Water Journal June 1978

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Official Journal of the AUSTRALIAN WATER AND WASTEWATER ASSOCIATION Vol. 5, No. 2 June 1978 Registered for posting as a publication -

Category 'B '.

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HEAD OFFICE • Hoechst Au stralia Limi ted P.O. Box 4300 MELBOURN E, Vic. 3001 Tel: 51 0321 BRANCH OFFICES • P.O. Box 25, NUNAWADI NG, Vic. 3131 Te l: 8743011 • P.O. Box 126, KINGSGROVE, N.S.W. 2208 Tel: 5023555 • P.O. Box 961 M, BRI SBAN E Old. 4001 Tel: 443661 • P.O . Box 137, BROOKLYN PARK, S.A. 5032 Tel: 3522655 •P.O. Box 118, PERTH, W.A. 6001 Tel: 3866311

EDITORIAL COMMITTEE Chairman: C. D. Parker Committee: G. R. Goffln G. F. Scott F. R. Bishop R. L. Cllsby Joan Powllng B. S. Sanders A. G. Longstaff W. Nicholson J. H. Greer A. Macoun B. J. Murphy Editor: Publisher: E. A. Swinton A.W.W.A BRANCH CORRESPONDENTS CANBERRA A.C.T.:

A. Macoun, P.O. Box 306, Woden, 2606.

NEW SOUTH WALES: G. R. Scott, James Hardie & Coy. Pty. Ltd., P.-O. Box 70, Parramatta, 2150.

VICTORIA: M. Smith, Ministry of Water -Resources and Water Supply, 9th Floor, 100 Exhibition St., Melbourne, 3000.

QUEENSLAND:

G. F. Scott, 46 Tucker St .• Chapel Hill, 4069 SOUTH AUSTRALIA: R. L. Cllsby,

C/- E. & W. S. G.P.O. Box 1751, Adelaide, 5001.

WESTERN AUSTRALIA: B. S. Sanders, 39 Kalinda Drive, City Beach, 6015.

TASMANIA:

W. Nicholson, 101 Acton Road, Lauderdale, 7021.

NORTHERN TERRITORY: C/· N. R. Allen, 3 Johns Place, Nlghtcllff, Darwin, 5792.

Editorial Correspondence: E. A. Swinton, Box 310, South Melbourne, Vic. Or to State Correspondents.

Advertising Enquiries: Mrs L. Gaal, C/-Applta, 191 Royal Par., Parkville, 3052.

Phone: (03) 347-2377.

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1,ssN 0310

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Officia Journal of the !AUSTRALIAN WATER ANDI

l'A5TEWAT£11ASSOC!AT10~1 Vol. 5, No. 2 June 1978

CONTENTS

Editorial ......... ..................... .

7

Association News ...................... .

8

Ocean Outfalls -

I. G. Wallis. . . . . . . . . . . . . . . . . . . . . . . . .

10

Use of Reclaimed Water in Australia - M.A. Smith ...... ·. . . . . . . . . . . . . . . . . .

Legal Implications and Complications Associated with Inland Water in Victoria - R. Bird.......................... . .

14

16

Clarification of Dairy Farm Water by Electrocoagulation -

I. B. Hubble and A. T. Griffin. . . . . . . . . . . .

18

Giving New Life to Extended Aeriation Package Plants

- J. A. Crockett ....................... ·. . . .

20

Conference Calendar ................. , . . . . . . .

22

INSTRUCTIONS TO AUTHORS Articles should be of orlglnal thought or reports on original work of Interest to the members of the A. W. W .A. In the range 1000 to 5000 words. Diagrams or photos would be appreciated. Full Instructions are avallable from Branch correspondents or the Editor.

COVER STORY of the most Intensive oceanographic and marine biology studies ever One undertaken In Austral/a has recently been conducted for the Sydney Metropolitan Water Sewerage and Drainage Board. The Board's consultants, Caldwell C(mne/1 Engineers, concluded that both present water quality criteria and probable future criteria can be met by discharging to the deep offshore waters and that It is feasible to construct deep water outfalls offshore from Sydney.

The three major shoreline discharges, North Head, Bondi and Malabar, are at the base of near-vertical cliffs with no shoreline work space. This factor and the frequently adverse weather and ocean conditions ruled out traditional construction techniques such as trestllng, bottom-towing, floating and sinking, and barge laying In nearshore waters. As shown by the outfall profile on the cover, tunnelling through the sandstone beneath the seabed as far offshore as the start of the diffuser section represents a practical solution and has been used for somewhat similar reasons in other places. The diffuser section, located well offshore In a water depth of 60 m or more, could be laid from a barge.

[Photo by courtesy of Ansett Transport Industries Ltd.]

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AP 108

6

FEDERAL SECRETARY: P. Hughes, Box A232 P.O. Sydney South, 2000.

EDITORIAL

FEDERAL TAEASliRER:

The 9th International Conference of the International Association on Water Pollution Research (1.A.W.P.R.) was held in Stockholm, Sweden, between 12th and 16th June. The papers and associated activities were attended and appreciated by some twenty-five Australian delegates and their wives .

The Conference was officially opened at the Stockholm Concert Hall by the Prime Minister of Sweden, Mr Thorbjorn Falldin, who was assisted by Bertil Hawerman, the National President of

J. H. Greer, C/- Melbourne & M.B,.W., 625 Lt. Collins St., Melbourne, 3000.

BRANCH SECRETARIES:

Canberra, A.C.T. D. Henley, P.O. Box 306, Woden, A.C.T., 2606

New South Wales: P.J. Mitchel I, C /- Envirotech Australia Pty. Ltd ., P.O. Box 220, ¡Artarmon, 2064.

Victoria: R. Povey, P.O. Box 409, Werribee, 3030.

Queensland: A. Pettigrew, P.O. Box 129, Brisbane Markets, 4106.

South Australia: A. Glatz, C/- Engineering & Water Supply Dept.

Victoria Square, Adelaide, 5000.

Western Australia: R.J. Fimmel, P.O . Box 356, West Perth, 6005.

Tasmania: P.E. Spratt,

Cl- Fowler, England & Newton, 132 Davey St., Hobart, 7000.

Northern Territory: A. Wade, C/- Dept. of Construction, Mitchell St., Darwin.

Thanks to the Victorian Branch for organising contributions to this issue.

THE PERIL OF PULLULATION*

1.A.W.P.R.

Mr Hawerman included in his remarks the following comment"a matter of concern to me is the close relationsh1.p between water supply and water protection. When and where there is a shortage of water-as we have experienced several times in the last ten years - this relationship is more and more evident. We have to look upon it as different aspects of a common problem."

He then went on to call for closer cooperation and coordination of these activities in the international sphere .

This observation was acknowledged to be pertinent internationally, but there is an even greater need to strive for a similar close relationship between the water management and the pollution prevention agencies on the National and State scene .

Too often the prevention of pollution is regarded as an end in itself, with the major problems of resource management and funds availability being regarded only in supportive roles.

This fragmentation of the total picture occurs in both the government and business arenas and, when considered with the pullulation of technical and professional organisations, it is timely that Mr Hawerman should have made his observations and that we shou Id heed them.

Our Association , at its inception, recognised that many disciplines and areas of endeavour are necessary to encompass the field of water management in its widest sense. Perhaps we could allow ourselves some measure of self-satisfaction in that we always have, and possibly always will, provide a total fo, um for all things directly or indirectly associated with water. However, we still have a long way to go before similar comments can be made of our work-day activities.

J. S. ROGERSON, President, Victorian Branch. *Footnote: Ed- Even I had to use the dictionary. " To propagate by budding, to breed, to m_ u ltiply- with connotation of rapid increase."

A.W.W.A. MEMBERSHIP Requests for Appllcatlon Forms for Membership of the Association should be addressed to the appropriate Branch Secretary.

Membership is In four categories : 1 . Member- qualifications suitable for membership In the Inst. of Engineers, or other suitable professional bodies . ($12 p.a.)

2 . Associate - experience In the W. & W . W . Industry, without formal qualifications. ($12 p.a .)

3. Student . ($5 p.a.)

4. Sustaining Member-an organisation involved in the W. & W . W .

Industry wishing to sustain the Association. ($65 p.a.)

Plus State levy of $3 in N.S .W. and Vic. 7

el

ASSOCIATION NEWS FEDERAL The last meeting of the AWWA Federal Council was held in Adelaide in May at 'Glen Eden', the South Australian Health Commission 's lnservice Training Centre at Marryatville.

Mr Don Montgomery, the Federal President, presided at the meeting which was attended by Federal Councillors from al I Branches except the recently re-formed Northern Territory Branch. Federal Counci I were pleased to hear from Dr Wade that the Northern Territory Branch, which had suspended operations fol lowing Cyclone Tracey, was once again active.

The Council welcomed Dr Don Weiss, the chairman of the Australian National Committee of the IAWPR , to the meeting , it having been decided that to further co-operation between IAWPR and AWWA the chief executive of each organisation should be invited to attend the other's executive meetings until more formal arrangements can be cons id ered. Federal Counci l be lieves the IAWPR and AWWA are complemen tary organisations and that it is in the interests of both that co-operation should be close and their activities co-ordinated . The principal area of co-operation at present is concerned with arrangements for the IAWPR's forthcoming International Conference on Developments in Land Methods of Wastewater Treatment and Utilisation which is to be held in Me lbourne, and on which a number of AWWA members are act ively engaged.

Federa l Counc il discussed Henry McFie 's report on the recently conclud_ed summer schoo l o·rganised by the Tasmanian Branch and congratu lated the organising committee on the successful outcome of their hard work.

Discussion then followed on lessons to be learnt from Hobart which might effect the next summer school which is . scheduled for Adelaide at Flinders University between 4th and 8th February 1980 . Dr Fuller reported that the organisation is progressing under the contro l of an active and enthusiastic committee. In formation supplied by the Hobart organising committee and the results of the questionnaire circulated to those who attended should help the Adelaide committee maintain the high standard set at previous summer schools and avoid staging "just anotner conference".

8

As reported by Allan . Pettigrew, oranisation is well advanced for the 8th Federal Convention to be held at the Chevron Hotel in Surfers paradise between 1st and ·5th October 1979.

Federal Council dealt with many items of a routine nature not the least of which was the Federal report submitted by the Treasurer, Jim Greer, indicating that a greater proportion of AWWA funds could be returned to State Branches. The State Branch Treasurers will, no doubt, welcome Federal Council's decision to increase the proportion of funds available to them.

The next meeting of Federal Council is scheduled for Saturday 28th October, 1978, to be held in Melbourne to coincide with the conclusion of the IAWPR Conference to be held there.

A.C.T. The Canberra Branch meeting of 23rd February was addressed by Mr Peter Cullen and Dr Don Rosich of the Canberra C.A.E., on the very relevant theme "Nutrient Problems in Lake Burley Griffin" .

On Thursday 20 April, 1978, Dr Ross Sutton, Assistant Director General, Medical Laboratories, Commonwealth Department of Health, gave an address on Water Related Diseases, graphically illustrated by some fairly close-to-home case studies.

Dr John Langford of M.M.B.W., was guest speaker of the Branch on 15 June 1978. Dr Langford, a Churchill fellow, gave an address on Catchment Management Research .

Future meetings of the Branch are planned as follows : 17 August, 1978: A.G.M . and presentation of Annual Reports. A forum type meeting is planned, discussing Australian involvement in overseas engineering projects.

25 October, 1978: Joint meeting with the Institution of Engineers on the topic "The Lower Molonglo Water Quality Cootrol Centre" .

Meetings are held at the Institution of Engineers Headquarters Building, 11 National ·circuit, Barton, commencing at 7.30 p.m . Supper is served at their conclusion .

The Branch Vice-President, Mr Bill Higgins, has left Canberra to take up an appointment as City Engineer, City of Stirling, Perth. Mr Alan Hatfield was elected to the vacant Federal Counciller P,Osition."

SOUTH AUSTRALIA The branch meeting of 30th June was addressed by Mr K. R. McCloy of the School of Surveying, S.A.I.T. He described the relevance of the "Landsat Programme" to water resources management. Remote sensing from satellite assisted by a proposed Australian receiving station, will enable us to map changes of water bodies, monitor

quality , depth and turbidity of lakes and shallow ocean areas, and extent of algal blooms . Evapotrans,:>iration studies, and monitoring of temperature plumes from power stations are further possibilities .

VICTORIA Approximately 180 people attended the April meeting, which was held In conjunction with the Institution of Engineers, Australia . Three speakers discussed various aspects of the design and operation of package sewage treatment plants . One hundred and eighty people cannot be wrong, so it would seem that thi&, is a subject that could well form the basis of further papers .

In May, Dr David Mitchell presented an excellent address on the management o'f aquatic plants. The 50 people who attended this meeting, which was held in the Royal Society Building, voted it to be among the best on record.

Following popular demand , the annual dinner dance has been brought forward and will be held in midwinter on Friday, 14th July. The venue wi II be the City and Overseas Club, which has proved so popular in the past. The annual conference of Engineers and Operators will be held in the MMBW Theatrette on 21st and 22nd September, 1978. A wide range of topics have been listed for discussion . A well known personality (in wastewater circles) will be giving the keynote address on "re-use".

The annual weekend conference will be held on 13th to 15th October, 1978.

This year the conference will be held at the Victoria Hotel at Shepparton and appropriately the theme will be "Water and Agriculture". As always, it will be a family affair fwith the emphasis on informality and relaxation. Why not decide right now to be there and enjoy the northern Victoria spring sunshine for a relaxing weekend.

TASMANIA The Branch's first meetings for 1978 were held in May in both Hobart and • Launceston when John Bowen gave a paper on The Ti Tree Bend Wastewater Treatment Plant recently commissioned to serve The Launceston City Area. The meeting was well attended in Hobart, but unfortunately the Launceston meeting was rather short on numbers. It was particularly pleasing to have a number of new and potential members at the meeting . Our thanks to John Bowen for an interesting and informative talk.

The next meeting of the branch will be in Hobart on Tuesday 25th July at the H.E.C. Theatrette when R. Gudde, an associate of Camp, Scott and Furphy will discuss the Southern Metropolitan Sewage Study. This meeting is being held in conjunction with

the Environmenta l Branch of the Institution of Engineers, so we are hopeful of good numbers!

Our congratulations to Western Australia on reaching the Magic 100 Membership Figure . Our own Branch Membership now stands at 69 , with 13 admitted in the last year . The membership total includes 9 sustaining mem bers. Possibly we will achieve that Magic Figure ourselves in the not too distant future .

QUEENSLAND Queensland Breaks the Tonne!

102 members and vis itors attended the meeting on 28th June, for our annual presentation of Treatment Plant Operators' Certificates to the Local Authority and Industry Plant Operators who successfully comp leted the 1978 correspondence courses .

96 operators completed the courses thi·s year in one or all of the various sections , water treatment, wastewater treatment , and/or swimming pool plants . 19 of the operators attended our meeting to receive their certificates from Mr Vince Schmidt , Chief Engineer, Department of Local Government , Old .

Guest speaker for the night was Mr Bob Delange , a member of the supervisory staff of the Metropolitan Public Abbatoir Board , Brisbane , who gave an informative talk on "Metropo l itan Abattoir Effluent Treatmerit Plant-Problems and Solutions."

Our previous meeting was on 17th May , when Dr Peter Wood of a.I.T's Paramedical School provided the next ep isode to his paper published in the December 1977 issue of 'Water' on the subject of 'Transmittab le Diseases in Water and Food' . Dr Wood provided a summary of possib le transmittable d iseases ~hich could be contracted by each of us and possible methods of dec reasing their incidence. Branch Chairman Geoff Cossins was forced to put a stop to question t im e after 45 minutes , and we hope to get Peter to put his talk down on paoer for a future publ ication of 'Water' .

Future meetings plann ed are :• 11th J uly , com bin ed meeting with Chemica l Eng in eers at Queensland Uni ., to hear Mr Frank Barnes of Melbourne and Metropolitan Board of Works, give a talk entit led " Wastew·ater Treat men t in Melbourn e-A n Exe rci se in La nd Utilisation ."

• 9th Aug ust , A.W.W.A . An nu al General Meeting at which Pres iden t Geoff Coss in s wi ll hand over the rostrum and in doing so will g ive a Presidentia l Reti ring address o n the wet and watery doings and undoings of the branch over the past 12 months.

• October - in spection of construction progress and operat ion of Luggage Point Sewage Treatment Plant .

The 1978-79 Committee as elected will be:Allan Pettigrew President and Fed. Councillor lmmed. Past Geoff Cossins President Vice President and Brian Rigden Treasurer Secretary John Ryan Fed . Councillor Murray A ll an John Bristow Robin Black Programmes Bill Garsden Richard Hopkins Peter Hughes Correspondent Neville Jones Clive Norton Membership Leo Roessler Norm Whyte Bill Volk Due to pressure of work, Allan Pettigrew has relinquished the Secretarial role that he has so ably held for the past seven years and accepted the Presidential position instead . Con gratulations , Allan , on your election to this position and thank you for keeping

AWWA Eighth Convention SURFER'S PARADISE 1-5 October, 1979

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CALL FOR PAPERS

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Synopses by Oct . 1978 to Convention Secretary, P.O . Box 129 Brisbane Markets 4106.

the show on the tracks for such a long time. Talking is less t ime-consuming than writing! Incidentally, as soon as Allan becomes President he is off to S. E. Asia for a short trip to get a, pol luted look at their environment .

New members elected to A .W.W.A. in Queensland in 1978 to date include , Habib Yesdani, R. Hughes , Alan Ginn, Peter Sheridan , Ernest Lote , Pat Mccourt , F. W. Purches , Irrigation and Water Supply Commission (sustaining) Ampo l Refineries Ltd (susta in ing), G. W. Mcilwain , R. L. Maas, G. K. Bowring , T. A. Walmsley , Alan K. Davie , J. G. Atherton, P. J . James, A. G. Powell , M. Ogsten , T. McNally .

Ou r membership drive is cont inuing and we anticipate additional members fol lowing ou r record breaking meeting on 28th June.

NEW SOUTH WALES On 11th April , at the 729 Club , Mr L. A. McDonald, Water Supply Engineer from the N. S. W. Dept . of Public Works , spoke to a genera l meeting on " Contro l

of Dispersive Soils Affecting Water Quality " . Much lively discussion took place after the paper rtut the most notable topic under discussion by our Association gourmets was how the 729 Club could afford to serve a hot meal for $1.50 . " Trihalomethanes in Pub lic . Water Supp l ies" was the paper presented by Mr A. R. Trussel at our May Meeting . Mr Trussel is a chemist with the Environmental Research Laboratories of James M. Montgomery , Consulting Engineers , Passadena, California.

It was obvious that Mr Trussel had carried out extensive research into his subject as he outlined the controversy that has arisen in the U.S. A. over the presence of T.H.M . in dri nking watP.r.

The United States Environmental Protection Agency has now issued a Standard for primary drinking water of 0.1 mg/litre of total T.H . M. for public water supplies.

A very popular event was the Wine Tasting Evening held at "Len Evans" restaurant on 16th June. It was a "full house" as 70 members and wives dined on roast beef , Yorkshire pudding, fresh beans and new potatoes with fresh baked crusty bread and cheese to follow . Wines appropriate to the occasion were included with the meal.

Pots of black coffee and a superb port brought the happy evening to an end .

Notice of the July Meeting arrived complete with a very appropriate cartoon heading penned by "Auto" to announce that Dr Ian Wallis would address a General Meeting on "Design Performance , Cost and Construction of Ocean Outfalls" .

Dr Wallis , Principal >I nvestigation Engineer of Caldwell Connell , Engineers , outlined the four steps involved in the design of an ocean outfall.

Mr J. M. Stoke~ Managing Director of Elson Ltd . , London, lectured to the Association at an extra-ordinary meeting on 26th July in the P.W.D .

Theatrette, on "Chemical Sanitation Systems" the role, the sanitary _fluids and the disposal of waste .

Mr Stokes is Managing Director of Elsan Ltd ., he has world w ide experience in this field and has lectured extensively on the subject. Further information can be obtained from Dav id Barnes , Schoo l of Civi l Eng in eering, The Un ivers ity of New South Wales, P.O. Box 1, Ke nsington , 2003 (Te l.

662301 3).

The Annua l Ge neral Meeting will be held on Frid ay , 18th August. Further detail s w ill be circ ul ated to all members shortly.

Planning is well under way towards hold ing a Workshop in September on " Chlo rin e Handling ".

The Reg ional Confere nce Subco mmittee has planning wel l under way and has suggested the 1979 Weekend Conference be held at "The Everglades" , Leura . An " Open Forum" type conference is under consideration .

9

OCEAN OUTFALLS Performance, investigation, construction and cost

by I. G. Wallis, INTRODUCTION Ocean outfalls are a practical and economical way of discharging effluents into the ocean. An outfal I is most acceptable for discharging organic materials which are naturally degraded and assimilated in the ocean. On the other hand , the discharge of cumulative nondegradable materials to the ocean should be permitted only after careful evaluation of the consequences and other options. Thus an outfall is only one component of a wastewater management system : usually a combination of source control and wastewater treatment are needed to compliment the effluent disposal role of an ocean outfall.

Basically, an ocean outfall consists of a diffuser , forming the seaward section of the outfall, and a pipe leading from the shore to the diffuser. The diffuser is a length of pipe with numerous small holes , known as ports , which acts as a manifold to distribute the discharge as uniformly as possible along the length of the diffuser. Various optional extras can be purchased in addition to the basic outfall . At the landward end , these could include : a pumping station, energy dissipation structure and wave control structure ; and at the seaward end, port covers which can be opened and closed at will and a gate which can be opened if it is thought necessary to flush the outfall. This paper, however will discuss the basic outfall in terms of performance, investigation , construction and cost .

If the outfall discharges beyond the surf zone , effluent being carried back to shore is reduced because ocean currents inshore of the surf zone tend to be separated from currents further offshore , and there is restricted exchange of water through the surf zone . Ocean currents tend to carry the effluent along depth contours which are generally parallel to the shore , although at times onshore and offshore currents can occur . However , as a general rule, the further the point of discharge is from shore , the smaller Is the proportion of the time in which effluent will be carried back to bathing areas.

Fresh water is about 2½ per cent less dense than seawater . However , in certain circumstances , an ocean outfall can use the natural ocean stratification to keep the effluent in deeper water below the ocean surface . Density stratification in coastal waters is mainly due to the vertical temperature grad ient, although the vertical salinity grad ient also has an influence . The temperature gradient ar ises from solar heating of the upper layers of the ocean and the salinity gradient is a result of net evaporation and freshwater in f low .

Both gradients are reduced by storms which cause mixing in the water col umn . The seasonal variation in solar radiation means that , during summer, the density of wat er near the ocean surface is usually significantly less than th e density of water in the deeper layers . When fresh water effluent

Since this is greater than the given density of seawater near the ocean surface , the effluent field will not rise to the surface but w ill begin to spread horizontally some distance below the ocean surface . Alternatively , if the initial dilution is only 5:1, then the resulting density of the effluent field would be 1021.67 kglm 3 , which is less than the density of the upper layer and so the effluent field would rise to the ocean surface and form a surface field .

For this example ,•the calculation of th e position of the effluent field was

Fig . 1 Schematic Repre$entatlon Submerged Effluent Field .

Fig. 2 Schematic Representation Surface Effluent Field.

at the surface and those at the bottom, the effluent will rise to the surface and form a surface field as illustrated in Fig . 2.

As an example of the situation in which a submerged field would form, the density of ocean waters offshore from Sydney during the summer months varies from about 1024 kg/ m 3 near the surface to about 1026 kg/ m 3 at 60 m depth . The density of domestic sewage effluent is al5out 1000 kglm 3 If the outfall provides an initial dilution of 20 :1 as a result of the effluent mixing with the higher density waters near the seabed , then the resulting density of the effluent-seawater mixture , known as th e effluent field, would be : (20 X 1026) + (1 X 1000)

=

1024. 76 kg / m3

(20 + 1)

OCEAN OUTFALL PERFORMANCE The major advantage of an ocean outfall in contrast to a shoreline discharge is its ability to protect shoreline activities from "high concentrations of effluent.

An ocean outfall can be designed to separate the discharged effluent from recreational activities at the shoreline, and also provide rapid and substantial dilution of the effluent with seawater. Each of these aspects will be discussed in turn .

Separation of Effluent from Recreational Activities An ocean outfall separates the effluent from recreational activities due to the distance from the point of discharge to the shoreline and the vertical distance from the outfall diffuser on the seabed to the ocean surface . * Dr Ian Wallis is Principal Investiga-

tions Engineer of Caldwell Connell Engineers , South Melbourne.

This paper is an abstract of his address to the February meeting of Victorian Branch at Geelong.

10

of

is discharged through a diffuser into a denser bottom water , the resulting effluent-seawater mixture may achieve a density slightly greater than that of the surface seawater .

In such cases, the mixture will rise to an intermediate level and then begin to spread horizontally , forming a submerged field , as illustrated in Fig . 1.

When there is little or no density difference between the ocean waters

of

simplified by considering only two density layers in the ocean . Actually , the ocean consists of many different layers and the computation of the den sity of the effluent field has to take into account the contribution of each layer to the volume and density of the r ising effluent plume . Nonetheless, the mi xing principle on which the cal culation is based is correct whether there are two or two hundred layers .

Dilution of Effluent with Seawater The term 'initial dilution ' refers to the amount of mixing occurring during the rise of the effluent from the diffuser to the submerged or surface field.

The two forces responsible for initial dilution are the momentum of the discharge and the buoyancy resulting from the density difference between the effluent and the adjacent ocean water.

For a discharge from deepwater diffusers , the buoyancy force is the major cause as the initial momentum is dissipated within a short distance from the diffuser.

The initial dilution of the rising effluent plume can be predicted using a computer program (Wallis 1977).

The equations used in the program are based on a series of differential equations describing the plumes: (1) entrainment; (2) horizontal momentum; (3) vertical momentum; (4) buoyancy; (5) horizontal displacement; (6) vertical displacement; and (7) dilution. The equations are integrated step by step along the path of the effluent plume from the diffuser until either the ocean surface is reached or a submerged field forms.

A comparison of predicted and measured initial dilutions and effluent field positions for t he Hyperion and West Point outfalls on the West Coast of the United States has shown that the program successfully reproduces the performance of an ocean outfall (Gibson 1978). In general, initial dilutions are predicted to within about ± 15 per cent and the average position of effluent fields are predicted to within about ± 10 percent in comparison with field observations . To illustrate this point, Fig . 3 shows the measured and predicted position of the submerged effluent field above the West 0

shown in Fig. 4. The variables used in Fig. 4 are the depth of the diffuser and the discharge per unit length of diffuser . For example, a diffuser at a depth of 60 m discharging 1 m 3 /sec of freshwater effluent through a 100 m long diffuser, corresponding to a discharge per unit length of 0.010 m 3 /sec m, would produce an initial dilution of approximately 200:1 in a surface field. Fig. 4 may be used to estimate the initial dilution corresponding to a range of diffuser lengths or depths, or to estimate the performance of a diffuser under a range of discharge rates.

After reaching equilibrium with its surroundings and forming either a submerged or a surface field, the effluent-seawater mixture undergoes further dilution as it moves away from the discharge area under the influence of ocean currents . The term 'subsequent dilution' refers to the mixing occurring during the horizontal movement of the field by ocean current.

The total dilution of the effluent is the product of initial dilution and subsequent dilution, with initial dilution being the major factor. In general terms, it is usually possible to achieve initial dilutions of from 50:1 to 300:1 , while subsequent dilutions are usually in the range of 2:1 to 10:1 within a few ki Iom et res from the outfal I.

PRE-DESIGN INVESTIGATIONS pre-design investiA thorough gation is an essential prerequisite to obtaining an outfall which provides satisfactory performance throughout a long useful life . These investigations can be divided into two categories: those necessary to predict the performance of an outfal I; and those necessary for engineering design. Together, the two categories include eight major investigative activities.

The first

--------~====:----:::::::== August

January

10 15

22 26

, :r•£ ~ jJlf~,, PREDICTED

50

=\\i:tf.

MEASURED

60 70

<\ ./' Diffuser at ~~~¥-:ttt,..i!i-,,1:

7Om

·=

<fl

;f~-.,~-~\t!~;iit~".~r.r,,,¥)~\1''-,.

Fig. 3 Comparison of Predicted and Measured Position of Surface Effluent Flelds Point Outfall. It can be seen that there is reasonably good agreement between the measured and predicted positions.

It is possible to make an approximate estimate of the initial dilution in a surface field using the design chart

category includes investigations of (1) stratification, (2) ocean currents , (3) microbiological conditions , (4) background chemistry, and (5) biological conditions . The second category includes investigation of (6) seabed

conditions, (7) ocean waves and weather , and (8) peak ocean currents .

Of course the scopi and extent of field studies must be tailored to fit the specific conditions of the possible outfall systems under investigation . It is expected that the cost of investigations for a $10 million outfall would greatly exceed those for a $100 ,000 out fall . Nonetheless , outfalls are generally cost ly structures and involve marine construction with a significant risk of damage or failure . A thorough in vestigation can provide a basis for minimising both the costs and the risks. The paragraphs below indicate the scope of studies invo lved in a thorough investigation of conditions in the area of a proposed qutfall.

1. Stratification : Density stratification in the ocean controls the height to which th e eff luent rises in the water above the outfall diffuser and influences the rate at which the rising effluent plume mixes with the seawater surrounding it.

Field investigations of stratif icat ion should establish the mean strat if ication and the statistical frequency distribution about the mean on a monthly or periodic basis .

2. Ocean currents are of great interest because they determine the excursion of the effluent after discharge from the outfall . They also supply the fres h seawater which is entrained in the effluent plume in the initial dilution process . Field investigations of coasta l currents should establish the relative contribution of tide, wind , large scale coastal water movement , waves , and edd ies to the observed currents and establish the frequency distribution and time of travel to shore for various effluent discharge locations.

The dilution produced • by an ocean outfall is constrained by two factors : the mixing produced by initial momen tum and effluent buoyancy , and the supply of seawater for the dilution process. This means that there must be sufficient currents at all times to supply dilution water or the effluent plume will begin to recirculate, thus reducing the actual dilution achieved .

To illustrate this, if a 100 m long out fall diffuser in 50 m of water is to discharge 1 m 3 / sec of effluent and is designed to achieve an initial dilution of 170:1 , then a current of at least 0 .034 m I sec normal to the diffu ser is required to supply the seawater used in the dilution process . Although it will usually be found that ocean currents exceed the critical value most of the time , it is important to determin e the frequency and duration of occurrence of currents below the critical valu e .

3. Field investigations of microbiological conditions should relate observed levels of various m icrobiological indicators (such as E. coll density) to nearby sources . If the des ig n of th e outfall is likely to be influenced or controlled by water quality requirements for these indicators , then con sideration should be given to conduct ing field experiments of the rate of di eoff of indicators to provide design val 11

ues of T-90 (J. T. Bellair et al. 1977).

The results of these experiments can be used in conjunction with estimates of initial dilution and various effluent trajectories and travel times to predict the frequency distribution of faecal coliform levels, or other microbiological indicators , in bathing waters .

4. Field investigations of the background seawater chemistry should establish the seasonal distribution of nutrients and , where necessary, other such as wastewater constituents metals or other potential toxicants in the receiving waters . If a number of outfalls discharge into the same general area, then the investigations of background chemistry should establish the relative contribution of wastes to the seawater in the area of the proposed outfall. As an illustration, a recent investigation by Brown & Caldwell (1977) determined that the cumulative effect of the 39 outfalls discharging into San Francisco Bay is to produce a background concentration throughout the lower reaches of the Bay equivalent to about 1 per cent effluent . In this situation it is impossible for a new outfall to provide an initial dilution of 100:1 or more, because this is the background concentration of effluent in the seawater available for use as dilution water.

5. Field studies should provide background information on existing biological conditions in the study area and give a basis for estimating any major impacts of effluent discharge on the marine community . An outfall alignment should avoid any unique localised habitats and highly productive areas .

Local biological conditions may set a limit on the quantity and quality of the effluent discharged .

6) Field investigations of seabed conditions should establish the bathymetry , topography , composition , and rate of sediment movement in the study area. The investigations should establish the locations of any seismic faults and of any soils subject to liquefaction along possible outfall alignments and provide a reasonable description of bearing capacity and construction conditions, including the type of excavation and construction equipment needed .

7) Investigations of ocean waves and meteorological conditions should establish the conditions which an ocean outfall and associated construction equipment must be designed to withstand, and determine the proportion of each season of the year during which construction on the ocean can take place .

8) An ocean outfall and any associated rock protection must be designed to remain stable against the lift and drag forces associated with peak ocean currents . Consequently it is necessary to predict peak lift and drag forces which , in turn, makes it necessary to 12

predict ocean currents near the seabed , where the outfal I is to be located .

It is interesting to note that outfalls tend to disappear when they experience currents greater¡ than those for which they have been designed.

CONSTRUCTION TECHNIQUES The results of the field investigations provide a basis for selecting the most economic procedure for constructing a particular outfall. There are five con struction methods which can be used either singly or in combination to construct an ocean outfall. The se are (1) trestle construction , (2) barge con struction , (3) prefabricated construction , (4) towed construction , and (5) tunnel construction. Each method has advantages and disadvantages in a particular situation .

1. Trestle Construction can be used to lay an outfall from the shoreline through the surf zone to a point where the ocean depths is from 9 to 13 m deep. A trestle is constructed along the align ment of the outfall with several metres clearance from the ocean surface .

Sheetpiling , excavation , pipelaying and backfilling equipment is operated from the trestle and the outfall is laid between two rows of sheet piles in a trench which is excavated underneath the trestle . In general, trestle construction is a high cost , low risk method .

600

z 0 ;::

::, 400 ...J

0 ...J

"" E

~ 300

~

2

x0

IE

200

Q.

""

0 ' - --'--'---'--'---'---,'---'-,----,"c--c' ~

m

w

w

~

w

ro

~

~

DEPTH OF DIFFUSER (m)

Fig. 4- Approximate Initial Dilution of Surface Effluent Fields.

2 . Barge Construction can be used to lay an outfal I starting from a point where the ocean is about 10 m deep and proceeding to the seaward terminus .

Excavation , pipelaying , and backfilling equipment is operated from a large barge moored above the outfall alignment. Individual lengths of pipe are conveyed from the barge to the seabed using a special pipelaying 'horse, which supports the pipe in a subframe. The

horse is lowered until the main frame sits on the seabed . The position of the subframe (and th\Js the pipe) is adjusted by a series of hydraulic rams which allow the pipe to be levelled , aligned and then pushed into the spigot of the pipe section previously laid. In Australia , the economics of barge construction depend considerably on the cost of bringing a suitable barge to the construction site .

3. Prefabricated Construction can be used to lay an outfall starting from an ocean depth of about 6 m and proceeding to the seaward terminus .

Sections of the outfall , each 50 to 150 m long , are prefabricated in areas not subject to large waves or currents and towed by boat to t h:e outfall construction site where they are sunk into predetermined positions along the sel ected alignment and jointed together to form the outfall. The jointing of the sections together is the most difficult part of this construction operation. A recent development of this technique applicable to small diameter outfalls involves fabricating the whole outfall on shore from high density polyethylene, moving it into position and sinking it.

4. Towed Construction can be used to construct the entire length of an outfall.

Jointing of pipe sections and other preparatory work takes place on land using a temporary rail line extending back from the beach. Next , the outfall , design ed to have a slight negative (sinking) bouancy, is towed into a preformed trench by a barge and anchored to the seabed. This method is applicable for outfalls up to about 1 m in diameter.

5. Tunnel Construction can be used to construct either an entire outfall or the pipe section of an outfall . In the former case , a tunnel is constructed beneath the seabed v:ir the full length of the outfall and vertical risers are drilled from the seabed to the tunnel to form the equivalent of -diffuser ports. In the latter case, the tunnel terminates in a vertical shaft connecting the tunnel to a diffuser section laid by barge on the seabed. Tunnel construction is limited to situations with suitable geology and topography, but could be favoured where an outfall is to be constructed¡ into deep water adjacent to a cliff . Fig .

5 shows an example of the section of a proposed outfall which would involve tunnelling from the shoreline to a distance 2700 m offshore .

There are many factors which need. to be considered in selecting the con struction method to be adopted for a particular outfall. These include the availability and cost of materials, manpower, and equipment. The economic comparison represents many of these factors . However, marine con struction also involves a degree of risk which should be quantified as much as possible as part of the evaluation of alternative construction methods. In an exposed site experiencing unpredict-

able weather, high wave energy and many storms, it may be preferab le to se lect a construction wh ic;h involves higher cost but less risk.

COST OF AN OUTFALL The cost of an outfal l consists of the high initial construction cost and a re lative ly low operating cost .

Local circumstances have a large influence on the construct ion cost of an outfall. Hence a realistic cost estimate must be based on a detailed est imate of materials, manpower, and equipment requ ired for the particular outfal l and se lected construct ion method. Neverthe less, construction costs of recently comp leted outfa ll s can be used as a guide in making preliminary cost estimates .

Fig. 6 shows the unit construction cost in U.S. do llars per metre for 40 installed and 7 proposed outfalls as a function of the inside diameter of the outfall. Of the 47 outfalls, 36 are on the West Coast of the United States, 3 are in Hawaii, 2 are in Puerto Rico, and 3 are in Sydney . All cost information has been converted to a common val ue of the ENA (Engineering News Record) Construction Cost Index of 3200.

It must be noted that the costs presented in Fig . 6 do not include contingencies, legal , surveying and

frequent high wave energy, or where unusual construction cond itions were used, for example tunne lling under the surf zone . Inexpensive conditions in volve outfal ls termin'at ing at shal low depths, in waters less than 12 m deep , or extensions of existing outfal ls without any construction in the .surf zone. Ordinary cond itions, of course, are al l those conditions which do not fal l within either expensive or inexpensive cond itions .

Fig. 6 shows that the unit construction cost is a function of both construction conditions and outfa ll diameter. Larger diameter outfalls have more concrete and reinforcing , requ ire more excavation and rock protect ion, and invo lve heavier construction equipment. Therefore , they cost more per metre of length than do smaller diameter outfal Is .

For each category of construction cond itions , a l ine of best fit has been drawn between unit construction cost and outfall diameter. The scatter about the lines of best fit is due to factors which influence construction costs other than those discussed above, such as seabed conditions, ease of site access , hau lage distances , avai lab le hydrau lic head, attitude and comm itments of prospective contractors at

O .-'S""EA-'-" L=EVc=E=..L_ _ _, - - - - - - - - - . - - - - - - - - - , , - - - - - - - - - , - - - - - -- ,

\

20

\-

1

\

-., r -...

40 -

I

. / PROJECTED

\

1...

SEISMIC SURVEY LINE 113 PROFIL E ~, , -

I --

' -, -\ .......... _,

I

-I 700m DIFFUS ER

"",.. . . . .

'

~ ------..r.;_

60

INFERRED POSITION OF FAULT~ ACCESS SHAFT

'f, __ ../ SEDI MENT

80

100

120

L-- - -- --,-L,------....,..,..J..,-- - - - - - - ::-:-c,: - - - -- - - : : - . J . . , - - - - - -:--'

0

1000

2000 3000 ST ATIONING FROM ACCESS SHAFT, m PROFILE

4000

5000

HO RI ZONTAL SCALE 1: 10000 VERTICAL SCALE I : 4 00

Fig. 5 Section of a Proposed Outfall Involving Tunnel and Barge Construction Methods time of tendering , variations between engineering costs . As a guide, the sum the design of d ifferent outfal ls and of these addit ional cost components d iffusers , and the degree of rock cou lei be 15 to 25 per cent of the conprotection needed , all of which may struct ion cost of the marine component co ll ective ly be termed 'local' circum of an outfall. stances .

As ind icated in the legend of Fig . 6, Therefore, as stated above, although construction conditions have been the cost data shown in Fig . 6 can be di vi ded into three categories . For used to deve lop an approximate est isimplicity, these have been designated mate of the projected cost of construct as expensive conditions, ord inary co ning an outfall , a detailed cost ana lysis dit ions and inexpensive conditions . The based on a specific outfal l design and general bas is of classification was as local circumstances is needed to obtain fo ll ows : expensive co ndit ions invo lve an accurate estimate . construct ion under difficult circumstances , for examp le, in areas of With regard to operating cost, it has

been demonstrated by Wal l is & Reinsch (1977) that the buoyancy 2f the effluent has a much larger inf luence on initial d il ut ion than the initial momentum of the discharge.5 Consequently, it is not necessary to use high ex it port ve loc ities to achieve large initial di lutions. It is poss ible, therefore, to operate an ocean outfall with a 0

o,

t0,000

8000 86000

~

,o

,., ,~

OUTFALL DIA METER, metre

"

3·0

,.

t l_J

•·O

.

20,000 ;

l

~

~4 000

l0,000-_

~

0 0 8000 :::

~ 2000

""'°

•ooo ~

~

t;

1000

8

000

§

z

Q

g ,oo

2000

~

~

400

8

K>OO

~

~

~

z

w

EXPENSIVE CONOITIONS

200

OROOU,RY COt.OtTIONS INEXPENSIVE CONDITIONS

..

•

BOO

0

0 0

i1

; 8 ~

~

600

>00~~~-~~~-~~--~

020

40 6 0 8 0 I O O l 2 0 1 4 0

OUTFALL DIAMETER, inch

Fig. 6 Unit outfall Construction Cost as a Function of Diameter. reasonab ly small head loss, and in many situations the available gravity head may be sufficient . Operating experience with large outfal ls discharg ing either comm inuted sewage or primary treatment plant effluent has shown that the maintenance cost of a well designed and carefully constructed outfall is limited to the coi,t of annual inspect ions and f lushing at, say five year intervals . Thus, an outfall has a small annual operating cost.

CONCLUSION A wel l designed' ocean outfa ll has two principal advantages . First , it separates treatment plant eff l uent from shore li ne activities.

Second it prov ides initial dilutions in the range of 50:1 to 300 :1 and total di lut ions in the range of 100:1 to 2000 :1 within a few ki lometres from the d iffuser. In many c ircumstances, such a system wi ll invo lve on ly a smal l operating cost.

However, the construction cost of an outfall is measured in thousands of do llars per metre and th is emphases the importance of conducting sufficient field studies to be ab le to make a thorough analys is of the required length, location, and geometry of an outfal l pipe and diffuser.

Outfal ls may be constructed using any comb ination of trestle, barge, prefabricat ion, towing, and tunne l construct ion methods. Field studies provide a basis for estimating the construction cost and risk of outfall damage or fai l ure associated with each method so that the preferred combination of cost and risk may be selected.

(References, p. 25) 13

USE OF RECLAIMED WATER IN VICTORIA M.A. SMITH II LANDSCAPE IRRIGATION TH E MILDURA STUDY Th e use of reclaimed water for landscape irrigation has been practiced in variou s parts of Australia for many yea rs. In recent years this form of re- use of water has grown in importance as more people realize the many benefits that flow from such projects .

Glenelg Sewage Treatment Works in South Australia marks the start of what is probably the most extensive re-use scheme of this type in Australia .

Appro ximately 47 Ml/d or 90 % of the plant's output is used for irrigation of eight sportsgrounds , four golf-courses, ¡ a public caravan park, a bowling green , tennis courts , 40 ha. of public lawns adjacent to the Patawolonga River, the Gl enelg Beach foreshore and extensive areas of the Adelaide Airport .

In Western Australia eighteen country towns with a totaf population of 80,000 re-use water for irrigation of local parks and sporting facilities . The responsible authorities required that re- use of effluent be considered as an int egral part of all proposals for the provision of sewerage facilities to rural townships within the State . The prohi bition of the use of surface waters on parks and gardens unless all other sources of supply have been exhausted , tog ether with substantial financial subsidies has accelerated the re-use of water in that State. An impressive sch eme is proposed for the use of effluent from Fyshwick Treatment

Ill AGRI CULTURAL POTENTIAL BENDIGO STUDY

Plant , Canberra, to water sportsgrounds at Duntroon Military College.

These are just a few of the more noteable example of re-use for landscape purposes but no doubt there are numerous examples of re-use for recreational purposes in other States.

In Victoria this form of re-use has been I im ited to date , probably because of the availability of water from other sources at little expense. However, considerable interest has been shown over recent years and currently reclaimed water is used to irrigate the fairways of four golf-courses and one racecourse. Approval has also been given to the use of reclaimed water for the irrigation of two public parks.

In order to examine the real benefits resulting from the re-use of water for landscape irrigation , the Victorian Reclaimed Water Committee commissioned Caldwell Connell Engineers Pty Ltd, to make a feasibility study of wastewater re-use for landscape irrigation in Mildura. Mildura was chosen because of its extensive public gardens that are currently watered using fully treated water from the City's reticulation system .

The study investigated two possible schemes ; the first using sewage effluent to irrigate a number of widespread public reserves and the second using sewage effluent to irrigate a group of public parks close to the treatment works. In both cases the

THE COLI BAN WATER

As the demand on Vi~toria's limited water resources increases, there is going to be a growing conflict between various groups of users for a share of th e remaining water .

Already potential areas of conflict between agricultural and domestic requirements are starting to develop.

One area where this conflict is likely to reach significant proportions is the Bendigo region in Central Victoria.

The City of Bendigo and a number of nearby townships, as well as the adjacent irrigation area , receive their wa.i er supplies from three major storages on the Caliban River and from Mike Smith is the Projects Engineer of the Victorian Ministry of Water Resources.

14

re-use of effluent was compared to the use of raw water pumped directly from the river.

The capital and annual costs associated with the alternative schemes show that scheme one , (supply to widespread reserves) is not economically feasible .

However scheme two , (supply to reserves adjacent to treatment works) has an economic -. advantage over irrigation with river water . The cost of chlorinated sewage effluent delivered to the parks , at $50/MI. , is lower than the current cost to the City for domestic water supplies ($55 .50/ Ml.) .

Public health aspects of this form of re-use have been considered and it was concluded that , subject to certain basic safeguards (such as placing signs at appropriate locations , use of taps that cannot be operated without special keys , allowing surface to dry before being used by public), there were no health risks involved .

In conclusion the study shows that re-use of effluent can be economically attractive under certain circumstances ; the main criteria being that the areas to be irrigated are located close together and within reasonable proximity to the sewa~_e treatment works. Mar,y other benel1t:; can also c1ccrue e.g. retarding the need to expand or relocate the sewage disposal facility.

More detailed information on the items that should be considered by any Council or organization contemplating this type of r~-use can be obtained by referring to the feasibility study report.

~30M l/o

EFF LUEN T

5200 MIJo

EFFLUEN T

CO LIBAN WATER BENDI GO URBAN SUPPLY

~30M l/ o

52 0 0 Ml/ a EX CESS ~

~30 Ml/a

SEWAGE FARM IRR IG ATI ON HUNTLY 1

I RR IGAT ION DI STRI CT PERMIT AREA

!1 3 0 no -

- --,___ _.....__,

AREA 14 2 ho

IRRIGATED

IRRIGATION WITH COLIBAN WATER

AREA

HUNTLY IRR IGATION

DISTRICT -

IRRIG ATED

14 2 ho

--___ _....._,

IRRIGATION WITH TREATED EFFLUENT

Fig. 1 Existing system. Effluent used for pasture only .

Fig. 2. Scheme 1, Irrigation at Huntly Using Treated Effluent in lieu of Caliban Water.

Lake Eppalock on the Campaspe River.

In 1974/75, the total volume of water released from these storages to meet the various demands was 45 300 MI .

This was made up of 18 300 Ml for domestic purposes and 27 000 MI for irrigation requirements. It is estimated that by the end of this century total

demand will have increased by 38% to 63 500 Ml per annum.

Latest computations suggest that the safe yield of the existing headworks is 56 800 Ml per annum . This volume of water would be sufficient to meet the predicted requirements only up to the year 1990.

Augmentation of the headworks wou Id be extremely costly and cou Id not be justif ied from an economic point of view . Because of the potentially serious situation, no new irrigation· permits have been issued since January, 1976, and the present policy is to rationalize the irrigation system by transferring or cancelling existing permits as farmers leave the area .

In view of this conflict, the Reclaimed Water Committj:je commissioned Cald we ll Connell Engineers Pty Ltd to make a study into the feasibility of replacing existing irrigation supplies to a section of the irrigation area with reclaimed water from the Bendigo Sewerage Treatment Works, and using the high qual ity water thus saved to augment domestic supplies within the city of Bendigo . Fig . 1 shows diagrammatically the existing system with some eff luent being used for pasture irrigation.

Var1ous schemes were investigated .

For the first scheme an area in the Shire of Huntly was selected primarily due to its proximity to the treatment works . Currently some 142 ha of land in this area is irrigated ; an average of 530 Ml per annum of water being applied to the land . The proposed scheme is shown in Figure 2. Basically it is proposed to transfer the water currently used for irrigation to the City of Bendigo for domestic purposes and replace this water with treated wastewater.

The costs and benefits associated with this proposal are summarized in Table 1. The estimated cost of delivering disinfected effluent to the farms ($33/ MI.) is the same as the actual cost of the existing irrigation

SCHEME 2 COUBAN

SCHEME 3

!530 Ml/o

8£NOIGO UR8AJlf SUPPLY

BENDIGO URBAN SUPPLY LUCERNE

8~ 360 850

CA88AGES SOYA

760 8"0 1080 MIio

MAIZE

SCHEME 1

HUNTLY

IRRIGATED

1RRIGATION [)($TR1CT

142 ho

Total estimated cost ANNUAL COST Interest and redemption Operation and maintenance Labour Chlorine Maintenance Health monitoring programme

LUCERNE

LUCERNE TOMATOES SUNFLOWERS

3840 Ml/a

SUNFLOWERS 31 60 WHEAT 13!50 TOMATOF.S 3160 CABBAGES 2B30

I

MIio Ml / a MI i o MIio

!~ ~:~: I

~~izAE

5 I~- E.-F-LU-EN-T~

/// 2

:ig~:j:1

·sT ORA GE

90 0M l/. o

LUCERNE TOMATOES SUNFLOWERS

I

TOT AL PE AMIT AREA IRRIGATED 530 ho

HUNTLY IRRIGATION

--,;,....;..,;.;..,;=;..I

t0_3_0_M_ll•...,I -

ANNUAL IRRIGATION REQUIREMENT FOA LUCERNE

Fig. 2 Schemes 2, 3, 4 and 5; Alternative Irrigation Development Proposals

supp ly, offset to a small extent by the value of the nutrients contained in the effluent.

However, there would be a significant monetary benefit resulting from implementation of the scheme due mainly to the provision of additional water for domestic purposes.

I

SCHEME 3

-

Pasture seed

-

Maize

Wheat

Tom-

atoes

-

-

U!l!l 46 200

28 500

28 500

28 500

28 500

85 500

3 000

3 000

3 000

3 000

10 000

4 000

4 000

4 000

300

-300

4 000

2....QQQ

2 000

2 000

300 2 000

4 10 2 2

17 500

9 300

9300

9 300

9 300

29 300

33

5.6

5.6

6.1

9.8

2U

41 8000 46 650 8 000

39.000 46 540 8 000

53 000

62 OOQ

46 650

46 650 8 000

304.00Q 46 650

8 000

8 000

Total gross benefits

51 650

80 450

77 650

91 650

100 650

342 650

NET BENEFITS Total net benefits Net benefit/ ha (ha vary with enterprise) Net benefit/ Ml

34 150 240 65

71 150 310 43

68 350 295 41

82 350 411 54

91 350 244 97

313 350 1 365 229

-

300

-

-

000

900 400 000

5 000

-

2 00 ""

SUPPLY

45 000 4 500 18 000 3 500 8 000

-

MA I ZE

CO SSES /

5 200

GROSS BENEFITS Fertiliser replacement Gross marQin on crop Saving in Caliban water Loss in pasture revenue

DISTRICT

530 Ml /o

4 500 18 000 3 500 2 500

Cost per Ml delivered

230 "IO 3 7~ r\ Q 2 30 -:a 230 t'C 2 30 ro

J

4 000 5 000 1 300 2 000

Total annual cost

IRRIGATION

TOMATOES CABBA GES SOYA

SCHEME

4 500 18 000 3 500 2 500

12 000 5 500

23 0 "'o

SUN FLOWE AS

~C-OL-IB_A_N-WA-T-ER~

BENDIGO URBAN

~IL_UCE_RN_E_

i

1.UCERNE

HUNTLY

EFFLUENT

4 500 18 000 3 500 2 500

-

SOYA MA IZE

LOSSES

DI STR ICT

'7 ,

BEN DIGO CREEK ~

SCHEME 4 !COLIBAN WATER

,_,. A/

CABBAGES

AREA

4 500 18 000 3 500 2 500

24 500

WHEAT TOMATOES

. ,.

EXCESS.

AVAILABLE OURmG IRR IGATION SEASON

WHEAT

Dairying CAPITAL COST Chlorination Channel improvement Gravity feeder Contingency Engineering

EFFLUEN T

~200Mllo EFFLUENT

SUNFLOWERS

Ml/a Mt/a Ml/o MIio

SUNFLOWERS WHEAT TOMATOES

530MII\

LUCERNE

1030 MVa

Table 1-Summary of Costs and Benefits for Schemes 1 and 3 [$. 1977)

I

I

COLIBAN WATER

WATER

46.650

The above scheme does not utilize ful ly the available reclaimed water, and a number of socio-economic problems wou ld be associated with implementation of the scheme. For these reasons a number of other proposa ls were studied to determine the benefits of optimizing agricu ltural production in the region by fully utilizing the avai lable wastewater resources. The schemes investigated are shown diagrammaticall y in Figure 3.

• All the schemes investigated showed a positive monetary benefit , confirming the opinion that treated effluent is a resource that is currently being wasted in the study area.

From a purely agricultural standpoint, scheme 5 is the most attractive but this scheme does not increase the water available for urban requirements in the Bendigo region.

Of the other schemes, scheme 3 appears to be the most advantageous .

This allows optimum development of the irrigation area by utilization of all the flow from the sewage treatment works during the irrigation season on crops instead of pasture while still releasing some 530 Ml per annum of high quality water for use within urban areas .

While the economic advantages of the schemes considered are obv'ious, there are a number of other issues that need to be reso lved before any of the schemes could be implemented.

The report therefore recommends that detailed studies be undertaken w ith a view to imp lementation of scheme 3 in the near future .

15

THE LEGAL IMPLICATIONS AND COMP·L ICATIONS ASSOCIATED WITH INLAND WATER IN VICTORIA R. BIRD* A recent Court action in which an Authority is being sued for allegedly flooding the Plaintiff's land , serves to illustrate the title selected for this address.

Simply stated, the Authority constructed a drain to take away surplus irrigation water to a river and the Plaintiff is suing that Authority for dam~es because the drain was not designed nor intended to remove all floodwaters following rain in excess of a designed storm. Here is an example of th·e implications and complications inherent in the management and control of water- and an example of the conflict which arises when the community assumes that the legal power to construct works for a specific drainage purpose carries with it absolute responsibility for totally protecting property against natural flooding .

This conflict is not new - historically water has always been of importance (the Ganges and the Nile were "sacred" rivers) and those who controlled the waters were powerful persons indeed .

Nat ions such as the Medes , the Persians and the Romans identified the beneficial uses of their limited water supplies and developed the extensive quanats (underground tunnel irrigationsystems)in Iraq, Iran and Afghanistan and the great aqueduct systems of the Roman Empire. The scarcer the water resource , the greater the need for rules to be developed for its effective utilisation. The water codes of countries located in the arid areas of the world such as Iraq, Iran, Syria , Turkey were good examples , whilst they differed both in approach , responsibility for control (the tribe, the individual , the state) , their underlying purpose was water resource management . Thus these water managers or conservationists preceded by a millennium those who currently espouse the same philosophy .

It is doubtful if the early settlers on Australian shores ever considered these functional water codes . The First Fleeters almost starved because they underestimated the water requirement and overestimated its availability. Victoria's settlers found the place for a village at Melbourne and, because they v. ere not wastewater experts and could find none to consult, quickly polluted the water supply sources.

For example, in 1846, when the population of Melbourne was almost 11 ,000, contemporary reports(1) complained "a row of slaughter houses, boiling down works and candle factories polluted the river above the point of supply ."

The Government passed, some seven years later, the Sewerage and Water Supply Act 1853, setting up an independent Board of Commissioners, with power to control sewerage and waterworks . Pressed by its wastewater experts , the Government then decided to clean up the Yarra River and passed the Yarra Pollution Prevention Act of 1855.

The 115 years since this legislation was enacted are illustrative of the conflict between those who saw the need to identify and conserve the water resource (both in terms of quality and quantity) and those who viewed the lakes and waterways of the developing State as a ready-made cesspool into which they could dump with impunity, their watewaters , their industrial contaminants and their mining sludge .

• Secretary, State Rivers & Water Supply Commission, Victoria.

Condensed from an address to the Victorian Branch Conference, October 1977.

16

From the point of view of a water resource manager, the legislation seemed a reasonable tool for the successful development (so far) of the State's water resources. This was not so much due to the " strength" of the legislation but rather the cessation , for economic reasons , of many of the activities which were having adverse effect on the water system . Such cessation fortuitously occurred before permanent harm was done to the water · nvironment. The legislation in question owed much to the discovery of gold and the min ing needs of the gold seekers as well as the domestic needs of a rap idly increased population and the industrial infrastructure which developed to support it .

Examples of the legislation and the relevant "water quality" provisions are :(a) the Ovens Goldfields Water Company Act of 1860- typi cal of a wide range of such legislation which sought to protect waterworks by provisions not dissimilar to Sections 245 and 246 of today's Water Act ; (b) the Public Works Statute 1865 which attempted to prevent anyone doing on his land anything which might injure the water supply and to prevent gas-making substances from flowing into the water supply ; and a similar provi sion is still to be found in the Water and M .M .B.W. Act s (Sections 247 and 122, respectively) ; (c) the Mines Act of 1865 which concerned itself with persons who allowed sludge and other mining by-products to pollute the water in any reservoir; (d) the Health Act of 1865 turned its attention to persons carrying on business near the Yarra River and who might pollute that river; (e) the legislation of the 1870's attempte,d to ·prevent pollution of Melbourne's harbour and to protect fish from poisonous or noxious materials entering into any stream; (f) the legislation of the 1880's covered much the same ground , sometimes varying the offences , sometimes increasing the penalty , someti ~ es carrying the appropriate phraseology into new legislation such as the Irrigation Act of 1886; (g) the Wc1ter Act 1890 had two provisions relating to pol lution , one concerned the pollution of water for irrigation and the other water for domestic purposes; and (h) the Health Act of 1890 retained a penalty for the pollution of the Yarra by unwholesome trades and gave the Health Board, or any Council, the rights of a riparian proprietor to prevent the pollution of any watercourse , well or reservoir. The Act also imposed a penalty for throwing nightsoil into rivers - an admirable sentiment .

By the middle 1890's this legislation , coupled with a changed direction of economic circumstances , was having a beneficial effect. On 9th May , 1896, the State Chemist was able to report that, while water pollution problems still remained conditions had improved . He commented : " the early settlers of Victoria were in no way critical as to the quality of the water they drank and It Is but reasonable in considering the standard of purity to be attain ed in our public water supplies to bear in mind that the country is only just growing out of the stage in which the standard of purity already attained would have been regarded as an unnecessary luxury. " Mining activities in some areas continued to be a problem but not until 1915 was the Sludge Abatement Board formed .

Past experience shows that there is a need to identify the beneficial uses of water to determine the activities which will adversely affect such uses and the need to organise these activities so that compatability can be achieved. In short the adverse affects of progress must be limited. For example, a potential adverse affect (at least on the water resource) is wastewater- and yet is progress possible without wastewater?

The 1905 legislation which initiated and established the Water Commission-one of the first statutory corporations of its kind is considered by many to be the most important legi slative event in our history over 115 years. The Commission was , and is, intended to have the power of Government and the flexibility of private enterprise; a situation which is somewhat limited in practice because all financial arrangements are, necessarily, subject to Treasury control. Since 1905 , the powers and responsibilities of the Commission have been varied and increased so that today , as a water resource authority, its duties include the management and protection of the water resource to ensure that : (a) the quality of waters is maintained at the highest practical level consistent with their proposed use ; (b) stream and watercourse regimes are not affected to the extent that their ability to carry natural flows (including .floods) is impaired by development activities which may increase runoff , cause erosion or siltation or interfere with natural flow patterns; and (c) consideration is given to the most efficient use of existing facilities and of available resources as far as the provision of water, drainage and flood protection services is concerned .

The implications of this management role are fairly straightforward : to plan for and provide an orderly use of water resources to enable the State to progress and , in turn, to ensure that such progress has no adverse effects on the water resource.

Legislative history demonstrates ad-hoc so lutions to unplanned events. The unplanned events generally related to land use and the lesson for us today is the need for planning; to frame a time scale for development, to provide the supportive resources for such development , to provide the necessary infrastructure and to ensure that the inevitable adverse effects of development are identified early and then monitored and contained .

The implications of the control of inland waters can be identified but the complications cannot be so clearly predicted . There has been a pattern of conflict during the past 115 years . These conflicts of interest continue in one form or another because too many land -use activities have an effect on water resources. Some everyday examples are: (a) the removal of timber to enable land to be used for agricultural purposes can cause variations in runoff patterns, increased soil erosion and the salting of land; (b) the subdivision of existing " rural" holdings for hobby farms or rural/ residential purposes results in overgrazing (which , in turn , leads to the break-up of the soil structure and erosion and drainage problems detrimental to streams and drainage lines), problems associated with noxious weeds and fire hazards (in turn, resulting in erosion and si ltation), the risk to public health from the po llution of streams resulting from inadequate waste disposal methods and, above all , an undue dispersion of basic services representing an unreasonable and un economic use of capital resources; (c) residential subdivision in unsuitable or "sensitive" areas can result in a rise in the water table and the destruction of soil structure , highly increased surface run -off (in turn, leading to erosion, si ltation and blockage of streams and drainage lines), contamination of streams and groundwater aquifers by sewage, sullage and polluted urban stormwater runoff; (d) the subdivision of land in flood-prone or inadequately drained areas can result in an increase in flood water velocities which , in turn, cause damage to lands and

property and a risk to life and limb as well as the diversion of flows on the areas which would not otherwise be flooded ; (e) river improvement works , particularly desnagging, straightening and bank protection measures , can result in a reduction in landscape values as well as altering the habitat for fish and wildlife and, in some instances, increasing the magnitude and distribution of downstream flows ; and (I) the use of natural streams and lakes for water supply and water conservation purposes can confl ict with their use for fisheries and wildlife or other environmental purposes.

The conflicts in the above cases are self-evident; indeed they are about something which is practically and physically identifiable ; something with which one can , as it were, "come to grips" . In the case of the wastewater engineer, there is another , deeper, conflict to be found, for to the lay mind f he term wastewater has unpleasant, ,even sinister, connotations ; to the public in general, the term equates to sewage or the residue from a nasty industry . Therefore , the situation arises where many commendable , desirable and quite aesthetically acceptable wastewater projects may never be initiated because of objections based on pure emotion.

Examples of this are all too familiar ; arguments on the location of sewage lagoons , objections to the granting by the Environment Protection Authority of licences to discharge treated effluents to watercourses , objection to the use of stock raised on sewage farms - are but a few examples.

In response to the leading question, "has the water legislation of the past sustained the water environment?", a typical co untry town's development will be traced . Initially , it develops slowly for natural reasons, it has a reasonable water supply, probably treated , it has a sewerage system with treated effluent discharging onto irrigated pastures or'" to an adjacent stream (probably the latter because there are few cities in Victoria with reasonably large populations using total land disposal means); possibly the effluent itself is inadequately treated (though not grossly so); the sewerage mains are old , inadequate in size and stormwater infiltration means that on occasions , raw sewage is discharged to watercourses ; industrial waste may be treated on site , or it could be discharged to the town drainage system with little or no prior treatment; the town stormwater system discharges directly to the adjacent streams and in addition to carrying an urban stormwater loading which is now recognised as being highly polluted, al1,o carries septic and sullage eff luents from the unsewered areas of the town . The watercourse downstream of the town is perhaps not grossly polluted but is showing signs of stress.

This examp le demonstrates that short term solutions have been found but that long term forward planning is lacking.

Only too often has "eco nomics" prevented the installation of a more sophisticated sewerage system , being used as the excuse rather than the reason ; the easiest way of disposal has been to drain the wastes into the nearest watercourse without really considering the consequences or, alternatively , leaving the watercourse to be cleaned up by a municipality or some other Governmental Authority .

All sorts of laws exist therefore but the problems and conflicts must be reso lved by planning - land use planning, economic planning , resource usage planning and developmental planning .

It is possible that the conflict really occurs because the legislators have seen fit to compartmentalise a number of agencies all having, some degree of responsibility for the same resource . For example, the development of land as a resource is influenced by the policies of the Lands Department , the local municipality, the Town and Country Planning Board , the Soil Conservation Authority and the Ministry of Conservation and so on. Legislatively speaking , water and land , a total resource, is divided between the Health Act, the Water Act , the Environment Protection Act , the Mines Act, the Drainage of Land Act and the Groundwater Act and a number of Acts dealing particularly with land.

Continued on Page 23 17

CLARIFICATION OF DAIRY FARM WATER BY ELECTROCOAGULATION I. B. HUBBLE* and A. T. GRIFFIN* INTRODUCTION About half of Victoria's• 13 ,600 licensed dairy farmers use water from dams or irrigation channe ls for cleaning equipment in milking sheds. Clay and other part iculate matter deposits in pipes, tanks and water heaters, but more seriously, the colloids interfere with the process of disinfection by ch lorine. The Gi lbert Chand ler Institute of Dairy Technology, w ith the support of a grant from the Austra lian Dairying Research Committee, has been assessing clarification techniques which wou ld be suitab le for operation by farmers .

Treatment by alum in dams and in tank systems can be successful (Hubb le and Griffi n 1978) but an alternat ive system is electrocoagulat ion where aluminium ions are re·Ieased by electro lysis from an al um inium anode, along with release of bydroxy l ions at tne catnooe . Alumin ium hydrox ide floe is thereby formed w ithout significant change in the pH or salt content of the water. Small-scale systems have been described. (lzyurova and Ovchinkin, 1947, 1968; Pashenkov et al, 1964; Ly le and Hi ler, 1972; Si lin . and Yarosiavskii, 1964; Di ll on et al, 1975:) . They offer operating convenience for sma llscale users.

Prototypes of similar systems were deve loped in conjunction with the State Rivers and Water Supp ly Commission . Subsequent development was conducted by Commando Water Treatment Ltd, Torrensville , S.A. and by Davey Dunlite Pty Ltd , Huntingdale, V ic.

This paper summarises the resu lts of extended field tests of these commercial units on three dairy farms in Northern V ictoria.

System 1. [Davey Dunllte Pty. Ltd.] The plant consisted of an electrolytic ce ll and an open, mu lti-media filter housed together in a mou lded polyvinyl chloride cas ing. The electrolytic ce ll consisted of two aluminium plates (3 .3 mm thick , grade B-1200) and three stain less stee l plates (1.6 mm thick, grade 316) in paral lel succession . The plates, spaced at 6.4 mm interva ls had an effective anode area of 1.0m 2 .

Electric current was supplied to the plates by a 225 W (maximum) constant current rectifier . The filter media comprised 0.02 m 3 gravel (3 .2 - 6 .4 mm diameter), 0.05 m 3 sand (1.5 - 2.5 mm diameter) and 0.02 m 3 plastic beads (4 .8 mm diameter).

During treatment the water f lowed through the electrolytic cell in one pass, and then through the f ilter where the

f loccu lated matter was entrapped .

Sodium hypochiorite was added to the water prior to filtration by a smal l 25 W metering pump (Sta-rite Industries, U .S.A. Model 024). A 910 li tre overhead tank provided for storage of the treated water, holding time for disinfection and a supply of treated water for backwashing of the filter. The pressure pumps associated with the system allowed water to be treated and stored in the overhead tank as a un it volume of treated water was used .

The unit treated 18.2 litres of water per minute although 23 litres per minute is claimed depending on water qua lity .

It was located on a farm at Rochester, where water was obtained from a dam primarily filled by irrigation water from Eppa lock Reservoir.

System 2. [Commando Water Treatment Pty. Ltd.] The plant cons isted of two electrolytic cells connected in series , and an open, multi -media fi lter made of fibreg lass . (Patent Appl. No . 71456/ 74 PB 4256). Each electro lytic cell

Tabla 1-Reductlona In Turbidity and Colour

Water source: Turbidity means log (t + 1) LSD (p 0.05) Colour means log(c + 1) LSD (p0.05)

System 1

System 2

System3

Eppalock

Waranga

Waranga

Raw

Treated

Raw

Treated

Ray;

Treated

25 1.4

25 1.4

25 1.4

8 0.9

63 1.8

20 1.3

25 1.4

50

2~ 1.3

63 1.8

0.08 32 1.5

0.33

0.33

0.12

1.7 0.21

16 1.2 0.19

Table 2-Physlco-Chemlcal Characteristics-Means and Std . errors

System 1 Raw Alkalinity (mg/I CaCO3 Hardn ess (mg/I CaCO3 Chloride (mg/I Cl) YDS as E.C. x 0.6 pH

112±12 210±12 238±12 578:;!; 9 8.5

Treated 124± 6 198±19 250±14 ~11± 8 · 8.5

consisted of two concentric tubes, with a distance of 12.7 mm between them .

The outer tube or anode, 6.4 mm thick and 89 mm internal diameter was made of grade B6063-T5 aluminium al loy.

The inner tube 1.6 mm thick and 63 mm internal diameter was made of grade 316 stainless steel. The system had an effective anode area of 0.61 m2 . Electric current to the cell s was supp lied by a 300 W (maximum) variable current

*Gilbert Chandler7nstitute of Dairy Technology, Werribee, Vic .

18

rectifier . The f ilter media consisted of 0 .06 m 3 anthracite (0 .6 - 1 mm diameter), 0.07 m3 of sand (0.25 - 0 .05 mm diameter) and 0.04 m 3 grave l (0.5 - 1 mm d iameter) .

The water to be treated f lowed through each electrolytic cell and filter where the flocculated matter was entrapped.

It was disinfected by addition of a solution of sodium ·hypochlorite by a ventur i, activated by a pressure d ifferential across a 0.56 kW pump associated with the system. A 9000 litre overhead tank provided storage for the treated water, holding time for dis infection and a supp ly of treated water for backwashing of the fi lter .

The water was treated on a batch basis .

The unit treated 11 .4 litres per minute, although 15 litres per minute is claimed depending on the water quality .

It was located at Kyabram , treating irrigat ion water from the Waranga basin.

System 3.

This plant was the same as for System 2 except that an extra electrolytic

System 2 Raw 68 ± 2 63 ± 3 25±0,6 124:!:2.5 7.5

j

Treated 67 ± 2 59± 3 27±0.8 126± 3 7.8

System 3 Raw 83±7 90±9 26±1 136:t 9 7.3

Treated 85±6 87±8 31:±:6 141± 9 7.8

cell was added , thereby increasing the effective anode area to 0.91 m 2. It was located on a farm at Lemnos, where water was obtained randomly from an irrigation channe l supplied with water from the Waranga Basin and a farm dam filled by surface-run-off.

Analyses The performance of each system was monitored over a 6-8 month period.

Bacterio logical samples were taken on 13, 20 and 24 occasions respectively, residua l chlorine, colour, tur-

Table 3-Bacterlologlcal Medians and Ranges SYSTEM 2(1)

SYSTEM1 Untreated

Treated(2)

Untreated

4000

SYSTE/ltP)

Treated(2)

Untreated

Treated(2J

Total Count/ml 37'C

500 120-5700

70-66000 (0)

2100 100-65000

665 1-71000 (5)

710 70-5000

235 1-3600 (1)

Total Count/ml 22' C

14150 5300-49000

2135 640-93000 (1)

7200 60-1320000

950 1-380000 (5)

5400 520-41000

1610 30-25600 (1 )

Yeasts and Moulds Count/ml

1 1-20

1 1-510 (10)

1 1-580

1 1-120 (16)

10 1-80

1 1-20 (17)

Coliform Count/100ml

79 1-540

1 1-49(11)

17 1-340

1 -(20)

33 1-350

1 1-350 (17)

E.coli Count/ 100 ml

17 1-49

1 1-13(12)

1 1-23

1 -(20)

6.8 1-170

1 1-130 (22)

60 20-150

30 1-80 (3)

20 1-170

1 1-1900(18)

1-1140

Thermoduric Count/ml

60

50 1-1000 (5)

(1) Measurements made on 13, 20 and 24 samples from each system respectively.

(2) Figure in brackets indicates the number of results of less than 1 / unit volume.

bidity measured on 17, 11, 14 occasions, and pH, alkalinity, ch loride, electrica l conductivity, hardness on 5, 11, 14 occasions .

Bacteriologica l samp les were transported on ice , the delay between collection and testing being approximately 16 hr .

Results

Reductions of turbidity and colour are summarized in Table 1, physicochem ica l characteristics in Table 2 and bacteriological quality in Table 3.

Turbidity and colour were signifi cantly reduced by systems 2 and 3, ' treating Waranga Basin water, but not

by System 1, treating Eppalock water, with higher pH, TDS, hardness and alkalinity . This fai lure may be due to the high pH, since the. residual solubility of aluminium at pH 8.5 would significantly reduce the amount of alumin ium hydroxide precipitated . (Dillon, Hiler and Peters (1975) successfully clarified water of pH 8.2 by electrocoagu lation , but their dosage and the characteristics of the raw water were different .) It was not possible to increase the current in System 1, in order to increase the dose of aluminium, though throughput could have been reduced .

The large variations in raw water quality during the test period were such that Systems 2 and 3 failed to clarify the water on some occasions, even when the current was increased in an attempt to cope with increased turbidity .

The bacteriological qual ity of the disinfected water from each system was good, with marked reductions in all counts, with the exception of the 22·c total count for System 1. The poor clarification being obtained with this unit cou ld account for this.

All systems operated rel iabl y. The need for filter backwash varied according to the turbidity of the water. The anodes gradually became fou led, and had to be removed for cleaning when current flows decreased. This was considerably easier for System 1.

For disinfection , each system aimed at a free ch lorine residual of 0.5 ·mg/I

at the point of use . To achieve this, 1 mg/ I was dosed for Systems 2 and 3 but 8 mg/I was required for System 1 because the point of addition was prior to the fi lter, where much of the chlorine reacted with the entrapped sludge .

Costs

Capital and operating costs for these trials are summarised in Table 4, including estimated costs for replacement of the anodes as they became consumed. In these field tests, Systems 2 and 3 were designed to operate throughout 24 hours so that they took advantage of power at off-peak rates.

System 1 was designed to operate on demand , so that only day-rate power was used.

The total operating costs as listed are approximately twice those for chemical treatment.

(Hubble and Griffin 1978).

Discussion

The poor clarification results can probably be ass igned to the failure of the systems to adjust dosage of aiuminiu m to accord with variations in influent turbidity , allied to the effect of the high pH .

Electrolytic generation of ch lorine from the chloride content of the water, as described in the references, is an alternat ive which was not taken up in these field trials because of the cost of the electrodes required.

All systems would derive cost benefits from operation during the night, at off-peak rates .

Fouling of aluminium anodes by Table4-Costs [Jan. 1977]

1

2

Capital,$ Anodes , $ Power, kwh/kl

1070 12

839 27

3 900(1) 27

1,4

1.4

1.9

Operating Cost, Anodes(1) Chlorine Power (2) (3) TOTAL (2)

c/kl 5.6 3.1 6.1

4.5 0.8 6.4 3.6 11.7 8.9

4.5 0.8 8.6 4.8 13.9 10.1

System

14.8

(3)

(1) Estimated .

(2) 100% dayrate power.

(3) 60% dayrate power.

formation of a layer of bayerite (Al2.0 3.3H20) is known to occur in eiectrocoagulation. Dillon, Hiler and Peters (1975) indicate that anodes of 6000 series aluminium alloy became sealed after approximately 500 operating hours , but this did not occur with anodes of 1000 series aluminium . The tests described in this paper involved operating periods of approximately 200 hours only, so that no conclusions can be drawn in this respect.

Conclusion

These trials on prototype electrocoagulation systems have shown them to have limited value in farm conditions in Northern Victoria. This is mainly because of the large variation in physico-chemical characteristics of the water supplies. require The systems examined further modification before they cou ld reliably provide clarified water from dams or irrigation sources.

ACKNOWLEDGEMENTS The authors wish to e~ress appreciation of the assistance of: Mr K. Calder, Mr I. Patterson and Mr J . Stewart for the col lect ion of samples. Miss L. Ruddick, Miss D. Womersley, Mr P. Drew and Mr R. Stewart for microbiological testing . Staff of the State Rivers and Water Supply Commission for physico-chemical analyses . Mrs C. Calder, Mr I. Gledhi ll , Kyabram Irrigati on Research Station , Department of Agriculture for their co-operation , provision of facilities and operation of the treatment system. Mr G. Cox for his technical advice .

The work was supported by a grant from the Australian Dairying Research Committee.

REFERENCES Dillon, R. C. , Hiler, E. A. and Peters, J . L. (1975) Technical Report No. 66 , Texas Water Resources Institute, Texas A and M University , Texas, U.S.A .

Hiler, E. A. and Lyle, W . M. (1970) Technical Report No. 31 , Texas Water Resources Institute, Texas A and M University, Texas, U.S. A. Hubble, I. B. and Griffin , A. T. (1978) Ag . Eng .

Aust. (7). (3) , 1. lzyurova , A. I. and Ovchinkln, I. P. (1948) Glglena I Sanit 13, (7). 5.

Lyle, W . M. and Hiler, E. ·A. (1972) Transactions of the American Society of Agricultural Engineers, 15, (3), 580.

Paschenkov. Ya . M .. Sil in , E. A. and Yaroslavskii, Z. Ya. (1964) Vestnik Selsko Khozylastvenlo Naukid, SSR, 9, (8). 91 .

Silin , E. A . and Yaroslavskii , Z. Ya . (1964) Tr. Vses .

Nauchn-lssled Inst. Gidrotekhn I Melior, 44 , 219.

Steel , E. W . (1960) Water Supply Sewerage, McGraw-Hill Book Comeany, p. 247-248.

World Health Organization (1971) " International Standards for Drinking Water". Geneva .

19

GIVING NEW LIFE TO EXTENDED AERATION PACKAGE PLANTS J. A. CROCKETT* INTRODUCTION

The extended aeration activated-sludge package plant has become the most common type of treatme nt plant for sma ll isolated catchments . However, in most cases, performance of EA plants is unsatisfactory. A recent survey by Crockett & Oliff , 1977 showed that out of twelve plants surveyed , only one came close to meeting the effluent quality requirements. This survey and subsequent work has high lighted four common reasons for this observed poor performance : 1. no provision for regular wast ing of excess activated sludge and therefore no regular wasting except over the weir with the effluent , 2. unsatisfactory desi'gn of the clarifier , 3. flotation of sludge in the clarifier due to denitrification, 4. difficulty in maintaining good sludge sett ling characteristics.

The first problem is simply solved (but at substantial cartage and construction cost) by providing an on-site ::;torage (either aerated or simply a covered tank) . It will not be considered further. The latter three problems require for their solut ion an understanding of the mechanisms involved .

This paper is intended to offer solutions to these problems .

The solutions have been drawn from recent advances which have been made in the understanding of the activated sludge process .

DENITRIFICATION IN THE CLARIFIER EA plants are designed to produce as little excess sludge as possible and also a relatively stable excess sludge . To ach ieve this the sludge is retained in the plant for long periods . That is , the sludge age (defined as the total mass of mixed liquor suspended solids (MLSS) divided by the mass of sludge wasted per day) is high , ideally from 15 to 25 days depending on sewage temperature.

As a consequence of this high sludge age, slow-growing nitrifying bacteria can be retained In the aeration tank and hence most reduced nitrogen in the influent Is oxidised to nitrate . In the clarifier, oxygen is depleted by continued resp iration of the sludge and under the resulting anoxlc conditions the nitrate can be reduced to nitrogen gas by denitrifying bacteria. These bacteria are a group that can use either elemental oxygen or oxygen in nitrate and the switch from one to the other has been shown to be very fast (van der Geest and Witvoet 1975) .

The result of this production of nitrogen gas within the settling sludge is that large quantities of sludge can be floated to the surface of the clarifier. This problem is not just confi ned to smal l plants (vo n der Emde 1976, Bailey & Thomas 1975, White 1975, van der Geest and Witvoet 1975) .

Clarifiers with mechanica l scum rakes can handle this sludg e to a certain extent but the common hydraulic type skimming device on small tanks will not work effectively as the floating sludge bridges around the sc um drawoff .

The solution to thi s prob lem is to provide conditions su itable for denitrification pri or to the clarifie r. Over the last ten years rapid advances have been made in design of activated sl udg e plants to give nitroge n removal. The early two and three sludge systems us ing methanol have now been sho wn t o be unnecessari ly complex for most wastewaters when compared with the sing le sludg e system (von der Emde 1976). Si mply by allowing anox ic condition s in certa in areas of the aeration tank, virtual ly complete denitrification can be achieved. As we ll as prevent ing den itrif icat ion in the c larifier,

*Chemical Engineer, Gutteridge, Haskins & Davey Pty Ltd 20

the incorporation of denitrification in the aeration tank has two additional benefits : 1. power requirements can be reduced since the oxygen in the nitrate is reused to stabilise the incoming organic material (this saving can amount to 14% (von der Emde 1976) ), 2. the common problem of low pH due to complete nitrification can be partly overcome si nce denitrification uses up hydrogen ions produced during nitrification .

Whilst the single sludge denitrificatiqn system is being incorporated _into an increasing number Of new and existing large activated sludge plants it has only had limited application in small plants (Matsche 1977).

However, it can be simply incorporated in existing and new EA package plants . An anoxic zone can be provided w ithin aeration tanks by installing a baffle and electric powered mixers . The configurat ion favoured by the author is based on the work of von der Emde and is shown in Figure 1.

Anolic Zone iHolnormll Aeration lone

Aeralion Zone &Mi of no,mal Aeration Zone

Figure 1.

Proposed Layout for an EA Plant Incorporating Denitriflcatlon

The important features of this proposed system are as follows : 1. the volume of the aeration anti anoxic zones can be the same as the volume of a conventional EA aeration tank .

Sizing based on an MLSS of 5 kg/m3 and an F/M of 0.05 is suggested, that is a BOD volumetric loading of a 0.25 kg BOD/m3 .d. Thus an anoxic zone can be incorporated within an existing plant .

2. for domestic wastewater the s ize of the anoxic zone shou ld be at least 20% of the total volume of the two zones . The size depends on the nitrogen and organic carbon content in the wastewater.

3. a high mixed liquor recycle is essential since on ly that nitrate which is recycled to t he anoxic zone can be converted to nitrogen gas . The 10 x ADWF (average dry weather flow) recycle means that up to 10/ 11 or 91 % of the nitrate leaving the aeration zone can be rem oved.

The onl y pe nalty of t his system is greater mechanical complexity and co nsequent higher cost , estimated to be about 10% higher than for a conventional plant.

However, there are the possibilities of energy savings of up to 14% (savi ng in aeratio n power less the energy used for recyc lin g mixed liquor and mixing t he anox ic zone) and more importantly , improved performance and decreased labour for operation .

CLARIFIER DESIGN

In the Author's ex perience many p~ckage plant c larifie rs perform poorly due to excess ive solids loading.

White (1976) and Dick (1976) have both discussed the rational design of clarifiers and shown t hat the solids loading

is the crit ical factor. Whilst these authors point out that sludge settling characterist ics determine the maximum sat isfactory so lids loading , it is more reasonable to design new plants on a solids loading basis, than on a surface overflow rate at peak flow (which is the current practice in Australia). The latt er design method can lead to undersized c larifi ers where peak flow is limited by , say , the pump in g system to less than three times ADWF .

For example , if peak flow is 4 x ADWF, the sludge recycle flow 1.5 x ADWF and the MLSS 5 kg/m3 then, to not exceed the maximum solids loading recomme nded by the Author of 80 kg/m2 .d, the surface overflow rate at 4 x ADWF will have to be less than 1.06 m/hr. This is sim ilar to figures currently used . However, if there is a pump well prior to the plant and the pump flow is 3 x ADWF the surface overflow rate will have to be less than 0.80 m / hr at 3 x ADWF to meet the same solids loading criteria .

It would appear to be satisfactory to neglect solids loading at peak flow in most cases since a short period (say up to an hour) with solids loads over 100 kg/m2 .day will be taken up by the blanket bui lding up.

An important operating variable for the clarifier is the recycle rate. Too often this is set at excessive ly high va lues (more than 3 x ADWF) . This results in higher solids loadings on th e clarifier and also in more turbulence . Theoretically, if th e.sludge can be conce ntrated in the bottom of the clarifier to 2 x MLSS concentration then the return rate need only average 1.0 x ADWF . Allowing for returning s ludg e during peak flow periods there should be no need to exceed a return rate of 1.5 x ADWF. BULKING SLUDGE Bulk in g sludge is commonly due to excess ive quantities of filamentous micro-organisms in the sludge. The presence of fi lam ents decreases the settling velocity of sludge particles and sludge is lost over the clarifier weir .

The theory has been advanced that because of their high ratio of surface area to mass when compared to discrete floes, the filaments have an advantage over floes at low food conc entrations. In a complete mix plant (many EA package plants) the sludge is always in contact with the low food concentrat ion in the f inal ef fluent . In a plug flow plant however, the floes are in contact with a high food co ncentration at the start of the aeration tank and therefore the filaments have a lesse r ad vantage . This advantage of plug flow is also gained by the oxidation ditch aeration system as during every circuit eac h f loe particle passes through a high food concentrat ion zone at the wastewater feed point . Thus it would appear that package plants shou ld include some degree of plug flow.

In clu sion of the denitrification zone described in Section 2 would introduce a degree of plug flow and therefore might d iscourage filaments .

Addition of waste ferrous sulphate from stee l pickling is an effective means of controlling sludge bulking and also removes phosphorus .

CONCLUSIONS By app lying some recent advances in the understanding of the activated sludge process to package plants there is a strong possibility that performance of new and ex isting plants can be improved .

Inclusion of a stirred ano xic zone wi ll help to so lve problems with flotation of sludge in clarifiers due to denitrification and might also tend to discourage f ilame ntous slud ge.

The importance of design of clarifiers cannot be over emp hasised . Whil st c urrent design practice based on surface loading at peak flow normally gives adequate tanks, an und erstanding of th e sol id s concentration and transport mechanisms in the clarifier is invaluable in avoid ing incorrect design in some cases .

The cost of the add ition of an anoxic zone to a new 600 perso n EA plant wou ld be about $8000 on top of the co mmissioned plant cost of a conventiona l plant of around $90 000 (including a sludge storage, foundations, fencing,

blower enclosures , testing equipment etc) . Power savings wou ld amount to about $180 per year out of ~total aeration and pumping power cost of around $1300 plus a sludge disposal cost of at least $3000. Th is saving in power cost ¡ might not justify the additional $8000 expenditure on its own, but savings in labour cost due to fewer operating problems , and improved effluent quality , wou ld , in th e Author's view justify the extra expenditure. It must be remembered that few EA package plants are meeting effluent quality requirements at present .

HAVE EA PACKAGE PLANTS A FUTURE? EA package plants have provided a relatively cheap way of complying with legis lation requ irin g treatment of sewage from smal l isolated catchments . Whilst th ey have reduced pol Iution , they have not generally met the strict effluent qua lity requirements now in force. This is because essential parts have been undersized or left off in an effort to reduce Q, cost.

There is now a trend towards genuinely attempting to meet effl uent qua lity requirements and consequ ently the EA package plant is becoming more expensive.

With inc lusion of essential features such as a sludge disposa l system and process refinements to improve performance the EA plant might well become more expensive than other alternatives including rotating biological discs or perhaps larger regional collection and treatment systems .

However there will st ill be cases where the EA process will have advantages . There will probably be more in-ground concrete EA plants in future, with steel package plants being lim ited to the few cases where the plant will not be required for more than a few years . In all cases a proper engineering design wi ll be needed .

Final ly , even if the sales future for EA package plants is perhaps bleak , there is a huge investment in existing plants and these plants will need modification .

REFERENCES Bailey , D. A., and Thomas , E. V., (1975) "The Removal of Nitrogen from Sewage Eff luents by Blologlcal Denltrlflcatlon" Water Pollutlon Control. 497.

Crocket , J. A., and Olliff, R. M., (1977) "Experience with the Design and Operation of Small Extended Aeration Wastewater Treatment Plants" , I.E. Aust. National Conference Publication No. 77/4 , 98 .

Dick , R. I. , (1 976) " Folklore in the Design of Final Settling Tanks" Journal of ' the Water Pollution Control Federation 48 4. April 633 .

Mat sche , N. F., Private Communication 1977 . von der Emde, W. (1976) " Activated Sludge Process II Nitrogen Removal , Phosphorus Removal , Aeration - Transfer of Pure Oxygen" IAWPR Post Conference Continuing Education Courses, Melbourne. van der Geest, A. T., and Witvoet , W. C., t1975) " Nitrificat ion and Denitrification in Carrousel Systems" IAWPR Conference on Nitrogen as a Water Pollutant Copen hagen , August.

White, M." V. P., (1976) " Design and Control of Secondary Settlement Tanks", Water Pollution Control, 459 .

SIMON-HARTLEY AUSTRALIA

Mr Geoff Windfield has been appointed as Sa les/Projects Manager for SimonHartley Australia.

Simon-Hartley Australia was recently formed to manufacture and market the well known range of Simon - Hartley water and effluent treatm ent plant in Austra lia and is based in the offices of S i mon - Carves Australia, in Sydney .

21

INTERNATIONAL CONFERENCE ON DEVELOPMENTS IN LAND METHODS OF WASTEWATER TREATMENT AND UTILISATION Melbourne, Australla 23-27 October, 1978 KEY NOTE SPEAKERS: Dr Curtis C. Harlin, Environmental Protection Agency , USA: - "Land treatment methods in perspective" Mr J. B. McPherson, M.M.B.W. Melbourne: -" Land treatment of wastewater at Werrlbee: Past , present and future" Professor E. J. Underwood, University of Western Australia: -"Environmental sources of heavy metals and their toxicity to man and animals" Professor E. Gloyna, University of Texas , USA: - " Status of lagoon treatment" Mr C. D. Parker, Water Science Laboratories , Melbourne: -" Biological mechanisms in lagoons" Dr G. G. Ci Ille, National Institute of Water Research , South Africa: -" Sludge treatment , utilisation and disposal" PAPERS: Papers will be presented in a single stream.

Surface irrigation with sewage effluent In New Zealand - A case study. B. F. Quinn (Ministry of Agriculture and Fisheries , New Zealand) .

Ecological and agricultural aspects of nitrogen balance In perennial pasture irrigation with municipal effluents. T. Klpnls , A. Felgin (Agricultural Research Organization , Israel), A. Dovrat, D. Levanon (Hebrew University of Jerusalem, Israel) .

Changes In biological parameters on grass, hay and in silage following Irrigation with domestic sewage. K. Grunnet and J. Mol ler (University of Aarhus, Denmark).

Changes In duplex soil caused by drip lrtlgatlon with saline eff luent. R. D. Bond (C.S.I.R.O. Division of Soils, South Australia).

The effectiveness of some crops in removing minerals from soils Irrigated with sewage effluents. A. Feigin, T. Klpnls , H. Bleloral, Y. Dag, I. Shalhevet (Agricultural Research Organization, Israel).

Establishment and performance of Eucalyptus and other trees on land disposal areas irrigated with winery and sewerage effluents. J. G. Edgar, H. T. L. Stewart (Forests Commission, Victoria) .

Overland flow treatment of a municipal lagoon effluent for reduction of nitrogen, phosphorus, heavy metals and collforms. C. R. Lee , A. E. Peters (U .S. Army Engineer Waterways Experiment Station , Vicksburg, U.S.A.).

Water movement in a land treatment system of wastewater by overland flow. Y. Nakano (U .S. Army Co ld Regions Research and Engineering Laboratory; U.S.A.). R. A. Khalid, W. H. Patrick Jr., (Louisiana State University, U.S.A.).

Pilot scale study of overland flow land treatment In cold climates . T. F. Jenkins, C. J. Martel, D. A. Gaskin , D. J. Fisk, (U.S . Army Cold Regions Research and Engineering Laboratories , U.S.A.) Effects of redox potential and pH on phosphate removal from wastewater during land application. I. C. A. Holford (Department of Agriculture, N.S.W.), W. H. Patrick Jr., (Louisiana State University, U.S.A.) .

Overland flow and slow rate systems to upgrade wastewater lagoon effluent.

M. C. Kemp , (CH2M Hill Inc, U.S.A.), D. S. FIiip , D. B. George (Utah State University, U.S.A.).

Effects of cultivation on the availability of metals accumulated In agricultural and sewage-treated soils . D. J. David , C. H. WIiiiams (C.S.I.R.O. Division of Plant Industry, Canberra A.C.T.).

Uptake of cadmium from aqueous solutions onto oxide and clay components of soil systems . I. H. Harding , P. J. Stlgllch , A. 0 . James, T. W. Healy, (University of Melbourne).

The effect of the application of piggery effluent to soils and pastures . J. Jeffrey, N. C. Uren, (La Trobe University, Melbourne) .

The long term effects of land application of wastewater. J. H. Reynolds , M. 0 .

Braun , L. R. Anderson , A. W. MIiier, W. F. Campbell, (Utah State University, U.S.A.) .

AUSTRALIAN WATER RESOURCES COUNCIL WORKSHOP ON GROUNDWATER POLLUTION PERTH February 19th-23rd, 1979

AWWA SUMMER SCHOOL 1980 ADELAIDE 4-8 February "Water for the 1980's?"

Secretary: Dr J . Cugley, State Water Laboratories, Private Bag P.O. , Sa lisbury, S.A. 5108 .

22

Removal of pollutants from sed imented sewage In the overland flow (grass filtration) system . T. Scott, P. Fulton (M .M.B.W. , Melbourne) .

Eco logical studies in lagoons at Werrlbee with special reference to B.O. D. and nitrogen removal. S. U. Hussainy (M .M.B.W., Melbourne) .

The trace metal accumulation in soils Irrigated by sewage and Its effect on the plant-animal system. K. J. Evans , I. G. Mitchell, B. Salau (M .M.B.W., Melbourne) .

Wind effects on oxygen transfer and mixing In facultative lagoons. S. N. Kumar, E. A. R. Ouano (A .1.T. Bangkok, Thailand) .

A pH controlled activated algae system for the advanced wastewater treatment.

I. Sekoulov (University of Stuttgart, Germany) .

Facultative lagoon performance . J. H. Reynolds , R. H. Swiss , C. A. Macko, E. J. Middlebrooks (Utah State University, U.S.A.) .

Factors influencing the treatment of food processing wastes by anaerobicaerobic lagoon systems. B. J. Lyons, J. G. Parker (Water Science Laboratories Pty. Ltd ., Melbourne) .

Effective ditch lagoon treatment of palm oil mill effluent . J. E. Morris, I. W. Cooper, Tan Yee Thong (Sime Darby Plantations Berhab, Malaysia) .

Recirculation and high rate oxidation pond systems . G. Shelef (Israel Institute of Technology , Israel).

Algal denitrification with carbon dioxide as a carbon source. D. L. Regan, J. Skicko, (Division of Chem ical Technology, C.S.I.R.O. , Victoria) .

Studies of the efficacy of polishing ponds In New South Wales , Australia. J. J. Wright, D. T. Lacey , M. C. Goronszy, J. D. Brown (State Pollution Control Commission, New South Wales).

Development of an improved quantitative relationship between bacterial die-off , design and operational factors for anaerobic-aerobic and maturation type lagoon systems . G. P. Skerry (Water Science Laboratories Pty. Ltd ., Melbourne) .

Investigations on the use of sludge as a fertilizer in a market garden area north of Adelal1e, South Australia . M. P. C. de Vries (C.S.I.R.O. Division of Solis, South Australia) .

Vaccination of calves against Infection with the beef-measles parasite Taenla saglnata. M. D. Rickard (Veterinary Clinical Centre, University of Melbourne) .

Elimination mechanisms by soil filtration and application as a hillside seepage system in the area of a reservoir for potable water. Arno Grau (Lehrstuhl fur Siedlungswasserwirtschaft, Aachen , Western Germany) .

Disappearance of microorganisms by Infiltration and percolation of sewage. K. Grunnet , C. J. Bonde (University of Aarhus, Denmark), S. Elsnab Olesen ( Danish Land Development Service) .

The utilisation of waste nutrients for aquaculture. P. Tortell (Commission for the Environment, New Zealand) .

Domestic wastewater utilisation through aquaculture- Studies at Nagpur, India. K. P. Krishnamoorthi , M. K. Abdulappa (National Environmental Engineering Research Institute, Nagpur, India).

Tertiary treatment with aquatic macrophytes. M. A. Simmonds (M . A. Simmonds and Bristow, Queensland) .

ENQUIRIES: For furth er information and registration forms contact: I.A.W.P.R. Conference Secretary Melbourne and Metropolitah Board of Worj<s Box 4342 , G.P.O. , Melbourne 3001 Australia.

Telephone: (03) 615-4431 .

Cable and Telegraph : Metropolis, Melbourne Australia Telex: AA43220

NATIONAL WATER WELL ASSOCIATION Conference and Exhibition SINGAPORE, PERTH OCT. 27-NOV. 10

WATER POLLUTION CONTROL FEDERATION 51st ANNUAL CONFERENCE/EXHIBITION ANAHEIM, CALIFORNIA October 1-6th, 1978

INTERNATIONAL WATER REUSE SYMPOSIUM WASHINGTON D.C. March 25-29th, 1979

HEAVY METALS IN THE ENVIRONMENT London 18-21 Sept. 1979

Call for papers: 500 word abstracts

by September 15th, 1978 to: American Water Works Research Foundation, 6666 West Quincey Avenue, Denver, Co lorado.

-Call for papersFor further information contact Dr D. Barnes , School of Civil Eng., Univ. of NSW. Tel. 02-662-3013.

INLAND WATER - Cont. from Page 17 If the harmful consequences which must stem from this evident lack of co-ordination in resource planning are to be avoided or minimised, the land use planning process must be influenced by those people associated with the treatment and disposal of wastewater- for wastewater itself is a resource and a valuable one , in this arid continent . Inputs by the resource managers to the planning process at the commencement of that process will substantially avoid many of the conflicts mentioned . The very nature of the planning process, which seeks a compromise between a vast number of competing and diverging interests cannot be expected to satisfy any or all of those interests or to totally obviate conflicts. However, if that input process is followed, the time frame for land-use development and the relevant zonings in which it occurs , will pay due regard to the need for the provision of a servicing infrastructure of capital works so located as to function correctly and, if · need be, unobtrusively . Certainly such inputs will ensure that th e decisions inherent in this compromise process are reasonable , are based on the best input data available and exclude those emotive issues which tend to lead to conflict.

The conflicts which are inherent in the use and control of water may appear to have been over-emphasised but at least they are illustrative of the implications and complications of that control.

PESTICIDE RESIDUES IN DRINKING WATER A new technique for monitoring trace organics in water now makes it possible to measure second generation pesticides at levels well below the maxima allowed by the U.S .A. Safe Drinking Water Act of 1974. Compounds covered by the Act, such as 2,4-D and Methoxychlor, are not easily determined by standard gas chromatography methods because of their thermal instability .

While previously used conventional I iquid chromatography methodology could separate these compounds, it sometimes lacked the sensitivity necessary for residue analysis .

A recent breakthrough in liquid chromatography methodology enables the determination of organics in aqueous media even at parts per trillion levels. This new technique called trace enrichment was developed by Water Associates in response to inquiries for an analytical method that: • Can be used to "screen" water samples for residue levels of organics .

• Permits direct analysis of water without recourse to lengthy, less efficient organic solvent extraction .

• Has virtually unlimited sensitivity .

• Can be performed in a matter of minutes.

Pesticide residues determined in minu tes with Trace Enrichment.

,I SpjlbAn1w ,o,.,._,.., J • S f

lOpp&MoMl,on

10,PIIO.w, on IOHO~o, atfttOft ~pp&,....tho oyct,lo,

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I MIH02.I D

tsopp11s., •• ,"

10SPl>tC0<1>« rt 11 IOPf*IMtfty lpou tft -

Col umn :

.1180NDA PAK/C1a

Sim ple :

4 mm x)O cm Ste Up wuer spiked witl'I pr1tlddu

Flg.1.

Sol ven t :

A } H 20

8) CH,CN 60" B,C1.1rvr 20min

o" e Dete"or :

for

Model 440 @> 254 nm ind 280 nm , 0 .0S AUFS

Conclusion s: - legislation has changed little in charact e~ over the last century or so and demonstrates th e need for appropriate policies sensibly applied ; - there is a pressing need to find definition s of wastewater which do not raise emotive issues ; - there must be appropriate and timely "wastewater" inputs to the planning process; - there is a need for co-ordination between many Authorities and at many levels in the planning field and particularly in the land use planning area; - above all, there is a need for co -operation with a willing ness to compromise within acceptable limits to achieve the development to which a community aspires without, in turn , destroying the very resources which sustain the community .

It may be well to heed the words of an old Moslem text • which sings the praises of water. "the Lord added that the water cleans up virility of men and fecundity of women and also makes it easy for women to bring forth children; purifies milk and increases cattle and herds ; it brightens and makes green all over the country through affluence, happiness and riches. So keep the water always clean , do not pour into it dirts and corpse of animals and also avoid to bath in it ." "

The chromatogram , Fig . 1 shows the use of trace enrichment for pesticide residues In drinking water . A 5 ml aliquot of water was drawn from the tap, spiked with residue levels of eleven different second generation pesticides and injected directly into the chromatograph . A solvent gradient . from 100% water to 60% acetonitrile separated all pesticides in about 20 m inutes . Waters' Model 440 UV /Visible Absorbance Detector was used to monitor the separation simultaneously at two different wavelengths. The simultaneous dualwavelength monitoring capability of the Model 440 is very useful in this analysis because different pesticides have absorption maxima at different wavelengths. With this capability, repeated injection and a·nalysis are avoided and the time for the separation is cut in half.

The key to trace enrichment is the Waters' LC system allowing injections of large sample volumes, and a special LC column packing material uBONDAPAK C18 as shown in Fig. 2.

The surface of uBONDAPAK C18 has more affinity for the organics than does the water. If a large water sample volume is pumped across a uBONDAPAK C18 column, the organic

Trace Enrichment conce ntrates organic resi dues from aqueous media.

,11BON D APAK C

.' ..

, ,·;·.r ..

18

non-poluc.olumn

-

. ...

i:1g. 2.

compound s in the water exhibit an affinity for the packing material surface which cau ses them to "adhere to" or be retained by the column . When enough sample has been pumped through the column, a solvent with an increas ing proportion of methanol or acetonitrile mixed with water ~s pumped across the column . This solvent gradient forces the organics off the column sequentially, with each compound emerging as a distinct peak .

Trace enrichment techniques have application possibilities wherever low levels of organics in aqueous media must be measured . For information on trace enrichment techniques call Waters Associates Pty Ltd, 02211 -0552 or 03·347-5605 .

JOURNAL SUBSCRI PTION S AUSTRALIAN WATER & WASTEWATER ASSOCIATION JOURNAL I enclose herewith the sum of $ .. ... .. ....... (Australian) as prepayment for supply of the following issues of 'WAT ER' .

197Marcy O June O Sept . 0 Dec. D Note: All subscriptions conclude with the December issue, renewals are due by the end of February for a full year's subscription. Price, Including surface mail to all countries, is $1 .00 (Aust.) each issue, made payable to the A.W.W.A . 'WATER'.

Name ... . ...... .. ..... . ..... ... ... ..... .. . ... . ... .. ..... . . .. .. ............................ .. . . .... .... .

Address ... ..... .. .. . .. . .. .. .. . ... . . ... . .. . .... .. ... . .. ... ..... ... .... . .. .. .. .... .. ... . . . .... . .. . .... . .

Mail this form to : Subscriptions Manager, F. R. Bishop, 390 St. Kllda Road, c/- Camp, Scott & Furphy Melbourne, 3004.

23

HEARD ABOUT OUR SOLUTION TO POLLUTION?

44 Koornang Road , Scoresby 3179

.., . \ BOBY

Telephone 763 8988 J

~

BOBY ANALYTICAL LABORATORY SERVICES

m

PETTIGREW

CONSUL"l"ANTS PTY . LTD. Pollution Control & Water Treatment Engineers P.O. Box 94 , Rock lea 4106 Telephone 200-1176

INDEX OF TECHNICAL REPORTS ON WASTEWATER RECLAMATION AND RE-USE Produced by the Reclaimed Water Committee Victorian Ministry of Water Resources

By the appropri ate co mbination of impell ers, impell er housings and meth ods of install ati on, th e Model CS31 26 can rem ove a wide vari et y of pollu ta nts.

And th at' s not all! With Flygt's wide ran ge of model s, th e individ ual combinati ons are such th at a Fl ygt Pump can get rid o f your muc k.

Co nsult Fl ygt on handling • trad e was tes • sludges • efflu ents • contami na ted fluid s etc.

FLYGT AUSTRALIA LI:J.V.1:ITEI> A member company of the world-wide F/ygt Organisation.

29 Hope St., Ermington, N.S.W. 2115. Tel.: 858 2399 AUSTRALIA WIDE DISTRIBUTION NETWORK BRISBANE MELBOURNE HOBART LAUNCESTON 59 0566 560 5333 34 3781 31 4077 ADELAIDE PERTH KALGOORLIE 278 2532 65 5111 21 2635

24

Fl 377

1. Report on th ~ Potential for Re-use of Wastewater in Victoria .

November, 1976.

2. The Re- use of Wastewater.

April , 1977.

3. FeasibiWy Study of Wastewater Re-use for Landscape Irrigation in Mildura. July, 1977.

4. Viruses in Sewage and Treated Efflu'ent. July, 1977.

5. Feasibility Study of Wastewater Re- use for Agricultural Irrigation in Bendigo . August , 1977.

6. Strategies towards the Use of Reclaimed Water in Australia .

August , 1977.

7, Feasibility Study into the Use of Reclaimed Water for Watering of Maribyrnong Valley Metropolitan Park .

8. Rate of Bacterial Die-Off in Sewage Lagoon Systems . November, 1977.

9. Planning for the Use of Reclaimed Water in Victoria . February, 1978.

10. A Pilot Study of Groundwater Recharge at Carrum using Treated Effluent. April, 1978.

11 . The Prevalence of Helm inthiasis in the Population of Mel bourne. June, 1978.

Copies of any of these reports can be obtained on request from the ministry.

MARTEK DIGITAL WATER QUALITY ANALVZER/CONTROLLER . . . for multiparameter measurement and control and water and wastewater.

The Mark VII is a reliable portable Instrument for undertaking spot-tests, vertical profiles through water columns, bloassays, bore hole surveys, and long term measurement of water samples aboard floating laboratories, in water treatment and waste water facilities. It can also be used for in-situ measurements in water bodies such as rivers, reservoirs, ponds, lakes, coastal and inland waters, and sewage and Industrial plant effluants.

• Monitors up to four out of eight Interchangeable water quality parameters and will control two parameters.

• Accuracy ±1 % of full scale.

• Controls - ON/OFF with single or dual set points; adjustable dead band ON/OFF; and proportional control.

• AC or DC power operation with Internal rechargeable batteries.

• Portable or installed, unattended use.

• Rugged, splash-proof construction.

SELBYS SCIENTIFIC LTD. Melbourne 544-4844

Sydney 888-7155

Brisbane 371-1566

Perth 321-9431

Adelaide 51-4651

Hobart 28-4691

Monitor ENVIRONMENTAL

POLLUTANTS

wi

th

li~uid

CHromatography

*

Contact BRIAN WALKER SYDNEY (02) 211 0022

MELBOURNE (03) 34 7 5605

AUCKLAND 70 390

WATERS ASSOCIATES, the Liquid Chromatography People REFERENCES (From Page 13)

AWWA 1977 CONVENTION PAPERS "Public Aspirations and Realities In Water Resources Management" Copies of papers presented at the Convention are now on sale in limited numbers . The bound volume of 622 pages is available for $15 postage , packing and handling included.

Send cheque payable "Al/I/WA 7th Convention" to: The Chairman·, Convention Committee, AWWA 7th Federal Convention,

P.O. Box 359, CANBERRA CITY 2601 .

AWWA Summer School 1978 ·Preprints of the lectures are stlll available and can be purchased for $25 from the Secretary, Tasmanian Branch, AWWA Box 336, Sandy Bay , Tas. 7005.

Bellair, J . T. , Parr-Sm ith , G. A., and Wallis, I. G. (1977) "The Significance of Diurnal Variations in Faecal Coliform Dieoff Rates in the Design of Ocean Outfalls" Journal, Water Pollution Control Federation, 49, 9. 2022-2030.

Brown and Caldwell, California . (1977) "Evaluation of Bay and Ocean Discharge of Bayside Dry Weather Effluent From the City and County of San Francisco".

Gibson. C. H. (1978) "Evaluation of Initial Di lution for Ocean Discharges" Final Report to State Water Resources Control Board, Callfornla.

Walli s, I. G. (1977) " fnitial DIiut ion with Deepwater Diffusers" Journal , Water Pollution Control Federation, 49, 7, 1621 -1626.

Wal lis, I. G. and Reinsch, D. A. (1977) "Relative Influence of Initial Momentum and Buoyancy on the Performance of Deepwater Ocean Outfall s", 3rd Aust. Conf . of Coastal and Ocean Engln.

96-102. '

25

THE PARBURY HENTY RANGE OF WATER PURIFICATION EQUIPMENT INCLUDES:

SIMONACCO DISC FILTERS The Simonacco Rotary Vacuum Disc Filter provides continuous filtration of chemical slurries, mineral concentrates, sewage sludges, etc., and can be adapted to a wide range of industrial applications. Available with discs 1.8 m diameter up to 6 discs (24 sq. m) and with discs 3.96 m diameter up to 14 discs (266 sq. m).

MANOR FIL TEA PRESSES Manor Engineering Co. Ltd. equipment is supplied by Parbury Henty for sedimentation, thickening, filtration, chemical handling, pumping, elutriation, flotation, sewage and industrial effluent purification. Manor fully automated presses of the type i II ustrated have extensive uses for materials on short filtration cycles and having â&#x20AC;˘ good cake release characteristics .

SIEBTECHNIK CENTRIFUGES The Siebtechnik Decanter is a screenless centrifuge, in which the solids are conveyed..,Jrom the large to the small diameter against the centr.ffup!t.'.Jprce. The worm acts as a conveyor as well as a_regulating element, and its field of application includes rnaterials which are too fine for the screening centrifuge, provided the solids have an adequate sedimentation rate, ¡ such as flotation concentrates and waste water .

END VIBRATING & STATIC SCREEN Rotostrainer PROBLEMS? The Rotostrainer@ screen is a new concept applicable to total effluent and in-process waste treatment. Properly used, it cleans itself, and will not blind.

Influent passes through the slowly rotating screen . Solids ride over the top and are removed by a wiper. The large mass of falling influent continuously backwashes screen members.

........

The screen revolves smooth'{ and quietly at 10 R.P.M . It won't shake itself to pieces. And its rugged, stainless steel, all-welded construction requires no tension adjustments or periodic maintenance to kl ep it operating, trouble-free for months at a time.

TOO GOOD TO BE TRUE? THERE'S MORE ••• The high-capacity Rotostrainer@ screen (up to 2500 GPM) is less expensive than old-fashioned equipment to purchase, install, and operate. Its low head loss (36 inches) provides an easy fit. even in existing systems.

It performs better than traditional screens. It continuously produces drier solids, 15 to 20% dry weight, down to fines as small as 0.01 0 inch. Its gentle action will not break up the solids it removes. And the Rotostrainer@ screen does all this while cleaning itself.

Contact:

WILLI AM BOBY & CO. (AUSTRALIA) PTY. LTD. 44 Koo rnang Road, Scoresby, Victoria, 3179 Telephone: 763 8988 . Telex : 31868 Also at: Sydney 93 0311 . Brisbane 229 5800. Ade laide 278 4135

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l<ENT Clearspan

P100L series recorders Kent Instruments (Australia) Pty. Limited

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P101 L single-pen rec order/ con troller

P102L two-pen recorder/ controller

General purpose recorders with advanced features The Clearpsan P100L series comprises a range of sing le and two-pen electronic strip-chart recorders and recorder/controllers for applications in the power and general processing industries.

These compact and robust instruments have a 100mm writing width and can measure and record d.c. and a.c . voltage and current, frequency, power, power factor, and temperature .

All instruments in the series employ a d.c. linear E motor to provide a direct pen drive across the scale. ~

the GEORGE KENT group

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The ~~ Aquasieve

For fibre recovery and pollution control • • • • • •

Reduces sewered waste and water pollution Recovers reusable solids to increase total product utilisation Requires minimal maintenance Rapidly pays for itself Installs easily in confined spaces Reduces capital outlay and operating costs

We are more than willing to demonstrate this unit to you. Ring, write or call personally - let's talk.

ANZIEL PTY. LTD. 3 Bowen Crescent MELBOURNE. 3004. Australia.

Telephone 267-1333 Telex 31 -308

32 Hastie Avenue MANGERE, AUCKLAND, NEW ZEALAND. Telephone 633-969 Telex NZ-2473

Study the basic features of a solid-bowl, continuous-discharge Sharples Super-D-Canter Ž centrifuge. ¡

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Internal design and operating G level selected for optimum performance on sludge to be handled . Wide,range of sizes.

Torque overload release is simple and can be reset without tools.

Provision for coagulant additions (internal or external) where optimum use can be made of them.

Selected hard surfacing provided where needed most - feed ports of conveyor, feed zone, discharge ports, housing, flight edges and faces of conveyor.

All components designed to highest standards for operation over a wide range (up to 3100 x G) of G forces .

G level selected according to type of sludge.

Replaceable liners protect casing in solids-discharge area, and in the bowl opposite feed ports.

One-piece, heavy, cast-iron base reduces vibration .

Conveyor and bowl -speed differential infinitely controlled to optimize process performance.

Forced -feed oil circulating system is floor mounted and connected to the centrifuge by flexible connections.

Heavy-duty bearings , designed for long life, support rotating assembly.

High throughput and cost/perform ance because of many internal designs and G levels available.

Highest Sigma (pool surface area x G) available.

12 Tungsten-carbide feed-port inserts for long wear.

13 Heavy duty planetary gear boxes.

14 Automatic operational monitoring systems.

15 Tungsten-carbide tiles in beach area, if required , for particularly abrasive sludges.

The Sharples Super-D-Canter centrifuge is built to the highest standards with no-compromise design. Our philosophy is to give water and wastewater treatment plants a cost-effective , rugged, and adaptable thickening and dewatering centrifuge.

As a result the Super-D-Canter centrifuge is not limited by de-

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Operation of a horizontal Super-D-Canter centrifuge.