Water Journal March 1978

j 1ssN 0310 - 0357

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Official Jowrnal of the AUSTRALIAN WATER AND WASTEWATER ASSOCIATION fVol. 5, No. 1 March 1978 Registered for posting as a periodica l -

Category 'B'.

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EDITORIAL COMMITTEE

Chairman: C. D. Parker Committee: G. R. Goffin M. B. Dureau.

F. R. Bishop R. L. Cllsby Joan Powllng B. S. Sanders A.G. Longstaff W. Nicholson J. H. Greer A. Macoun G. R. Scott 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: P. R. Hughes, 46 Tucker St., Chapel, 4069.

(P.O. Box 466, Toowong, 4066) SOUTH AUSTRALIA: R. L. Clisby, C/- E. & W. S. Q.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, Nlghtcliff, Darwin, 5792.

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

Advertising Enquiries: Mrs L. Geal,

C/- Applta, 191 Royal Par., Parkville, 3052.

Phone: (03) 347-2377.

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[ 1SSN 0310 0367j

Official Journal of the !AUSTRALIAN WATER AND j

,...

l'ASTEWATElfA'SSOCtATION:

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Vol. 5, No.1 March 1978

CONTENTS Editorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

8

European Experience in Water Management - Brian J. Ford . . . . . . . . . . . . . . . . . . . . . . . .

10

The Dynamic State of Perth's Water Supply - B. J. Fleay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13

Extended Aeration in Perth - B. S. Sanders; R. J. Fimmel . . . . . . . . . . . . . . . . . .

16

Nitrogen Removal from Effluent Soil Percolation - K. Mathew; G. E. Ho; P. W. G. Newman . . . . . . . .

20

The West Australian Scene . . . . . . . . . . . . . . . . . . . . .

22

A. W. W.A. Summer School . . . . . . . . . . . . . . . . . . . . .

24

Comparison of Composite and Grab Sa.mples '

- I.M. Lowther; I.G. Wallis. . . . . . . . . . . . . . . . . . . .

25

Personalities and Products . . . . . . . . . . . ., . . . . . . . .

26

Conference Calendar . . . . . . . . . . . . . . . . . . . . . . . . .

29

INSTRUCTIONS TO AUTHORS ·, Articles should be of orlglnal thought or reports on orlglnal 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 The Westfield Wastewater Treatment Plant is situated 23 kilometres south-east of Perth. The incinerator, which was designed and built by Hawker Siddeley Water Engineering, is a 3.27 metre diameter, six-hearth furnace and has a design feedrate of 0.9 tonnes per hour of sludge, grit and skimmings. The combined sludges and grit are fed into the furnace by a chain and flight conveyor. The conveyor, in turn, is fed by a live bottom hopper which also acts as a storage area. The skimmings are separately injected into the combustion hearth of the furnace.

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Process Engineering Thermal and chemical sludge conditioning plants TC Incinerator for screenings Multiple hearth, fluidised bed, rotary drum sludge incinerators Static grate incinerator Dissolved air flotation Carbon regeneration and absorption systems

Biological Engineering Standardised activated sludge plant for small populations of up ! to 20,000 persons Extended aeration plant, Aerobic sludge digestion.

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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 applicatiqns. 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 FILTER 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 illustrated have extensive uses for materials on short filtration cycles and having good cake release characteristics.

SIEBTECHNIK CENTRIFUGES The Siebtechnik Decanter is a screenless centrifuge, in which the solids are conveyed from the large to the small diameter against the centrifugal force. The worm acts as a conveyor as well as a regulating element, and its field of application includes rcaterlals which are too fine for the screening centrifuge, provided the solids have an adequate sedimentation rate, such as flotation concentrates and waste water.

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AP 108

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

FEDERAL TREASURER: J. H. Greer, CJ- 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. Mitchell, CJ- Envirotech Australia Pty. Ltd., P.O. Box 220, Artarmon, 2064.

Victoria: R. Povey, P.O. Box409, Werribee, 3030.

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

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

Victoria Square, Adelaide, 5ooq.

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

West Perth, 6005.

.EDITORIAL WINDS OF CHANGE This issue of "Water" contains papers describing aspects of the problems facing the rapidly developing city of Perth.

In 1976, the Metropolitan Water Board in Perth decided that its objects and responsibilities be reviewed in a detached, objective study. The Board engaged Binnie International (Australia) Pty Ltd to prepare a Development Study Report and this was released to the public by the Premier, Sir Charles Court, on 28th February, 1978.

The termination of the National Sewerage Programme cut off considerable funds available to the Board over recent years.

Traditional funding from loans for capital expenditure showed signs of proving inadequate so other measures were investigated .

Association Members who attended the A.W.W.A. Conference in Canberra in September last year will recall the lively discussion that occurred from the papers presented by Mr Eric Gilliland and Professor S. H. Hanke. Their philosophy of marginal cost pricing is included in the Development Study. Marginal costs are forward-looking and not based on past investments as are accounting costs. Analysis conducted during the Study has indicated that the marginal cost of supplying additional quantities of water to Perth is likely . to more than double by the end of the century.

The Report sets out a series of policies and options that the Board should consider. Emphasis is placed on the establishment of corporate objectives as guidelines for the Board's staff. These would provide the base for determining the long-term strategies for the different services.

Public participation in the Board's decision making is advocated.

This is to include public education on the need to conserve water and in water-saving techniques.

The Report recommends that the Board should urgently investigate the feasibility of using septic tanks permanently in some areas. This will be an interesting exercise in public participation in Board decision-making.

Considerable discussion will arise in the implementation of the options outlined in the Study and the $200,000 aut layed for the Report may be saved many times.

D. MONTGOMERY, 14.3.78 Chief Engineer, Metropolitan Water Supply, Federal President, Sewerage and Drainage Board, Perth A.W.W.A.

Tasmania: P.E. Spratt, CJ- Fowler, England & N e w t o n , - - - - - - - - - - - - - - - - - - - - - - - - - 132 Davey St., Hobart, 7000.

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

Thanks to the West Australian Branch for organising contributions to this issue.

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 .

2. Associate-experience In the W. & W.W. Industry, without formal qualifications.

3. Student .

4. Sustaining Member-an organisation Involved In the W. & W. W. Industry wishing to sustain the Association .

7

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conducted the second session on instrumentation, chemical handling, flotation and turnkey installations.

Speaker for the conference dinner was Mr Barry Cohen, . MHR, and the plant inspection was at the Wyoming Treatment Works and Plot Plant .

ASSOCIATION NEWS WEST AUSTRALIA The first meeting of the Branch for 1978 was held in February when the Authors of the recent study on the Swan and Canning Rivers presented and defended the highlights of their report . Our thanks go to the principal authors , Mike Fitzhardlnge and Max Hipkins of Forbes and Fltzhardlnge for an interesting and well attended meeting . 路 Four members of the Branch attended the recent Summer School in Hobart and all felt the Tasmanian Branch should be complimented on an excellent week . There was some feeling however about the rather unfriendly odds discovered at Wrest Point, as this local " hazard" certainly increases travelling expenses!

NEW SOUTH WALES On the 16th February, Mrs Penny Gadiel of Water Diagnostic Services addressed a General Meeting. Her subject was : " Practicability of Use of Polyelectrolytes for Potable Waters" .

The subject provoked much lively discussion as it appears that the N.S.W . Government is at last giving approval to the use of polyelectrolytes .

After the Meeting, those of us who were able to stay adjourned to a local restaurant. I guess it is the first time that Mrs Gadiel has been escorted to dinner by fourteen gentlemen. . In August 1977 the Water Research Foundation arranged a tour of the Water Laboratories complex at Manly Vale for senior secondary school students .

A prize was offered for the best essay submitted after the visit , and was won

by Jeff Ellis of the James Ruse Agricultural High School , Carlingford for an excellent, well illustrated report on the Importance of Hydraulic Modelling. 路 1978 season started with a clean drive down the fairway of the Gosford Golf Club , as the weekend Regional Conference swung into action on the 17th March . The venue was the ever-popular Hotel Terrigal, and the technical and social sessions on the Saturday and Sunday were as stimulating as ever .

Messrs Barnes, Skinner and Spangaro spoke on aspects of sludge technology in the first session , and Dureau, Mostyn , Gebbie and Scott 8

The Chairman of the Water Research Foundation of Austral/a, Mr. J.G. Beale [left], and Professor H.R. Vallentine, Head of the Department of Water Engineering at the University of New South Wales congratulates Geoff Ellis on winning the Water Research Foun dation's essay competition.

VICTORIA Eighty-five members attended the first meeting for 1978 which路, in line with tradition, took the form of a technical inspection . This year' s inspection was made in leisurely style from aboard two launches as they cruised around the Port of Melbourne, under the Lower Yarra Crossing and then up the Maribyrnong River. The view of things from the river, supplemented by explanations of points of interest by experts on board the launches , made for an excellent and informative tour .

Following the tour the party disembarked adjacent to Flemington Racecourse to sup on chicken, pavlova and champagne . No one could accuse the Victorian Branch of doing things by half and this function certainly got the year's activities off with a bang!

Many toasts were drunk on the return voyage to our worthy Secretary, Robin Povey, for making the arrangements for this meeting . I believe that some members were singing his praises well into the night!

The second meeting was just as well attended, despite the journey to Geelong, and past that fair city to their sewerage outfall on the ocean at Black Rock . The technical session was conducted by Mr Ian Wallis of CaldwellConnell , on the subject, Design of Ocean Outfalls - a subj ect in which he specialised during his sojourn in U.S.A .

The April meeting is a joint meeting with the Civil Engineering group of the Institution of Engineers , Australia. The topic for the meeting is "Package Plants" and three people with expertise in various aspects of package plants will present short papers.

QUEENSLAND Queensland BranQh has had a successful 1978 to date following a prolonged Christmas break . On 8th March, Habib Yesdami of Queensland Institute of Technology's School of Biological and Environmental Science, spoke on the subject " Limnology" . Dr Yesdami is an expert on the microbiological aspects of Environmental Science .

17th May; Dr Peter Wood of Q.I.T.'s Paramedical School, on Transmittable Diseases in Water and Food . Dr Wood previously spoke at an AWWA/QIT symposium in 1977 following the finding of cholera in the Albert River at Beenleigh (S .E. Old) earlier that year.

28th June: Annu aj Presentation of Plant Operators' Certificates to all the Local Authority and Industry Plant Operators who have satisfactorily completed in 1978 the correspondence courses for operators of water treatment, sewage treatment and/or swimming pool plants . This is the路 climax ot a course sponsored by AWWA , under the guldance of the Dept . of Local Government and supervised by the Education Dept . Mr Michael Lever will speak to the operators and others present at this meeting.

11th July : Combined meeting with the Institute of Chemical Engineers at Queensland University; Dr Frank Barnes of the Metropolitan Water Works, Melbourne on "Waste Water in the Melbourne Metropolitan Area" .

The Queensland committee has been considering the following: Federal Council's recent decisions on the standards and qualifications for membership of AWWA; Plant Operators liaison ; AWWA image in the community; 8th Biennial Conference at Gold Coast/Brisbane in 1979; and format and programming of our six meetings for 1978.

Brisbane ~ Branch meetings are usually dinner meetings, held at the Majestic Hotel, George St., Brisbane commencing about 6.00 p.m. Changes in locations and times are advised to members when necessary.

Murray Allen (Fed. Councillor and Old Branch Committee Member) has been granted 12 months leave of absence to travel overseas with his wife Phyl , visiting family In England, and' sightseeing on the Continent . Phyl and Murray are due back at their retreat on the side of Tamborine Mountain (Gold Coast hinterland) in October. - Believe it when we see them!

Geoff Cossins (Old . Branch President) as Investigations Engineer, Water Supply and Flood Mitigation , Brisbane City Council , claims that he cannot be blamed for the current B.C .C. water restriction s - It was an act of God and to show good faith has accepted th e position of AWWA liaison committee member on the Water Branch of I.E. Aust. - Old Division.

Alan Davie has recently completed his Graduate Diploma in Environmental Engineering at Q.I.T . Brisbane , and in doing so has won the Don King -Scott

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Memorial Prize for the top graduating student. Congratulations Alan.

NEW EDITOR

Peter . Nystrom (Member, Qld Branch), 1 N.Z. High Commission in Boroko , Port Moresby, P.N.G. (P .O. Box 1144, Boroko) has recently writteri to the Old Branch , offering contributions to "Water" etc .

TASMANIA General activities of the Branch have been in abeyance to some extent lately as the Branch Committee has been in toto the Summer School Committee.

Having completed that task successfully the committee is now back to Branch affairs , and has made arrangments for John Bowen to deliver a paper in both Hobart and Launceston during May, the subject being the Ti -Tree Bend Sewage Treatment Plant, which was recently commissioned for the City of Launceston . The meetings are to be followed by a site visit which will give southern members an opportunity to meet those in the north of the State.

Meetings are also being arranged for June and September, the latt'er to be the A.G.M. It is likely that the June meeting will be a combined one with the Environmental Branch of the Institution of Engineers .

The Branch Committee continues to be the same old stalwarts with one .exception - Tony Young has taken over the reins of Treasurer from Bill Nicholson. It's good to see a new face up there and we would like to see more members become interested in Branch affairs at Committee level - so give it a thought when nominations are called for the Committee prior to the A.G . M.

SOUTH AUSTRALIA The 1978 program began with a combi~ed meeting with the Hydrological i Society of South Australia .

Approx·imately 70 members of both the Association and the Society heard a panel of three speakers on the subject of the Blue Lake, Mount Gambier. Mr. G. F. McIntosh of the E. & W.S .D. spoke 1 on the "Blue Lake in the framework of Regional Water Resource Planning" . Mr. P. C. Smith of the Dept. of Mines and Energy spoke on the "Blue Lake in relation to the Regional Groundwater", and the final paper was given by Mr. J . Turner, C.S.I.R.O., dealing with "The Blue Lake Study the application of isotopes to groundwater and lake water balances ."

The Branch meeting of April 7th was a Wor~s visit to the Hope Valley. Water Treatment Works. Mr. M. J. Porter of the E. & W.S.D., supported by his staff, conducted a party of 60 members over the Works .

E. A. (Bob) Swinton has taken on the Job of Honorary Editor of this journal.

Bob has been a member of the Victorian Branch Committee for some years, and has served on the Editorial Committee for the past three years .

He is a Principal Research Scientist in CSIRO, in the Water Technology Group of the Division of Chemical Technology . He started up the CSIRO pilot plant for physico - chemlcal treatment of wastewater, and has a continuing interest In aspects of wastewater re-use and water treatment.

His main speciality, however, is ion exchange , and he Is currently developing a continuous version of the Sirotherm process for desalinating brackish water, in conjunction with engineers of the I.C .I. Central Research Laboratory.

Bob is an Englishman , and graduated from Manchester, 1942. He joined the CSIRO in 1951, so he is well established in the Australian scene. He was at one time President of the Society of Chemical Industry of Victoria, and says that both that Society and the A.W .W.A. seem to have more vitality than those of the other professional associations. This is probably because of the multi disciplinary approach to a common set of problems.

WATER PLANNING WORKSHOP A water planning workshop was held on 29-30 March 1978 under the auspices of the Australian Water Resources Council (AWRC). The objeictive of the workshop was to investiga1te principles for water resources planning in Australia .

The workshop was hosted by the Melbourne and Metropolita1n Board of Works and organised by the AWRC Technical Committee on Planning and Management. It was attenoled by over 50 invited participants, including senior representatives from all of the major water authorities in Australia and a number of academics and consultants .

After the opening by Mr. Best , Deputy Chairman of the M.M .B.W ., the keynote address was give1n by Sir

Bernard Callin an. Authoritative speakers from each State outl ined their c urrent position s in water planni ng , and s yndi cates t hen d i st:ussed the situ ation . O n t he second day , add ress es on the su bjects of plan ning and managem ent were g iven by Dr O'Bri en of th e Cent re for Environ mental Studi es, Un iversity of Melbourne, by Mr I. Meac ham of the V icto r ian S.R .&W .S.C., and Mr N. W. Fisher of the De partm en t of Env iro n me nt Housing and Com munity Develo pme nt .

Th e sy ndic at es t hen disc ussed princ ipl es and guidelin es for plann ing o f wat er resour ces , a nd t he n deliberat ions were formu lated in to a join t statement .

There was general agree ment at the workshop that water pl anni ng in Australia was entering a new era and that a number · of Im proveme nts on current method s of water plan nin g were required . These incl ude among other thing s the con sideration of fi nancial , environ mental, admin ist rative and lega l aspects of pro posed deve lo pme nts at a mu ch earli er stage in t he plan ning process ; th e need fo r p lannin g to be more flexible an p respo ns ive to rapid ly changing conditions and uncerta inty ; the ability to id entify and res pond to public needs, priorit ies and as pirat ions; revi ews of in stitutional arrangem ents and integration of water pl ann ing with other resource and envi ronm ental pl anning; con sideration of demand management ; and t he re-evaluati on of existin g sc hemes to determi ne if they can be Improved or chan ged . A stro ng need was ,also seen for a publ iceducation prog ram in water resources both to devel op a greater pub li c awarenes s of water managem ent iss ues · and to allow fo r effective comm unit y involvement I n m ajor, d eci s io ns .

Deficiencies in baselin e data rel at ing to other disciplin es in com pari son to water resources data were hi ghli ghted as a key area for iv, mediate acti on.

The workshop consi dered t hat the concept of a planning approach aim ed at meeting the requirem ent s of several objectives (e .g. economic , environ mental, social) was now ge nerally accepted, but th at th e specific methodology ou t lined in th e U.S. Principles and Standards was not suitable for wat er plannin g in Au st ra lia.

There was general agreeme nt t hat guidelines for Aust rali an w ate r planning should be developed as soon as possible usin g the res ults of th e workshop as a bas is.

A numb e r of principl es and guidelines developed by syndi cate groups of the wo r k s hop were considered and the se will provide t he basis for the development of general guidelines for water resource s plannin g in Australia by the AWRC Techni ca l Committee on Planning and Management . The proceedings of the works hop will be published shortly. It will contain the papers presented at the workshop together with a summary of th e resul ts of the two syndicate and pl enary sessions referred to above .

9

EUROPEAN EXPERIENCE IN WATER MANAGEMENT BRIAN J. FORD

This is an edited abridgement of the keynote address delivered by Dr Ford to the AWWA Summer School in Hobart, Feb. 1978.

Keynote or Undertone?

Water purification has gradually happened over thousands of years; those of you who have trained in the field and spent all or most of your working lives active in It have acquired a whole armoury of received ideas and traditional concepts which it may now be time to adjust or even to abandon altogether. I seek to persuade you to conceptualise water purification not as a technological sophistication, but as the optimising of natural ecological processes . Sub-themes like this can do much to reorientate our attitudes towards the subject and, as the undertones of a musical instrument enhance the sound of Its key note, so the subtle alteration of our way of looking at a discipljne can reinforce and diversify our studies, That is how I see a 'keynote' address .

Wonderful Water Firstly, what is it that we are trying to manage? Water is not just a handy and convenient universal so lvent . It refuses to obey many of the fundamental rules of science and just as wel l: without It and its peculiar behaviour, life would not be possib le. The fact that water Is composed of two elemental gases, hydrogen and oxygen In the ratio of 2:1, may be elementary enough ; but how often have you stopped ,to realise that all other compounds of similar complexity tend· to be gases at standard temperature and pressure-the common oxides of . sulphur, carbon and nitrogen are examp les. If water is unusual In being a liquid, it is almost unrque in that its solid phase-ice-floats on the liquid water.

If ice did sink, as it should, we would have a negative feedback cycle In the lake: water would cool and freeze from the bottom, protected from the sun , insulated from the warming effects of unfrozen water masses. The aquatic population would be forced nearer and nearer the surface until left stranded in the dry air. It is th·ls strange but fortunate circumstance that makes the Earth such a pleasantly inhabitable planet.

Water is also corrosive. It may not seem so but this is because it has already reacted, violently in many cases, with most of the availab le reactants. Many of our surface rocks contain the -OH radica l derived from hydrolysis; and some metals-such as sodium-will virtually explode on contact with water. It will attack steel, too; we call the phenomenon 'rusting' , but it is still enough to destroy the fabric of a European motor car within a decade or so .

Do not see water as an everyday, undistinguished liquid, then; it is truly a phenomenal substance. Our dependence on it is profound. Yet it is interesting to put our demand into 10

Brian Ford Is a research scientist and science Journalist from the Science Unit, Cardiff, Wales. He has published many papers and books, the latest of which, "Microbe Power", has explored mlcroblology In terms which can be fully understood by the layrnan. He Is also deeply Interested In microscopy, and Its beginnings.

perspective . How much water exists? The volume of the hydrosphere is 1,370 x 106 KM3. It amounts to 7% of our planet's total mass .

Only 3% of this water is fresh, and three-quarters of this is locked up in frozen form and much of the remainder is held in lakes. The amount remaining in rivers and streams is as little as one ten-thousandth of the global freshwater total, that is three parts per million of the whole.

The total waste water output of the globe is a little less than one part per million . Of the vast amount of saline water available for use as an effluent sink, most is remote from areas of civ ilisation. Major cities frequently collect around estuaries, which concentrates the wastewater load further.

Meanwhile demand and production of waste is steadily increasing .

By the end of the century, the urban pop1,1lation's demand for water will increase four or five-fold even at the most conservative estimate; in theory it could even increase ten times over present levels of demand.

The Past-and the Future water. The European's Thus must a world citizen look view imparts special dimensions to the question of water management . Some of these are at variance with your experience in Australasia or in the United States. The first of these is tradition . Purification of water and the management of the resource has naturally evo lved in Europe since before recorded history. Naturall y heated waters were tapped for domestic use long ago, and the primitive water ducts were hollowed out of three-stumps .

Europeans know that a few centuries ago our water supply was not only inefficient, but dangerous; our historical view of piped and purified water is strongly flavoured by the knowledge that water once transmitted great epidemics of cholera and typhoid that did not merely interfere with a growing and newly nascent nation, but which threatened a long-standing and deeply traditional society .

We have seen the derivation of filtering methods-like the slow sand filter used in London-which were formulated on a strictly trial-and-error basis or pure pragmatism, yet which w<;>rked well. Only now are we realising that the sand grains alone are no filter for pathogens; it is the complex communities of micro-organisms ·in filter beds which are specialised to do this on our behalf. In an era of presclentific craftsmanship, you could afford to experiment, trying one way and then another, until the practical answer emerged.

But in a new society- like Australia-one tends to look more for scientifical ly proven techniques which have a prime facle rel iabi I ity.

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International Cooperation A second factor is the question of national boundaries. In Europe, water for one country often comes from another nation state .

In recent years we have seen severe pollution in Western Germany by the great steel plants of the Ruhr. Germany 's effluent is Holland's intake and the water of the Rhine was seriously contaminated by the time it reached the Dutch border , just in an age when Dutch demand was increasing .

Since 1953 the attempts to control upstream pollution of the Rhine have been coordinated by the International Commission for the Protection of the Rhine River Against Pollution to which all the riparian states belong. Naturally enough, not everyone is as interested in cutting down pollutant leve ls: at a rough estimate there seems to be a direct correlation between the level of protest in the community and the percentage of phosphate in the water.

In spite of Dutch protests, the quality of the Rhine water has deteriorated steadily. Flow rates in the 1960's dropped by 20% and dissolved oxygen by 10%. Over the same period, BOD increased by 25%; nitrate by almost 50% , and phosphate virtually doubled. The two other important rivers that feed Holland-the Meuse and the Scheidt-are less serious problems and the Belg ians and Dutch have reached a formal agreement which has stabilised the situation .

The planning of water management policies on a European, i.e . community-based , level, will help to overcome conflicts of national interest like this. Not that they will overcome deep-seated patriotic or chauvinistic motivations!

Wales , as an example , provides much of the water supply of inland English cities such as Birmingham; and the Welsh people-ethnically and culturally distinct from the English in many ways-sometimes consider this to be a form of unjustified and poorly rewarded pirating of a valuable resource.

Water, water . .. everywhere?

A third distinction between the European and Australian view of water management is that Europe is not "short of water" . Rainfall is reliably high and the whole land mass is temperate and verdant compared with much of Australasia . A " severe shortage", such as our drought of 1975, would problably seem I ike a super-abundance to someone trying to irrigate part of the deserts of Central Australia . This leads to further historical perspective . Nations like Australia enlarged their support systems as their population increased . Your history of water supply has , over its relatively short life, shown a close correlation with the demands put upon it.

However, in Europe we have become blinded by generalities. For example, I have said that Europeans generally have quite enough water to manage, but amounts on paper do not always concur with amounts on the ground; and mean levels do not reflect day-to-day conditions.

Consider Cartegena, in Southern Spain. There an entire year may pass without any rainfall. When it does rain , precipitation occurs within a matter of hours and in this period the entire rainfall for a year may occur. The result is erosion of the already poor agricultural land, flood damage and a serious risk to safety and life. Such a phenomenon is familiar in Australia, but to the European, areas like this are so exceptional that they do not ordinarily receive the consideration they should-indeed the existence in Europe of the climatic behaviour just described would surprise a good many specialists in Britain .

The concept of mean can be deceptive even in Northern Eur.ope. The Meuse, which flows from Belgium into Holland , and is entirely rainfed , has a mean flow rate of 250 m3/sec and yet the actual flow under summer conditions can be virtually nil.

Europe- Past ...

The European's view of water management, then, has several important distinctions ; it has evolved through tried and tested traditional means which are often poorly understood . It has laid strong emphasis on the notion that water is a national resource, and that the solution to one nation's effluent problem can be the origin of its neighbour's difficulties . The who le idea of water management has been

founded on the principle that there is abundant water to manage; and the importance of water as playing a role in public health , and as a greatly-improved commodity compared with what we would have provided a century or two ago . . . . And Future ... Holland And yet things are changing . For many years the Dutch have used groundwater as a standard supply of potable water. Its advantages are many: It is readily available, has a predictable quality, and is bacteriologlcally sound . Given such a convenient supply , it was natural that groundwater would be exploited as a primary resource, surface flows only being tapped off when necessary to supplement supplies .

However, when periods of contamination of surface water are likely, as in the case of Holland , this policy might be better turned on its head : thus we should harness surface waters as much as possible for as long as practicable , confident that large groundwater reserves existed as a back-up when the quality of surface supplies decreased . The Dutch emphasise that water is nobody's property, in contradistinct ion to countries such as Italy and Japan which have declared that all water belongs to the government . Though the Dutch have had a series of relatively passive controls over such primary interests as navigation and recreation they have had no legislation covering water management . At present a general law is being formulated, during a relat ' â&#x20AC;˘ly difficult time in m for water control Dutch politics , and a complex five-year is under way . Th is includes emphas 1:, , PPP-the 'polluter pays principle'-and strict licencint of discharges into waterways . Something like 100 million guilders are raised annually in so-called pollution chargP-> where the levels of nitrogen and oxygen demand of an effluent are related to a strict financia l scale .

France A somewhat different approach has been adopted by the French , who are as addicted to regulations as they are to the suppository . The Civil Code and their Code of Public Health both define the limitations that apply to users of natural watercourses on their land, stipulate that barriers must be maintained around intakes for human consumption , protect water mains and so forth. One example of the long line of legislative controfs and enactments is an act which lays down general water regulations and enforces riparian Ian.downers to apply for local Authority permission to use the water. It is a complex act , and It was pjissed on 18th April , 1898. The French consider this to be somewhat long In the tooth, and the Act of 16th December, 1964, did much to bring together such conflicting Interests as agriculture and industry ; water sports and fisheries ; water conservation and the purity of supply . lest that sound \s though the French legislation was making an uncharacteristic leap into the present , it may come as something of an antidote to realise that the 1964 Act was intended to complement all the earlier legislation , and not in any way to replace it!

Germany In Germany water is managed on a more parochial basis , though through well-coordinated machinery. A projection by the Battelle Inst it ute for 1969-1985 lies behind much of the German planning : it is suggested that heavy industrial use of water would increase from 6.5 to 9 x 106 m3/d , whilst domestic and small industrial users would produce wastewater at a rate that rose over the 16 year period from 8.7 to 14 .7 x 106m3/d . During the previous twelve years from 1957, by comparison , the total volume of wastewater had increased by 75% whilst the residual pollution load rose by 50% .

German water-management lies in the thousands of Water Associations spread across Federal Germany . They are selfregulating and independent , and raise lev ies by way of membership fees which vary according to an industry's output of wastewater , the number of employees, the factory's products , its production processes and the chemical nature of the effluent .

On Federal level, a new Wastewater Charges law proposes complex formulae to levy 0.5% of domestic cost index towards pollution control and waterway improvement.

11

United Kingdom A fou rth example of the way Euro pe has tackled water management may be found in United Kingdom practice . The variou s earlier attempts to regulate water su pply an d its control ca used so me co nflict and a certai n measure of dissipation of effort. Part of the reason doubtles~ lay in com- · placency: in absolute terms, there is no shortage of freshwater in Britain . The mean daily flow is equ ival ent to 190 x 106 m3 / d for 54 m ii lion peop le. There is therefo re no shortage as such: the on ly difficulties lie in the geographical distribution of the water, which falls mostly in the Wes t whilst it is needed by the population and by indu stry predomimantly in the Midlands and South -East . Under the terms of the Water Act , 1973, th ere are now ten Regional Water Authorities .

They are obliged to raise whatever income they require to balance the books , and have considerable freedom in doing so. The control of pollution is bro ugh t about by laying down standards of eff luent purity , which are left to an industrial establishment to meet in it s own way. As a rule, this is a satisfactory way of doing things . The difficulty is that t he penalties for breaking this regulati·on are derisorily small : the maxi mum penalty for a first conv iction is U. K. ·£200.

However in parts of Britain we are beginning to feel the pinch of limitation s , not of quantity , but of quality. Nitrate levels in th e River Lea have rise n steadi ly and in conditions of low flow may pose a hazard of co nsiderab le proportions - and in a .case like this, who are we to apportion blame to users of agricultural ferti li sers who may ind irect ly pollute waterways without reali sing it , particu larly since some of the nitrate may be indirectly of nat ural or microbial origins? This problem is beco ming stead ily worse .

Indeed , there is a certain irony in that, just as London water is rega ining it s clarity and its fish populations, its dissolved nitrogen content-as nitrate and nitrite-is pos ing a new and in some ways more insidious threat .

Too Many Cooks?

I have outlined how four member nations of the European Community go about the business of water management.

The ways they adopt to attack the prob lems vary; but the aims are of course similar and in many respects they mirror the aims of all of us. Deficiencies rema in , however. One of th e greatest is the enormous comp lex ity of the rules and regulations that apply to water management in its broadest sense: altogether there must be tens of thou sands of bodies in Europe responsible in one way or another for water, its purity, and its distribution.

Now it is true that so me attempts have been made to lay down standards. But in Eur9pe at the moment too many bodies are doing so . NATO are investigating a set of standards; WHO are putting forward anoth er; whil st the EEC itself is drawing up a third group . The OECD publish documents and reports too . Four separate bod ies are considering the same end , and. what is even more absurd , the same people crop up time and time again on quite different committ ees and di scuss ion groups; all of them duplicating the same effort and reaching, no doubt, sligh t ly different conclusions in so me irritating respect-and particularly in regard to b,iCterial and viral.standards .* The difficulty with our lack of criteria emerges when we try to assess how mean ingful the _standards might be. Thus the EEC has suggested a stand ard of no virus per 10 litres of drinking water or water for sw imm ing. Why not 1 litre, or 100? Why not 9½? How does one virus particle per 10 litres compare- in terms of cost and safety margin-with the death rates on the road s or in the home? Ind eed (and thi s is a point with which I suspect many of the eng ineers amongst you may concur) do viru ses matter? We have managed without bothering too much abo ut them in th e past, so why should we now suddenly lay such stress on th em as though they had only just been invented? The reason for that is a matter of professional pride, sure ly . If you market a product as a profess ional , you must want to know what it s specifications are: wh at you are producing, in other words .

On the other hand, only agreed criteria can ever make sense out of the extent to whi ch viru s cou nt s can be made

12

meaningful . At the moment there are none : and any engineer who raises his eyes to heaven when the top ic comes up has my sympathy. The argument that viruses do not matter, though, will not do ; an epidemic in NeV:,. Delhi involving 30,000 cases of infectious hepatitis is one example of what our ignorance of viruses in drinking water can cause.

Conclusions In some ways this failure to come to meaningful terms with the quantificat ion of water-transmitted pathogens is a symptom of what I have called our " blind spot " towards microbes and the microscopic world in gen 11ral.

I am not personally bemused or irritated: by the growing importance of viruses in the practice of water management.

Quite the converse-my principal reaction is one of surprise that we have had to wait so long for virus standards to be laid down . I find it astonishing that microorganisms and viruses have remained so much in a limbo , and a growing tendency to think in microbial terms when we look at eco logy - particu larly the micro-ecology of water purification - can exp lain a host of phenomena which at presen \ remain largely myste rious . During this week we will hear a good deal about t he concept of eco logical integrity, for example; an ex traordinarily attractive way of examining Jhe environment's capaci ty to assimilate given products ' as a metabolic substrate without losing its normally balanced populations of microbes and other organisms. Yet would it not be helpful if we cou ld quantify the exact role and ,'function of each species, to predict and modify biological ~recesses perhaps by seeding or microenvironmental control? When we look at a sludge tank , a " microbe reactor", as I prefer to call it-since the term better connotes the beautitu lly coordinated communities of microbes that live there - :it would be better to see it as a busy and teeming world working on our behalf in a manner that has existed for 100 times as long as mankind him se lf! We shou ld respect our unseen confederates rather than dismissing them as Invisible, somewhat unhygienic entities which are far less interesting than their endproducts.

I cannot presume to interpret the topics that this week's pan el of lectures are to expound, and it would seem impertinent of me to suggest in advance what you might make of them . But I could entreat everyone here not to think profoundly about where water management is going - but to rethink it. Water supply is a topic that is profoundly inter-co nnected with public li fe and with the future fabric of an industrialised world .

My wish is that everyone will come to see water management as we see it -as a c1ptivating, stimu lating, confusing challenge; a challenge which we are well placed to re -think for this week at least.

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J

THE DYNAMIC STATE OF PERTH'S WATER SUPPLY B. J. Fleay, B.E., M.Eng.Sc., M.I.E.Aust., M.A.W.W.A. * INTRODUCTION

In the last decade, water supply to the city of Perth has posed problems which must be resolved if the city is to continue development Into the next century.

The population of Perth in 1976 was 805,000 people and is expected to increase to 1,436,000 by the end of the century . It is the fastest growing State capital city in Australia. Table 1 shows the population increase for each of the States and their capital cities for the period 1966-1976.

In the same period water supplied to Perth has increased from 119 million m3 to 195 million m3 while supply has increased from 555 litres to 681 litres per person per day. The comparison with other major Australian cities is shown in Table 2.

The contrast is even greater when Perth's 20,000 private wells supplying groundwater for home garden watering and public parks are taken Into account.

HISTORICAL

to increasing pollution of the underground water.

Perth 's first public supply was from Victoria Reservoir on Munday's Brook in the Darling Ranges and constructed in 1891 . This was quickly supplemented by a number of artesian wells near the city . In 1906 eastern suburbs at Midland and Guildfor.d were reticulated from Mundaring Weir which had just been constructed to supply the goldfields at Kalgoorli e and Coolgardie .

This small supply system with some additional artesian wells catered for metropolitan needs to the mid 1920's when the first major Hills scheme in the Darling Ranges was constructed . This scheme comprised run -of-river pipeheads on the Canning and Wungong rivers and a small dam on Churchmans Brook , a tributary of the Canning River.

Pipelines were constructed to the city .

During the 1930's a major dam was constructed r :, the Canning River to replace the p1r~head . This was completed in 1 1 M) .

Postwar population expansion plus increasing per capita water usage put f urther pressure on supply sources.

Kangaroo Gully was diverted into Canning Dam in 1952. Muridaring Weir was raised in the early 1950's to cater for proposed reticulation extensions to t he mining and rural hinterland . In the interim, during the mid 1950's, it was used to supply Perth until â&#x20AC;˘ the Serpentine Scheme was constructed.

The first stage of the Serpentine Scheme comprised a small pipehead dam on the SerpQntine River and a 1200 mm pipeline and was completed in 1956. It was immediately followed by construction of the Main Dam, com pleted in 1962 and followed by progressive duplication of the pipeline, which was finally completed in 1969.

The Serpentine Scheme is the biggest single supply source in the metropolitan system, currently contributing about one third of annual yield .

After a twenty three year interval further artesian wells were drilled at Attadale in 1954 and Balcatta in 1960 and 1962.

Throughout most of the 19th Century water in the Fremantle and Perth areas was obtained from private wells and springs. During. the 1870's a public supply to shipping at Fremantle existed with water pumped by hand from wells and infiltration gallerys under Fremantle Gaol. Later in 1888 pumping machinery was installed at the Gaol for public supply and reticulation to the city of Fremantle. This scheme was abandoned in 1930 following introduction of the Canning River Scheme, due

THE LAST DECADE By the mid 1960's when planning commenced for the next major surface source of water on the Dandalup Rivers it was clear that remaining Hills sources near to the city were limited or were brackish. Consequently investigation began on the considerable unconfined groundwater resource on the coastal plain beneath the city .

Exploratory drilling commenced in the Mirrabooka area in 1964 with a small pilot scheme planned for the late 1960's

Growth caused by the mineral boom of the late 1960's plus a succession of dry years forced a programme of accelerated development . More recently the situation has led the Board to commence reviewing strategy on water supply to give greater emphasis on demand management and re-use of water, among other matters.

This paper outlines the historical sources of supply to the city , plans for possible future surface sources, and some related problems of land use conflicts in the catchments. A further outline is given of the extent and nature of the underground water resources under the coastal plain and their future role in the water supply system for Perth in an integrated conjunctive surface/underground water supply system . Fig . 1 is a simplified map of the catchment and groundwater systems .

TABLE 1 POPULATION INCREASE 1966/1976

W .A. N.S.W. VICTORIA QUEENSLAND S.A. TASMANIA PERTH SYDNEY MELBOURNE BRISBANE ADELAIDE HOBART

35% 12.7% 13.25% 21.7% 13.7% 8.5% 44% 19% 22.3% 23.1 % 16.7% 14.7%

TABLE2 AVERAGE WATER CONSUMPTION, litres per person per day

MELBOURNE SYDNEY ADELAIDE

343 470 487

BRISBANE

649

PERTH 681 By the mid 1960's it was apparent that the traditional sources from rivers in the Darling Ranges close to Perth would not be adequate for the future and would need to be supplemented from elsewhere. Investigation commenced on the extensive unconfined groundwater resource on the coastal plain north of Perth with a view to accelerated use of this source from the late 1970's, to be preceded by several years operation on a pilot basis. * Engineer,

(Quality & Treatment) Water Supply and Maintenance Branch:, Metropolitan Water Supply, Sewerage and Drainage Board, Perth .

13

or early 1970's to provide operating information. Sustained development of unconfined groundwater was expected to commence in the late 1970's.

However, the mining boom of the 1960's so accelerated population growth and per capita water usagewater consumption increased 50% in one 5 year period-that the Board's forward planning was disrupted . Supply without restriction In this period was only possible on the basis of unused yield avai lable from Serpentine Main Dam .

The Dandalup Rivers Scheme comprising a pipehead dam on the North Dandalup River completed in 1971 and a major storage on the South Dandalup River completed in 1975 were advanced in time but did little more than balance supply with demand at the time of their completion .

Concurrent ly groundwater development was greatly accelerated with three schemes now operating at Mirrabooka (1971 /3) , Gwelup (1974/5) and Wan. neroo (1977/8). A further groundwater scheme at Jandakot is due to commence production during 1980. There was no time for a pilot experimental phase in groundwater development before making a major commitment.

While these groundwater schemes were being constructed a major exploration effort to assess the magnitude of the unconfined groundwater resources of the Swan Coastal plain was commenced. More recently exploration of the considerable artesian aquifers has been acce lerated . A more detailed description of the groundwater resource is given below .

Bourgeoning demand, and prospects for its continuation even at reduced rate, prompted a long term look at water r esources strategy . In 1974 the Metropolitan Water Board and the Public Works Department undertook a study of the water resources inventory in the South West Region together with one possible demand projection for several decades ahead, covering urban, industry and irrigation uses. A broad appraisal of development costs was made as well.

The study concluded that about one quarter of the divertible fresh and marginal surface and underground water in the South West Region had been developed wllile in the Metropolitan Zone (80 Km from Perth) about 50% had been diverted . ¡ The study drew attention to the three major rivers (Murray, Blackwood and Frankl in) that were brackish largely due to clearing on the catchments . Others were threatened by salinity increases (Warren, Co llie) . Continuation of historical trends could reduce the inventory of fresh and marginal water, the study concluded.

Transmission costs of South West water to Perth, quite apart from political prob lems , precluded its use in the 14

immediate future for metropolitan needs.

Consequently the Metropolitan Water Board has since concentrated on developing a more detailed strategy in the Metropolitan ¡zone for diversion of surface and underground water (fresh, marginal and brackish) to the end of the century.

DARLING RANGE CATCHMENTS. THE NORTHERN JARRAH FOREST

Metropolitan surface water catchments are located in the Northern Jarrah Forest on short west-flowing rivers incised into the western fringes of the Great Western Plateau and emerging through the Darling Scarp onto the sandy coastal plain . A number of environmental gradients ex ist. (a) Rainfall decreases from west to east (over 1200 mm down to 625 mm). (b) Valley forms are more deeply incised, rockier and steeper in the west than in the east where there are broad flat valleys with deep, often porous, soi l profiles. (c) The proportion of rainfall appearing as streamflow decreases from west to east, the latter region only contributing significantly to streamflow in wet years . (d) There is an increase in salt accumulation in the soil profile from west to east, its origin being saltfall in the rain. (e) Vegetation density decreases from west to east.

The whole area is State Forest and has been extensive ly cut over for timber in the last 100 years, especially In the west. The high land has an extensive laterite profile containing low grade bauxite.

In the eastern parts of the catchments (as elsewhere in the South West) only the high transpiration rate of vegetatio n, espec ially deep rooted jarrah, keeps groundwaters low and prevents mobilisation of salt into rivers.

This sal ination risk is neg li gible in the wetter western parts of catchments and increases towards the east.

A fungus disease (Phytopthora C'innamoni) , common ly called dieback, is severe ly damaging the western part of the forest, espec ially the Jarrah. The disease is spread largely by human activity, in particular by rubber tyred vehicles . So far on ly isolated outbreaks have occurred in the sensitive eastern area . In order to inhibit the spread of the disease the Forests Department has quarantined large tracts of the forest in the south west (over 500,000 ha).

Vehicle access is strict ly prohibited unless absolutely essential. Movement in the forest is subject to hygiene contro l.

ALCOA of Australia has a bauxite mining lease over most of the area and is operating bauxite mines at two sites just east of the Scarp at Jarrahdale and Dwellingup , both on MWB catchments.

Currently some 6 to 7 mi lli on tonnes of

ore is mined annually . The mining operation is expected to aid in the spread of the dieback disease. Water Authorities are con~rned about the consequences of mining extending to the eastern salt sensitive zone and its ultimate impact on stream salinity, and to a lesser extent turbidity.

An active research programme is under way to assess the effects of bauxite mining and rehabilitation techniques on the water resources of the area affected . There is cons iderable public controversy on the pros and cons of bauxite mining especially as Alcoa wish to establish a third alumina refinery and mine site at Wagerup south of Metropolitan catchments and in catchments controlled by the Pub lic Work s Department ih the irrigation areas near Harvey.

A man-made landscape is in the making and is of crucial concern to the water authorities because of its potential impact on water quality. The management structure for this area and appropriate rehabilitation practices are sti ll evolving and is undoubtedly the most important environmental management problem current in W.A.

l

j

FUTURE SURFACE SOURCES

The opportunity for further diversion of fresh water from existing surface catchments is limited, and will most likely be undertaken during the 1980's.

Other major sources of surface water near the city are the Murray River and a number of tributaries of the Swan-Avon River, the main stream of which is saline. The Murray River is a major stream with considerab le potentia l for volume development but is brackish and some 130 Km south of the city . The economics do not favour its early explo itation wh ich is unl ike ly to occur this century. The Swan-Avon tributaries were fresh untfl much of the land was cleared for agricultural purposes . The smaller of these streams are of marginal quality whi le the larger ones are brackish to sa line. One of these streams is on the urban fringe.

Detai led prel iminary investigation of these sources began in 1977 aimed in the first in stance at assessing the treatab ili ty of the waters and to rank the sources in future options for investigat ion and development. Unlike existin g surface water sourcAs .the Swan~ Avon tributaries will require ful l treatment of the water plus, for the larger streams, desalinat ion.

The attraction of these. streams is the ir closeness to the city, hence low transmission costs of the water to northern suburbs . In addition they are adjacent to the major unconf ined groundwater source, the Gnangara Mound, and therefore lend themselves to con ju nctive development with underground sources and their associated treatment works together with the poss ibi lity of aq uifer recharge, both for storage and di lution .

l -'

THE GROUNDWATER RESOURCES OF THE SWAN COASTAL PLAIN 1. Unconfined groundwater The principal unconfined groundwater resource is in the Gnangara Mound between the Swan estuary and the Moore River some 80 Km north of Perth .

The aquifer covers about 2000 Km2. The aquifer is a series of north-south trending aeo lian dune systems, the youngest being on the coast and becoming progressively older inland.

Saturated aquifer thickness is up to 70 m. Fig. 2 shows the geology of the formation and Fig. 3 the contours of the groundwater. The depth to the water table is sha llow for the most part and tends to follow the topography.

Fig 2

i I

[i]...,.,, .., _

m~ ffl'l'LMC--

o.,__..,~

-.Ol'O'IO

C...-

l!i9oiw1Al;ll0,,II _ _ _

o - -~As well as the Gnangara Mound to the north of Perth there is a smal ler uncon f in ed groundwater system south

of the Swan estuary known as the Jandakot Mound .

Mineral content is least at the most elevated parts of the Mound increasing towards the groundwater sinks due to the concentration effects of evapotransp iration . It is believed most of the mineral content of the water is derived from salt fall in the rain .

Storage coefficients range from 0.15 to 0.20 and transmissivity from about 270 to 1100 m2/day at Gnangara and 250 to 750 m2/day at Jandakot respectively .

A tentative water balance has been made for the Gnangara Mound and is shown diagramatical ly in Fig . 4.

This is a considerable water resource.

2. Envlronmental Factors There are widespread systems of lakes and swamps on the coastal plain which are in direct connection with the groundwater table. These are important habitats and drought refuges for water fow l and other fauna . In addition there are characteristic vegetation systems that have some dependence on the water table . Further over the Gnangara Mound, in particular where it is proposed to establ ish the Board's groundwater schemes, there are extensive areas under Forest Department pine plantations . Lowered groundwater tables could adversely affect all the above features . Many studies are under way involvin g the Department of Conservation and Env ironment, the W .A. Forests Department, the Museum , the Metropolitan Water Board and others to define and understand these ecosystems and to predict the possib le effects of groundwater abstract ion on them. Some lakes and swamps are pegged for mining of diatomaceous earth that would serve to deepen them. Management strategies for the area are being deve loped based on this work.

On the Jandakot Mound where the Board has proposed to establish a groundwater scheme there has been considerable opposition from the local rural population to the Board's proposals.

3. Water Quallty In the Spearwood Dunes the water is mostly fresh with a variable iron content (up to 10 mg/I), and sli ght ly hard. The only operating Board groundwater scheme in th is dune system is at Gwe lup where the wellfield is entirely within the suburban area. This plant receives half of its water from the Leederville artes ian formation and half from unconfined groundwater.

Water from the Bassendean dune system - the major resource-is of poorer quality, mostly fresh, but high in colour (up to 450 HU, mean 100 or more), sometimes quite turbid and with iron and hydrogen su lphide. This water is most difficult to coagu late and flocculate . Polyelectrolytes are essential and chemical costs are high.

--°'~-..-

ESTWATEO PRESElfT WATER BALANCE

WATER IN STORAGE

GNANGARA MOUND 13,000

FIG. 4

There are a number of groundwater pollution problems adjacent to some groundwater schemes current ly operating-a san itary landfill site and a septic tank liquid waste disposal site. The behaviour of the pollution plumes from these sites is under investigation.

Groundwater recharge using imported surface water and secondary wastewater effluent is being seriously considered. Pi lot schemes are under way or about · to start. There is considerable potential to amp lify the water resource and reduce wastewater disposal costs by this means.

4. Confined Groundwater , There are two artes ian aquifer systems of interest, the Leedervil le formation and the Yarragadee forma• tion.

The Leedervil le formation is separated from the superficial formations mainly by the Osborne formation which comprises relatively impermeable siltstones, maximum thickness 450 m.

Below the Leederville formation is the Yarragadee formation and separated from it by the South Perth Shale. The Yarragadee formation is up to 3000 m thick, but only the top 400 m or so Is tapped by we ll s due to water quality considerat ions . These formations are much faulted .

The extent of this artesian resource is not fully known as yet. Current !nve_stigations and exp loratory drilling Is aimed at determining this, including defining storage coefficient, transmissivi ty, water balance and recharge areas . The deeper artesian water has been used for public supp ly in Perth for nearly 80 years .

The Leederville wells produce fresh to marginal water, commonly high in iron (up to 16 mg/I). Yarragadee water is marginal to brackish and hot up to 40° C. The latter water only r~quires Cont. on Page 23 15

EXTENDED AERATION IN PERTH B. S. Sanders, B.E., Dip.T.R.P., M.I.E. Aust., M.A.W.W.A.and R. J. Fimmel, A.P. T.C., M.I.E. Aust., M.A. W. W.A. * INTRODUCTION This paper describes the experience of the Perth M.W .S.D.B. both with the ex t ensive use of factory-bu ilt extended aerat ion treatment p lants , and also with the use of the extended aerat ion process as a temporary step in introducing permanent treatment systems .

Until the mid 1960's Perth 's growth had been unspectacular and limitations on funds had led to a reliance on sept ic tan ks in a number of areas . This meant that the sewerage system was con centrated in, inner suburbs and therefore not able to quickly cater for any rapid suburban expansion . The industrial and commercial growth in W .A. ca used a housing boom in Perth .and the expans ion was accom panied by the introduction of compulsory sewerage for most new·· subdivislons In order to prevent further increases in the unsewered back- log .

Most of the housing development was in the form of low density, residential suburbs located in urban corridors some distance from the City.

Th e associated sewerage therefore required a large number of temporary treatment plants while main sewers and permanent plants were being constructed . Eve n the new p~rmanent plants were built in stages both to save time and to spread the co& ts over a number of years.

TEMPORARY PLANTS Installation Plants were .purchased based on a 24-hour extended aeration design specification . Ten small plants , of 90-140 m3 capacity , were installed fro m 1968 to January 1978. Three of them were transferred two or even three times, so that in all fifteen locations were served.

Seven are still in operat ion .

Eight medium plants (230-360 m3) were in stalled , two being relocated .

Two are still in operation .

Of the five large plants (460-690 m3) on ly one has been phased out so far, though two should terminate during 1978.

Sites for these plants were generally very close to the subdivisions to be served and were normally located on land not immediately required for developm ent . This was frequently land reserved for future shops , freeway interchanges or subdivisions .

The location of plants was mainly governed by the prob lem s of effluent disposal . Due t o the regulations of the Swan River Management Authority (formerly the Swan River Conservation Board) discharge to water courses is not acceptable and therefore sandy areas were required for surface spreading of eff luent . These sites had to be dry and well above the permanent water tab le to ensure bacteriological control.

While such sites were readily available in northern subdivisions, their restricted availability in other areas was often a governing factor as to whether or not early development could occur . In general , asbestos contou r gutters were employed for small plants and either sprin klers or broad contour drains for larger in sta ll at ion s. The gutters turned out to be very hard to level and as flows increased , most plants reverted to earth contour drains which proved much easier to maintain.

One of the reasons for using factory-built extended aeration plants was their portability . Rectangular units up to 140 cubic metres per day capacity can be moved by truck from one simp le limestone base pad to another. The larger rectangular units can also be moved by truck after cutting the steel tank into two sections. At the present time plans are under way to move a large circular unit by cutting the tank into segments and rewelding at the new site .

Capital Costs These are made up of the cost of the treatment unit , its installation and the cost of other site works , but no cost for the land which was usually on loan from the developer .

Prices vary for plants of the same size depending on shape, type and place of manufacture of the machinery , but average costs can be stated . For the three sizes the prices for plants in place around 1972 were, for small, $23,000 to $30,000 ; for medium $40,000 to $60,000; and for larger plants built into slabs, $70,000 to $100,000.

16

Design Features Figures 1 and 2 show the typical rectangular and circular plants used in Perth . There have been some slight variations to these layouts such as "tw in " aeration tanks- in place of one continuous segment in circular units .

Except for one recent installation there have been no " completely-mixed " units using surface aerators. Many of the rectangular units were equipped with a flow -balancing weir between aeration tank and clarifier in order to dampen the effects of "shock" loads from inlet pumps . These floats allowed water levels to rise in the aeration tank and were quite effective although the Board required a number of alterations to: the original designs to prevent clogging and air-locking .

The clarifiers of rect~ngular piants were equipped with t ither square inverted pyramidal hopp~rs or, In a fe.,; case_s , with cone-shaped hoppers in cluding small scrapers for cleaning the s!eep sides of the cone . The larger circular plants had normal circular c larifiers equipped with continuous rotation sludge scraper~ of either the plough or "s uction" ,type . All plants used a_irlift~ to return a¢tivated sludge and sk immings to the aeration tank .

The first plant supplied to the Board had a c larifier upflow rate (at design flow) of 39 c!ibic metres per square gh this is a metre per day. Althou_ standard rate for large activated sludge plants , it was soon shown to be much too high for small plants subject to varying rates of inflow . All later plants were designed for 19.5 m3/m2/day and very small units used even lower rates. . All the small and medium plants were installed on I imestone pads but the • circular units were welded to a /NFLU£NT

- - [,CJZU[NT

A£.R.ATION

6anfs Principa l As s istant Engineer, Sewerage and Drainage and Engineer, Sewerage and Drainage Branch respect ively ; Metropolitan Water Supply, Sewerage and Drainage Board, Perth , W .A.

Other site works such as roads, fences and effluent disposal, facilities . would be extra but could vary from $5 ,000 to $25,000 dependi11g on arrangem~nts for inlet pumping, effluent disposal and pipeline sizes and lengths .

of

aero/ors ..,.,,,

FiG

f.

RECTANGULAR TYPE

CLARtn£R

ring-beam set in a concrete base . One circular plant was constructed of concrete, but all others consisted of site-we lded , pre-curved steel sections.

There was little difference in cost between the two types and of course the concrete un it is not portable .

EFFLUENT

AERATION

FiG

2. CIRCULAR TYPl

Operating Limitations Screening:- It is essential that these plants have some type of inlet screening or blockages will occur in transfer pipes and air-lifts , and diffusers will quickly become clogged . The only practical device is a commun itor but these have been a source of endless trouble to the Board because of their need for frequent maintenance .

Pumping Rates:- Due to Perth 's flat terrain the only method generally available for del ivering f low to these plants is by pumping from the last manhole on the ret iculation system.

However pumping to small plants res ults in a problem as "shock loading " is most difficult to avoid . To minimise this effect most of the later installations used "grinder type" pumps thus enabling lower pumping rates through small (62 mm) pressure mains . Balanc-

but this was not effective except at the initial , very low load situation .

Fixed Diffusers:- The smal l size and relatively low cost of these plants does not justify th e installation of diffusers that can be removed while t reatment continues , but this res trictio n certain ly contributed to operati ng problems in some plants.

Air Lifts:- Once again because of the scale of these units and the economies available, return sludg e systems norm ally consist of air lift s, but these proved easy to block and often difficult to adju st to a particular flow rate .

Detention Times:- Unless spec iallystrengthened tempo rary baff les are used in the aeration tanks (and th is was don e only once in Perth) , there is no contro l over detention tim es until the plant approaches design load. Th is has resulted in nit rification -denitrif icat ion problems and also caused cons id erabl e lowering of pH with t he consequent formation of a " bulking " s ludge. To control this problem lime was added to aeration tanks at regular intervals .

Plant Performance Table 2 provides an averaged pe rformance summary for all temporary plants . It should be noted that th e figures include tho se from plants which became overloaded (particularly the figures for small plants) and. therefore shou ld not be taken as an indication of performance under ideal conditions . ¡ The actual res ults obtained from three plants are shown in Fig ure 3.

Generally the larger plants achieved better re.suits but this is to be expected as th ~i have more so phi st icated equipment and are not as susceptible to shock load s and high up-flow velocities in clarifiers resulting from pumped inflows . However small units which were not overloaded either hydraulicall y or organically did perform particularly well, arid all plants in sta lled served their purpol?e des pite difficulties in

TABLE 2 TYPICAL AVERAGE PERFORMANCES OF TEMPORARY PLANTS PLANT SIZE B .O .D.5 S.S. PERFORMANCE Influent Strength

Small-up to 140 m3/d

mg/ I 323

Medium - up to 360 m3/d Large - up to 690 m3/d

346 278

% Reduc .

Influent Strength

Ettl.

mg/I 28

91

mg/I 425

mg/I 47

89

32

91

255

56

78

21

92

306

40

87

Effl.

ing-tanks were also used when more than one plant was installed at a site .

Air Rates:- These are generally not adjustab le, especial ly in the small er plants , and this has led to prob lems from overaeration when plants were underloaded. Time controls for shutting off the air for short periods were used,

% Reduc.

some cases . The smallest plant used, 23 cubic metres/ day , was at a construction site and could be loaded by gravity following some flow balancing and it achieved 20 :3; effluents regu larly despite its si ze .

As would be expected perform ance declined under overloaded conditions

but the larger plants proved capab le of producing a reasonable effluent under very heavy loads as shown by the Gosnel ls plant in figure~ .

From 1970 onwards there have occasionally been cases of aerat ion tank foaming in all sizes of plant . The foam , cream to light brown in co lou r, appears suddenly and covers both aeration and c larifier surfaces . It consists of a branching growth, Actinomycetes myceli um , which has multiplied out of normal proportions and floated to the surface with air bubbles .

2f2P

197.3

FIG. J

1974-

TEMPORARY PLANTS

Efflu ent deteriorates slightly but the main problem tips been drying foam dirtying tank wal ls and walkways .

Pos itive removal by scooping off the water surface is effective but normally the foam reduces slow ly if the pH is kept to neutral and excessive aeration avoid ed .

Efforts were made to minimise turbulence caused by the in com ing mixed I iq uor by trials of different entry ty pes .

In the smaller tanks with square clarifiers entry was made in a corner furthest from the outlet weir. Use of an ad ju stab le deflector plate was also made but no s ign ificant difference for different ,adjustments was found .

Larger pl ants had in let pipes turned upwards. in the centre and one clarifier i ncorpo rated a bank of inc lined tubes whi ch su ffered from rag blockages .

One of the ad van tages of the exte nded ae ration process is th " low excess sludg e production compared with most ot her treatment processes. It is important ¡to accept that excess sl udge mu st be removed from t he system if a sat isfactory and cons istent 17

performance is to be obtained . There have been manufacturers who claimed that no sludge was produced from their plants , but such an approach can only lead to poor effluent quality.

In Perth it was found that best results could be obtained with M.L.S.S . somewhat higher than those normally associated with extended aeration . The level normally adopted was 5000-6000 mg/I. Despite these high mixed liquor solids level, excess sludge production was also reasonably high at 0.4 to 0.5 kg/kg of B.O .D. applied.

Effluent disposal was effective at all sand sites as in most cases flows were low enough to allow rotation of disposal areas throughout the site. Al l but the smallest and most temporary sites were ringed with monitoring bores to check on the groundwater condition .

No problems have been detected at these disposal areas.

With the exception of one plant which became heavily overloaded, no odour problems have occurred, even though some plants were adjacent to ·houses .

Noise was a prob lem in some early installations even when houses were some distance from the plants . The Board eventual ly specified low-speed blowers and in small instal lations when blower buildings were not provided, the blowers were often moved from the top of the tank to the ground on the opposite side to the subdivision .

Operation In order to ensure good performance and prevent odour complaints a high level of operator attendance has always been maintained . If skimmings and foam are not controlled regularly and disposal areas rotated, both odours and f ly-breeding can occur in addition to decreased effluent quality . Attend ance was one to two hours per day on every weekday (up to three hours at Gosnells) and in addition a quick check was made of all plants on Sunday mornings . Excess sludge was regularly removed by tanker and at the larger plants when on full load. This was an expensive aspect of operation.

It was noted that a fresh water supply was essential for cleaning purposes as the use of effluent alone eventually led to unhygienic conditions . This meant that' a water main was often laid over considerab le distances from the nearest subdivision .

The operators carried out sludge sett leability (S .V.1.) tests daily in most plants when on full load . Thus was an "grab" or "bulked " samples to measure plant performance. This testing was occasionally supplemented with longer sampl ing programs bulked over a working day. Performance samp ling was original ly done by chemists but their tours were frequently delayed by periods of no flow, and eventually operators took over this task, leaving the samples on ice at the plants for later collection by the chemists.

18

without some interim step. ,·l\ ' was Maintenance decided that the best metnod of Comminutors failed regu larly on providing ,early -relief . for the small most plants and required considerable temporary plants wa~ to construct the attention. It appeared that most units aerati9n taDkS and sec'?n-d·ary'..,c larifiers . provided were under-powered for the of the _per,rnanent p.lants and operate job required. Blowers were generally these under -extendep aerati.PIJ. unti l the reliable and required minimum mainprimary and sludge treatmelft+-facilities tenance but some required shading in cou Id be .added. summer time to prevent cut-outs from Fig . 4 shows average results of two overheating. of the plants.

Fitters and electricians visited plants Table 4 shows the details of the five once per week for regular maintenance plants including the results achieved and checking . None of these plants was and the method of effluent disposal. equipped with alarms to the Board's The Beenyup plant which has just been central control room and this was the converted to conventional treatment main reason for the operator check will be connected to an ocean outlet once on each weekend . within a few weeks, but the other three Site . Maintenance-The disposal plants wil l continue to use sand sites areas also required limited but regular for eff luent disposal. maintenance to prevent wet cond itions Kwinana will be converted to convenpersisting . Solids were carried over the weirs from time to time and thus areas tional treatment within a few months and Pt. Peron wi ll follow in about three had to be dried out and either raked, rotary -mown or ploughed. Occasional years. The convent ional capacities of cutt ing of weeds was also necessary these five plants (in the same order as Table 4) are 3636, 4730, 9460, 27270 and although on some sites this was effectively carried out by grazing horses 5450 m3/d . It should be noted that all from nearby riding schools. the conventional facilities are only initial stages and each plant wil l Although most of these plants were undergo further expansion from time to near housing subdivisions the actual time . sites were often in isolated bush It can be seen from Table 4 and the locations and despite the normal detailed results from two plants (figure security fence and patrols, vandalism 4) that effluent quality was generally was a problem in some areas. This very high. This was to be expected as common ly took the form of objects such large extended aeration systems being thrown into tanks and causing blockages . were less susceptible to the problems TABLE 3 UNIT OPERATING COSTS Costs are for operation and maintenance only and do not Include capital debt servicing PLANT SIZE

FINANCIAL YEAR

OPERATING COST C,ENTS/m3

SMALL (BULLCREEK)

1971 /72 1972/73 1973/74

25 44 23

MEDIUM (ROCK. PARK)

1972/73 1973/74

23 13

LARGE (EDEN HILL)

1974 / 75 1975/76 1976/77

12 14 16

(GOSNELLS)

1974/75 1975/76 1976/77

10 11 13

Operation Costs-typical costs are set out in Table 3. Although these seem high they are not unusual for smal l plants and certain ly don't detract from the convenience and flexibility of small extended aeration plants .

INTERIM STEPS FOR PERMANENT PLANTS Installation and Results Planning for sewerage in Perth's expanding urban corridors required the construction of five new permanent treatment plants but there was neither time nor funds to achieve this objective

of high pumping rates and excessive upflow velocities in clarifiers. However Canning Vale and Westfield were both eventual ly overloaded hydrau lica lly due to increased pumping rates and their performance did deteriorate .

Beenyup was the only plant served by gravity and this, coupled with the largest units resulted in good results even when the plant became 250% overloaded. It should be noted however that the plant was extreme ly difficult to operate when overloaded and was particularly sensitive to slight variations in air or M .L.S.S. levels. Bulking was a regu lar occurrence in the last

twelve months but control was regained quickly . The amount of excess sludge produced at Beenyup was very high and removal was expensive despite the use of some onsite sludge lagoons .

The best resu lts were obtained from these five large extended aerat ion systems when the M.L.S.S. levels were able to be kept high at 8000-9000 mg/I. Operating Problems-Although upsets were less frequent for the reason given these systems stil l had some prob lems of their own . One difficulty was the lack of skimmings contro l on the secondary clarifiers and this facil ity is recommended for any temporary extended aeration stage in a major plant . The same problems were experienced with comm inutors . Also the build-up of grit and rags in aerat ion tanks interfered with diffusers and in the case of the rags , blocked weirs and sludge pumps .

The actinomycetes organism caused prob lems at two plants and regular pH adjustment with lime was necessary at all plants. The quantities of excess sludge to be removed were naturally larger than for the small temporary plants and tankering proved to be a very expensive operation as loading increased. It was possib le to introduce sludge lagoons at two plants and this technique is recommended for any future usage of the extended aeration process on this scale .

Lagoons , however, introduce the risk of odour emissions .

One major advantage these plants had over the smal l temporary units was the removab le diffusers which enab led cleaning and replacement without interruption to the process.

l2~

f,00

__,.,.,

f'lOW

IOQ_

JQ_~

r---- _,,--

CONCLUSIONS The use of factory-built extendedaeration plants to provide temporary treatment facilities for iQew subdivisions has proved most satisfactory . The plants proved flexible and were portable , two advantages they had over other processes. The plants were capable of producing a good quali t y effluent for disposal while only requiring a minimum of maintenance. Sludge production was also relatively low with this process and the sludge , being aerobically digested , was easy to handle. Wherever possible with large installations , sludge lagoons are recommended to limit the tankering costs for waste sludge.

400

o_{

~J:t

'

~

197.5

FIG 4

flÂŁP.MANENT PLANTS

Operating Costs- These are set out in Table 4 and it can be seen there is quite a wide range between the Beenyup plant and the Point Peron plant . This range occurs for a variety of reasons. For example the Beenyup plant handled much larger flows than any of the others and also had sufficient space for s lud ge lagoon s (thus eliminating tankering) and the low operating cost reflects these two econom ies . The Canning Vale, Westfie ld and Kwinana plants, while handling moderate flows, were much bigger than the temporary plants described in Table 3 and thus produced reasonab ly low operating costs . The higher costs at Westfield and Point Peron reflect very high tankering costs at Westfield and very smal l flows compared with design capacity at Point Peron .

TABLE 4 "PERMANENT" EXTENDED AERATION PLANTS AVERAGE PERFORMANCES

DATES PLANT OF CAPACITY m3/d OPERATION

PERFORMANCE S.S. BOD5 Intl.Elf .

% Reduction

lnfl. Elf.

% Reduction

UNIT OPERATION COSTS cents/m3

Canning Vale 1200

Apr. '70 to Apr. '74

222 8

96

210 18

92

9

Kwinana 1340

Oct. '70 to date

374 14

97.3

386 16

95 .8

13

Westfield 2500

Dec . '71 to Nov. '77

244 28

88.3

222 34

84 .6

21

Beenyup 7270

Dec. '72 to Feb. '78

248 27

89

245 35

85 .7

8

Pt . Peron 1360

June '75 to date

282 12

95 .7

246 15

94

36

NOTES: 1. Each effluent disposal to sand sites except Pt. Peron to ocean.

2. Operation costs are for 1976177 yr. except Canning Vale 1973/74.

[These costs do not include capital debt servicing].

3. Higher cost of Westfield due to waste sludge tankering.

4. Pt. Peron unit cost high due to lower flows treated.

It is considered that both designers and manufacturers should give more attention to the proper loading of these plants , particularly when pumping is necessary. Un less there are very good reasons for smaller plants, and loading cari be carefully control~ed, the ir,~_tallation of units below 230 m3/day Is not recommended . More research is required into the cause , effect and control of Actinomycetes scums as they proved highly disruptive in some temporary plants .

The value of the interim step of using extended-aeration when developing so many major plants at once can now be reviewed in li ght of the experience gained . One obvious advantage was the spreading of capital funds over a longer period due to the breathing space provided by extended aeration . In most cases it would have been impossible to provide treatment faci lities in time without taking this step and therefore possible disruption to ' the housing programs was avoided .

It was clear that this interim stage should be avoidtd if the flows are expected to increase quickly, thus requiring the conventional facilities almost immediately. There were also problems created by the need to make early " layout" decisions and sludg e pumping selections which were then difficult to fit into the conventional plant following further detailed design .

However, despite these problems and the difficulty of operating in half a plant while construction work is proceeding, there is no doubt that this interim treatment step made it possible for the Board to cope with unprecedented housing growth in the Perth Metropolitan Area.

ACKNOWLEDGEMENTS The Authors wish to thank the Chief Engineer of the Metropo litan Water Board , Perth, Mr H. E. Hunt for permission to publish this paper and staff of the Wastewater Treatment Section for their help in col lect ing operating data.

19

NITROGEN REMOVAL FROM EFFLUENT BY SOIL PERCOLATION -ASTUDYRELATINGTORECHARGEOFGROUNDWATERby K. Mathew, G. E. Ho and P. W. G. Newman School of Environmental and Life Sciences, Murdoch University, Murdoch, W. A. 6153 Introduction

Increasing pressure on groundwater resources is forcing water authorities around the world to consider artificial means of recharging aquifers. The use of purified wastewater· has considerable appeal because of its constant assured flow and reasonably consistent quality.

The diminishing water resources of Perth have been described by O'Hara (1) and Fleay (2) . The problem has led to proposals by Binnie and Partners (3) to use recharge In the future, particularly from the treatment plants located Inland as described by Sanders (4) . Quantities of more than 10GI per year are being considered, and the Metropolitan Water Supply, Sewerage and Drainage Board Is planning a pilot study . Many factors need to be studied, Including principally the following: (1) water resources and demand (2) quality of water available for recharge (3) quality of existing ground water (4) depth of unsaturated layer above ground water (5) vertical soil permeability (6) properties of soil at recharge site, especially Its capacities for wastewater purification This paper describes a research project to be performed on the last of these factors, in particular the reduction of nitrogen pollution by the process of nitrification-denitrification in the column of soil.

as there are numerous surface lakes connected to the ground water. A high concentration of nitrogen reaching the groundwater by leaching of nitrate or nitrite can cause health problems if the water is used for domestic supply. (10) General Principles of Nitrogen Removal

The process reactions that take place when wastewater effluent is charged to soil are given in fig . 1, (adapted from Sepp (11) . Nitrogen in effluent occurs mainly as NHt, During recharge, conversion of ammonium to nitrate and eventually to nitrogen gas takes place by the activities of soil microorganisms. By proper management a method can be obtained to optimise the removal efficiency. This requires an understanding of the balance between nitrification and cmnitriflcatlon (see references 12, 13, 14). (i) Nitrification may be defined as a biological conversion of nitrogen in organic or inorganic form from a reduced to an oxidised state. The two principal genera of microbes of importance in biological nitrification process are the aututrophic organisms Nitrosomonas and Nitrobacter.

FIGURE1 THE NITROGEN CYCLE IN SOILANDGROUNDWATER (AFTERS EPP)

Review of Recharge Practices

Examples of low-rate land application of waste water are numerous, and vast areas of land are needed for operation.

Because of this a large quantity of water Is lost by evaporation and transpiration and very little reaches to any great depth to join underground water. High-rate land application has been attempted recently to overcome the disadvantages of the low rate system . The main examples are the Waste-Water Reclamation project at Whittler Narrows, Los Angeles, California (5), the Santee Reclamation project near San Diego , California (6), the Flushing Meadow's project near Phoenix Arizona (7), the Sewage Reclamation project and Recharge project Dan Region Israel (8), and the Recharge of Carbonaceous Saline Aquifer In South Florida (U.S.A.) (9).

The Need for Removal of Nitrogen During Recharge

All the normal water quality criteria must be considered if waste water treatment plant effluent is to be used for recharge e.g. total dissolved sol Ids, suspended sol Ids, BOD, bacteria, viruses and nutrients such as phosphorus and nitrogen compounds . However soil Is an effective medium for removing suspended solids, BOD, bacteria and phosphorus . Increases In total dissolved solids usually occur but in Perth's case the groundwater has low sallnlty and this is not considered to be a problem . Virus removal should be studied at some time as sol ls differ greatly In their ablllty to remove tnese tiny negatIveIy cnargeo panicIes. However, the prime need at the moment is to examine the question of nitrogen removal.

Nitrogen, which is essential for all living organisms, appears in the environment in a number of forms. In the form of ammonium ion it exerts biological oxygen demand when present in water. Nitrate is also a key nutrient and can cause eutrophication of surface waters, which is important in Perth 20

They derive energy for growth from oxidation of inorganic nitrogen and use carbon dioxide for synthesis .

NH4 + 30 Nltroaomona92H + + H2O + NO2 + (58-84 kcal) NO + ONltrobacterNO + (17 .5-20kcal)

2

3

Supply of oxygen is the most essential condition and 1 mg of N needs 4.57 mg of oxygen for completing the reactions. Slightly alkaline pH is optimum for nitrification and very little activity occurs below pH 5. Even though the optimum temperature is between 30°C-35°C the activity may continue down to 2° C. Mostly autotrophic bacteria are responsible for nitrification but lately it has been observed that heterotrophic bacteria, Actlnomycetes and fungi also perform nitrification.

(II) Denitrificatlon is a biological process which Involves the

conversion of nitrate Into gaseous forms of nitrogen . A relatively broad range of facultative heterotrophic bacteria can accomplish denltrlfication. They use NO 3 as electron acceptor during the synthesis of organic matter but only in the absence of oxygen . Hence anaerobic conditions and the availability of organic carbon are essential for denitrification. When the oxidation reduction potential (Eh) of the environment is less than + 300 denitrlfication may take place but more

activity wil l take place below + 225, the ideal being negative Eh , The problem in recharge is therefore how to obtain the right balance of aerobic and anaerobic conditions to achieve the two stages in the nitrogen removal process .

HIGH LEVEL TA NI<

I

Proposed Experimental Project .

The most detai led study of ground water recharge us ing wastewater effluent Is that by Herman Bouwer et sf (7) In their pilot plant study at Flushing Meadows project, Phoenix, Arizona. They found that land application of efflu~nt by alternate flooding and drying can reduce the nitrogen concentrat ion. The first f looding period enables NH 4+ to be adsorbed to the soil. Drying a,tirates the,11011 and promo~es oxidation of adsorbed NH 4 to . NO3 . . :he foll_owing flooding period establishes anaerob ic cond1t1ons again and denitrification of NO 3 to N2 gas is promoted as well as adsorption of a new batch of NH: . They have established that in a sequence of short inundation periods (2 days wet and 3 days dry) all the nitrogen in the eff luent was converted to nitrate but very little denitrificat ion occurred. However, with a sequence of inundation periods of 14 days wet and 7 days dry about 30% remova l of nitrogen occurred . Qf th_e N that passes into the ground water more ~han 70"".o Is tn _a nitrate peak formed immediately after _wettin_g. If this ~low 1s col lected and recirculated with the 1ncom1ng flow 1t was found that nitrogen removal increased to the order of 80 per cent. The experiment has been done with river loamy sand as medium. An attempt will be made in this study to examine a simi lar procedure under Perth conditions, complementing the pilot plant study proposed by the Perth Metropolitan Water Supply Sewerage and Drainage Board.

.h

The co lumn wi ll be flooded with effluent from a treatment plant in Perth or liquid prepared in the laboratory with 25 ppm of NH: . Initial tests will adopt a flooding period of 10 days followed by a drying period of 6 days. The flow will be 50-100 cm/day which is the proposed velocity of recharge.

Oxidation reduction electrodes connected to an Eh meter are inserted at seven points in the column and oxygen sensors at three points connected to a Beckman analyser.

Liquid sampling points are f itted w ith a 'U' tube and a valve connected to a porous tube inserted into the soil. By applying vacuum the liquid will be sucked out and collected in the 'U' tube . Small soil sampling ppints are provided at every 0.5 m. The samples will be co ll~cted with minimum disturbance to the soi l structure and re'fl!led wi!!) fresh so~ Liquid samples will be ana lysed for NH 4 , NO2 and NO3 by means of a Technician Auto-Analyser, and the soil samp les tested for NH;, NO 2 , NO 3 and number of nitrifying microorganisms, by the methpd of analysis given In ref . (15) Discussion of Experiment Before nitrification and den itrification can occur In the f lood ing and drying method, the NH In the f low must be absorbed in the soil. One objective of the study Is to model mathematically the movement of NH: through the sand medium while undergoing the process of dispersion and

i

.... V"

-'I.,-

~ ~

~\r

hf Ill

P7,

: hr"

·h? : hr

.

hr" n

' hr SOIL -

Procedure of Experiment Soil columns are being made with perspex pipe of 10 cm diameter (Fig . 2). They wili be fi lled with the Bassendean • sand which is found in the site proposed for recharge. Each column consists of a 2.50 m length of sand with 0.5 m of gravel at the bottom, packed to the bulk density of the soil found at the site . The soil has an effective size of 0.15 mm and a uniformity coefficient of 2, i.e. it is a fine grained sand .

It contains no organic matter or clay. The cation exchange capacity (by ammonium saturation method) is 0.5 m eq per 100 gram of soil, which is virtually negligible. The pH of the soil is found to be between 4-4 .5, which is unusual ly low. The ground water table is 3 m below the top soil and hence a safe depth of 2.5 m of sand is adopted in the laboratory experiment.

I

12 LIT RE CAPACITY

,!'~E~

Trf!f r

~

, hr"L.t..

Lo

-

•::

:::•

EFHUEN GRAVEL -

._:.:·

STORAOE TANK 24 LITRE CAPACIT Y

I

...

:.=.:·

A. B. C. D. E.

-

;

I

Oxidation reduction electrode Oxygen sensor Liquid sampling device Soll sampling points To vacuum

adsorption . Normally the organic or clay portion of the soil will adsorb NH: thus cation exchange capacity gives an Idea of how easy it is for NH: adsorption Jo occur. It may be possib le for a small portion to be incorporated Into microbes (15) . Bassendean sand with low cation exchange capacity, no clay and an absence of organic matter Is expected to be a poor media for adsorpt ion of ammonium. The model should provide the necessary information to optimise the flooding in this sand . period for adsorption of NH During the drying period, nitrification of the adsorbed NH 4+ wil l take place as oxygen enters the column . The low pH value of the Bassendean sand may cause problems .

Subsequent f looding removes oxygen and If sufficient mineralisable organic carbon is prese_!lt denltrlflcatlon takes place, but on starting flooding, NO 3 Is leached from the so il and a peak is observed in the effluent, i.e. the concentration of NO 3 is high just above the wetting front In the column. Sufficient minerallsable carbon Is rarely avai lab le in the flow to denltrify the entire nitrate peak .

(Recirculation, or the addition of methanol has been attempted in some places to assist this stage.) Both will be examined in detail and mathematically modelled In order to optimise the who le process.

Conclusion Recharging underground water with sewage effluent Is a poss ible method of increasing the availability of water resources. Nitrogen compounds present in sewage effluent shou ld be removed before or during recharge so that they do not pollute the ground water. It should be possible to remove them by careful management of the recharge procedure.

CONTINUED ON PAGE 30 21

t

THE WEST AUSTRALIAN SCENE SWAN AND CANNING RIVERS ACTIVITY STUDY

The W .A. Department of Conservation and Environment recently released the above report which had been prepared for that Department by Forbes and Fitzhardinge . The Consultants were commissioned to undertake an "Activities Study", the aim being to provide a detai led analysis of activities associated with the two rivers and their foreshores, so that future decisions relating to their utilisation could be made with the benefit of knowing existing usage patterns.

The Swan and Cann in g Rivers are central to the Perth metropolitan region and provide the major feature influencing the City's character. The central city area overlooks the Swan, both rivers are ringed with suburbs and the Port of Fremant le is located at the Swan's mouth. The river system is of great visual importance and is also an important recreational asset for the metropolitan area.

The report covers the history, natural environment and built environment of the rivers and then describes the river usages under such headings as Pub lic Utilities, Commerce and Industry, Transport and Recreation. Both present and future conflicts are then discussed such as the needs of wildlife, urban uses,. the conflicts between urban uses and recreation and the conflicts between different recreational activit ies.

Priorities are considered for resolving these conflicts and these deliberations result in 123 recommendations . In general the authors call for the protection of existing wildlife areas and the encouragement of the least disruptive recreational activities. Thus rowing and cycling are seen as "first priorities" with yachting and waterfront wining and dini ng also being favoured over power boating and foreshore playing fields for active sports.

It is recommended that commercial fishing be phased out in favour of the amateur and that the discharge of all industrial wastes be elim inated. There is a plea for abandonment of any further riverside roads and for a restriction on stormwater drainage to the river. The report considers that seepage from unsewered riverside suburbs may be effecting water quality and also suggests that no further water supply dams should be bui lt in the interests of keeping up water flow for wildlife preservation.

Public discussion has been invited and certainly in view of the wide reaching recommendations , comments from various authorities and members of the community should be of considerab le interest.

22

WASTEWATER SLUDGE INCINERATORS COMPLETED

Two new slud ge processing facilities have been installed for the Metropolitan Water Board, Perth and are currently undergoing performance trials.

One system at the Westfield Wastewater Treatment Plant has been supplied and in stal led by Hawker Siddeley Water Engineering to serve a design population of 52,000 persons. It consists of facilities for processing and burning grit, primary sedimentation tank skimmings and the combined sludge from an activated sludge plant.

Grit and sk imming s are both pumped to the sludge processing area using positive displacement pumps , and following dewatering are introduced to the multiple-hearth furnace. Excess activated slud ge is settled in the primary sed imentation tanks and the combined sludge is pumped to gravity thickening tanks . The thickened sludge is conditioned using cationic po lymers and then dewatered by centrifuge. A conveyor is used to transfer the sludge cake to the top of the seven hearth furnace for burning and then transfer to the ash storage bin . The thickeners are covered and equipped with an odour scrubber while all other facilities (except the furnace) are installed in a process building which also incorporates the contro l room . ·The second system is at the Beenyup plant and was supp lied and in stalled by Envirotech Australi a to serve a population of 150,000 persons. This system receives screenings , grit, skimmings and combined sludge for processing.

The first three waste streams are pumped to the process area and after dewatering are introduced to the multiple hearth furnace . The primary sludge and excess activated sludge are separately delivered to the gravity thickeners and the thickened sludge is again dewatered using polymers and centrifuges. The cake is then pumped to the top of the six hearth furnace for · burning and final ash storage. This system also includes odour scrubbers and a control room for operation and monitoring of all functions.

It is planned to provide separate thickening facilities for excess activated sludge in the next stage of each system.

Following the current performance trials, each system will undergo a three months commissioning period before fina l acceptance by the Board.

COCKBURN SOUND EN~RONMENTALSTUDY Owing to the very restricted space for berths in the port of Fremantle, Cockburn Sound has long been regarded as the ultimate outer harbour for the Perth-Fremant le area. Relatively deep water close to shore on a we ll drained sand plain presents an attractive

location for industries requmng bulk shipments of materials to be Imported or products for export.

Over the past 22 years an industrial complex has built up on the eastern margin of the larger basin. In 1969 the Commonwealth Government announced plans to build a naval establishment on Garden Island, which forms the western boundary of Cockburn Sound.

During 1971-72 a solid fil l causeway with two open bridge sections (305m and 610m respectively) was built across from the southern entrance to Cockburn Sound , from Point Peron to Garden Island.

Although the primary concern has been to develop the area for industrial purposes , Cockburn Sound was also highly attractive for a wide range of recreational activities , having sheltered clean beaches , good f ishing, etc.

However, development of industries around the foreshores progressively reduced the beach areas available.

Waste discharges and spillages lowered water qua I ity .

The Fremantle Port Authority sought the aid of the Environmental Protection Authority, and early in 1975 a firm of consu ltants was engaged to review the problems. Their report was received In February 1976, and the West Australian government then approved a three year study oriented to understanding the environment of the Sound so that its multipurpose uses can be maintained .

The project was to be directed along the following lines: (i) Monitoring of indl.JStrial discharges, and studying the impact of these upon the Sound's ecosystem . (ii) Assessment of the causes of the death of s~agrass . (iii) Assessment of the causes of and possible cures for the algal blooms. (iv) Analysis of the social and recreational uses of the Sound and its tourist and recreational value . (v) Assessment of the fisheries potential -and productivity for professional and amateur fishermen. (vi) Appraisal of water movements to re-assess: flushing of effluents · and to provide alternative options to treatment on land by discharge of effluents , into we ll flushed areas. (vii) Beach movement studies to assess the role of seagrass in the control of erosion, and as a basis for the design of artificial control structures.

COMPLETION OF NEW BREWERY EFFLUENT TREATMENT PLANT

Construction is now virtually complete at the new Swan Brewery complex at Canning Vale , Western Austral ia.

This new brewery will replace the

existing Swan/Emu Brewery in the centre of Perth which itself originally commenced brewing operations in 1837.

The new brewery and effluent treatment plant, which have been designed by the Canadian firm of Kappele, Wright and Macleod Ltd., will be commencing production in April this year. The eventual daily production capacity will be 1530 m3 which would result in a daily effluent discharge of some 7340 m3, with a BOD5 of 1500 mg/I and suspended solids of 600 mg/I. As sewerage is not available in this area, and stormwater drain disposal to the river system is not permitted, it has been required that, prior to ground disposal, the brewery effluent be treated to at least 20 mg/I BOD5/30 mg/I suspended solids standard to protect underground water quality. The treatment plant which is an extended aeration type consists of coarse screens, a combined flow equalisation and grit removal tank with a hydrogritter, two extended aeration tanks with fixed surface aerators, two secondary clarifiers and two final effluent polishing lagoons with floating surface aerators. Sludge treatment consists of dissolved air flotation thickening, aerobic sludge digestion with floatinQ surface aerators, followed by sludge drying beds .

The final effluent will be sprayed onto a grassed 12 ha irrigation area on the brewery's own property. The plant design provides for dissolved oxygen monitoring on both the aeration tanks and sludge digester, nu trient addition of both nitrogen and phosphorus and automatic sampling at various stages throughout the plant.

Preliminary work prior to the start up of the treatment plant included regular quality testing of the ground water from bores sunk throughout the irrigation area, and for the last twelve months two 600 m2 trial irrigation areas have been under test to evaluate suitable effluent dosing programs and also the suitability of various types of grasses for the main area.

The final effluent will also be used for general reticulation of the extensively landscaped site, for the brewery's own garden nursery, and for supplying water for a large ornamental pond.

At present a mixture of activated sludge from a M.W.S.S.&D.B. treatment plant and brewery sludge from the existing Perth brewery Is being aerated with compressed air at the plant to provide a seed bioculture for the main production startup.

PERTH'S WATER SUPPLY CONT. FROM PAGE 15

dilution and cooling before putting into supp ly . .

Recent artesian production wells have been mainly into the Leederville formation with the water treated with the unconfined aquifer water sources.

These artesian aquifers also represent a considerable water resource.

THE FUTURE Up to 1970 supply of water for Perth was in many ways a water supply engineer's dream. Water from Darling Range rivers was of excellent quality with no biological or eutrophication problems, very low colour and turbidity.

Only token chemical monitoring was needed. Dam and pipeline construction was comparatively easy and uncomplicated and possible at low cost. As a consequence water was cheap to consumers and there was no strong incentive to encourage careful use or conservation . This era has ended.

The boom years of the late 1960's coincided with the end of the era of traditional easy Hills sources and combined with a period of relative drought and the financial and staff stringency of the 1970's. During the same period a massive expansion of the sewer system was launched, both In new and older unsewered suburbs.

Coping with this situation has severely taxed the technical and financial resources of the Board.

On the other hand these circumstances have started to encourage innovation in what is traditionally a conservative industry. This stimulus Is now extending from the engineering side into the mangement and financing sides as well. A major financial and management study on the Board's future strategy for sewer and water development has just been completed.

The report recommended the integration of planning for engineering, funding and revenue-raising , pay-asyou-use water charging and a number of other initiatives directed at water conservation and its efficient use. A number of areas where cost effectiveness of capital works could be improved were pin-pointed as worthy of further investigation .

Such is the dynamic state of Perth's water supply.

A new fire fighting agent ICI has an nounced the discovery of a new fire-fighting agent to add to their existing range. Known as W.A.T.E.R. (Wonderful And Total Ext ingui shing Resource) , it augments, rather than replaces, existing agents such as dry

powder and BCF which have been used since time immemorial. It is particularly suitab le for dealing with fires in buildings, timber yar'tls and warehouses. Though required in large quantities , it is fairly cheap to produce and it is intended that quantities of about a million gallons should be stored in urban areas and near other installations of high risk ready for immediate use. BCF and dry powder are usually stored under pressure, but W.A .T.E.R. will be stored in open ponds or reservoirs and conveyed to the scene of the fire by hoses and portable pumps .

ICl 's new proposals are already encountering strong opposition from safety and environmental groups.

Professor Connie Barrinr:,er has pointed out that if anyone immersed his head in a bucket of W.A.T .E. R. , it would prove fatal in as little as three minutes. Each of ICl's proposed reservoirs will contain enough W.A.T.E.R . to fill half a million two-gallon buckets. Each bucketful could be used a hundred times, so there is enough W.A .T.E. R. in one reservoir to kill the entire population of the UK. Risks of this size, said Professor Barrinner, should not be allowed, whatever the gain. If the W.A.T.E .R. were to get out of control, the results of Flixborough or Seveso would pale into insignificance by comparison. What use was a fire-fighting agent that could kill men as well as fires?

A Local Authority spokesman said that he would strongly oppose planning permission for construction of a W .A .T.E.R. reservoir in his area unless the most stringent precautions were followed . Open ponds were certainly not acceptable. What would prevent people from falling in them? What would prevent the contents from leaking out? At the very least, the W.A .T.E. R. would need to be contained in a steel pressure vessel surrounded by a leak- proof conc_.ete wal I. A spokesman from the Fire Brigades said he did not see the need for the new agent . Dry powder and BCF could cope with most fires. The new agent would bring with it risks, particularly to firemen , greater than any possible gain .

Did we know what would happen to this new medium when it was exposed to intense heat? It had been reported that W.A.T .E. R. was a constituent of beer.

Did this mean that firemen would be intox icated by the fumes?

The Friends of the Eart h said that they had obtained a sample of W.A .T.E.R. and found it caused clothes to shrink . If it did this to cotton , what would it do to men?

In the House of Commons yesterday , the Home Secretary was asked if he would prohibit the manufacture and storage of this lethal new material. The Home Secretary rep I ied that, as it was clearly a major hazard, local authorities would have to take advice from the Health and Safety Executive before giving planning permission. A full investigation was needed and the Major Hazards Group would be asked to report.

23

A.W.W.A. SUMMER SCHOOL The 1978 AWWA Summer School on the t heme "Water Quality" was organised by the Tasmanian Branch , and conducted in Hobart from 5th to 10th February .

The school was officially opened on the Monday evening by the Premier of Tasmania , the Honorable D. A. Lowe, M . H . A . who delivered a most appropriate and stimulating speech which was very well received. This was followed by Brian Ford's keynote address (wh ich is summarised in this issue of Water) and then a very pleasant supper function to welcome the participants, who numbered over 120.

The sessions were conducted in the excellent facilities of the University Centre and the Arts Lecture Theatre .

The school examined and discussed Water Quality along the lines of : new concepts , pol icies and practices object ives and criteria of water quality from the viewpoints of environmental control, public health , irrigation, industrial and municipal usage biological criteria strateg ies aimed at maintaining wat er quality through the hydrologic cyc le Perhaps th e mo st valuable aspects of the School were the lectures and contributions mad e by the overseas visitors , Professor John Cairns and Mr Brian Ford, who were brought to the School by the organising committee .

generated at Hobart become waves of enthusiasm to see water in a different way. Historica lly, the control of water has been in the hands of authorities whose purpose is remarkably singleminded . Both the authorities which employ professionally qualified people and the learned societies to which their engineers and scientists be long have tended to perpetuate th is insularity .

Perhaps those peop le who are concerned with the use of water, particularly withdrawal uses , will become increasingly concerned not only with the techn ica l methods avai lab le to them to treat water for their own purposes (the importance of which is beyond question), but also with the effects on their operations of the quality of the raw water . All life, in whatever form, is affected by the quality of available water. To examine the management of water qua lity throughout the hydro logic cyc le may produce real social and economic -benefits to the nat ion .

The students took part in a programme which began at 8.45 each morning, and continued through to 9.30 p.m. at night , inc luding two even ing workshop sessions on Water Qua lity Management and Industrial Waste Treatment. These sessions gave opportunities for the participants to sound off a variety of views . Even the set subjects occasionally got a mention. The bar was also a scene of heated discussion ti ll long into the night .

A degree of relaxation was offered on t he Wednesday night. Part ic ipants were entertained by the comm ittee to a most enjoyab le even ing at the Wrest Point Casino dinner , sophist icated entertainment, and somewhat unprofitable pursuits afterwards.

For those who stayed in Hobart after the schoo l ended on Friday, another memorable evening was en joyed at the Bal l and Chain .

All in all, it was a week of intense activity and stimu lation.

Participants are urged to contact Counc ill ors of the Assoc iat ion and discuss what the objectives of a Summer School shou ld be. Comment at the Schoo l varied as to whether their aim should be to broaden the scope of one's knowledge, or to provide the latest answers to the day to day prob lems encountered by all profess ionals .

It is of the opinion of several "old stagers" that the organisation , standard of lectures and student participation was of high order, and the Tasman ian Branch and organising committee are to be congratu lated on a highly successfu l Summer School.

Preprints of the lectures are stlll available and can be purchased for $25 from the Secretary, Tasmanian Branch, AWWA Box 336, Sandy Bay, Ta~. 7005.

THE PAST-PRESIDENT MAKES A POINT AT THE 197;8 SUMMER SCHOOL IN HOBART

Brian Ford, a dynamic personality, is well known in U.K . and Europe as a science journalist and broadcaster, and his keynote address set a pattern of Insight and quest ioning which was maintained throughout the whole week .

John Cairns Jnr. is presently the Director of the Centre of Environmental Studies, and Distinguished Professor at Virginia Polytechni c Institute and the State University of Virginia . His speciality is aquatic biology , and he has a broad appreciation of the overall water environment, particularly the interaction of the biological component with physical and chemical characteristics. His input was most valuable and provoked thoughtful discussion .

The other lecturers came , in almost equal numbers , from government authorities , industry, consultants, and the academic field . About half were engineers, there was one medico , the remainder were biologists and chemists . Their selection was based not only on their wide knowledge but also on their sound practical experience.

The Organising Committee wil l be most interested to see if the ripples

24

L to R: Roy England [conrener], John Cairns, Barry Hart, Henry McF/e and Brian Ford.

Professor Cairns and Mr Ford were the overseas speakers at the Summer School.

COMPARISON OF COMPOSITE AND GRAB SAMPLES

by I. M. Lowthera and I. G. Wallisb Many water quality sampling programmes are based on collecting grab samples. Inevitably, in assessing the results of the sampling programme, the question arises as to how closely the grab samples represent the actual average level of the wastes over a period of time, such as a day. This question can be answered only by comparing the results of grab samples with the results of composite samples collected over a long period.

During the six months from July to December 1977, the Geelong Waterworks and Sewerage Trust (GWST) collected both grab and 24-hour composite samples of wastewater at the outlet of the Trust's outfall sewer at Black Rock. The composite samples were prepared automatically from 24 hourly subsamples composited in proportion to the flow rate at the time the subsample was collected. The grab samples were collected during the time the composite samples were being collected, usually between 9 a.m. and 12 noon . A total of _22 grab and 21 composite samples were analysed using standard methods for the constituents shown in Fig . 1.

RATIO OF (GEOM . MEAN CONCENTRATION IN GRAB SAMPLES ) GEOM . MEAN CONCENTRATION IN COMPOSITE SAMPLES

Fig. 1. Ratio of mean concentration In grab samples to mean concentration In composite samples .

Composite samples were taken by a vacuum operated sampler at a point of turbulent flow following commlnutlon of the wastewater. The composites were kept Ice-cooled during the collection period. The problems associated with automatic sampling are appreciated, particularly In regard to obtaining representative samples of suspended matter and to the preservation of composites. As the composite and grab samples compared in this study were collected and preserved in the same manner, the above considerations are not considered to have a significant effect on the validity of the comparison . Since completion of the sampling programme, the vacuum sampler has been replaced by a peristaltic pump sampler which has refrigerated storage for samples and is capable of collecting up to eight similar, proportional to flow, composite samples at the same time. This sampler will allow optimum preservation methods to be employed for individual constituents.

The scale in Fig . 1 represents the ratio of the geometric mean of the grab samples to the geometric mean of the composite samples. It cah be seen that both the mean total nitrogen and ammonia-nitrogen concentrations of the grab samples exceed the corresponding mean concentrations of the composite samples by about 20 per cent. On the other hand, the mean concentrations of zinc, lead, cadmium and iron of the grab samples were less than half those of the composite samples and the mean concentrations of BOD, nickel, chromium and suspended solids of the grab samples were between 60 and 70 per cent of those in the composite samples. On the basis of "t" tests, it was concluded that, at the 99 per cent level of significance, the difference between the means of the composite and grab samples was confirmed a Senior Chemist, Geelong Waterworks and Sewerage Trust b Project Engineer, Caldwell Connell Engineers

for all constitutents except copper, mercury and total phosphorus.

Overall, it may be concluded that the grab samples did not provide a good representation of the average waste concentrations over 24-hours. This is to be expected because of the large variation in the concentration of many of these wastes with time, especially those contributed largely from industrial sources. Furthermore, because the ratio of the mean concentra tions of the grab samples to the mean concentrations of the composite samples varies over such a large range (0.33 to 1.21 ), it is not feasible to ose the ratio of means for one constituent to describe the ratio of means for other constituents .

As would be expected, the variation of the concentration of individual samples about the mean concentration was much greater for grab samples than for composite samples . For example, the coefficient of variation (standard deviation divided by the mean) was 0.41 for the su spended solids concentrations measured in the grab samples and 0.16 for the concentrations measured in the composite samples .

Overall, the coefficient of variation of grab sample concentrations was about twice that of composite sample concentrations . This Indicates that about four times as many grab samples as composite samples need to be collected to estimate the mean concentrations of the various constituents to within the same limit. This is the reason why It Is often better to collect a smaller number of composite samples than a larger number of grab samples, even though the collection times of the grab samples could be staggered over the day, to provide a more representative sampling of average dally conditions.

Conclusion This comparison of grab and composite samples, collected by the GWST illustrates (1) the potential of drawing misleading conclusions on the basis of grab samples and (2) the importance of collecting composite samples. In some cases, as at Geelong, the additional work of collecting composite rather than grab samples ma.r be offset by the fact that, owing to the mixing and averaging which occurs during the formation of a composite sample, fewer compo site samples are nee.ded to estimate the mean waste concentration to the same limits.

The engineer's Idea of enlflronment - or reclamation and reuse.

(Photo by Frank Byrnes at the Victorian Branch visit to Geelong)

25

PERSONALITIES AND PRODUCTS KELLY & LEWIS PUMPS FOR HONG KONG WATER SUPPLY

Dr. Richard A. K. Lang has res igned from the managing directorship. of Hanson Sykes Pumps Pty. Ltd. and is now practising as consultant in design of pump systems for groundwater control, pipeline transport, and heat transfer. His address is Kingston, Long and Associates, 62 Daley Avenue, Daley's Point, N.S.W.

The contract to supply pumping and ancillary equipment for the Muk Wu station augmenting the Hong Kong Water Supply has been awarded to Kelly and Lewis Pumps .

Kelly & Lewis will supply pump extensions consisting of three KL 825/900 mm vertical split casing, double suction pumps coupled to Vefloun -KK, 900 kW, squirrel cage induction motors to supply three 2.21 m /sec. pumps .

Michael B. Dureau

1977 shuttled actively from NSW Branch Committee to Victorian Committee, and is now back in Sydney again . We wish him well.

Mr. Dennis, his predecessor , has returned to the United Kingdom to direct the newly-formed European Division.

Dr. Richard A.K. Lang

KENT INSTRUMENTS Mr. John R. Hubbard, who was Chairman and Managing Director of Davies Shepard Pty . Ltd. (Kent Water Meters) has been appointed chairman of Kent Instruments (Australia) Pty. Ltd .

One of three Kelly & Lewis 825/900 mm, vertical split casing, double 1 suction pumps.

POLYL-AG

Mr. Robert J. Chappell, Victorian Division Manager, Kent Instruments [Austral/a) Pty. Ltd.

The new Victorian Manager is Mr. Robert J. Chappell, a Member of the Institute of Engineers and of the Institute of Instrumentation and Control.

HAWKER SIDDELEY

John R. Hubbard

Mr. Michael B. Dureau, who was appointed Manager of the Victorian Division only last year became Managing Director of the Australiar, Company at the beginning of 1978.

Mike is well known in AWWA, and in 26

Mr John R. Fulton, C.Eng., M.I. Mech . E., has been appointed general manager of Hawker Siddeley Water Engineering (Australia) .

This division handles Hawker Siddeley Brush's operations in water and waste water treatment, process and chemical engineering and environmental engineering .

In 1975 Mr Fulton took responsibility for developing Hawker Siddeley's water, process and environmental business.

There can be a high heat loss from unlagged copper tubes laid in concrete slabs. A uniquely Australian product, Polylag is an .,Australian breakthrough in pre-insulated copper tube. Developed

by Crane Enfield Metals Pty. Ltd., it has won formal recognition from the Federated Master Plumbers' Union of Australia for its benefits to the plumbing industry and the community.

It consists of copper tube pre-lagged with a tough flexible sheath of foamed polyethylene which withstands the rigours of transporting and handling on site. It is easy to install being light and readily bendable around quite tight radii. The natural cushioning of the insulating material allows thermal movement of the copper when it is embedded in concrete or masonry .

Good insulated joints are easily provided by first cutting and peeling back the polythene sheath which will then snap back into place once the join is made . Because of its ease of installation, Polylag will in many cases, result in lower installed cost to the householder. Furthermore, it saves on running costs by reducing heat losses from pipes carrying hot water. The polythene sheath is water resistant and inert resu lting in extended service life even under arduous conditions .

NEW RANGE OF SCREW PUMPS FROM AJAX McPherson's Ltd . Pump Division, which manufactures the Ajax range of. pumps , is marketing a complete range of screw pumps applicable for sewage disposal applications.

The Ritz Archimedian screw pumps . offer long life, simplicity of maintenance, high efficiency even on partial load, elimination of the need for screens, reliability in handling coarse deposits, self-regulating turbulencefree throughput and efficient bacteriological treatment of effluent due to low velocities . .

Maximum efficiency can be achieved even under partial load conditions and very little power is used u_nder no l?ad conditions, making the unit economical whether on a continuous flow application or on a highly fluctuating flow of effluent .

Purifax Sludge Stabllsatlon

the treatment of Paper Mill waste, which , because of the wide variety of been operational conditions , has difficult to treat with a standardised and universal system in the past .

The Purifax system is also particularly suited to domestic sewage pre-treatment plant where it can replace digesters with a significant reduction In space requirements and cost, according to the manufacturer.

The Purifax· system can be used In place of anaerobic digesters or can supplement anaerobic digesters, If required.

It can also be used successfully in scavenger treatment systems .

Further information is available from:Lightnin Mixers Pty . Ltd ., 34 Hercules Street , DULWICH HILL, N.S.W. 2203 TELEPHONE : 560-4066

DIGITAL NITROGEN DETECTOR

Ritz Arch/median screw pumps are particularly applicable to the pumping of sewage because of their efficiency and minimal power absorption under low or fluctuating loads.

SLUDGE STABILISATION SYSTEM SOLVES IMMEDIATE AND FUTURE PROBLEMS .

Recently released by Lightnin are details of the BIF Purifax Rapid Sludge Stablization System .

Described as a wet chlorination process, the unit stabilizes, coagulates and deodorises in one rapid high efficiency operation . No pretreatment is necessary beyond the usual removal of gross debris and the breaking up of large solids.

In its industrial application, the Purifax system has been proved particularly efficient in de-coloris~tion, oil separation in laundry operation~, :r eduction in the phenol content in fibreglass plants, treatment of brewery waste, meat processing waste, heat treatment process filtrates a~d ~lyc?I. waste . It has a particular applIcatIon in

The Antek Model 720 Digital Nitrogen Detector is based upon an entirely new approach for analysing chemically bound nitrogen . Using the proven principle of chemiluminescent dete?tion it is a simple, accurate, and rapid tech'nique to analyse gases , liquids and solids . Combined nitrogen determinations are analysed in less than a minute.

This instrument finds application in waste wat~r. sewage, petroleum petrochemicals, fertilizer, foods , beverages, drug, tobacco and pesticide . . analysis: • The nitric oxide-ozone chemIluminescen't detection system is simple to operate and forms no dangerous

vapours, such as with the Kjeldahl analysis .

• It measures trace bound nitrogen with a lower detectability of 10 -8 grams.

• Used in conjunction with an oxidative furnace - the Antek model 771 Pyroreactor is recommended.

For further information, please contact:JOHN MORRIS PTY . LTD., P.O . BOX 80 , CHATSWOOD, N.S.W. 2067 .

Tel.: 407-0206 .

INSERTION FLOWMETER The Quadrina 'Probeflo' Insertion Flowmeter has now been installed for both portable and permanent monitoring of natural gas flo s in several States.

The freely rotating turbine is inserted' into the pipe while under pressure , and provides a large digital electrical signal suitable for distant monitoring of flow rate and total flow . Pressures up to 1500p.s.i.g . (10MPa) and flow rates to 200ft/sec. (60 metres/sec .) can be accommodated .

The 'Probeflo' is also suitable for monitoring the flow of water, both in closed pipes and open channels .

Allowances are made for the blockage caused by its insertion and for the velocity gradient over the pipe cross section .

TECHNICAL & SCIENTIFIC EQUIPMENT PTY . LTD., 108 Queen St ., Melbourne 3000

I

Antek Nitrogen Detector

27

POLYALUMINIUM CHLORIDE March's heavy rains and floods provided an excellent opportunity to test AQUAPAC (polyaluminlum chloride) under extreme conditions of very muddy river water out of the Macquarie River at the Bathurst water filtration plant. The . object was to see if it would perform as well at high levels of turbidity as it had done at normal levels of 15 to 50 earlier.

On the day (Tuesday, 21 March) the Macquarie River was running a banker at Bathurst and the raw water available to the Council's filtration plant was virtually untreatable during the morning when it was reading 250 NTUs turbidity and 440 Hazen units of true colour. Water temperature was 18° C and it s pH was 7 .0.

Dosage rates of solid alum (17% A1 2 03 aluminium sulphate) from 140 pp, to 240 ppm were applied to the water In standard jar test equipment. Ttlese tests snowed an optimum dosage level of 180 ppm of solid alum with associated deterioration of performance at levels over 180 ppm . But even the most effective dosage rate (180) was still not adequate for use in the plant. It took a further addition of 0.2 ppm of non-ionic polyelectrolyte floccu lent aid to pull down the remaining fine cloud to an acceptab le clarity.

The performance of polyaluminium chloride improved with increasing dosage to an optimum level of 130 ppm, falling away at higher concentrations. At 130 ppm the water was clarified to a standard that was acceptable for use In the plant with a larger and much stronger floe than alum and with markedly reduced colour in the water. However, 'there sti ll remained a faint cloud residue from the highly turbid raw water which was effectively removed by addition of 0.1 ppm of flocculent aid.

After sett ling , the sample treated with 130 ppm AQUAPAC was compared with the sample that was treated with 180 ppm of alum plus 0.2 ppm of LT20, with the following result.

Polyalumlnlum Alum 180 ppm Chlorlde 130 ppm + 0.2 ppm LT20 Condition of Floe: larger and stronger normal than normal Turbidity of supernatant water: 17 NTUs 21 NTUs 4.35 pH : 4.8 Turbidity after filtering through 2.25 NTUs 2.50 NTUs Whatman No. 1 fl lter: paper (2 microns) Coagulant:

On the same day tests were also carried out with a sample of especially "difficu lt" water taken from the river a week earlier when heavy rain in the hills upstream from Bathurst brought down a run of muddy water. This water contained a "white cloud" of colloidal clay that until then had resisted all attempts at removal. It showed a reading of-280 NTUs on the turbidity meter.

Various dosage levels of alum were tried, and an optimum level of 200 ppm was arrived at, although the result was very poor, with substantia l "white cloud" and most of the colour stil l remaining in suspension. The 200 ppm level of alum was again tried with the addition of 0.2 ppm of flocculent aid. A good floe formed, and settled, but the "white cloud" remained.

Polyaluminium chloride was then tested In the s~me "difficult" water at dosage rates of 50 ppm through to 170 ppm. At all these levels of addition a large firm floe formed and sett led rapidly. At levels of 120 ppm, 140 ppm and 170 ppm all visible suspended matter was brought do,;_,n In the floe, leaving a completely crystal clear water that was totalli clear of all cloud and colour. The "white cloud" had disappeared .

We acknow ledge with thanks the co-operation and assistance given to us in the conduct of these tests by John Hay (Plant Superintendent) and Peter Catellotti (Chief Chemist) of the Bathurst City Council.

For further information contact: Peter Say Pty. Limited, 20 Harris St. , Paddington, N.S.W. Makers of AQUAPAC in Australia.

28

MINISTRY FOR CONSERVATION

ENVIRONMENT PROTECTION ACT 1970 Notice of Intention to Declare a

STATE ENVIRONMENT .

PROTECTION POLICY The Environment Protection Authority has prepared a draft policy for environmental management relating to water quality for

THE LATROBE RIVER TRIBUTARIES Public Review and Comment People likely to be affected are ifivited to write to the Authority giving any relevant comments, recommendations or information which they wish to be considered when the policy is being finalised for adoption by the Government. Copies of the Draft Policy may be obtained free of charge from the EPA. Comments etc. should reach the _ Secretary, Environment Protection Authority no later than June, 1978 (Please (lluote 77/1824).

This notice is issued pursuant to Section 19 of the Environment Protection Act, 1970.

ENVIRONMENT PROTECTION AUTHORITY 240 Victoria Parade, East Melbourne, 3002.

Tel.: 651-4011.

CONFERENCE CALENDAR INTERNATIONAL CONFERENCE ON DEVELOPMENTS IN LAND METHODS OF WASTEWATER TREATMENT AND UTILISATION Melbourne, Australla 23-27 October, 1978 SPONSORS:

rv,r. J.B . McPherson, M.M .B.W. Melbourne : - "Land treatment of wastewater at Werribee: 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. Gioyna, University of Texas , USA : - "Status of lagoon treatment " Mr. C.D. Parker , Water Science Laboratories, Melbourne: "Biological mechanisms in lagoons" Dr. G.G. Gillie, National Institute of Water Research, South Africa: - "Sludge treatment , utilisation and disposal "

The conference is being held under the auspices of the International Association on Water Pollution Research and is being co-sponsored by : Australian National Committee of I.A.W.P .R. Australian Water and Wastewater Association Asian Regional Division of International Association of Hydraulic Research The Melbourne and Metropolitan Board of Works The University of Melbourne The C.S .I.R.O . Division of Chemical .

Technology Financial support is being given by a number of industrial firms and PAPERS: government bodies.

Thirty-two papers have been selected for presentation at the Conference.

INVITATION TO ATTEND: The conference is open to all persons Authors come from U.S.A., Israel , New who are interested or active in land Zealand, Germany, Thailand, India, Malaysia, Denmark and from within methods of wastewater treatment and utilisation.

Persons accompanying Australia . delegates will be welcome.

PROGRAM :

POST CONFERENCE TOURS :

The Conference will be concerned with irrigation, grass filtration (overland flow) and lagoons (stabilization pones) as used in the treatment of wastewater.

It will include keynote addresses and submitted papers dealing with: • the design, operation and effectiveness of these methods; • the application of these methods to wastes from various sources . including domestic and industrial, food processing, palm oil mills, piggeries and wineries; • the utilisation of wastewaters for the production of pastures, crops , trees, grapevines and for aquaculture ; • waste-borne diseases, public and animal health; • soil effects and heavy metals; • utilisation and disposal of sludge.

The technical sessions will be held at the University of Melbourne. All papers will be presented in English. The program will include a full-day Inspection of the sewage treatment farm at Werribee .

Inspection tours will be conducted on Saturday 28th October, 1978 to the Shepparton Wastewater Treatment Plant (central Victoria), orto the Bolivar Sewage Treatment Works and Angle Vale vineyard (near Adelaide, South Australia), or to the South Eastern Purification Plant (near Melbourne) .

KEY NOTE SPEAKERS:

Dr. Curtis C. Harlin, Environmental Protection Agency, USA: - "Land treatment methods In perspective"

SOCIAL PROGRAM :

Social events will include the Conference Dinner, a State Reception and a theatre-restaurant evening. Day tours to wildlife sanctuary , historical museums and scenic areas will be arranged for persons accompanying delegates .

ENQUIRIES :

For further information and registration forms contact: I.A.W.P.R . Conference Secretary Melbourne and Metropolitan Board of Works Box 4342, G.P.O . , Melbourne 3001 Australia .

Telephone: (03) 615-5209 Cable and Telegraph : Metropolis, Melbourne Australia Telex : AA43220

ARTIFICIAL GROUNDWATER RECHARGE A conference convened by the German Geological Society and Water Authorities of the Federal Republic of Germany on Research Results and Practical Applications.

15-18th May, 1979 Dortmund , F.D.R .

(Further details are contained in the Information Note No . 1 held tiy the Editor of this Journal.)

VICTORIAN BRANCH SPRING BREAK-OUT CONFERENCE SHEPPARTON. 13-15th OCT·, 1978 "INLAND WATER MANAGEMENT" Irrigation, Flood Control, Groundwater Salinity, Waste Disposal.

[Wives and children special attraction!- Shepparton Show .]

WATER POLLUTION CONTROL FEDERATION 51st ANNUAL CONFERENCE/EXHIBITION ANAHEIM, CALIFORNIA October 1-6th, 1978 AUSTRALIAN WATER RESOURCES COUNCIL WORKSHOP ON GROUNDWATER POLLUTION PERTH ' February 19th-23rd, 1979 ENGINl;ERING AND THE ENVIRONMENT -HARMONY OR CONFLICT?Symposlum, 6-7th December, 1978 - London The Institution of Water Engineers and Scientists A discussion of the influence of

environmental and sociological factors on the promotion, design, construction and operation of major engineering works .

Further information from the Secretary, 6-8 Sackvllle St., London .

INTERNATIONAL WATER REUSE SYMPOSIUM WASHINGTON D.C. March 25-29th, 1979 Call for papers: 500 word abstracts

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

29

CONTINUED FROM PAGE 21 Laboratory studies using soil from the recharge site and adopting local conditions should produce a model for predicting the best management options . Pilot plant studies designed with the information from these laboratory studies should precede any large scale recharging scheme .

ACKNOWLEDGEMENTS Financial support of the Australian Water Resources Council (Grant no. 78/112) is gratefully acknowledged . Mr Mathew is supported by Murdoch University Research Studentship.

REtERENCES (1) O'Hara, I. J., 1973, 'Perth's Water Supply and Groundwater' Institution of Engineers (Austral la) Conference papers, 1973.

(2) Fleay, B. J. " The dynamic state of Perth's watersupply". Water- this Issue.

(3) Binnie and Partners (Austral la) 1976, Perth Groundwater Recharge study.

(4) Sanders, B. S., 1974, 'Recent Expansion of Perth's Sewerage System' Civil Engineering Transactions Vol. CE16, No. 2, 1974, Institution of Engineers , Australia.

(5) McMlchael , F. C. and McKee, J. E., 1965, "Final Report of Research on Waste Water Reclamation at Whittler Narrows" State of California . The Resource Agency . State Water Quality Control Board publication No . 33 , 1966.

(6) Merrel , J. C. et al., 1967, "Santee Recreation Project" , F.W.P.C.A. Report . Water Pollution Control Research Series Publication No. WP-20-1 .

(7) Bouwer, Herman , R. C. Rice and E. D. Escarcega, 1972, "Renovating Secondary Sewage by Groundwater Recharge with Infiltration Basins".

Water Pollution Control Research Series 16060DRV 03/72 . · (8) Amramy , A., 1968, Reuse of municipal waste water. Civil Eng. 38: 58-61 .

(9) Garcia, J. 1. - Bengoehea 1970, "Recharge of Carbonaceous Saline Aquifer of South Florida with Treated Sanitary Waste Water' ' Artificial Groundwater Recharge Conference 1970. Water Research Association, England. Supporting paper C p,431 .

(10) Winton, E. F. et al. 1971 , Nitrate In Drinking Water, Public Health Aspects. Journal AWWA . Vol. 63, No. 2 PP 95-98.

(11) Sepp, E. 1970 Nitrogen Cycle In Groundwater, Bureau of Sanitary Engineering, State of California, Department of Public Health .

(12) "Process Design Manual tor Nitrogen Control" , U.S. Environmental Protection Agency , Technology Transfer, October 1975, pp 2-7.

(13) Lohr, R. C. 1973 Development and Demonstration of Nutrient Removal from Animal Wastes, EPA-R2-73095 January 1973.

(14) Lance, J. C. 1975, "Fate of Nitrogen In Sewage Effluent Applied to Soll".

Journal of the Irrigation and Drainage Division ASCE . Vol. 101 No. 1R3 proc. paper 11570, September 1975 pp. 131-144.

(15) Black , C. A., 1965, Method of Soll Analysis . American Society of Agronomy Inc., Madison, Wisconsin, U.S.A. ALLAN PETTIGREW CONSULTANTS

PTY. LTD .

Consultants in Pollution Control & Water Treatment P.O. Box 94 - ROCKLEA 4106 TELEPHONE : Business 275-3322 Private 200-1176

44 Koornang Road, · Scoresby 3179

Telephone 763 8988 W •Tll

\

BOBY j

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BOBY ANALYTICAL LABORATORY SERVICES

~ Pettigrew Engineering Co. Pty. Ltd. Pollution Control & Water Treatment Engineers For Full Turnkey Projects 34 Reginald Street, Rockies. 4106 Telephone: 275-3322

POLLUTION SOLUTION IN HAND ...

Handling unwanted efflu ents, sludges and simil ar by-produ cts of th e indu stry bring plenty of pollution probl ems which mu st be solved.

1llu strated is the CS3126 - one of t11e Flygt poll ution solvers. A CS31 26 will help you with your particular pollution probl em.

By th e appropriate combination of impell ers, impell er housings and methods of installation, the Model CS3126 can remote a wide variety of pollu ta nts.

And that's not all! With Flygt' s wide range of model s, th e individual combinations are such th at a Flygt Pump can get rid of your muck.

Consult Flygt on handling • trade wastes • sludges • effluents • contaminated fluid s etc .

FLYGT AUSTRALIA LI:iv.l:ITED A memper company of the world-wide Flygt Organisation.

29 ffope St., Ermington, N.S.W . 2115. Tel.: 858 2399 Al/STRAL/A WIDE DISTRIBUTION NETWORK BRISBANE 59 0566"

MELBOURNE 560 5333

HOBART

LAUNCESTON

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31 4077

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KALGOORLIE

278 2532

65 5111

21 2635 F1 477

30

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 smoothly and quietly at 10 R.P.M . It won't shake itself to pieces. And its rugged, stainless steel, all-welded const ruction requires no tension adjustments or periodic maintenance to keep 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 perfo,ms 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:

WILLIAM BOBY & CO. (AUSTRALIA ) PTY. LTD .

44 Koornang Road , Scoresby, Victoria , 3179 Telephone: 763 8988 . Telex: 31868 Also at: Sydney 93 031 1, Brisbane 229 5800. Adelaide 278 4135

from

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P100L series recorders Kent Instruments (Australia) Pty. Limited

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Sydney (02) 525 2811 Melbourne (03) 874 1233 Adelaide (08) 352 1455 Brisbane (07) 36 1311 Perth (09) 277 5377

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General purpose recorders with advanced features The Clearpsan P1 00L series com prises a range of single 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 GEORG E KE NT group

31

New lab nephelometer!

• • • •

EPA (USA) Approved Low Cost - $788 Direct Digital Readout Recorder Output

Monitek's new Model 21 lab nephelometer makes EPA-required turbidity measurements easy, fast and positive. You just load your sample , select one of three turbidity ranges (0-2 , 0-20, 0-200 N.T.U.) with a front panel switch, and read the value on a 2½ digit LED display-with 0.01 N.T.U. resolution.

In addition , the recorder output gives you a source of precise data for monitoring trends and rate changes , and for subsequent analytical work .

In short, the Monitek Model 21 is the most practical way to make fast, accurate turbidity measurements that satisfy the EPA. For details and a demo , call or write.

Dunros (S) Pty. Ltd. 763 HIGH STREET, KEW EAST 3102, AUSTRALIA Telephones: Melbourne 859 6871 Sydney n13333

( 111[)f1ITEtf I MONITEK, INCORPORATED

"A Complete Range of Laboratory and in-line turbidity and sludge monitors".

MELTON SEWERAGE AUTHORITY Applications are invited from suitably qualified or experienced persons to fill the newly created .,. senior technical posts of:-

(a) Operations and Maintenance Engineer and

(b) Purification Plant Superintendent.

Applications are invited from suitably qualified or experienced persons to fill the newly created senior technical posts of:Preference will be given to applications who are professionally qualified engineers or chemists who are members of the Institution of Water Pollution Control or similar body, with proven experience in the management of technical staff, and who have substantial experience in the operation and maintenance of sewers, pumping stations, and on activated sewage purification plant for a town of at least 30,000 persons.

The Authority may be in a position to offer modern family accommodation at the purification works .

Further details of these positions and application forms may be obtained from the undersigned, Shire Offices, Melton, Victoria, 3337. Application forms must be returned not later than Monday, 29th May, 1978.

M. B. Watson, SECRETARY. 32

Fo,r fibre recovery and pollution control • • • • • •

Reduces sewered waste and.., water pollution Recovers reusable solids to inc~ease total product utilisation Requires minimal maintenance Rapidly pays for itself Installs easily in confined space~ 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

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

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

Torqu e overload release is simple and can be reset without too ls.

Provi sio n for coagulant additions (interna l or externa l) where optimum use can be made of them .

Selected hard surfacing provided wh ere need ed most - feed ports of conveyor, feed zone, discharge ports, housing , flight edges and faces of conveyor.

All components designed to highe st sta nda rds for operation over a wide range (up to 3100 x G) of G forces.

G leve l selected according to type of sludge.

Replaceable liners protect casing in so lids-discharge area , and in the bowl oppos ite feed ports. o ·n e-piece , heavy, cast-iron base reduce l vibration.

_L

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8 Con veyor and bow l-spe ed differential infinitely controlled to optimize process performance.

9 Forced-feed oil circulating syste m is floor mounted and connected to the ce ntrifuge by flexib le co nnections.

10 Heavy-duty bearings , des igned for long life, support rotat ing assemb ly.

11 High throughput and cost/performance because of many internal des igns and G leve ls avai lable.

Highest Sigma (pool surface are a x G) availab le.

12 Tung sten-c arbide 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 part icu larly abras ive sludges.

The Sharp les Super-D-Canter centrifuge is bu il t to the highest standards with no-compromise des ign. Our phil osop hy is to give

5

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water and wastewater treatment plants a cost-effective, rugged , and adaptab le th icke ni ng and dewatering centrifuge.

t

As a result the Super-D-Canter centrifuge is not li mited by design, materials of construction, or abrasion protect ion to operate on ly at low G forces. Opt imum G force can be selected for lowest pol ye lectrolyte cost, d ri est cake, most effective power, and least wear and tea r. Sta inless steel construction reduces maintenance and provides long life.

And hard surfac ing techno logy inc ludes the new replaceab le sintered Ste ll ite and tungsten carbide con veyor hard surfac ing with up to· 20 times t he abras ion res istance of conventional mater ials.

-SHARPLES-STOKES PTY. LTD. 99 RESERVE ROAD, ARTARMON, N.S.W. MAIL BOX 367, ARTARMON, N.S.W. 2064. PHONE: SYDNEY 439-3378. CABLE: PENNWALT, SYDNEY