a settled weather period in Melbourne, that city of much maligned climate came nobly to the party with a full compliment of glorious autumn days showing the city and surroundings at their very .best. . Luncheon arrangements inv olved a short walk from the venue, the Hilton Hotel through the adjacent gardens to a spacious marquee , inviting full appreciation of the weather and th ankfuln ess th at it was so benign . Total registration was approximately 350 with over 70 'accompanying perso ns' [your Editor is contemplating a competition for a more pleasing phrase]. Day Registrants totalled 110 with some 50 guests. The restistration included 70 from overseas representing 14 countries - a component which fell a little short of numeri cal anticipation s but made up for this in quality and provided a truly international flavour. The pattern of the week-long Convention was that now well establ ished by tradition ; an informal gathering on the Sunday, always one of the most enjoyable social aspects, the official ' Opening' and Keynote Addresses to start the ball rolling on the Monday , a programme of some 78 papers during the week - a heavy programme in two streams, a State reception , an International Night, social a nd technical tours, the Convention Dinner on the Thursday night which introduced the second innovation of th e occasion and the final Closure with its heartfelt recognition of the efforts of so many people and its touches of nostalgia. The Hilton provided excellent facilitie s a nd coped well with the peak-load problems presented by thi s type of gathering. The separate location of luncheon activities was of cons iderable assistance in avoiding the trauma of change-over of lecture accom modation for 4 or 500 to eati ng faciliti es in the sa me area . The manufacturers di splay with 26 exhibitors was excellent if a little cramped, and provid ed on-the-spot in forma tion and displays of a wide range of equ ipm ent and processes. As participation increases , and it should, the provision of adequate space for displays in near and convenient vicinity to the lecture theatres is go ing to prese nt problems in future venues. The Keynote Speakers, Harry Tow (USA) and Hugh Fish (UK) provided an international touch on the opening day. The third

Keynote Speaker, Keith Lewis from South Australia provided an intern ationa l touch in reverse, Governmental matters took him out of th e country and hi s paper was most ably delivered by John Shepherd of South Australia. The invited speakers, by their presence emphasised the international aspect of thi s Co nvention - Messrs. Y. Murayama (Japa n), K. J . Miller (USA) , D . W. Osborn (South Africa) and N. W . Schmidtk e (USA) all made a much appreciated contribution to th e technical prese ntations . All Co nventions reflect the enthusiasm and sheer ha rd work of a large number of people, members a nd wives, toget her with great input and support of ogranisations in the industry, departmental and private. The fo cal point of activity is the Organising Chairman and Co nvention Com mittee. To Chas Wilkes and Glad and to Wayne Drew, Sam Rogerso n, Brian Bolto, Bill Dulfer, Keith Levey, John Parker, Jon athan Crockett, Peter Nadebaum, Robin Povey, Tony Bellair, Bob Turney and their wives, congratulations and sincere thank s from the Association as expressed by President Robert Lloyd at th e Closure .

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SPONSORS AND SUPPORT AN APPRECIATION The Association is fort unate in having continuing support from Governmenta l so urces and private indu stry in the day to day co nduct of its affairs . This is ma nifested in Sustaining Membersh ip which is apparent and obvious to members but also in many other ways not so obvious. In the admini stration of A WW A, staff support and provision of faci lities by the Sydney and Melbourne Boards are a major factor. Wh en Conventions and major meetings are staged, then the contributions and support of Departments a nd Authorities in the 'home' city are subject to heavy demand s and are vital to the ventures. Financial sponsorship is also a major factor, Conve ntion s dem a nd considerable funding beyond registration fees and here again, Governmental ass istance both Federal and State, contributions by Aut horit ies and from private industry are essential to the viabi lity and hen ce to the continu ance of such activities. During the co urse of Convention '85, President Bob Lloyd and C hairman Chas Wilkes expressed the appreciation of th e Associa tion for the support received and sponsors are acknow ledged and listed after these com ments . Special mention must be made of the generous co-operation of the Melbourne and Metropolitan Board of Works for the tours of its operations and the accompanying most liberal hospitality, for

the services of so many staff involved, for the photographic coverage and finall y but not least, for the floral displays for th e International Night and the Convention Dinner . The Manufacturers Exhibi tion is an important and va luable co mponent of our Conventions a nd complete coverage follows later in this iss ue. The cost in time, effort and cash in mountin g di splays is fully realised and is appreciated.

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SPONSORS Victorian Government Department of Water Resources, Victoria Melbourne & Metropolitan Board of Works Metropolitan Water Sewerage & Drainage Board , Sydney Australian Development Assistance Bureau Hunter Dist rict Water Board Rural Water Comm iss ion of Victoria Wormald Engineering Pty. Ltd. Engin eering & Water Supply Department , South Australia Dandenong Valley Authority Hawker Siddeley Engineer ing Pty. Ltd. Geelong & Dist rict Water Board Metropolitan Water Authority, Perth Victoria's 150th Ann ive rsa ry Committee Albright & Wil son (Australia) Ltd. Austra li an Chemi cal Spec ialities Manufacturers' Association Australian Paper Manufacturers Ltd . Camp Scott Furphy Pty. Ltd. Gutteridge H as kins & Davey Pt y. Ltd. Humes Ltd. N.E.l. J oh n Thompson (Australia) Permuti t Company~f Australi a Pty. Ltd . Qantas Airways Trans Australian Airways (T AA) Sinclair Knight & Partners Pty . Ltd. Si mmon as & Bristow Pt y. Ltd. The East Melbourne La boratories Pty. Ltd . Dandenong Sewerage Auth ority Sharples-Stokes Tioxide Australia Pty. Ltd.

PAPERS Careful attention to the a udio-visual aspect of paper presentation avoided the pitfalls and fru strations of poor sound and the proj ection of diagra ms and ta bles unsuited to lecture theatre delivery . The format a nd presentation of papers for th e Co nvention were speci fied in detail and the length prescribed with th e objective of ensuring that the presentation sess ions could run to time and the proceedings cou ld be prepublished and printed in such form and volume as to be conve nient for handling and for reference during prese ntation. The Proceedings, in one volume are avai lable, from Hon . Sec ., AWWA, PO Box 409, Werribee, Victoria 3030 . Price A$25 with in Austral ia, plus postage elsew here. WAT ER Jun e, 1985

21


CONVENTION ... 1985 ... MELBOURNE

OPENING Some 550 delegates and visitors were present for the official opening of the Convention on Monday April 29th to hear the welcome by A WW A President Bob Lloyd and the opening address by His Excellency the Governor General of Australia, Sir Ninian Stephen, Patron of the Association followed by the Keynote Addresses.

Brothers who initiated large scale irrigation in the Mildura area. He traversed the problems and success of the venture and the presen t day legacies of rising ground water tables and salination.

USA to China to South Africa and the UK, offering as it does, exchange of views on a world-wide basis. In these days, when the media carries more bad news than good, it is pleasing to have a successful Convention which is in the latter category with its messages of effective work in the sphere of public health and of reducing service costs. He concluded with appreciation of His Excellency's pride in his office and of his attendance and opening of the Convention.

A WW A PRESIDENT

KEYNOTE ADDRESSES HARRY A. TOW 'Global Challenges in Water Pollution Control

In his opening remarks, Bob Lloyd explained the multi-disciplinary nature of the Association and the international nature of Convention '85 through partnership with the Washington-based Water Pollution Control Federation. He welcomed members of the WPCF and other kindred Associations with special mention of Harry and Shirley Tow with Bob Canham from WPCF and Hugh and Nancy Fish from UK and expressed appreciation of the work of the Convention Committee and the many who contributed to the staging of the Convention. Emphasizing in this dry continent of ours , the precious nature of our water resources, he then turned to the value of those who dedicated themselves to the water industry, the water engineers and scientists and their contribution to the community. President Lloyd warmly welcomed His Excellency Sir Ninian Stephen and Lady Stephen, expressing the appreciation of the Association in Sir Ninian's acceptance of the role of Patron and of his presence to perform the official opening.

HIS EXCELLENCY THE GOVERNOR GENERAL Sir Ninian warmly welcomed the overseas delegates to the Convention and drew a parallel between the visits now of experts from the USA and the actions of Alfred Deakin in the 1880s in visiting the United States and attracting to Australia the Chaffey 22

WATER June, 1985

In commenting upon the uneven distribution of rainfall over the continent, Sir Ninian spoke of the growing costs of expansion of water supplies and the moves now to better utilisat ion with greater efficiency and of altered approaches to management in the in dustry and of the poss ibilities or recirculation. He concluded with reference to the appalling droughts now ravaging parts of Africa and the emphasi's they give to dependance upon water supply and to the interchange of knowledge resulting from internationa l meetings .

Harry Tow is a Civil Engineer and is President of the Water Pollution Control Federation. He has been involved in the public and private sectors of the industry since I 948 and has been associated with the Federation sphere since I 950.

ORGANISING CHAIRMAN

C Chas Wilkes thanked Sir Ninian for hi s attendance at the Convention and for his address and particularly for his comment as to the contribution of the water industry to the community. He summari zed the international attendance at this Convention, some 60 delegates and wives from 14 countries ranging from

Opening hi s talk with references to 'transboundary' pollution problems, acid rain in Canada and elsewhere, eutrophication in lake systems and pollution in the Mediterranean he developed the themes of national regulatory problems, the technical knowledge necess ry for control and the role of pollution control associations. He outlined the comprehensive pollution con trol legislation of 1972 in the USA and drew comparisons with the action in the UK which mo ved in the opposite direction with decentralisation on a drainage basin basis with integration of water supply and effluent control. A further contrast is offered by Germany with supply and pollution control decentralised with self governing management associations. Global interchange of knowledge is essential, both pollution and technical information


CONVENTION know no boundaries. H arry Tow illustrated this by contrasting th e move to land trea tment of efflu ents in the USA with the adopti on of centralised biological treatment in South America. He concluded with the comment that the activities of Governments in thi s area of interchange must be a ugmented by the private professional organisations such as A WW A and th e WPCF.

KEITH L. LEWIS Dominant Issues Facing The Water Industry in Australia Keith Lewis is a Civil Engineer and is Engineer-in-Chief of th.e Engineering and Water Suppl y Department , South Australia. · Due to hi s absence overseas, his paper was most ably presented by John Shepherd who is Director o f Technical Services, of Keith Lewis' Department.

• • •

1985 ... MELBOURNE.

Western Austra li a with dry land salinit y and in the Murray-Darling system with its repercussions in South Australia . Asset deterioration is a major factor world wide and requires not only a replacement policy but also rehabili tation . Research and technology in the industry has lagged a nd th e cryin g need for multi-s tate centralised or coordinated approach has failed through lack of State Governmental support. Cost recovery a nd changing systems to ac hi eve such is essential if the industry is to achieve and retain viability and the public must be made aware of the real costs of services and ed ucated to accept such . T he spea ker terminated with the conclusions of the paper, in bri ef: • Erosio n of recognition of achievement s of the industry • First steps to redressing the situation are in hand through current cha nges • Hopefull y, the industry has learned that decisions do and must involve the community • Awareness of th e foregoing, transla ted into action will restore the support for and status of the industry as custodi an o f Au strali a's most important reso urce .

HUGH FISH Managing the Thames River Basin

Mr. Fish concluded his very rapid traverse of some of the high-poi nts of his paper with comment on the Governmental direction of increased water charges and the resulting nomina l profit of some 61 million pounds profit in the Governmental book-keeping sense, qu es tionable in the busin ess sense .

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MANUFACTURERS' EXHIBITION OPENI G THE MINISTER Manufacturers and equipment suppliers mounted 28 di splays for Water Tech. '85 in close and conveni ent proximity to th e lecture theatres . In opening the Exhibition , th e Victorian Minister fo r Water Resources, Andrew McCutcheon M.L.A. stressed the significance of the Convention and the great value of the exhibition in providing a showcase for the industry. Mr. Mccutcheon emphasised the changes confronting water industry management today, greater public awareness, the increased impact of social and economi c costs and shift in concentration from co nst ruction to maintenance and operation. He concluded by pointing out that effective use of tec hn ology is a first essential and the importa nce in this area, of information exchange and availability, a function admirably served by the Manufacturer's Exhibition.

MIKE DUREAU RES-PONDS The highlights of the presentation are summarised as follo ws: There is a changing managemen t scene in the water industry which is, as a result , undergoing 'cultural shock ' . These changes includ e vas tly different approaches to manage ment and organisation in most Authorities which can no longer fun ction il1 isolation from the community. This is accompanied by some concern as to detrimental effect on technical, scientifi c and operational expertise . The ' Water 2000' report identified eight major iss ues co nfronting the water indust ry a nd one overall conclusion is that little fur ther Federal financial assistan ce can be expected a nd that direct charging must be directed to cost recovery. The challenges facing the industry were enumerated as: integr.ated resource planning and managem ent, water quality, deterioration of assets, research and technology, cost recovery. After touching on the problems of water quality a nd small communities, John Shepherd turned to salinity as a dominant wate r quality problem and experience in

Hugh Fish from the UK, is Chairman of the National Environment Research Council , Member of the Thames Water Authority and Pres iden t of the Institution of Water E ngineers and Scientists. With mu ch reduced tim e for the presentation of hi s paper and by accomplished use of th e proj ecto r he gave an interesting and enterta ining coverage of the integrated Thames River Bas in management. With a quick historical sca nning from the time of Magna Carta he presented the 1974 creation of 10 regional water authorities for England and Wales. With a desc ription then of the Thames area he moved to th e management structure of 1984, commen ting on board changes, decent rali sing of control and showed the present areas of Operating Di visions.

In respo nding to th e Minister's comments on behalf of the Manufacturers, Mike Dureau, Man aging Director of Kent Instrum ents and al so Vice-President of A WW A, thanked Mr. McCutcheon for giving hi s time in the middle of a heavy Parliamentary session. He pointed out that the success of trade exhibitions can only be judged from the interes t of visitors to the displays and that such is esse ntial to co ntinued support by manufacturers. He concluded with an appeal to delegates to make full use of the opportunities provided by the displays and the attendant personnel.

A BREAK IN THIS DESCRIPTION FOR SOME PHOTOGRAPHIC COVERAGE. WATER Jun e, 1985

23


INTERNATIONAL CONVENTION 1985 Peter Casse ll (NSW) , Bertha Lang (USA), Donna Povey (Vic).

Hugh Fish (UK) , Graeme Legatt (NZ) , Nancy Fish (UK) .

'

l John Carter (NSW) , Don Walters (Tas). Mickie Bishop (Vic) , Coral Orliff (Hong Kong).

\

Jill Bo Ito (Vic) , Alan H o ward (Vic) , J eanne Horgan (Ca nada).

Ron Freyling (NT) , Veronica Gard ner (S Aust) , Tony Gardner (S Aust).

PRE-CONVENTION GATHERING AT THE HILTON Bill Dulfer (Vic) , S ue Parker (Vic), Jim Greer (Vic).

Lyn and Don Montgomery (WA) .

J

Lai Cheng Cheong (Malaysia) , Wayne Drew (Vic) , Frank Bishop (Vic). Ke n Miller (USA) , Norbert Schmidtke (USA) , Alan Strom (Vic) .

·I David Philp (ACT) , J une O 'Connell (Qld) , Bernie O 'Conne ll (Qld).

Julie lvison (Qld) , Jeanette Williams (Qld) , Glad J ames (S Africa) , Ruth Bristow (Qld).


THE CONVENTION DINNER PROFESSORIAL ADDRESS BY 'SIR GARNET ACKROYD' (Alias Campbell McComas) AND AUDIENCE REACTION

lei

AYI.W.A. 1985 Inrernataanal TWO OF THE MANY PRESENTATIONS To Peter Hugh es for the M.W .S . & D.Bd . Sydn ey

To Christin e Forster fo r th e Rural Water Commission Victoria

A STROLL AROUND THE TABLES


CONVENTION '85 - MISCELIA~

INTERNATIONAL NIGHT - THE GREAT HALL, NATIONAL GALLERY LUNCHING AND CLOSURE - IN THE MARQUEE

t

Chairman Chas Wilkes thanks one of the many helpers . President Bob Lloyd superintends .


CONVENTION • • • 1985 ... MELBOURN-E

TECHNICAL SESSIONS Papers and addresses totalled nearly 80 and in conjunction with works hop sess ion s and technical tours constituted a formidable but enjoyable technical programme. Papers are grouped in the Proceedings under the headings: Theme A - Management and operations Theme B - Water treatment Theme C - Wastewater treatment Theme D - Water pollution problems Workshop sess ions covered three activities: - Activated sludge - Anaerobic treatment - Water quality and health Attendance at the sessions was good and sustained, organisation and cond uct was smooth and the audio and visual aids worked well and without significant problems. Carefu l specification and control of paper submission kept volume within acceptab le limi ts and permitted production of the Proceedings in one, easi ly handled, volume. Proceedings are avai lab le from the AWWA Victorian Branch Secretary, P.O. Box 409, Werribee, Victoria 3030. Price is $25, surface mail, to all places within Austra li a. Overseas, mail costs will be extra.

left the A WW A party free to admire the architecture of Queens Hall, to see something of the two Chambers and genera ll y browse around. A few parliamentarians were in evidence and their presence was appreciated. The evening was most pleasant and somewhat unexpected and provided an unu sual touch for visitors and also for many of the locals.

INTERNATIONAL NIGHT

SOCIAL ACTIVITIES

In the dignified and most impressive setting of the Great Hall of the National Ga llery, with the beautiful French roofing overhead, a gathering of so me 250 enjoyed a leisurely dinner, music, dancing and conversation (when music permitted). The ' International' aspect, primari ly fo r the benefit of the overseas contingent was provided by a small troup of aborigines who performed a number of traditional dances with the didgeridoo much in evidence . Eventually the present day equivalent of tribal dancing took over the floor (no didge ridoo) with some slight differences in the choreography. A pleasant night and, again, a lack of formalities unless one so characterises the piper who strode the stone floor as an acco mpaniment to cocktails. Your Editor enjoys the pipes but did wonder later whether this, as a preamble to the didgeridoo, was accidental or premeditated.

PRE-CONVENTION GATHERING

CONVENTION DINNER

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As a warming-up for the Convention proper, delegates, wives and visitors gathered for an inform al session at the Hilton on the Sunday even ing. Some 250 renewed old acquaintances, found out - sometimes sad ly - what the co uple of years since the last convention had done, welcomed new contacts and missed some of the older . This pre-convention drink and natter session is perhaps one of the most enjoyable social touches of the programmj: - wisely, no speec hes - entirely informal - a completely relaxed get together of old and new friends. It can st rike the note or set the tone fo r the quite strenuous week to fo llow and has much to commend it. Photos in this Conve ntion Report provide something of a record.

STATE RECEPTION On Monday night, the Victorian Government graciously favo ured the event with a State Reception at the dignified Houses of Parliament and some 500 delegates and others enjoyed the hospitality by co urtesy of the Premier and the good offices of the Minister for Water Supply, Andrew McCutcheon, MLA. A brief speech of welcome by the Minister and suitable response by president Bob Lloyd

A PROFESSIONAL PROFESSORIAL ADDRESS Our dinners have their establi shed pattern - the formalitie s of the official party arriva l and their introduction by the President - inroads into the meal, then, at a suitable stage, the introduction of the 'after-dinner' speaker, carefu lly selected to be informative and, hopefully, entertaining and finally, well meritted awards and presentation s. All went nicely to plan, Sam Rogerson neatly introduced Professo r Garnet Ackroyd, late Dean of En~ineering at Durham, UK, a nd then the proceedings - and the audience - fell apart (see pictures later). Sir Garnet embarked upon a rapid-fire delivery of humour with comment upon the A WW A, its functions , its guests and its kindred associations, with great impartiality . A few of the highli ghts, paraphrased a little: Of Hugh Fish of the Thames Authority and Water Resea rch Ce ntre: ' .. . weighed down with hi s barge-load of responsibilities for aq uatic affairs, he tends to have jurisdiction as much under the water as over it ... he actually lives there . . . In 1983 the Centre won an award for sacking its Counci l and replacing it with a computer ... nothing has had a bigger impact on operating efficiency

so, we're planning a return to the old system of having nothing .. . ! ' Re Harry Tow and Bob Can ham of the WPCF, visiting again ' . . . distinguished members of the 'World Professional Conference-goers Fraternity'. For the Minister of Water Supply and apropos of the drast ic reduction of water and sewerage Boards in Victoria: ' . . . the move, not forseen by the Boards, was forseen by Coleridge with the ageless stanza of the Ancient Mariner ' Water, water, everywhere,/ And all the boards did shr in k', and further, re the cuts, the Profess r suggested the Government may have had in mind Rupert Brooke 's lines ... 'O ne may not doubt that somehow, good/ sha ll come out of water and of mud ;/ And, sure, the reverent eye mu st see/ A Purpose in Liquidity'. Sam Roge rson followed up, informing th e sli ght ly hilariou s audience that the Pro fesso r, sans disgui se, was that well known com ic speechmaker, Campbe ll Mccomas in his 539t h character ro le. After a suitable response, President Bob restored events to normal with the presentation of plaques to represe ntatives of the major sponso rs: State Government & Water Reso urces Department - The Minister, Andrew McCutcheon. Melbourne & Metropolitan Board of Works - Ray Marginson. Rural Water Comm ission Christine Forster. Metropolitan Water, Sewerage & Drai nage Board, Sydney - Peter Hughes . Hunter District Water Board - All an McLachlan. Australian Industrial Assistance Bureau . Mementos of the occas ion were presented to the Keynote SJ)eakers and the in vited speakers and Certificates marking the award of Life Membership to Doug Long of South Australia and Jim Greer of Melbourne . The final presentation was by Harry Tow, USA to Alan Pettigrew, per son Malcolm for meritorious service to the WPCF.

CLOSURE The marquee and a balmy day provided a pleasing sett ing for final stage of Convention '85 with its express ion of appreciation and recognition of some of the contribution by so many. Chas Wilkes Organising Chairman struggled against fa iling vocal chord s to thank the members of the Ogranising Committee and the Ladies Committee for their good work and acknow ledged the generous assistance of the Melbourne Board , of Kents and the Atkinson and Hilton organisations . Bob Lloyd then announced the Michael Flynn Award winners, Mess rs Osborn and Nicholls from South Africa and thanked Authors and Chairmen for their cont ributions. Michael Dureau wound up the proceedings wit h enthusiastica ll y supported thanks to Chas and Glad Wilkes for their great efforts WATER June, /985

27


CONVENTION • • • 1985 ... MELBOURNE in lead ing the o rganisat ion of this very successfu l convention and made a suitable presentation to mark the occasion.

SOCIAL TOURS . On the T uesday, 60 odd gat hered at the Hilton for tea and talk on tapestry as a preliminary to an Art Gallery vi sit to Heide for a Sydney No lan Display and an amble around the grounds, finally driving through some of the attract ive suburbs to Rippon Lea, the beaut ifu l 1868 home bui lt for Sir Frederick Hargood. Drinks and savo uri es by the lake were fo llo wed by an excellent lunch indoors and a conducted tour of the fascinating old bui lding. Wednesday offered considerable variety. Some 20 vis itors to Ballarat and a ret urn to th e ea rl y days with a call at Eureka Stocade then a tour of the reconstructed mining vi ll age of Sovereign Hill. Shopping, gold panning, lunch with representatives of the Water Board, the Gold Museum then home - a good day . A slight admixture of the technical was prov ided by a tour which ca ll ed first at the Werribee Treatment Farm with nearly dire results - very thick fog in which the bus pulled up just short of one of the lagoons anaerobic at that! From there, a beautiful run to Anglesea and along the dramatic Ocean Road to Lorne. A pleasant lunch, a stro ll on the beach , then through the Otways home. Near ly 70 took the tour to the impressive Winneke Reservoir and treatment plant, morning tea then through the Hills to the Coranderrk Weir where the Melbourne Board put on a lavish ly served lunch in a delightful sett ing, co mpl ete with Bell -b irds. Then to the Healesv ille Fauna Park where kangaroos, koalas and emus de lighted not on ly the overseas contingent. Thursday offered a visit to the Opal Centre - very much a ' loca l' attraction to overseas visitors. An inform ative talk on the origin of the stones and their recovery and po li sh ing added to the interest. The alternatives then avail ab le were a well guided visit to the National Gallery, with far too much to see in the limited time avai lable or a pleasant and und emanding wander through Melbourne's Zoo, a most pleasant spot . In general, arrangements a nd organ izat ion were excellent, the hospitalit y generous and the weather - perfect! 28

WATER June, 1985

An information session at Sovere ign Hill, Ballarat.

FIELD VISITS Field visits followed well attended workshop sessions on: • Activated sludge • Anaerobic treatment • Water quali ty a nd health The primary feat ures of interest in the water a nd sewerage area were, of course, undertakings of the Melbourne Board of Works which was generous in facilitating visits, the provision of guide staff and hosp ita lit y.

WATER QUALITY TOUR This tour commenced with a visit to the Boards Winneke Reservoir where the group of nearly 70 divided, part remaining at Winneke and the balance proceeding to Maroondah Reservoir for a close-hand view of catch-

ment management activities. Winneke is a 95 000 ML storage to which water from the Yarra is pumped by a station in the Yering Gorge. The main wall has a crest length of 1000 m and height of 85 m and there are two smaller saddle dams. From the storage pumping li fts the water to a 450 ML/ day treatment plant of convent iona l clarifier and rapid filter design with liquid a lum feed into the weir overflow from the inlet basin. After chlorination the water flows into the distribution system. Sludge and washings are discharged to the metropolitan sewerage system . The second part¥ travelled through magnificent stands of mountain ash to several study areas in the Maroondah Catchment and were advised of the fascinat ing experimental work to date in determining the long term effects of the various forest

Pat O'Shaughnessy and Rae Moran have an attentive audience in the Black Forest Experimental Area


CONVENTION ... 1985 ... MELBOURNE management options, and of bushfire damage. In the mountain ash areas it seems that young forest uses a significant amount of water for its rapid growth over IO to 60 years, taperin g off with maturit y about 150 years. Controll ed thinning, fellin g and logging is yielding valuable information bearing upon usage of those resources. During both visits the Boards officers were most helpful and the hospitality greatly appreciated .

MELBOURNE'S WESTERN SEWERAGE SYSTEM The tour party of 50 visited first the Brooklyn Pumping Station, a flow -t hrough insta llation of two wells housing four pumps eac h, with a station capacity of 250 mgd, using six pumps. This station delivers into the old Outfall Sewer whic h will be progress ivel y replaced by the Western Trunk Sewer project , involving 15 .3 km of 4.4 m sewer construction in tunnel to Hoppers Crossing Pumping Station then a furth er 7 .3 km of 4 .5 m shallow sewer to the Werribee Farm .

lagoo n treatment anaerobi c and aerobic and the associated activities of stock breeding and raising. Werribee is a most impressive undertaking. On the return route to the City, a call was made at the Water Training Centre of the Department of Water Reso urces which is achieving eve r increasin g prominence in the trai nin g of operators and monitoring of field performances. Robin Povey a nd staff gave a concise and complete description of the aims and work of the centre .

ACTIVATED SLUDGE TOUR First sto p on this tour was the Mornington Wastewater Control Centre treating a flow of 5100 kl/day, an act ivated sludge plant with an anoxic zone for denitrification and process modifications to incorporate waste sludge thickening, a naerob ic digest ion and a filter belt press for the digested sludge. The Authority was generous with information and in provi ding lun ch-time hospita lity to the 60 odd making the visit. The remainder of the day was spent at the Melbourne Board's South Eastern Purification Plant with part of the party doin g a ge neral tour and part purs uing more specialised interests with the plant chemists . The plant, designed for staged increase to an ultimate capacity of 1800 ML/ d has a present capacity of 290 ML/d median flow. The flow- scheme is traditional activated slud ge, providing sc ree ning , pre-aeration and grit removal, primary sedimentation and aeration with secondary sed imentation . Waste sludge is thickened and all slud ge is anaerobically

di gested, sludge gas is used for power generation. The effluent, after chl orination dis charges through a lengthy outfa ll to Bass Strait.

ANAEROBIC TREATMENT TOUR The party of 70 initially split into two groups, part visiting the pol yet heline plant of Copol P / L and the remainder the H.P. Products Pty plant where wheat, starch/ gluten wastes are treated. At the Copol plant wastes are treated in an activated sludge based plant. The discharge passes through separators for removal of oi l and resin then to oxidat ion ditc hes and after separation of the sludge in an upflow clarifier the effluent, chlorinated is used for coo ling tower make-up or in land irrigation. In the H.P . Prod ucts plant the waste is treated by the Upflow Anaerobic Slu dge Blanket process - a William Boby/ Bunge approach under the tradename ' Brothane'. The whole party was then lunched by the Sunbury Water Board at the Shire Office and toured the Sunbury WWTP an advanced plant designed by John Scroggie Consulting Engineers P / L for 30 000 population and based on the rap id activated sludge process wit h an anox ic zone, phosphorus removal and finally, filtration of the effluent through a three media filter . The tour fini shed with a visit to the CleanA-Way waste disposal faci lity at T ullamarine for industrial so lid and liquid wastes. Land treatment is used for the wastes and the leachate is pumped to lagoons and final di sposa l is to the sewerage sys tem.

Western Trunk Sewer in open-cut.

After an underground inspection and explanation of the project the gro up travelled to Werribee for lunc h , courtesy of the Board and for visual and oral explanation of the various treatment processes used in this enormou s treatment project - primary sed imendation , land filtration, grass filtration,

Trunk Sewer in Tunnel.

Group discussion at the Board 's S.E. Purification Plant. WATER Jun e, /985

29


CONVENTION '85 -

MELBOURNE

The Victorian Minister for Water Resources, Andrew Mccutcheon, M.L.A. opening the Exhibition

; Michael Dureau, Managing Director of Kent Instruments and Vice President A WWA responds for the Manufacturers


[

MANUFACTURERS' EXHIBITION

THE EXHIBITORS Ultraviolet -

Adelaide

Tubemakers Prominent & Fluid Controls A. E. Stansen EUR Control Permaglas (Aust. Harvestore Products) James Hardie Russel Armstrong Enviro Systems Polyblend (Stranco) Humes Mono Pumps Butterworths Hawker Siddeley Flygt Aust. Wallace & Tiernan William Boby & Co. Memtec Austep Wormald (Kelly & Lewis) Kent Instruments Acromet Drager Walker Glass Selby CIG


MANUFACTURERS' EXHIBITION MELBOURNE 1985

1985 International Convention.

REGISTRATION & EXHIBITION

32

WATER June, 1985


GEELONG OCEAN OUTFALL PROJECT

Upgrading of Existing Wastewater Disposal Facilities at Black Rock D. D. McLearie and D. S. Barkley ABSTRACT Preliminary design proposals have recently been completed for the upgrading of the Geelong & District Water Board 's wastewater disposal facilities at Black Rock. {Ref. 1). The new works will replace the existing shoreline outfall which was fir st commissioned in 1916. This paper summarises the extensive environmental and engineering studies which have been undertaken by the Board and its consultants in the development of the current proposals . The preliminary design provides for construction of coarse screens , an effluent pumping station using Archimedian screw pumps, a milliscreening plant, and degritting facilities prior to discharge to a 1.35 m diameter ocean outfall pipeline extending 1.2 km offshore. Effluent will be discharged through a multiport diffuser located in 15 m depth of water. Screenings and grit will be transported to landfill .

INTRODUCTION T he disposal of domestic and industrial efflu ent to coastal waters has been receiving increas ing attention in many areas in recent years. A number of communities have tradi tionally used th e coastal waters adjacent to urban areas for di sposal of their domesti c and indu strial wastewater . With the growth in population and a grow ing awareness of the impact of such di scharges o n the marine environment re-appraisal of existing di sposal arrangements has become necessary at a number of locations around Australia. The City of Geelong is situated about 70 kilom et res south -west of Melb ourne on the shores of Corio Bay. Wastewater collection and di sposal from the area is the responsibili ty of the Geelong & District Water Board (GDWB) which was constituted on 1st July 1984 by an ama lgamation of the Geelong Waterworks & Sewerage Trust (GWST) with the coastal sewerage authorities of Queenscliff, Point Lon sdale, Barwon Heads and Torquay. Wastewater collected from th e Geelong Region is tra nsferred by a seri es of pumping station s into two main gravity sewers. These grav ity sewers then feed into a ¡single outfall sewer which discharges at the coast at Black Rock together with two pumped ri sing mains from the coastal towns (Fig. 1) . Existing fac ilities at Black Rock include two Archimedian sc rew pumps to pro-

Mr. Douglas McLearie is an Associate Director of Binnie & Partners Pty . Lid. and Project Manager for the Geelong Outfall Project. Mr. David Barkley is Project Liaison Engineer for the Geelong Outf all Project for the Geelong & District Water Board. 36

WATER Jun e, 1985

vide the necessary head at high tide and co mminutors to cut up so lids in the flow. Th e existin g discharge at Black Rock has been subj ect to licencing by the Environment Protection Authority of Victoria (EPA) since May 1977. Studies commissioned by th e Geelon g Waterworks and Sewerage Trust at that time identified the need for upgrading of the ex istin g faci liti es if the EPA's long term environmental standards were to be met. Various options have been co nsidered and the current proposal developed to meet standards for wastewater constitu ents concentrations and receiving water quality laid down by the EPA.

BACKGROUND AND DEVELOPMENT OF THE GEELONG SYSTEM The fir st major step in the development of the Geelo ng wastewater disposal system was taken in 1912 with the commencement of construction of the 111ain 1295 mm (51 inch)

deep Ovoid sewer wh ich transferred the city 's wastewater to Black Rock. Geelong had a population of 30 000 in 1916 when the scheme was fir st commissioned . Upgrading of the initi al faci lities was und ertaken in the ea rly 19 Os with duplication of th e Ovoid sewer through Geelong with 13 50 mm diameter gravity line. South of Reserve Road the Ovoid sewer was replaced by a new plastilined 1650 mm diameter rein forced concrete pipeline. At Black Rock a comminutor plant and effluent pumping station was also constructed to cut up solids in the flow and to provide additional head to di scharge the increasing flo ws durin i; periods of high tide. Connections from Torquay in the west and Queenscliff, Ocean Grove a nd Barwon heads to th e east were made in 1972 to allow di sposal from th e coastal areas through the existing outfal l. The existing shoreline outfa ll at Black Rock has th erefor e served the community for over 60 years. However, as in other locations

INDENTED HEAD

lack Rock Outfall r//////J

OCEAN ,STUDY

V:48~~Jj

BASS

LEGEND G.D.W.B. SERVICE AREA MAIN SEWERS

j,., ,.,,,.,j

STRAIT

Figure 1. General layout of Geelong System.


the higher flow s in recent years have result ed in a more noticeable impact on the beaches adjacent to th e site. Increasi ng use of th ese teaches a nd a rising awareness in the <;ommunit y of the imp act of wastewater di scharges on the mar ine environment has lead to the developme nt of the current proposals. The planned new wo rk s will be designed initia lly to ha ndle wastewater fl ows to the yea r 20 10. Provision wi ll be made for ex tensions to th e plant which will provide for at least 50 year des ign life based on current flow projections.

ENVIRONMENT PROTECTIO N AUTHORITY WORKS APPROVAL The discharge of wastewater at Black Rock has been subject to licenci ng by the EPA since May 1977 . The lice nce has been updated on a number of occasions, the most recent being iss ued in Augus t 1980. The ex isting licence specifies requirements for wastewa ter constituent concent rat ion s and standards to be ac hi eved in the receivin g waters and has .been used as th e basis for a number of the design paramete rs. In deve loping the prelimin ary design concepts close lia ison has been maintained with officers of the E PA to ensure that th eir requirements will be met. During mid - 1984 the Envi ronment Protection (Review) Bill 1984 was passed through the Victorian State Parliament wit h the major portions of the Act coming into force on January I 1985. The Act requi res industries and authoriti es, whi ch could di scha rge pollutants to the environm ent , to obtain approval in advance from the EPA for the con struction of any new work or for the modification of ex isting facilitie s. T he Geelon g Ocean Outfall proj ect is the fi rs t major proj ect of its kind to be subjec t to the req uirement s of thi s new Act and details were submitted with an appli cation for works approva l to th e EPA in Feb ruar y 1985.

WASTEWATER FLOWS AND LOADINGS Wastewater Flows The major contrib utio ns to the di sc harge at Black Rock come from the Geelong urban area and the coas ta l towns hips of Torquay , Queenscliff, Ocean Grove and Barwon Heads . Monitoring of flow s is carried out o n a regular bas is by the GDWB a nd this information toget her wit h projections of population growth in th e a rea have ena bled est imated flow s to be calcul ated over the Ii fe of the scheme . Flow projections are sum mari sed in Table I . TABLE l. PROJ ECTED A VERA GE DRY WEATHER FLOW (M3 / S) Area

1984

/ 987

2010

2040

Geelong Area Coastal Townships Total Flow

0 .59 0. 14 0.73

0.63 0. 16 0.79

0.92 0.22 1.1 4

1.34 0.33 1.67

Des ign of the proposed treatment and di sposa l facilitie s will be based on a flow of twice the average dr y weath er fl ow (2 x ADWF) in the year 20 10. Flows in excess of

twice the average dry weather flow in the year 20 10 will be diverted through the ex isting facilities at Black Rock . Provision will be made for extension of the works beyo nd th is date to hand le projected flow s for at least 50 years of operation.

Wastewater Loadings Measurements of effluent constituent concentration is required by the EPA, a nd th e G DWB ca rri es o ut a regular sampling and analysis programme. Wastewater const ituent which will be monitored by the EPA after com mencement of th e offs hore discharge are listed in Table 2 together wit h recently meas ured levels. TABLE 2. CHA RACTE RI STICS OF BLACK ROCK WASTEWATER Constituent

80%

Max

Total P NH 3 Org. N

285 340 9.2 36 31

320 375 9.7 42 39

370 428 12.6 45 43

NO3 pH (uni ts) Colou r (Pt/ Co)

.3 7.2 110

.5 7 .3 120

.8 7.5 360

BO D5

ss

Cd Pb Hg Fe Cu Cr Ni Zn TDS

Mean

.007 .06

.0009 2. 1 .20

.O IO .09 .0013 2.9 .23 . 18 .09 .88

. 12 .05 . 75 1350

1500

.020 0 .1 4 .0063 3.2 .28 .29 . II 2.0 2150

Note: Co ncentrations a re give n in mg/ L un less otherwise noted.

A number of major industries operate in Geelong and trade wastes contribute a co nsiderable proportion of the BOD, suspended so lid s and heavy metals being discharged at Blac k Rock. Stricter co ntrol of trade wastes is recogni sed as an effective way of improving effluent standards. The tightening up of trade waste ag reements by the Board has lead to a significant reduct ion in a number of cons ti tuent conce ntration s , particul a rl y heavy metals as major indu stries have installed trea tment faci liti es and modified processes to ensure the conditions a re met.

INITIAL STUDIES In 1977 the GWST appointed Ca ldwell Connell Engineers Pty. Ltd . (CCE) to underta ke detailed engineer ing and environmental studies to es tablish the most suitable scheme for upgrading of the exis ting fac ilities at Blac k Rock . Together with a team of subconsulta nts specialisin g in oceanographic a nd marine biological inves tigations, CCE carried out a detailed stud y of poss ible wastewater treatment and di sposal options. The results of this study were presented to the GWST in Apri l 1979 (Ref. 2). The 1979 report was subsequently reviewed by CCE in 1983 a nd a Conceptual Design Report (Ref. 3) prese nted to the GWST in December of that year.

As a separate exercise to the studi es being carried out at Blac k Rock ~e Trust commissioned a study bri ef of the possibility of secondary treatment of the wastewater followed by re- use . The stud y ca rri ed out by Gutteridge H ask ins a nd Davey Pt y. Ltd. (Ref. 4), showed that thi s option woul d be signi fica ntl y more expensive than ocean disposal th ro ugh a n extend ed outfall at Black Rock . CCE (Ref. 3) also reviewed the fea sibility of this method of di sposal and fo und that on ly 13 0Jo of the an nual wastewater flow co uld be re-used in th e tradi tion al way o f irrigating public open space. Through much of the year a n alternative method of disposal such as the ocean outfall wo uld st ill be required .

MARINE BIOLOGY An initi al stud y of the marine environment was commi ss ioned by the GWST in 1977 at the time when public hearings were held in relation to the issue of the EPA di scharge lice nce. This work was carr ied out by Marine Sciences & Eco logy (Ref. 5) and provided a broad desc ription of th e waters surrounding th e existing sewage discharge and a general assessment of the environmental impact. Some quantitative work was carried out on marine popul ati ons a nd samples were taken for biomass determination and for heavy meta l tiss ue a nalysis. T his initial work showed that there was a clearly dist ingu ishable zo ne in whi ch the shoreline discharge was having an impact on marine life and that the extent of thi s zone was cons istent with observed general movements of the effl uent plume. Furt her biological survey wo rk was carried o ut as part of th e CCE stud y in 1979 (Ref. 4) . This wo r k included more detailed study of the benthic algae which occur along th e reef areas close to the site . The benthic in fa una in a reas of sa nd y sea bed were also sa mpled and compared with co ntr+>1 sites at Torquay. T his wor k confirmed a zone of significant influ ence on the a lgae community within the zo ne immediately adjacent to the ex isting o ut fa ll but that influence o f the discharge was not detectable at di stances of about 1 km. Addition al ecological studies were also carried out in 1979 by D . W. Parso ns and R. M . Synnot of the University of Melbourne 's Department of Zoo logy. This wo rk co mpri sed a qualitative survey of sub-tidal reef fa un a 1.2 to 1.6 km offshore from Black Rock in the area where an offshore di scharge point may be located . T he resu lts of this work were published as an appendix to CCE's 1979 Report (Ref. 2) . Most recently Marine Science and Ecology have ca rried out furth er offshore surveys bot h at th e location of the existing di scharge and in an area exten ding 1 to 2 km offshore from Blac k Rock. A comprehensive review of earli er environmental work together with thi s most recent survey was then used as the basis for identifying th e mar in e environm ent and ecology of the area and to assess the likel y effects of the proposed offs hore disc harge. This latest work was carried o ut under th e direction of Binnie & Partners and has been pub lished as part of the Prelimin ary Design Repo rt (Ref. I) . WATE R June, 1985

37


Independent sampling and testing of abalone tiss ue and rock lobster specimen was carried out in December 1980 by the Health Commission of Victoria for the EPA . These tests showed no significant levels of heavy metal contamination in any samples taken.

PHYSICAL OCEANOGRAPHY A detailed understanding of the physical oceanograph y of the coastal area is required to predict the dispersion of the effluent plume discharged from an offshore diffuser and to establish an understanding of the conditions which wi ll contro l selection of the methods of construction . To provide the necessary information studies have been undertaken of the wave conditions, wind conditions, ocean currents, tides and ocean density stratification in the area offshore from Black Rock.

Wave Conditions Wave data which could be applied to the design of an extended outfall at Black Rock was not avai lable prior to the commencement of the Board 's,studies. In 1979 Ports & Harbours deployed a wave rider buoy at a point 3 km offshore to monitor the sea state. This initial exercise produced 13 months of data which was analysed and presented by Ports & Harbours in January 1981 (Ref. 6) . The analysis presented a frequency of occurrence or return period for maximum and significant waves. The limited amount of available data made extrapolation of the frequency of occurrence beyond five years open to considerable doubt. During the recent studies undertaken in preparation of the preliminary design proposals, longer period wind records both from Black Rock and from other local wind stations have been used to generate sea conditions using well accepted hindcasting techniques. This data is then more reliable in producing extreme conditions for engineering design.

Wind Conditions Data obtained from the anemometer at the Point Lonsdale lighthouse was ana lysed during earlier studies and during the development of the preliminary design, further analysis of wind records from Point Lonsdale, Black Rock, Cape Otway and other weather stations around Melbourne has been carried out by Prof. Hinwood and Dr. Blackman at Monash University. This more recent analysis has cast doubt on the reliab il ity of the Point Lonsdale record and it has been concluded that the Board's anemometer at Black Rock provides the most reliable record a long this section of the coastline. Eight years of data are now availab le from this source. Anemometer tapes have been ana lysed by the Board to produce one hour average wind speeds divided into 16 points the compass. This data together with reliable long period records available from Essendon airport, will be used during detailed design to provide the information needed to develop design wave and current conditions.

Ocean Density Stratification Ocean density stratification must be considered as it could have a significant influence on the dilution and dispersion of an effluent plume . Stratification can arise from variations in salini ty and seawater temperature with depth. Salinity and temperature profiles taken offshore from Black Rock have shown the stratification is too small to produce a submerged effluent field. However the stratification is sufficient to enable the difficult surface layers in the ocean to travel in different directions under suitable conditions .

Bacterial Disappearance

Tides

The combined effects of microbial disappearance and subsequent dispersion act to reduce the concentration of bacteria in the ef-

Data on tide levJls at the site are necessary to determine tidal currents, to establish sea surface levels to be used for design purposes

15 0 14·0

13-0

'

12 0

'- \

11 0 10·0

90 8·0

-

~HAX

MEAN \.' / ......... '\ ~_.-MIN '\ :(\

\",~

7·0 6·0

,,I ......

I

/, I ~

-

'~ . ,. ,....... ./~

1 ... ciESIG N T;,

4·0

3-0

I"'

20

~--r-

rr-1

I

0200

0400

0600

0800

1000

I 1200

l/ V ~/ ~ V ~ ~ ,:,,,';"'

WATER June, 1985

~

-----

~

1400

1600

An understanding of ocean currents is required primarily to predict the dispersion of 38

'I I V, 'I

VALUES OBTAINED FROM FIELD EX PERIMENTS AT BLACK ROC K

~

50

00

J/

PREDICTED VALUES

1·0

Ocean Currents

fluent plume as it is transported from the initial mixing zone. Determj,pation of the rate of microbial disappearance is needed to predict the concentration of bacteria from the effluent discharge at the local beaches . . Microbial disappearance rates are commonly expressed at T90 values wh ich is the time required for the microbial concentration to be reduced by 90%. Ea rlier studies by CCE obtained T90 values as a result of a series of confined field experiments in the Barwon River Estuary. Samples of effluent mixed with sea water, enclosed in polyethylene bags, were supported at the water surface and the rate of microbial disappearance measured . The difficulty with confined field experiments is that the bacteria in the sample are insulated from the natural ocean environment and are therefore not subject to the complete range of influencing factors. As part of the recent study, the rate of microbial disappearance was based on data collected from field experiements carried out by the Metropolitan Water Sewerage and Drainage Board of Sydney in coastal discharges off the Sydney Coast and ser ies of in situ field tests carried out by the GDWB at Black Rock. The results are summarised in Figure 2.

the effluent plume di scharge from an offshore diffuser. Investigations of the current conditions offshore from Black Rock were carried out initiall y by CCE using a combination of moored current meters, tethered drogues and free floating drogues. Further deployments of a Neil Brown Instrument Systems (NBIS) acoustic current meter were also used to co llect data at two points along the proposed outfall a lignment. These ear lier studies and in particular the deployment of the NB IS instrument give a good sample of current speed and direction which can be expected at the diffuser . However, the influence of the proposed offshore di scharge on adjacent beaches will be dependent on the movement of the plume once it leaves the initial mixing zone . Some information cou ld be derived from earlier deployments of tethered and free-floating drogues. This data is however limited to a number of discrete points and to periods of reasonab ly calm weather when observations were possible. During the most recent work which lead to the preparation of the Preliminary Design Report (Ref. 1) it was decided to augment CCE' s earlier data with a more extensive study of currents in the area using a computer model. The Vi ctorian Institute of Marine Sciences (V IMS) had already developed a model for prediction of currents for the general area of the Bass Strait. From this model VIMS were able to build a nested model which extends over an area from Barwon Heads to Tor.quay and to a distance of 12 km offshore. This model produces current vectors on a 400 metre grid at various depths in the water co lumn . It can be driven by any selected combination of tidal and wind cond itions . Track plots of effluent plume movement can then be produced, providing the basis for dispersion calculations.

1800

2000

2200

2400

TIME OF DAY - HOURS Figure 2. Results of in situ T90 test.


and to provide in for mation for co nstruction purposes. Earlier studies carried out by CCE used data collec ted over a two year period at a gaugin g sta ti on set up in th e Barwon Ri ver Est ua ry 6 km east of the site. · As part of the recent stud y of tidal currents during the prepa ration of the preliminary design Aanderaa tid e gauges were deployed at two stations offs hore from Barwon Heads and Torquay. T he data collected has shown a close co rrela ti on in tide height and period between the two sites which has allowed th e dat a to be use d for predication of astronom ical tides at Black Rock. The studies carried out in the area have shown th at meteorological effects can cause a change in sea surface levels up to 0 .55 m in addition to the astronomical tides. This is mad e up of the effects of wind forces during periods of strong onshore wi nds co mbin ed wi th a drop in atmosp heric pressure at the site. From the data collected at the offshore stations an astronomical tidal range of 2 .86 m has been es tab lished . The chart datum for the · area (equi valent to the Lowest Astro nom ical Tide) has been give n by Ports & Habours as 1.485 m below AHD. This gives a hi ghest expected astronom ica l tide of + 1.375 m AHD and a poss ible highes t sea sur face leve l of + 1.925 m AHD when meteorologica l effects are added.

CHAINAGE 00 ~ ............· (N 5 759 033) ··· (E 274 034) ,/

-

SEABED CONDITIONS Information on the seabed conditions offshore from Black Rock has been bu ilt up over a period of tim e by a number of offs hore surveys. This has includ ed details of the bath ymet ry and sub-bottom conditions. During the early studi es by CCE, echosounding was carried out by Ports & Harbours over a n area extendin g 6 km offs hore and a pprox imately I km to th e east and west of the existing outfall. A geo ph ys ical survey was also carr ied out over the same general area using side-sca n so nar a nd a sub-bottom profiler to identify the seabed geology . These genera l surveys were used to identify possible outfa ll alignments. Supplementary information was a lso obt ained by di ver inspections and sea bed probing. In prepa ring the preliminary design the need fo r more detail ed sea bed in format ion was identified . More accurate seabed levels were required for engineering design and contact document prepa ration. Further investigation of the favo ured outfall alignment was a lso required to establ ish the extent of basalt and limestone reef known to occur in the area. Marine sur vey specia li sts, Associated Osiris Surveys, were appo inted to carry out a co mbined bathymetric and geo physica l survey. This work was carried out in August 1984 . The following equipment was used: • Honeywell Elac LAZ 720 precision ec ho sounder • Klein oval channel side scan sonar sys tem comprising a Klein 422S-00 IA KHZ two fi sh and a Klein Model 532 Hydroscan recorder • EG & G Uniboom contin uous sub-bottom profiling system co mpri sing an EG & G 230 Uniboom catamaran seismi c source a nd

NOTE : 1. ALL LEVELS ARE IN METRES BELOW CHART DATUM (-1. 375 mAHD)

--

Figure 3. Outfall alignment.

EG & G hydrophone array seismic detector. Posi tion fi xing was carri ed out using a Del Norte Trisponder 540 microwave system. Fo ll ow ing the offshore survey a programme of offs hore drilling was undertaken along the se lected pipeline a lignment. Samples of sea bed sediments and rock core were obtained by drilling from a jack-up platform . The NQ wire line system with a triple tube core barrel was used . Add itional data was also obtained by diving inspection. Probing of the seabed along the selected ali gnment was carr ied out by divers usin g an airprobe . From the information collected an a lignment for the outfall pipeline has been selected which ge nerally runs at right angles to the seabed contours (Fig. 3). This alignment provides the most suitab le route for achiev ing maximum depth for the shortest possible length wh ile avoid ing sign ificant reef structures identified at the offshore end .

The most sui table longitudinal profile a long the a lignment wi ll be determined during detailed des ign.

DESIGN OF ONSHORE FACILITIES The incre as in g occu re nce of n onbiodegradable materi al deposited on nearby beaches has been one of th e major reasons for the proposed upgrad ing of facilities at Black Rock. T he GDWB cu rrently operates three comminutors at Black Rock which cut up the solids a nd return them to the fl ow prior to discharging to the ocean through the shoreline outfall. The conceptual design prepared in 1983 (Ref. 3) recommended the use of a milliscreening plant to remove float able material from the wastewater prior to di scharge to the ocean through a long seabed out fall. The most recent work has included a review of th e conceptual design . This review WATER June, 1985

39


concluded that the co ncepts would generally comply with the requirements set by the EPA.

Milliscreening Plant Milliscreening eq uipment was originally developed for the treatment of industrial wastes. In recent years milliscreens have been used in the treatment of domestic wastewater as an alternative to conventional primary treatment prior to di scharge to the ocean . A range of screens is avai lable on the market. These include: • double pass rotating drum screens • ax ial entry rotating drum screens in which the wastewater enters axia ll y and is discharged via an interna l weir • rotating cone screen which the wastewater enters axially. Of these three types of milliscreens the cone screen is considered to be more applicable to the treatment of industrial wastes with high solids loadings . Both the double pass and axial entry . rotating drum screens have been used successfully in the screening of domestic wastewater . Both have advantages and di sadvantages. The double pass screen co llects screen ings on the external surface of the wedgewire and they are removed using a doctor blade . Difficulties have been experienced with this cleaning operation leading to a build up of screenings on the doctor blades and blinding of the screen . The axial entry rotating drum screen does not suffer from same difficulties but if blinding does occur this can cause an overwash at the downstream end of the screen and flooding of the screenings landing equipment. Two types of axial entry rotating drum screens which have been used on domestic sewage are currently availab le on the market. These are: • Contras hear. This screen provides for discharge from the internal weir box over a single side overflow weir with the screen rotating contra to the direction of flow. This screen is manufactured by Contrashear Developments Ltd . in Auckland, N.Z. and has been installed at a number of wastewater treatment plants in New Zealand , England, U .S.A. and at a limited number of location s in Austra lia. Australian agents for Contrashear are Babu , a division of Envirotech. • Rotoshear, which provides for discharge from a double sided in ternal weir box. Therefore part of the flow is contra to the direction of rotation and part is with the direction of rotation. The Rotash ear screen is manufactured by Hycor in the U.S.A . and is mark eted in Australia by William Baby Pty . Ltd.

Preliminary Plant Design The preliminary design of the proposed treatment facilities at Black Rock is shown schematically in Figure 4. Wastewater will be lifted from the gravity sewer by Archimedian screw pumps which will provide t'he necessary head through the treatment -works and for the ocean outfall pipeline. Coarse bar screens will be provided upstream of the pumps to provide protection for gross solids. 40

WATER Jun e, 1985

COARSE SCREENS

SCREW PUMPS

GRIT REMOVAL TANKS

MILLISCREENS

TO EXIS TING SHORE LI NE DISCHARGE

FUT URE CHLORINAT ION

BYPASS BYPASS PE NSTO CK WEIR

DISCHARGE TO OCEAN OU TFALL

COARSE SCREEN INGS

PRE SSATE

i ~~iT~l~I¼~ PRESSES

DEWATEREO SCRE ENINGS

WA SHED GRI T

LAN OFILL

Figure 4. Treatment plant schematic.

The main treatment of the wastewater will be provided by two banks of milliscreens. Screens with a wedgewire apertu re of 0.5 mm have been recommended. These screens have been selected in prder to remove all floatable solids and visible floatin g oil a nd grease from the wastewater before di scharge to the outfall pipeline. In addition it is expected that small but significant quantities of suspended so li ds (1 7%) and BOD (10%) wi ll a lso be removed . In preparing the preliminary design , a llowance has been made for grit removal faci liti es down stream of the milliscreens. This is cons idered as a necessary element of the treatment process in order to reduce the possibility of sil tation occurring in the ocean outfall pipeline. It is proposed that the screenings and the grit initially be coll ected, dewatered and transported to a landfill site situated within the existing GDWB's property at Black Rock . Facilities will be designed to handle twice the average dry weather flo w to the year 2010 with provision for extension of the work s to handle flows to 2040. The current EPA dicharge li cence a llows flow s in excess of 2 x ADWF in the year 20 10 to be diverted and discharged through the existi ng comminutors to the shoreline outfall.

OCEAN OUTFALL PIPELINE The proposed alignment of the outfall pipeline is as shown in Figure 3. The pipeline of 1.35 m internal diameter wi ll extend 1200 m offshore . The offshore end of the pipeline wi ll comprise a 225 m long multiport diffuser discharging the screened and de-gritted wastewater into 15 m depth of water . A miminum dilution of 50: 1 wi ll be provided in the initial mixing zone above the diffuser. A total of 60 diffuser ports will be provided to caler for flows in the year 2040. It is expected that approximately 20 ports will be required to di sc~arge the design flow in the initial

years of operation and that additional ports will be opened in subsequent years as flows increase. The design of the outfa ll pipeline and the selection of the pipeline material is very much influenced by the method of construction likely to be adopted. One of the favoured options is the bottom tow technique, used in conjunction with a concrete weight coated steel pipeline. Internal protection would be by cement morta r lining and external using a fu sion bonded polyethylene ~oating. The bottom tow technique has a particular advantage for the Black Rock situation because the avai lable land behind the beach would enable the jomplete pipeline to be strung out prior to commencement of the installation operation . This would avoid the time consuming activ ities of string jointing, lining repair and weight coat completion which norma lly adds considerable time to a pipeline installation . Insta llation of the pipeline at Black Rock cou ld be completed in less than 24 hours using this technique.

PROGRAMME AND COSTS Detailed design of the scheme is now in hand and the first contracts for the supply of mechanical plant are expected to be placed later this yea r. Construction of the treatment plant and ocean outfall is sc heduled to commence in early 1986 with commissioning of the scheme expected in the first half of 1987 . The total scheme is expected to cost $23 million at December 1984 rates.

ACKNOWLEDGEMENT The authors wish to thank the Geelong & District Water Board and the Engineer- in Chief, Mr. Geoff Vines, for permission to publish this paper .

CONTINUED ON PAGE 44


Water Treatment Changing Perspectives N. D. Johnstone & R. F. Goode 1. ABSTRACT Changing community expectations will necessitate major changes within the water indu stry . This paper looks at changes in community values, institutional arrangements, funding of capital works and technology as they affect the water industry and water treatment in Victoria. The opportunities available to the water treatment engineer are outlined and the effects of these changes in practice are illustrated by reference to recent projects by Camp Scott Furphy Ply. Ltd. in Victoria.

2. CHANGING COMMUNITY VALUES Quality of Life Versus Further Development Historically, the public has accepted that the Government and its technical advisers knew best and had their interests at heart. They regarded harnessing of water resources as essential to development of Australi a as a nation. Furthermore, the expenditure on capital works on a very large scale was visible evidence of the benefits of government, the technical excellence of its engineers and efficient use of taxes. Today, however, the comm unity does not see development for development's sake as its fir st priority. With the completion of in frastructure sufficient to support the nation, community priorities have changed and are now directed towards the quality of life. The public's concern abo ut the size and efficiency of government including author ities suppl ying water, is clearly reflected in today' s press. The public is very conscious that an increased portion of their earnings is taken by government and requires detailed evidence that it is well spent. There is strong resistance to increases in government charges in real terms, that is , in excess of the inflation rate. Taxpayers and ratepayers are concerned about the equity of the taxation elements and whether they personally are receiving value for money. There is a questioning of subsidies to special interest groups such as rural water users, who have hi storically received a free allowance of water and water below cost. The commun ity's concern for greater accountability of water authorities has led to organisational change and greater emphasis on performance and efficiency. Even with these improvements, water authorities whose consumers now cons ider they have a right to greater quantities of good quality water, will sti ll need to educate their consumers that cost increases may have to exceed the inflation rate. The recent suggestion that the water industry should be as efficient as the beer industry has real support in the community. The public is concerned about the environmental effects of resource development. This public concern does not stop with private developers but also is directed to water a uthori ties constructing new works. The public now frequently questions the merit of the new works in meeting community requirements and whether the technology employed is cons istent with improving their overall quality of li fe. The public are now much more concerned with the quality of the water they receive. Some cons umers are very concerned about the addition of chem icals to water such as fluoride and chlorine. Union bans now prevent the use of fluoride at three major Victorian rural cities and a further town does not fluoridate although the equipment is installed. Victorian law now requires that where State funds have been used to provide fluoridation equipment it mu st be used. Chlorination of drinking water in some comm uniti es seems to be meeting with increasing opposition and the alternatives are being reevaluated. This concern extends to swimming pools as evidenced by the Ringwood City Co uncil decision to adopt ozone disinfection despite existing ch lorination facilities and a significant cost penalty.

Nigel Johnstone is Principal Engineer, Water Treatment and Rod Goode is Associate Directo¡r, Camp Seo// and Furphy Ply. Lid., Melbourne.

N. D. Johnstone

R. F. Goode

As results of these changes the technology employed must be seen to be consistent with community's objective of improved quality of life. Engineers are obliged to present detailed information on all alternatives including their environmental effects to allow scrutiny by a better educated, more concerned public. No longer is the Engineer's advice accepted with out question nor the authority's plans for development accepted as automatically justifiable. Against thi s background the community will often expect higher quality water at minimal cost increase. In some sma ll communities a lower quality of water may have to be accepted to limit their rate burden . The achievement of adequate quality at affordable cost will be a major challenge for water engineers for the eighties and nineties.

3. CHANGING INSTITUTIONAL ARRANGEMENTS 3.1 Historical Structure for Development The constitutional responsibility for water resources in Australia is principally vested with the States. The Commonwealth is only involved in special interest areas affecting more than one State such as the River Murray Commission, and in areas of data co ll ection and resea rch relating to Australia as a whole such as the CSIRO and the Meteorological Bureau. The arrangements within each State reflect the historical development. In South Australia and Northern Territory , a single authority is responsible, whereas in the remaining States the responsibility is shared between the state water authority, metropolitan water authorities, rural water authorities and local government. The formation of a uthorities resulted from the development encouraged by the existence of an assured water supply and stimulated further development. The growth of these water authorities was encouraged by the overall prosperity of the co untry, the high rate of population growth and the government policy of decentralised development to realise potential in rural areas.

3.2 Restructuring for Operational Effiliency Recently, the traditional organisation of water authorities has been subj ect to increasing pressure to reflect the community's changed priorities. The need for development has been reduced by lower immigration, lower economic growth and completion of rural settlement. The change in attitude is reflected in the Reports by the Public Bodies Review Committee on the Victorian Water Industry. This has led to amalgamation of the 334 smaller community a uthor;,; es into 147 regional water boards and establ ishment of an 'umbrella' organisation , the Department of Water Resources . These regional water boards are similar to the independent subsidiaries of a holding company. Each 's ubsidiary' is involved in providing a nd efficient se rvice to consumers within a framework of common rules. Emphasis on strategic planning, financial management and operational performance wi ll be requ ired in order that each authority can retain its share of scarce capital resources allocated by the state from general taxpayer revenue. The regional boards will be responsible for the preservation, allocation and conservation of water with in their catchm ents. Thi s will resu lt in their active involvement in planning of developments rather a passive acceptance of increased demand resulting from ad hoc development decisions made by others. This change of definition of responsibilities will require dynamic management at both regional and state levels.

4. CHANGING ECONOMIC CONDITIONS 4.1 Historical System In Victoria the capital funding took the form of grants and low inWATER June, /985

41


terest loans for capital works. Th e res ult of this was a crosssubsidisat io n of wa ter users by all taxpayers . The more astute loca l water authorities adopted a strategy under this economic environment consistant with minimi sat ion of costs to th eir 's hareholders', the ratepayers. This led to a co ncentrat ion on development and co nstruct io n of capital works with low operatio n and ma intena nce costs. It enco uraged provision of a genero us allowance for futur e dema nd in o rder to benefit from th e ca pital grants on capital wo rk s. The interest subsidy also encouraged capital works as the effective interes t rate was often less than the infl ation rate . This meant that in inflat ionary times that the user paid less than the true cos t for the asset used. The hi storical situ ation in Victoria from the users's viewpo in t was that the water rates represented the cost of operation and maintenance, plus sma ll depreciation allowance based on historical cost, a nd a portion of the loan serv ice on part of the capita l works. This clearly did not give the ratepayer any rea li sti c bas is to asses the cost of wa ter suppli ed . The cost of providing the serv ice has trad itiona ll y been principally paid for by a charge in the for m of water rat es based on the land value or improved property value. The rates then gave the user a 'free' allowance of water which was related to his rates and provided no incentive to reduce dem and .

¡ 4.2 New Economic Objectives There is now a far greater understanding in the water industry of the objectives a nd techniques for monitoring eco nomic performance. Some key issues are equity, efficiency and accountability. Eq ui ty is expressed in the user pays principle a nd the minimization or elimination of cross-subsidizat ion . More progressive rating policies are being introduced to overcome thi s problem . Users should pay for their own needs a nd should not be forced to pay for faci lities used by generations in the di stant future. Hence excess ive sizing of treatment plant unit s is no longer acceptable a nd rating poli cies must be ca refully structured . Efficiency is achieved in part by struct uring the organ izations in¡a simple a nd effect ive way and can be monitored by the rate of return on the current va lu e of the assets of the water board . As all Water Boards are public bodies th ey must report event ua lly to the Government and th e people whom they serve in a clearly defined manner. The effect of inflation mu st be give n proper acco unt in assessing fin ancial performance, not ignored as in the past.

4.3 Current Economic Trends Performance indicators for the effectiveness of the water suppl y system have been identified for both water qua ntity and quality. The cost per unit of water suppli ed will be closely monitored as a check on efficiency . A real rate of return of the order of 3 to 5% on the current assets of the Board is likely to be required. Accountability to the central Department of Water Resources should now be more easily achieved with th e much redu ced number of Water Board s. The gove rnment is now transferring the costs from the general taxpayer to the user of the service . The effect of this is that the cost of capital to water authorities is steadil y increasi ng from the earlier subsidised interest rates to curren t mark et rates. Authorities will be required to move towards the use of internally ge nerated funds to reduce their future borrowings. T he removal of capita l subsidies will mean that water authorities will need to balance the cost of new capital works aga in st the conti nuation of use of existing capital assets with associated higher o peration and maintena nce costs. There is now developing a strong trend towards the optimisation of performance of existing capital plant and equipment. The return to interest rates higher than the inflat ion rate wi ll necess itate staged development schemes. A further constraint is that in future years many existing assets will require replacement, and the cost of replacement is likely to exceed availab le capit al reserves . The stro ng trend now is for payment for water based on consumption rather than the ability to pay. This has th e advantage that it means all users will be aware of the true cost of the service provided and will be able to persona ll y mak e a decision based on market rates as to their consumption . The user-pays principle will lead, as costs of water rise to reflect the actual costs, to the users questioning the level of service they are willing to pay for and require . 42

WATE R June, 1985 '

From the industry viewpoint, the affect o f the regiona lisation of water authorities sho uld lead to a more consistent l~e l of charges and services. Additio nally the state umbrell a o rganisatio ns will be ab le to ensure th at the limited funds for capita l works are effi ciently all ocated and that competition for funds is on an equitable basis with health, ed ucatio n and welfare and oth er needs .

5. CHANGING TECHNICAL CONDITIONS FOR NEW PLA NTS 5.1 Conservatism No Longer Acceptable Th e governm ent subsidies of the past encouraged a conce ntration on cap ita l works. Engineers attempted to produce high quality water from treatment pla nts generall y in accorda nce with th e quest for engin eering excellence. Plan ts were sized to fo llow demand patterns based on users paying less tha n th e true cost of water and with users unconcerned with conse rvation of water. Allowance was sometimes made for demand in creases ma ny years into the future as the cost of capital to authorities was less than the inflat ion rate. Safet y factors were incorporated in designs of plants to overco me uncertainties in order to guarantee excellent water qu ality under all conditions . The co ncept of a reduction in water quality at times of peak demand was rejected by most a uthorit ies. New tec hnol ogies were only slowl y accepted by design engineers because of the pressure to guarantee excellent water quality at all times. Plants were designed for simple operation and maintenance, so th ey would perform sat isfac tori ly even when not well run . This allowed plant operators to achieve good water quality des pite their often sparse training, lack of detailed operating man uals and process mo nitoring a nd laboratory equipm ent. Engineers and authorities concentrated on design and construction and professional input during operation often occurred only when the plant fai led . Re-thinking of th\s traditional engi neer ing approac h is now required with the emphasis on sound eco nomics and engineering practice to provide accepta ble treated water at minimum overall cost .

5.2 Target Water Quality Must be Affordable Engineers must now aim for the quality of water that is affordable and matches the realistic requirements of the users, rath er than strive for a hi gher qua lity at a cost premium . What is required is social equi ty with a ll consum ers hav ing reasonable quality w'ater, rather than some with excellent quality and many others with unsafe poor quality water. As a fir st stage, a qu ality equal to the A WRC/ NHMRC desirable quality shou ld be the objective for all authotities. In general terms, the water must be safe, reasonably clear (25 turbidity, 50 colou r) without objectional taste and odour, excessive hardness and corrosiveness. For many authorities, this standard can be met by prolonged detention followed by disin fect ion . This qua lity may not be sufficient to ensure complete and sa fe disinfection. A realistic intermediate quality goal is the A WR C/ NHMRC long term standard of improved physical quality of 5 turbidity a nd 5 co lour units a nd improved chem ica l co mposition . H owever , some country consumers will accept a colour of 10-15 colour units without co mplaint . Generally authoriti es will be required to underta ke so me form of treatment to achieve these quality goa ls throughout the year. Often this treatment will a ll ow achievement of a lower turbidity of 2 units or ¡ less during the major portion of the year. The traditional a nd preferred long term goa ls of physical quality of less than I turbidity unit is desirable but will not be affordab le for many authorit ies. However, thi s stand ard is preferred where th e raw water source is subj ect to signficant levels of faecal cont ami nation since turbidity interferes with effect ive disinfection. Generally, treatment will need to include filtraton to achi eve thi s high sta ndard .

5.3 Demand Management Affects Plant Size As the rate charges become based on usage rather than on property values with a 'free' water allocation, some consumers will adopt co nservation policies reducing demand. Among the major users of water are large industries and th e public authorities responsible for mainta inin g publ ic recreationa l areas. With increased cos ts of drinkin g quality water, they will be encouraged to seek alternative water of satisfactory quality.


However, the above conservation measures will not resul t in sma ller treatment plant s, unless demand on ex tremely hot summer days is controlled. Authorities will have to consu lt with the communit y to determine whether rest rictions a re acc~ptab le or whether the com- . munity is wi lling to accept high er charges associated with larger plants and grea ter storage capac it y in the sys tem , wh ich wi ll be partially utilised for the majority of th e time . As the cost of cap ital exceeds the inflation rate , the sizin g of plants should make an a ll owance for the short term increases in demand. The plant should be designed to allow the simple addition of furth er treatment units a s required to meet demand .

5.4 Cost Effective Treatment Processes Required A more detailed knowledge of the raw water qu a lity, its treata bility, and a lternative processes and their costs is now required to en~ure selection of cost effect ive treatment. Co llection of raw water quality data now needs to be supplemented with stat istical review so that typical and extreme values are known with accuracy . The behaviour and treatability of th e water requires more than a cursory review of existing plants treatin g simil a r waters in the same area . Simple laboratory trea tab ilit y st udi es a nd often long term pilot plant studies are now necessary to ga in a better understanding of the behaviour of each raw water. These predesign studies wi ll a lways pay dividends as they provide knowledge to a ll ow selectio n of cost effect ive treatment methods. · severa l of the more commonly employed newer processes permit substantial capital cost sav in gs. The opportunities for employment of these recent processes are now outlined. Direct fi ltration a llows elimination of the sedim enta ti on process for raw waters of moderate turbid it y a nd co lour. Thi s permit s considerable savings in ca pital cost. The process requires the formation of ' micro flo c' which are tra pped and stored in the filter media. The coagulant dosage is lower as on ly suffi cient chemi ca ls to coag ul ate the colour a nd turbidit y are needed as large floe is not required. Thi s results in lo wer chemical costs and reduced sludge quantities for disposa l. Dissolved air flotation is app licable to highly colo ured, cold waters, particula rly those with low turbidity and high a lgal loads whi ch can prove difficult to sett le . The process has a relat ively low capita l cos t, but power costs caa be high beca use of the need to recycle some o f the plant throughput. In one version of the OAF process, the top portion of the fil ter vesse ls is used as the flotat ion tank and resu lts in con siderable cost savings by elimination of o ne tank. The Sirofloc process can be success full y applied to highly co loured wa ter of low turbidity, which can be difficult to treat using alum. Th e process uses 'activated' magnetite, rather tha n a coagulant, which is regenerated and re used. Therefore, t he wastewater contains on ly concentrated turbidity and co lour which can offer cheaper di sposal. In some plants, fin a l filtration of treated water is not required which permits significant sav ings in capital costs. Thi s emphasis o n the reduction of ca pital costs must not be taken to the ex tent that the p lant d oes not ac hieve on a continuous basis the quantity and quality of water spec ified at the minimum total a nnual cost . For sma ll communities, simple operation and maintenance should still take precedence over optimi za tion of process unit size. However, for larger communit ies, opt imi zation of process design is fully justifiable since extensive process monitoring can be afforded. Furthermore, as few plants can just ify fu ll manning for three shift s, capita l is well spent on semi and fu ll y a utom a tic controls. Finall y to ensure the plant is cost effective when bui lt, an operationa l review at the design stage is essential. This revi ew can take a form simila r to the hazard and operab ility studies of the chemica l industry. 5.5 P lant Operation to be Optimised It is of little help that the plant is better des igned a nd the engineer has know ledge of how to optim ise the process, if the operator is without the benefit of th is knowledge . The operator must be provided with a ll of the fo llow ing information if he is to achieve the expected current performance. • Tra ining in plant operation. • Detailed operation a nd maintenance ma nuals for the act ual plant. • Reli a ble monitoring equ ipment including laboratory equipment to

meas ure, record a nd co ntrol key process parameters. T he co ntinued importance of the operator has oflen been forgotten by man y authorities. To this extent , the ro le of th e Engineers should not cease after co mmissioning and preparat ion of manua l. The operator requires refresher training courses, upgrad ing of informat ion in the O&M Manua ls, ass istance with problems caused by cha nges in raw water quality and elim ination of any p la nt design problem s. The continu a ti o n of ad vice and encouragement by the E ngineers through routine inspections is esse nti al to th e achieve ment of a hi gh level of plant performance under the d ay to day co ntrol o f the operator.

5.6 Public must be Informed Fina lly, t he days of decision ma king behind closed doors are over. The public need to be kept full y informed . This cannot be over emphasized in these tim es when the publi c is qu estioning the decision s of a uth orities a nd their profess ional advisers to the point of stopping projects beca use of lack of information. This has been clearly demonst rated by th e emotional debate on iss ues such as flu o rid ation and disinfection which are seen by so me gro ups as a threat to co mmunit y qu a li ty of li fe goal s.

6. OPPORTUNITIES IN EXISTING PLANTS 6.1 Plant Efficiency Review is Essential Sign ifica nt opportunities a re availab le for deferrin g capita l works to meet increases in demand at man y existing pla nts by improving operating performa nce and by minor modifications to process units. Also, m a ny existing pl a nts have unused capacity in so me process units due to the inclusion of high ma rgins of sa fet y because of un certainty during the initi a l des ign. The current approach for new pl a nts o utlined earlier is equally a pplica ble to existing plants . Thi s strategy involves setting affordable water quality standards, controlling peak demands, detailed st udy to optimise process design , rev iew o f new techn ology, a nd concentration on achievi ng fu ll utili sation of capita l assets by optim ising operational performance. The plant efficiency review comprises two essential steps . Th e first step is to review in detail th e object ives for the plant. Thi s well require quantifying reali stic and affordab le treated water quality sta nd a rd s and a review of current demand together with a forecast of future demand. The seco nd step stage is to review the performance,of each process unit bearing in mind that the aim is to produce a n acceptab le wa ter qua lity and not necessari ly perfect water. Thi s review should involve an extensive on-site in spect ion of the p la nt , a detailed review of records indi cating past performance a nd ta lks with the o perato r to find how he actually operates the plant. .,_ This rev iew will usua lly quick ly identify where performance can be improved and a lso where additiona l th roughput ca n eas il y be accommodated.

6.2 Improvements to Operation T he improveme nt to operatio n by additional trainin g of operators, updati ng operations and maintenance manual s and repair of ex isting monitoring equipment is clear ly very cost effecti ve. A ll of th e above mu st be a ppropriate and need to be discussed with the operator prior to implementat ion. However, the operator ca nnot be ex pected to achieve excellent pla nt performance while minor d eficiencies ex ist. These deficiencies ca n usuall y be overcom e at minimal cost and range from replacem ent of fau lty equipment to inclusion of rapid mixers a nd baffles to improve chemica l mixing and flocc ul a tion.

6.3 Increased Plant Capacity Increases in unit throughput are often available as result of inbuilt unused capacity, a nd this can usua lly be realised by minor changes to pipework. Further increases in unit thro ughput req uire more major works, but are st ill fa r cheaper than new co nstruction of dupli cate units. Such works include provi sio n of po lyelectrol yte dosing equipment and / or tube settlers to increase settli ng tank throughput a nd additi on of a n ant hrac ite layer to increase filtration unit throughput. After the a bove modifications have been carried out a capacity bottlen eck may still ex ist with one treatment unit, but instead of a ddin g a co mplete duplicate process chain, duplica tion is on ly req uired of t hat process unit. WATE R Jun e, 1985

43


After all the above improvements have been carried out extensive new capital works may sti ll be required , to meet increased demands or to replace ageing assets. The designer mu st then consider recent technological advances whic h may be more appropriate to current econom ic conditions.

7. EXAMPLES OF ALTERED PRACTICES IN VICTORIA 7.1 Intermediate Water Quality - Tungamah Township Recent examp les of Camp Scott Furphy practice in Victoria are outlined and can be used elsewhere. The adoption of intermediate water quality goals and the adaption of existing facilities enab led the small township of Tungamah, Victoria to afford an acceptable quality water supply of 0 .5 ML/ d capacity. The previous system of storage without di sinfect ion failed to meet either the ARWC desirable physical quality or bacteriological safe quality. The treatment process adopted was based on the ana lysis of raw water results and simple laboratory coagulation tests. Treatment comprises coagulation, flocculation, sedimentation and di sin fection . A baffle wall was installed in an existing earthern storage basins to convert it to a horizontal sedimentation tank and a second existing basin was used as a balancing storage. The use of a conservatively sized sedimentation tank avoided the need for filters. A small building the size of a household garage was built for plant electrics; alum , lime, ¡and chlorine dosing equipment; chemical storage; and treated water pumps. The construction of new buildings in the township is now the highest for a decade and the Shire considers the water plant to be a major factor.

7.2 New Processes -

DAF, Redcliffs

The new 11 ML/ d treatment plant at Red Cliffs near Mildura in Victoria is an example of the application of new processes at substantial savings in capital cost. The nearby Mildura plant is a conventional sed imentation filtration plant and incorporates traditional technology. It produces excellent water, but has prob lems with algal loads in summer. The Red Cliffs plant has dissolved air flotation and filtration in the same cell and is able to cope with algal loads, but may not be always suitable for the high turbidities so metimes experienced in the River Murray. To ensure a high water quality at a ll times, a simple high rate sedimentation tank was added upstream of the plant to reduce incoming raw water turbidity. Even with this addition the plant was sti ll lower in capital cost than a convent ional plant. The adoption of the new process was made possible by the extensive knowledge of raw water quality from years of monitoring at Mildura and the knowledge gained during predesign studies. The plant incorporates coagu lation, flocculation, dissolved air ¡ flotation, dual media filtration and alum, li me and chlorine dosing. Operation is simple and automatically controlled except for filter backwashing which is manually initiated. Conservation of water is achieved by recycling backwash water after separation. The environment is protected by sludge drainage beds which dewater the flotation sludge and allow reuse of water and disposal of dry sludge by land fill.

7.3 Conventional Can Be Best -

Warrnambool

The 25 ML/ d Warrnambool water treatment plan adopted conventional treatment based on extended pilot studies. The pilot plant studies considered alternative sedimentation processes, direct filtration, colour removal using ozone, but found that a conventional plant was optimal for the variable water quality experienced. The process involves coagulation, flocculation, soli ds-contact clarification, dualmedia filtration and disinfection by ch lorine. T he plant is automatically controlled and monitored and is connected to a telephone alarm system which permits manning of the plant during the day shift only and therefore considerably lowers operational costs. Conservation of water is practised with backwash water recycle. The backwash water is first collected in a equali sation tank and then undergoes rapid upflow settling prior to returning to the head of the plant. This has dual benefits in that water which has been pumped for over 80 kilometres to the plant is saved and sludge is concentrated prior to disposa l 44

WATER June, 1985

7.4 Plant Upgrading -

Shepparton

The advantages of rehabilitation of existing ~ants is clear ly demonstrated at Shepparton, Victoria. Filter loading rates have been increased by the addition of anthracite, and the sedimentation tank loading rates have been increased by addition of tube sett lers. Pilot plant studies are current ly under way to review improvements to the flash mi xing , flocculation and polyelectrolyte addition in order to achieve greater settling tank performance . Pilot plant studies are also being conducted into alternative processes . A master plan for the progressive future upgrading of the plant in affordable elements is being developed on the basis of the pilot plant investigations, and with the particular aim of minimising overall future costs taking into account labour, chemicals and capital serv icing costs.

8. CONCLUSIONS The combined effects of changing community goa ls, economic objectives and new technology have created a climate of change in the water industry and water treatment. The change in community goals from development to quality of life has already affected the water indust ry and will continue to have a major influence. It has led already to a thrust towards better management and a higher level of accountability at a State level. Regionalisation will co ntinue this trend into local Water Boards and will res ult in authorities being more involved with strategic planning , financial management, operations and maintenance performance. It is however , the responsibility of the engineers in the water industry to ensure that technical aspects move at a rate to match im provements in management. The trend to much better use of resources and better plant operation and operator training will probably continue for the next decade and wi ll ease the need for capital works. In the longer term carefu l planning by all water authorities is essential so that the need for new works and the replacement of ageing assets does not coincide.

BIBLIOGRAPHY BISHOP , F. R., JASPER, I. W . and PRENDIVILLE, P. W. (1985). Trea1ment of Murray River Water, AWWA Conference , Melbourne. McL HOMES, E. (1985). Performance Measurement and Reporting and Accountability in the Water Industry in Victoria. Proceedings A WWA I Ith Federal Conference. ' LEWIS, K. W. (1985). Dominant Issues Facing the Water Industry, in Australia. Proceedings A WWA 11th Federal Conference , Melbourne. NADEBAUM, P.R . and FISH, E. J. (1985). 'Considerations in the Application of the 'Sirofloc' Process for Colour and Turbfit y Remo val. Proceedings A WWA Conference, Melbourne. Water 2000: A Perspective on Australia's Water Resources to Year 2000 . Water 2000: Consultants Report No. 3 Economic and Financial Issues.

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D. D. McLEARIE AND D.S. BARKLEY Continued from page 40

REFERENCES BINNIE & PARTNERS. Geelong Ocean Outfall project. Preliminary Design Report. Jan. I985. CALDWELL CONNELL ENG INEERS. Geelong Ocean Outfa ll Study. Study of Wastewater Treatment and Disposal in Bass Strait for Geelong Waterworks and Sewerage Trust. Apr. 1979. CALDWELL CONNELL ENGINEERS. Geelong Ocean Outfall Project. Concept ual Design and Cost Estimates. Dec. 1983. GUTTERIDGE HASKINS & DAVEY. Outline on Possibility of Secondary Sewage Treatment as an alternative to the Ocean Disposa l. Feb. 1983. MARINE SC IENCE & ECOLOGY. Preliminary Investigation of Ecology. Feb. 1978. PORTS AND HARBOURS DIVISION. Marine Models Laboratory. Analyses of Black Rock Wave Data. Report No. 81-1-309. Jan. 1981.

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Water Journal June 1985  

Water Journal June 1985