Water Journal December 1979

I 1ssN 0310 - 03671 Official Journal of the AUSTRALIAN WATER AND WASTEWATER ASSOCIATION Vol. 6, No. 4, Dec. 1979 - $1.00 Registered for posting as a periodical -

Category 'B'.

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MUNICIPAL WASTE · INDUSTRIAL WASTE · INDUSTRIAL PROCESS . POTABLE WATER Grit Removal Plant Trummer Tube Screw Pumps Screenings Press & Bagger Unit Circular Sedimentation Tank Scrapers Rectangular Sedimentation Tank Scrapers Sludge Consolidation Tank Thickeners Sludge Mixing Tank Stirrers Sludge Drying Bed Mechanical Lifters Sand Bed Lifters Sta ndardised Activated Sl udge Plant for Small Populations up to 20,000 persons Aerobic Sludge Digest ion Diffused Air Activated Sludge Plant Automatic Control Systems for Activated Sludge Plant

Thermal Sludge Condition ing Plant Chemical Sludge Conditioning Plant T.C. Incinerator for Sc,reen ings • Multiple Hearth Incinerator Fluidised Bed Incinerator Static Grate Incinerator Rotary Drum Incinerator Di ssolved Air Flotation Complete Indu strial Effluent Treatment Plant s Carbon Regeneration Chemical Dosing Equipment Clarification Rapid Gravity and Pre ssure Filtration Plants

Base Exchange Softeni ng Plants Dealkalisation/Degassing/ Ba se Exchange Plants Boiler Feed and Process Demineralisat ion Plan ts Deaerators Boiler Blow-down Equipment Ion Exchange Plants Ion Excha ng e Resi ns Coagulating/Settlemen l/ Filtration Plants Lime Softening Plants Packaged Potable Water Treatment Plants

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EDITORIAL

Chairman, C. D. Parker F. R. Bishop Mary Drikas E. A. Swinton T. M. Smyth B. S. Sanders Joan Powling T. Fricke W. Nicholson W. E. Padarin J. H. Greer B. J. Murphy P.R. Hughes J. Bales H. Wilson Editor: Publisher: G. R. Goffin A.W.W.A. BRANCH CORRESPONDENTS

CANBERRA A.C.T. W. E. Padarin, P.O. Box 306, Woden, 2606.

062-81-9111 NEW SOUTH WALES T. M. Smyth, G. H. & D. Pty. Ltd., P.O. Box 219, Neutral Bay Junction, 2089.

02-908-2399 · VICTORIA J. Bales, E.P.A., 240 Victoria Parade, East Melbourne, 3002.

03-651-4685 QUEENSLAND P. R. Hughes, P.O. Box 120, Kenmore 4069.

07-378-7 455 SOUTH AUSTRALIA Mrs. M. Drikas, State Water Laboratories E. & W. S. Private Mail Bag Salisbury 5108.

08-258-1066 WESTERN AUSTRALIA B. S. Sanders, 39 Kalinda Dve., City Beach 6015 092-21-0321

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ISSN 0310 0361

!AUSTRA'!.IAN WATER ANDI

(WASTE WATERASSOCIATION I Vol. 6, No. 4 December 1979

CONTENTS Editorial . . ..... ... ... . . . .... ... .. ... ..... . .. . . . News . . .. . . . . .. .. ..... .. . ..... a. . .. .

A ssoc1at1on

ADVERTISING

Mrs. L. Geal, Appita, 191 Royal Pde. Parkville 3052.

03-347-2377 WATER

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Review of Polyelectrolyte Use in Water Treatment in Australia - Ms P.A. Gadial .. .. . ....... . .

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Eighth Federal Convention - Queensland '79 .. .. .

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Waste and Wastewater tor Conversion of Brown Coal to Liquid Fuel in the Latrobe Valley - D. G. Evans ... . .. ........ ...... .. . ... . .

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Alcohol Manufacture - Wastewater Treatment - C. S. Barnes and E. J. Halbert .. . ........ .

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PAPERS REQUIRED FOR 'WATER' Members and others are invited to submit articles or proposals for such for publication in this journal. ' Articles should be of original thought or reports on original work of interest to the members of the A.W.W.A. In the range of 1000 to 5000 words and accompanied by relevant diagrams or photographs . Full instructions are available from Branch Correspondents or the Editor. OSIRO style Guide will assist.

TASMANIA

R. Camm, C/- Met. Water Board, Macquarie St. Hobart.

002-30-2330 NORTHERN TERRITORY H. Wilson, Water Div. Dept. of Transport & Works, P.O. Box 2520, Darwin NT 5794.

089-81-2450 EDITORIAL & SUBSCRIPTION "CORRESPONDENCE G. R. Goffin, 7 Mossman Dr., Eaglemont 3084, 03-459-4346

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Official Journal of the

COVER STORY Pollution control even before start-up .

This aerial view of the Victorian State Electricity Commission 's Loy Yang Power Station , was taken in September 1979, and shows an area appro ximately 1 km square of the construction work on the Power Station bench . This is only one of several areas of the $1400 million project where large earthworks are in progress .

In order to improve the quality of the stormwater run -off from these areas , since its discharges eventually to the Latrobe River, one of the first items to be constructed was the network of permanent drainage works , leading to a 25 ha settling pond, some 2.5 km to the East . Provision has been made for treating the storm water with polyelectrolyte to coagulate the clay suspension.

The earth works have been designed to permit the retention of natural vegetation wherever possible and regrassing has been carried out on all batters as early as practicable as shown on the right hand side of the photo .

Photo by courtesy of the Vic torian Lands Dept.

"To think, this simple oxygen process can help eliminate problems of odour and corrosion in sewerage system!;.:sor Julius Sumn:r Miller

• The prob lem of foul odours and corrosion in sewer mains is nothing new .

But it has been only recently that man has come to grips with these two related problems.

Until now, various chemicals have been used to help eliminate the odour . Unfortunately, these are cost ly, and produce a more difficu lt-to -treat sewage . However, now there has been a major breakthrough . It comes in the form of an exciting revolutionary process called CIG Sewer Sweetening .

It's simp le, effective and extremely economical.

Basically it involves the injection of pure oxygen into the sewer mains .

This al lows the oxygen breathing (aerobic) sewage bacteria, which is normally starved of oxygen in enclosed conditions, to active ly continue to brea k down the organic content

w ithout the excess presence of hydrogen sulphide.

And oxygen dosing is not.expensive. Costs per kilolitre are generally around half the cost of chemica l oxidising or sterilising agents.

Developed in Australia for Australian conditions, SEWER SWEETENING is a natural so lution to a natural problem.

Already there are many successful insta llations throughout Australia and many councils who will readily confirm its effectiveness.

For more information write to CIG Limited, 138 Bourke Road, Alexandria NSW 2015.

CG 891 / 79

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tree . This historje,mountain ash seedling was plant Jeeralang Tree ~m ef A,P.M. For4sls Pty. Ltd., Ranges, Southofthe Latrobe Valley in Victoria. @t ;· -,. , ·f =:~: .

Pioneer settlers ~reared most of the stee, agriculture during the latter part of the ninetee11t -' Over two generation,' t'many :Of the settlers.. suitable land and the farms gradually reverted to scrub, brae us weeds.

Today the Strzelec art eof one of the ost exciting arul succe rk1 i i'emes otlts kind in the world, brought about through the co-operation of the Forests Coml!)ission~Victoria arid A.P.M. ,.

4;;*" Across the hills new.forests are now growing. Our 150 mllliont e planting is amilestone which recognizes the changing of this desolate area intoanational asset.

0>" ' .

A.P.M. Forests has established atotal of over 70 000 hectares of pine and eucaiypt plantations in Victoria, New South Wales and Queensland. a,d , continues to plant for the future. · '···

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WATER

SYMPOSIUM ON. PUMPS AND PUMPING

A One-Day Symposium will be held at the University of N.S.W. on Friday, 22 February, 1980.

AUTO RANGING CONDUCTIVITY

The Symposium will cover the design, specification, commissioning and control of pumps. Speakers will include representatives of government authorities, manufacturers and educational institutions.

METERS 2102a Series

For further details contact: Mr. Peter Bliss School of Civil Engineering The University of N.S.W. P.O. Box 1 KENSINGTON, N.S.W. 2033.

Telephone: 663-0351

Sponsored by: The Australian Pump Manufacturers Association The Australian Water and Wastewater Association The University of New South Wales

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IAWPR 10th INTERNATIONAL CONFERENCE TORONTO 23-27 JUNE, 1980

METCARBON Pty Limited

For information apply to Secretary, Aust. National Committee: P.O. Box A232, Sydney Sth. 2000 .

ANTHRACITE filter media

JOURNAL SUBSCRIPTIONS

ACTIVATED CARBON

AUSTRALIAN WATER & WASTEWATER ASSOCIATION JOURNAL

powered and granulated

I enclose herewith the sum of $ ........ .... . (Australian) as prepayment for supply of the following Issues of 'WATER'.

June D Sept. D Dec. D 1979 March D Note: All subscriptions conclude with the December Issue, renewals are due by the end of February for a full year's subscription . Price, Including surface mall to all countries, is $1.00 (Aust.) each Issue, made payable to the A.W.W.A . - 'WATER' .

DESALINATION EQUIPMENi vapour compression and multi-effect distillation

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Mall this form to: Editor and Subscriptions Manager, G. R. Goffln, 7 Mossman Drive, Eaglemont, Vic. 3084.

PO BOX 785 NORTH SYDNEY 2080 TELEX: 24078

3 EDEN ST , CROWS NEST 2065 PHONE: (02) 9290393

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The Rimco miniature conductivity meter is suitable for testing laboratory water samples as well as numerous field applications such as measuring the conductivity or salinity of water in reservoirs, dams, irrigation channels and industrial cooling and rinsing systems.

SELBYS SCIENTIFIC LTD. Melbourne 544 4844

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Sydney 888 7155

Brisbane 3711566

Perth 451 2577

Adelaide 51 4851

Hobart 28 4691

WATER

!AUSTRALIAN WATER AND! !WASTEWATER ASSOCIATION!

FEDERAL PRESIDENT A. Pettigrew, P.O. Box 129, Brisbane Markets, 4106.

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

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

BRANCH SECRETARIES

Canberra, A.C .T. D. Coucouvinis, C/- Dept. of Construction, P.O. Box 306,

Woden, A.C.T ., 2606 .

New South Wales R. M. Lehman , Sinclair Knight & Partners, 2 Chan dos St., St. Leonards, 2065 .

Victoria R. Povey , S.R.W .S.C.,

Operator Training Centre , P.O. Box 409,

Werribee, 3030.

Queensland J. Ryan, C/ - Gutteridge Haskins and Davey , G.P .O. Box 668K,

Brisbane, 4001.

South Australia A. Glatz, State Water Laboratories, E. & W.S. Private Mail Bag, Salisbury, 5108.

Western Australia C. M. Tucak , 18 Ventnor Ave., West Perth, 6005.

Tasmania P.E . Spratt,

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

Northern Territory K. Sajdeh, Water Div. Dept. of Transport & Works, P.O. Box 2520, Darwin, N.T. 5794.

WATER

.EDITORIAL "POT.ENTIALLY -

AT LEA&T

a decision making body in the future of this nation ... " With these word s, Harry Butler, M.B.E., naturalist extraordinaire , spoke of the Association at the 8th Convention dinner .

Much of the same theme was expounded by Geoff Scott , President of the Water Pollution Control Federation , when he opened the Convention .

Since the 1950's, the public approach to environmental and water pollution has moved successively from Realisation to Recr iminat ion , Reaction and then Regul ation. The impetus came from the environment protection groups , particularly those who shouted longest and loudest in the public forum .

However, a fifth phase is emerging: " Rationalisation" .

The costs of reducing pollution escalate exponentially with the standard demanded . These costs are not just in dollars, wMch are just a handy measuring tool , but represent demands on our finite resources of energ y and material s The optimisation of this conflict cannot be I.eft to the emotional demands of the rabid environmentalist, nor to the pragmatic decisions of politicians , both national and local (who are swayed more by electoral emotion than by logic) .

Engineers , scientists , biologists must emerge from their shells of " professional dignity" and make them se lves heard , firmly , with authority , in the public arena. We have to be as vocal as the other pressure groups .

Such was the substance of Mr Scott 's talk .

Yet throughout the Convention the attitude of the members of AWWA to the po li t ical decisions which effect water supply and water pollution became most evident to me .

It was one of cynical apathy . Political "decis ions" and political names were bandied around and eyebrows were lifted , shoulders were shrugged.

Can AWWA ever aspire to assisting with the decision-making process?

It wi ll be difficult. Take, for example , those of our col leagues who work for the instrumentalities. They have the professional responsibility of tendering the best advice - but so often this is reversed by political action , and no doubt they would appreciate the backing of an authoritative lobby .

On the other hand , the engineers of any instrumentality ("QANGO") often see their own objects as the prime priority irrespective of side effects.

Would they then appreciate criticism from " outs ide" - even from their , peers?

Checks and balances are the basis of the democratic political system - but it is. up to knowledgeable people to join in and speak their piece .

Hopefully the Australian Water Coordinating Committee will help us in the future to speak out on water and environmental matters - with due authority . As a multidisciplinary body , we can be in a position to inf luence the decisions of the nation on Water - the Indestruct ible? - no - the Indispensable Resource.

E. A . Swinton , VICTORIAN BRANCH PRESIDENT

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

Membership is in four categories: 1. Member- qualifications suitable for membership in the Inst. of Engineers , or other suitab le profess ional bodies . ($12 p.a.)* 2. Associate -ex perien¡ce in the W.&W .W . Industry , wi1hout formal qualifications . ($12 p.a .)* 3. Student . ($5 p.a.)

4. Sustaining Member-an organisation involved in the W.&W.W. Industry wishing to sustain the Association . ($65 p.a.) ¡ * Plus State levy of $3 in N.S .W . and Vic .

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ASSOCIATION NEWS PRESIDENT'S REPORT The Eighth Federa l Convention is now in t he realm of historica l record , and will be reported elsewhere in this Journa l.

Council The November Federal meeting was held during Conference week , and I am honoured to be reelected for a second term of twe lve months to the Federa l Pres idency.

Mr. Geoff Scott , of Toronto , Canada , President of the Water Pollution Control Federat io n which has some 27 ,000 members, was our guest for the Conference . Mr. Scott attended t he Federal Counc i l meeting and made a considerab le contribution by way of compari sons and suggestions. The aims and co-operation of our two organisations were taken several steps forward , and long-term benef its wi ll ensue .

The Standing Committees as mentioned in previous reports now have t heir foundatio ns we ll laid, and wi ll hopefully make considerable progress in the next six months , when further reports wi'II be presented to Federa l Council.

AWWA has always been an informed but conservative body , with no wish to become controversial. We must also remember , however, that we have within our membership a great dea l of expertise , and have much to offer to the pub l ic by way of accurate and wellconsidered information . Many issues of publ ic importance , re leva nt to our fie lds of activity , are being presented through the med ia in a high ly emotiona l and freque nt ly biased light. Comments are being made by people who are illinformed and often most i II -advi sed.

In the light of these issues , perhaps AWWA has a ro le to play in giving wel l-in fo rmed and cons idered data in areas where there is need to be less emotiona l , and also less po l itica l. It has been suggested that we could also p lay a consu ltative role , presenting both points of view.

Perhaps the time has come for our Association to be both seen and heard , not to attract crass sensatio nali sm, but in the role of a wise and respected adviser.

I would appreciate the opinions and thoughts of members regarding this proposal.

Further, I would also invite your comments regarding any other areas w here members fee l we should be broadening our field of activity . If you have comments , please write to me at 8

my business address , P.O. Box 94 , Rocklea , Q. , 4106.

I would also take this opportunity on behalf of the Federa l Counci l , of wishing each and every member and all our friends a Happy and Relaxed Christmas Season , followed by a Prosperous and Challenging New Year.

ALLAN PETT IGREW , Federal President.

FEDERAL COUNCIL Allan Pettigrew has been prevai led upon to serve a second term as President and will lead the Association in 1980 - it has quite a ring to it doesn 't it? - entering the eighties , the start of a new decade! In spite of the cynicism and , on occas ions , the pessimism tending to prevail , it has a little of the underlying feeling of a New Years Eve , the st imulating thought that we must have learned from the period ending and wi ll benefit according ly from the one to come .

Vice President is Doug Lane of South Australia. The fu ll l ist of Counci llors is: N.S.W. W. Aust.

Trevor Jude II Don Montgomerie Ken Waterhouse Bob Fimmel Vic. O'land Frank Bishop Al lan Pettigrew Murray Allan Alan Strom S. Aust.

A.C .T. Doug Lane Cl ive Price Moss Sanders Allan Hatfield Tas. N.T .

Henry McF ie Bob Lloyd Don Walters Allan Wade

BIENNIAL GENERAL MEETING This meeting was held on Thursday , November 15th , during the course of the 8th Convention and was attended by some 150 Members. Reports of the 1976 meeting were presented and received.

In General Business the Queensland Branch was complimented and thanked for organising a most successful Convention . Chairman Allan Pettigrew advised that the next Convention wi ll be he ld in Perth in September 1981.

use of the water - time ly, in view of the opening of the reservoir for limited recreational use the following week .

At the November i-ieeting of the Branch on the 22nd , Mr. Ian Smalls of the Sydney Board spoke on emerging management options for operating a multi-reservoir system with regard for water qua I ity.

SOUTH AUSTRALIA The Branch c losed off its year with a fascinating guest night addressed by Mr . Harry But ler M.B.E. , and 180 members and guests had a delightful evening .

Mr. But ler's topic , presented in his inimitable fashion and with wide knowledge was " The Effect of Arid ity on Austra l ian Landscapes '. Having defined his subject , h discussed the adaption of p lant and anima l spec ies to survive in an arid environment and the methods of their survival.

Plants store and guard water gained during the sporadic periods of supply by a variety of methods. Anima ls survive either by relying on the moisture content of food or free water or high ly deve loped methods of conservation including the use of shade or burrows , virtual re-cycling of body moisture , the stor ing of water and adjustment of t he breeding rate to the availability of supp ly.

Mr. Butler made a number of pointed comparisons between the attitude of modern man who endeavours to mod ify his environment and the aborigine who adapted his I ifestyle to the environment .

He commented upon various major water supp ly proposa ls which have been put forward in the past , with keen awareness of economic factors and feasibi l ity . His ta lk was wel l illustrated with slides and film and concluded with an appeal , as an Honorary Life Member of A .W.W.A . for the Association to accept responsibility for the creation of pub l ic awarenei,s of the consequences of misuse of water .

A.C.T. Officers of the Branch for the coming year are: President , D. M. Philp; Vice President , R. Badger ; Secretary , D. Coucouvinis ; Treasurer , M. O'Keefe.

Committee members are: K . E. Barnett , P. W. Cu llen , T. M . Daniell , L.B. Devin , A . Hatfield , J . Mills and C. J . Price .

After dec laration of the 'establishment ' at the Annual Meeting on September 25th , a combined presentation on various aspects of the Googong Water Supp ly Scheme was given by Mr .

D. M. Phi lp, Ch . Eng. Sewerage Dept. of Housing and Construction ; Dr. B. Pratt , Asst . Director , Conservation and Agr iculture Department of the Capital Territory and Mr . B. Starr , N.S.W. Water Resources Commiss ion .

This interesting scheme ha¡s of course received considerable .publ icily within and outs ide of the AWWA and the threefo ld coverage provided an enjoyable and instructive evening , with attention focussed on the recreationa l

Harry Butler at the Branch Guest night .

WESTERN AUSTRALIA Current office bearers in the 'West ' are: President , J . Katnic ; Vice PresiCommittee dent , C. Tucak and members Dr. G. Hill , D. Montgom erie , R. Loo, K. Nelson , B. Robbins , R. Fimmel and R. Mercer.

WATER

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For the November meeting and having in mind the delights of the Swan and Perth 's summer and the States' 150 year celebrations , an evening on the river was proposed as some thing 'different'. Unfortunately the very good id ea became a non-event due to the lack of support from Members .

Plans for 1980 include a February meeting with a visiting lecturer, a combined meeting in March on a recently released report on the Cockburn Sound which sho uld attract a great deal of interest and a site inspection in April (no river trips!) .

The Branch Committee is working hard at Membership Services and wil l welcome suggestions from any quarter of the Association and also welcome a call by any Member visiting W.A.

NORTHERN TERRITORY A well attended September meeting was addressed by Mr . John Paul , a Principal Engineer of the N.T. Department of Transport and Works. Mr. Paul 's lecture , well illu strated by sl id es and diagrams covered recent Mining Company developments in the Alligator Rivers Region Uranium Province and hi s discussion included comment upon the functions of the Commonwealth Governments' 'Office of the Supervising Scientist ', the Northern Territory Government and Water Division , on scientific and environmental monitoring.

The Branch 's final function in December, fittingly was a social event which provided an opportunity for the screening of 'vintage ' films of life in the territory and the traditional wine , c heese and social gathering of wives and friends .

VICTORIA At the October meeting , Dr. Peter Thornton of Worne Biolytics, Europe out lin ed his Company's range of bacterial formulations ('Water' June '79 p.22).

Worne have developed a number of products each consist ing of approximately 12 different types of adapted mutant micro-organisms for treatment of food , sewage , paper or chemica l wastes. The addition of these products to a biological treatment system modifies the bacterial population which then must be maintain ed by regular doses of the special ised microorganisms to prevent the modified popu lation reverting back to the natural composition.

The technique is c laimed to have significant benefits in faster start-up better BOD/COD , better resistance to shock loadings , oxygen utilization and sludg e handling.

Dr . Thornton presented case histori es of successful application in Europe and convinced the meeting , initially somewhat sceptical , that the development of spec ialised bacteria has considerable potential in wastewater treatment .

The Branch November meeting was devoted to a 'double-bill'. The aims and achievements of the Soil Conservation WATER

Authority and the interaction of soils and septic tank effluents.

The soil conservation aspect was dealt with by Mr. A. Mitchell who is Chairman of the Soil Conservation Authority , Deputy Chairman of the Land Conservation Council and a Member of the Environmental Protection Council.

Dr . Van de Graaf , Senior Research Scientist w ith the Soil Conservation Authority discussed the properties of soi ls in relation to the absorption and purification of treatment plant effluents , and particularly , septic tank effluents. He has extensive experience w ith the In stitute of Reclamation in Holland and during his talk , drew upon this and recent experiments at La Trobe University. He also spoke o n the role of the Health Commission and the EPA in establishing criteria for septic tank usage.

The combination of subjects proved of considerable interest and most informative to the meeting .

Quite some years in Sydney M.W.S. D. Board were fol lowed by a period as a senior staff man with Consultants G.H. & D. Appointment as Deputy Chief Engineer took me to the Department of Works , Brisbane and then to the post of Chief Engineer and Manager.

Returning to the private sphere in 1954 with Humes Limited involved a number of senior positions terminating with retirement as General Manager , Technical in 1976 but continuing until recently as Editor and Publisher of the small monthly ' Hume News'.

Involvement with the AWWA commenced in Vi ctoria in the early 50's as a member , Committee man , Branch President and until 1978, Federal Councillor with two success ive terms as Federal President.

Continuance and refreshment of lifelong associations in the post of Editor of 'Water' is a great pleasure as is the opportunity to cont inu e to serve the Association .

George Goffin .

QUEENSLAND The Branch Committee and the many Members who contributed to the very successful Eighth Convention of the Association at Surfers spent the end of the year reverting to normal and less demanding Branch functions.

The final meeting was a Christmas function on November 28th hosted by C. I.G . Enviroshield at the Company's offices and plant at Rocklea by courtesy of Mr. Keith Strickland , Manager.

In spectio n of the production and bottling plants proved most interesting and was followed by an environmenta l film. The meeting concluded in true Christmas style with a combination of eating, drinking and pleasant socialising and a feeling of marked appreciation for the Companys' hospitality.

NEW SOUTH WALES The Branch held a joint meeting with the In stitut ion of Engineers , Australia on October 23rd at which Mr. P. Jessop , P.W.D . Manager for the Gosford Regional Sewerage Scheme gave an address on the work to some eighty members and visitors.

The scheme will serve an area with a current population of 70 ,000 , the total estimated cost is $130M and present expe nditure is at the rat e of approxim ate ly $1 M per month on two major treatment plants, estuar in e pipe cross ings , tunnels , pumping stations and an ocean outfal I. Mr. Jessop covered the initial strategic planning, investigations , designs and with slides , the construct ion work in progress.

NEW EDITOR An incoming Editor must , in fairness to his readers, provide some introductor.y information and background.

My own co nsist s briefly of a lifetime spent in the engineering spheres of water supply and sewerage ranging through design , co nstru ction and technical administration both in the public and private sectors.

IAWPR NEWS From the inception of the Australian National Committee of IAWPR , association and cooperatio n with AWWA has coincided wit h the development by AWWA of ties with other international bodies .

The next issue of 'Water' will carry ¡ an informative coverage on this subject and its significance for the information of Members and other readers of the Journal.

Pursuing these common interes ts , Dr. N. Norman on behalf of the National Committee of IAWPR has informed the Federal Council of the Association that up to $2000 per annum on a co ntinuin{l basis will be made available to support and improve the journal 'Water'. This pleasing offer has been accepted by the Federal ¡Council.

Future copies of this journal will feature 'IAWPR News' under the distinctive logo of that organisation.

9

A REVIEW OF POL YELECTROL YTE USE IN WATER TREATMENT IN AUSTRAL1A Ms P. A. Gadiel HISTORY OF POL YELECTROLYTE USE IN AUSTRALASIA

Polyelectrolytes have been used in potable water treatment in Australasia since 1965. At that time expertise in the field was limited ; there was littl e technical assistance from manufacturers and little or no practical experience . However, from results achieved with activated silica , sodium alginate , and starch based products, it became obvious that almost any correctly appl ied coagulant aid produced some improvement in the density and settlement rate of potable water floes, and allowed considerable uprating of clarifier flow rates.

In 1972, the Melton water treatment plant in Victoria, became one of the first Shire installations to emp loy routine addition of a polyelectrolyte coagulant aid. Magnafloc LT24 was used to uprate the clarifiers which were successf ully treating a water with a colour of 600 Hazen units , without the benefit of filters.

From then onwards, private and public water treatment plants in Australia have become increasingly aware of the ¡advantages of coagu lant aids, and have used them on the basis of approval by the relevant authorities in the United States and the U.K. With the introduction of synthetic polyelectrolyte coagulant aids to the world market a dynamic new branch of the science of water, fluid and effluent treatment has emerged . The rapid acceptance of these products, and their wide proliferation into many fie ld s of indu stry is testimony to their efficacy, and is probably as important a step forward for the industry as the original harnessing of coagu lat ion .

POLYACRYLAMIDE

the destabilisation of colloidal sols by the addition of ions which neutralise the electrical charges on the particles; whereas flocculat ion is only the aggretation of colloidal suspensions by means of high molecular weight 'bridging' polymers , other than by charge reduction.

Flocculation, therefore, by the engineering technology definition includes not only the collisions after charges are neutralised, but also the 'bridging ' type of aggregation performed by polyelectrolytes . We define primary coagulants as inorganic salts added to neutrali se the electrostatic charges on the particles and start coagulation (e.g . lime, alum , iron salts, etc .). If a polymer is then added to include 'bridging ' flocculation, we refer to it as a coagulant aid, and if this polymer is used alone without a prior primary coagulant, i.e . without alum etc ., we call it a primary polymeric coagu lant (e .g. polyaluminium chloride). The new synthetic polyelectrolytes are high molecular weight (up to 12 million) linear polymers , based on a repetition of molecular groups.

Their linear structure aids solubility, and the most commonly used units of the polymer chain are acrylamide and its derivatives. They are usually powders or beads, but some manufacturers are marketing liquids, e.g. in the form of a water/polymer gel dispersed as an emulsion in a hydrocarbon oil. On dilution with water the emulsion breaks and the very sma ll gel particles rapidly dissolve. These liquid s commonly contain about 30% w/w active ingredient.

POLYELECTROLYTES

ANIONIC

POLYACRYLAMIDE

CH=CH

I

C=O

-

ACRYLAMIDE

I

NH

POLYACRYLAM I DE

-1--CH2- H---7-

CATIONIC

t --CH 2- H---,- ,-CHret;7

1II I 1 1 I NH,_J l_ NH,_J L_ -1 -

, -

1

I

L_

C=0 /

C=O

1

1

- 7

-1-CH2-CH

POLYACRYLAMIDE

, -

I I

I

I

I

C,=0::

1

L_

I

- 7 CH2 -CH

I

I I

NH2_ J n L _

I

, -

I CH 2-etc I I I

Cl=O: I

~

I :

NR~J m L _

Figure 1 DEFINITION OF TERMS

In municipal engineering technology, the definitions of coagu lation and flocculation differ from those used in col loid chemistry. In the former , coagulation is defined as the 'sensitisation' or 'condit ioning ' of particles for flocculation ; this is associated with the neutralisation of charges, while flocculat ion is the bringing together of those particles. In the col loid chemistry La Mer definition, coagulation describes all Ms. Penelope A. Gadiel is the Chemical Consu ltant for Water Diagnostic Service, Water and Wastewater Analysts and Consultants , Sydney.

10

Figure 1 illu strates a commo n form of anionic polymers form ed by copolymerisat ion of acrylamide and acrylic acid , th ey may frequently also be formed by partial hydrolysis of acrylamide . Cationic polymers are commo nly derived from copolymerisation of acrylamide and quarternary ammonium polyacrylam id es . ¡ Their flocculation properties are based on their ability to ad sorb onto the particulate material in the water , and the polymer chain being of suffic ient length to 'bridge' the gaps betw een parti cles. The longer the chains (the higher the M .W.) the better the bridging potential should be. A diagrammati c representation of this is shown in Figure 2.

WATER

MECHANISM

OF

BRIDGING

FLOCCULATION

Figure 2

Most aqueous solutions with a pH greater than 4 predominate in particles with an excess of -ve ions on their surface . After the addition of a primary coagulant, e.g. Ai + 3 , Fe +3 , repe ll ing electrostatic charges on the particles are neutralised , reduction in zeta potential occurs , initiating coagulation . Also, by a series of hydrolysis reactions some further polymerisation and coagulation takes place . These reactions are pH sensit ive. The complex ions thus formed adsorb impurities in the water (e .g . humic and fulvic acis) . As the complexes grow they eventually form particles and precipitate .

Generally, this occurs in water after a size of approximately 0.1 micron is achieved , depending on particle density. If a polymeric coagulation aid is now added to a solution containing these nuclei, the polymer chains become adsorbed onto the particles. This adsorption may be due to charge e.f fects, dispersion forces or hydrogen bonding. The long polymers are believed to form loops extending from the surfaces . Collision of particles and intertw ining of loops then occurs. The number and size of particles formed depends on local concentration and velocity gradients . The shape of the polymer chain in solution depends on its state of ionisation (cationic or anionic , and the%) , the pH and ionic groups in the water. Bearing in mind that like charges repe l, it follows that a cationic polymer in acid solution will tend to extend and uncoil due to charge repu lsion along the chain, while in basic solution where its charges are neutralised , it will become randomly coi led, in which condition it would be a less efficient flocculating unit.

When a so lu tion contains a high concentration of dissolved salts (more relevant to process liquors and effluents than potable water) the polymer molecules may become highly compressed and even precipitate from solution. Compression of the absorbed polymer at a particle interface may occur , leading to peptisation (or protection) . Highly extended polymers are more viscous than when coiled . These effects help to explain the behaviour of polyelectrolyte coagulant aids ; for example, why an inhibition of coagulation is sometimes observed . According to the variation in chain length and the number and type of charged units, polyelectrolyte manufacturers should be able to make a polymer, as it were, for any season.

WATER

PLANT SOLUTION PREPARATION In the case of dry polyelectrolytes the first step in plant use is the dissolution step. The basis of good solution is discrete dispersion , i.e. all particles individually ..-etted. Several manufacturers supply eductor or air-blown systems which may be semi-automatic or automatic . Provided the usual care is observed in keeping the chemicals dry before use, the local humidity is not excessive, and in the case of eductors, the water flow is constant , no great difficulty should be encountered in making up solutions . The usual recommended strength for stock solution is 0.5% w/v. Liquid polymers should also be made up to about 0.5% w/v stock solution.

There is evidence that the polymer chains are broken up by shear, ultra-violet light and bacteria . Makeup tanks should be periodically cleaned, (say monthly), although the problem of bacterial degradation is not as severe with the synthetics as it was with natural products . The 'ageing' convention has also been largely abandoned.

At all points through the mixing and dosing system shear forces must be kept to a minimum . Sharp bends in pipework, radial turbines, baffles and centrifugal pumps should be avoided . Marine propellers (1 :1 pitch) or pitched turbines (paddle impellors with 45° pitched blades) mono or diaphragm pumps (positive displacement pumps) or compressed air mixing are recommended . lmpellor tip speed should be below 30 .5 m/min and agitator calculations based on viscosity of 1000 centipoise . Rotational speed should be below 600 r.p.m. and preferably below 300 r.p.m . Because of the high molecular weights of polyelectrolytes they diffuse very slowly in water, and mechanical mixing is required . After the powder is added to the stock so lu tion tank it should be gently mixed ; gentle turnover should be the objective rather than violent agitation.

The 0.5% so lution should then be further diluted to 0.01 0.05 % for dosing . This may be done on a batch basis but a continuous process is preferable . An in-line mixing zone should be provided to ensure a homogeneous solution, i.e. a long dilution line with a few bends; a static in-line mixing device, etc . Mechanical stirrers are not necessary for this stage .

DOSING Polyelectrolytes have traditionally been used in potable water coagulation in Australia only as coagulant aids , i.e. added after addition of a primary coagulant . There have been recent studies by Edzwald , Hoff and Boak 1977, of the use of primary polymeric coagulants in humic acid removal, but the dose levels suggested are higher than presently approved by Australian health authorities for polyelectrolyte coagulant aids. Generally the raw water will have been dosed with primary coagulants 15-60 seconds previously ; this delay is referred to as 'lag time' . In exceptional cases , a lag time longer than 1 minute may be required .

After the 'lag time' the polyelectrolyte is added and simultaneously flashmixed . It is vital to note that adsorption of polyelectrolyte onto solids takes place rapidly and irreversably. Following adsorption, floe size increases by collision and, due to the high molecular weights involved, agitation is generally necessary to induce sufficient collisions. The frequency of coll isions is dependent on local concentration and velocity gradient. Hence, the significance of the flashmixing stage in polyelectrolyte addition. In order to further facilitate homogeneous dispersion of the polyelectrolyte onto the floe nuclei , it should be dosed at 0.01 % w/v, through multiple dosing points . A maximum polyelectrolyte dose of 1 mg/kg of dry powder polyelectrolytes, and 3 mg/kg of liqu id polymers is currently recommended for potable water use . In practice, the optimum dose level may prov~ to be well below this ; 0.1 and 0.2 mg/Lare common.

Dosages as low as 0.1 mg/I are often sufficient, especially in plants employing direct filtration, or with emphasis on filters rather than clarifiers. Overdosing with polyelectrolytes may restabilise the col loid system, cause sticky sludge , or filter-bl ind i ng .

The dosed raw water is flashmixed for, say, 15-60 seconds.

Longer flashmi xing may produce shear and shorter times , inefficient coagulation . However, in certain cases , flash mi xing tim es as low as a few seconds have given satisfactory

11

results . Low temperature waters may require lag times up to several minutes , and increased flashmixing time.

FLOCCULATION Once more , due to the low concentration and diffusion rate of the particles present in the raw water, orthokinetic flocculation is normally required in potable water treatment . In ihe presence oi a veiodty gradient, coagulation rate is proportional to the velocity gradient and the particle volume .

The ratio of this shear induced (orthokinetic) to Brownian (perikinetic) flocculation is given by Muller and others : ~ = n (Rij)3du/dz I 2 kT where n is the fluid viscosity, Rij the particle collision radius, du/dz the velocity gradient, k Boltzmans constant and T the absolute temperature.

Substitition of numbers into Mullers equation shows that at velocity gradients of 1 sec-1, orthokinetic coagulation becomes increasingly significant for particles larger than 1 4m diameter. This indicates that slow st irring (or agitation) is desirable for efficient flocculation . However, care has to be taken to avo id breaking up the floe particles . When they are still coagula, i.e. before flocculation occurs , they may reform after shearing, but once they are polymerically bridged, shear is irreversible . Generally, coagula are small , weak and reversible, while floes are larger, stronger and irreversib le.

In practice, mean shear rates of 10-100 sec- 1 are common .

The mean shear rate G may be calculated and used in flocculator design.

In general floe strength increases with increasing molecular weight of the polymer, but the optimum dose also increases. Flocculated sludges which are to be further concentrated should be treated with care to avoid shear, and corresponding attention should be paid to pump types and pipework design of underflow systems.

TESTING OF COAGULATION AND FLOCCULATION OF POTABLE WATER AND StuDGE For water, the effect of polyelectrolyte on primary coagulant dosage should be determined. Other parameters to be assessed by laboratory jar tests are : Primary Coagu lant: Type , optimum dosage and range, ootimum oH. Type , optimum dosage and range .

Polyelectrolyte Flashmi xing and tlocculation, Coagulant Aid : energy input , times and detention time .

SLUDGE DETERMINATIONS The effect of polyelectrolytes on sludge volumes should be determined. There is often an apparent increase in measured volume as the large, tough, polyelectrolyte dosed floes frequently have larger interstitial gaps. Sometimes measured floe volume is reduced . Settlement rate is measured empirica lly with a stop watch, and supernatant turbidity can be determined if required .

OBJECTIVES OF LABORATORY TESTING OF WATER AND WASTEWATER By assessing the parameters listed above , data may be provided as a basis for overall plant design (e .g. whether , or not , direct filtration may be feasible , etc .) and as a guide to type, dose size, economy and relative merit of chemicals to be applied.

The objective for clarifiers is to improve the settiement rate. The laboratory rate cannot be applied directly to plant design , but with experience an appropriate factor may be applied. Relative rates with and without coagulant aid are valid. If testing for filtration without clarifiers , the emphasis is shifted to obtai ning satisfactory treatment with the smallest volume of discrete filtrable floes.

The effect of scaling up of laboratory tests must be considered and also variations in the raw water.

SLUDGE CONDITIONING With increasing environmental awareness in Australia , there will be a growing requirement for proper and acceptable

12

sludg e disposal systems . Polyelectrolytes will improve the dewatering characteristics of sludges of any kintl.

There are well established tests for determining sludg e characteristics; one being the Degrement ~ ludge Cohesion test , in which the expansion of a preformed sludge is measured as a function of the upflow velocity of the sludge.

Various filtration tests have been proposed , the most useful at present is probably the Capillary Suction Time (CST) test devised by Baskerville and Gale. Sedimentation tests , particle sizing and counting, and of course polyelectrolyte tests , eith er in a cy linder , or jars , all have their use. The results are primarily for co mparative purposes , with sufficient testing , co rrelation with plant operation shou ld be possible .

PROBLEMS IN POL YELECTROL YTE USE Even with correct so lutions and co mplete water testing difficul ti es may sti ll exist in polyelectrolyte use . These include the lack of an easy analytical procedure for testing for polymer or monomer levels in the treated water; filterblinding , usually due to overdosing; 'sticky ' sludge may appear in clarifiers , and has been known to happen over a short period in a plant which had been satisfactory for months , this can only be ascribed to raw water variations.

It is usually advisable when reco mmending a particularly polyelectrolyte for a given water , to choose the most tolerant one and not th e one that performs brilliantly but o nly under very rigid co nditions .

STATUS OF POLELECTROL YTES IN AUSTRALIA Until 1974, polyelectrolytes were used in Victoria, Western Australia , Tasmania and Queensland on the basis of approval by the U.S .A. and U.K. authorities. In 1974, a New South Wales Municipal Council requested official approval from the N.S.W . Department of Public Works , who referred it to the N.S .W. Health Commission, from where it went to the National Health and Medical Research Council. Two manufacturers , Messrs. Allied Colloids of Hornsby and Messrs . Catoleum of Botany submitted requests for approval of their potable ranges. Each supplier has more than six chem icals in their potable range . These submissions were approved in early 1978.

The National Health and Medical Research Council has approved Allied Colloids' Magnafloc/Percol LT Grades 20, 21, 22, 22SG , 24 , 25, 26 , 28 and 29 as suitable for potable use provided they do not contain more than 0.5% residual monomer calculated as acrylamide, and that the dose rate does not exceed 1 mg/kg. Catoleum 's Alfloc 8000 series of potable polyelectrolytes has been similarly approved , to a dose level of 3 mg/kg . of treated w~ er.

These recommendations are being referred to the Austra lian States and Territories for incorporation into food legislation , and the use of polyelectrolyte coagulant aids in potable water treatment will finally have come of age in Australia .

REFERENCES Akers , Richard. Flocculation I. Chem . E. Services , 1975.

Allied Col loids , Technical and Processi ng Data .

Atkinson , J. W. Practical Experience in the Use of Polyelectrolytes . Paper presented to the Society for Water Treatment and Examination , April 1971 .

Catoleum Product Bulletins.

Chappell , T. J . W. and Burley , M. J . A Review of Sludge Treatment and Disposal Practice in the Water Indust ry . Techni cal Paper 81 , The Water Research Association, July 1971 .

Edzwald , James K., Haff, James D., and Boak , James W. Polymer Coagulation of Humic Acid Waters , A.S.C.E. Journal of the Environmental Engineering Division , December 1977.

Hilso n, M. A. Pract ical Experience In the Use of Polyelectrolytes. Paper presented to the Society for Water Treatment and Examination , 6th April 1971.

Hubenthal , F. and Spitch , D. The Use of High Polymer Flocculants for Water and Trade Waste Treatment. Private pre-print .

Hunter, R. W. Some Notes on the Use of Polyelectrolytes at Mosswood Treatment Works. Paper presented to the Society for Water Treatment and Examination , 6th April 1971.

WATER

EIGHTH FEDERAL CONVENTION

-

Q'LD '79

OPENING

SOCIAL TOURS

Over 300 people atte nded the 8th Federal AWWA Convention held on the Gold Coast from 11-16th November 1979, in c lu ding over 60 wives , girl friends , or husbands who acco mpani ed the delegates. The Convention was held at the Chevron Convention Centre Corroboree Room. This was a most pleasan t venue , adjacent to t he tropical area surrounding th e sw imming poo l co mplex.

It al l started with a bang - or succession of bangs - on the Sunday evening , when a tropical storm provided some extra excite ment to th e welcoming Reception on the magnifi cent covered terrace of th e Convention Centre.

On the Monday morning in a packed con vention room, delegates and fr iends were welcomed by AWWA Federal Pres id ent Allan Pettigrew , the Convention was opened by Gold Coast Lord Mayor Aid Keith Hunt and the key not Address given by Mr. Geoff Scott from Toro nto , Canada , President of the Water Pollution Control Federation .

On the Monday even ing, after yet another tropic storm, a very in teresti ng boat trip and evening at Seaworld was at tend ed by 140 convent ion-goers . The 'act ion ' included an aq uat ic and water-ski exhibition , viewing of the large aquarium , fabulous food and general socialising.

A coach tour on Tuesday for ladies and Harry Butler (a mongst the birds again!) in c luded a tour of the Gold Coast south of Surfers Paradise , through new canal estates , past the proposed new Currumbin Development Area , and on to Coo langatta and Greenmount lighthou se on the N .S. W . Q'ld. border . The Currumbin Bird Sanctuary was visited on the way hom e. The trip was en joyed by al l in cluding Harry , eve n when the driver remarked that a new urban canal deve lopment was being built in an area that was " once on ly a useless old mangrove swamp".

Thursday brought a well organised trip to Mt . Tamborine in the Gold Coast Hinterland . Some exquisite scenery and views were snapped by th e fanat ical photographers en route.

Geoff Scott accompa ni ed the lad ies on this trip .

Thursday morning technical session. chairman, Bill Dulfer (Vic.) had probl ems with a power failure , no airconditioning , no microphone, no slides, and one lone light. Problems were so lved , and any slides etc., not shown during the blackout were shown later in the day.

On Wednesday , Thursday and Friday free evenings, various groups avai led themselves of evening activities on the Coast , including dining out at various Restaurants and Night Club s to 3 a.m. On e group had a slap- up dinner at the Tweed Heads Golf Club, and then played the pokies until midnight . Outside the normal session times many others were seen wandering along the beach , surfing or just sunbaking - th e benefits of a very pleasant venue .

TECHNICAL SESSIONS

Thirty -two papers were presented to the convent ion covering various aspects of research, development planning , -design and co nstruct ion of water and water pollution associated projects . Th e quality of papers and presentation was high , all sessions were well attended by delegates , and discussion was alm ost always incisive and fruitful.

The format of the Proceedings of the Convention into two volumes of easy handling size , was welcomed by delegates.

Further cop ies of the doub le volume are available at $25.00 per set from th e Convention Secretary.

CONVENTION DINNER

Allan Pett igrew chaired the Convention dinner and was abl y ass isted by Henry Mc F ie (Tas.) and Nevi ll e Jones (Q'ld .) in giving and replying to toasts. In addition Henry presented to Gail Scott (Geoff's wife) an autographed copy of Harry Butl er's " In The Wild " . Geoff Scott provided the Toast to the Association whilst Allan Pett igrew provided a diversion to the formal iti es by giving a little discourse on that " Wond erful and Total Extinguishing Reso urce" .

The star attractio n for the evening was Harry Butl er M. 8 . E., with his ta lk en ti tled " Wat er the Indestruct ibl e Resource " a term with which he in some aspects disagrees . A mo st enlightened ta lk whic h will be reproduced in the next editio n of " Water" .

Fo llowing this the diners viewed one of Harry 's " In Th e Wild " films , on a very app ropriate theme. Harry is the same in real life as he is in hi s film s, in his manner , talk and approach to a discuss ion topic. It was most fortunate that Harry was ab le to stay at the Gold Coast and participate in all Conven tion activities from Monday morning through to the Wednesday morning . He was mad e an Honorary Member of AWWA at the Dinn er, and for a most pleasant visit to the Convention we say thank you Harry !!

Ross Anderso n, (Q 'ld . and NSW) organised the one and one half days workshop which was attended by over 100 delegates , 60 of t hese staying on from the Convention . This was a well organised Works hop , completely down to earth, with talks on pumps, water treatment, fluoridation, vacuum sewerage reticulation systems etc. A very worthwhile exercise in the idealistic surroundings of the Tweed Sh ire Civil Centre with delicious food and great company .

FIELD INSPECTIONS

APPRECIATION

All day inspections were arranged to tour some of the water and wastewater fac ilities along the Gold Coast and in Alberf (Qld.) and Tw eed (NSW) Shires. Delegates and wives chose tours which could inc lud e: Hinze Dam (Albert Shire / Senora Point Sewage Go ld Coast Water Treatment Plant (Tweed Storage) Shire ox idation ditch) Mudgeeraba Water TreatJames Kemp Pty. Ltd. ment Plant (Gold Coast) foundry , and Elanora Sewage Treatment Condong Sugar Mill Plant (Gold Coast (near Murwillumbah) .

Activated sludge) Lunch was arranged at the ex tremely busy (and noisy) Terranora Country Club in the Tweed Heads hinterland .

Morning and afternoon teas were provided by co urtesy of James Kemp Pty . Ltd. , and th e Gold Coast City Council and our thanks to both organizations for their ass istan ce .

The Branch Committee wish es to thank Mr. and Mrs . Geoff Scott for attending the entire Convention and taking part in t he many activities and Dr . Trevor Judell (NSW Director of WPC F) for organising Geoff Scott's visit , and Mr. Harry Butler for having a " Holiday" in Queensland to co-incide with the timing for the convent ion.

Appreciation and than ks to the Convention Comm ittee and the many others who assisted and the firms and organisations who contributed to the success of the Convention at Surfers - all too numerous to list in detail.

Finally , the Committee acknowledges the great work done

by Mrs . Margaret Pettigrew, who organised just about everything including Registration Secretary , Ladies Programme , Secretary to Convention Secretary etc ., and in her spare time, so ught assistance from variou s organisations and business houses in the supp ly of gifts and the little things that make a convention so mu ch more enjoyable.

WATER

FRIDAY CLOSING

The official c losing of the Convention was carried out firstly by Geoff Coss ins (Q'ld .) Branch Past President who thanked al l for co ming , and then by Canada's Geoff Scott who with the assistance of three bi ki ni clad Golden Girls presented Golden Dollar medallions to the Convention Committee and Ladies Committee. Then followed a smorgasbord luncheon on the grass alongside the swimming pool And so end ed a most enjoyable and fruitful AWWA 8th Federal Convention .

WEEKEND WORKSHOP AT TWEED HEADS

13

THE EIGHTH FEDERAL CONVENTION

Mayor of Gold Coast - At opening

Geoff Scott, President W.C.P.F .

Allan Pettigrew, Fed. President welcomes the delegates.

Harry Butler, M. B. E.

'4evi lle Jones and Terry Plggot vid ing more than a paper.

14

pro-

Some of the exhibits

WAT E R

SURFERS SEVENTY-NINE

Happy faces at the dinner

· WATER

The Big Brass

Shy? Retiring Editor Bob Swinton promoting the Journal to a Golden Girl.

Allan Pettigrew and Murray Allen selling Golden Pendants.

15

WASTE AND WASTE WATER FOR CONVERSION OF BROWN COAL TO LIQUID FUEL IN THE LATROBE VALLEY D. G. Evans INTRODUCTION

The energy conversion industry has always been a great user of water and a great producer of wastewater. Energy conversion methods under consideration for the production of transport fuels for Victoria are no exception, and the problems of water supply and wastewater disposal may be crucial in deciding which process should be used. Our particular interest here is in the production of oil from Victoria's brown coal resources in the Latrobe Valley. This in turn implies water use and wastewater disposal in or close to the Latrobe Valley , as the high moisture content of the brown coal from the valley makes it uneconomic to transport to processing sites remote from the coal field . Although this paper refers particularly to the conversion of this coal to oil other coal conversion developments such as power stations for electricity generation are also examined , as these draw to a large extent on the same resources .

Water use in coal conversion industries

Water is used in coal conversion industries in various ways : as a coolant for hot process streams, including steam in power-station condensers ; as a thermodynamic fluid in steam-cycle power stations; as a source of steam for process heat ; as a conveying medium in coal slurry pipelines and ash sluicing; and as a source of hydrogen.

The purity requirement for the various purposes differ considerably . Cooling water, which is by far the biggest requirement in both power stations and coal conversion plants , has only to be pure enough to avoid fouling the heat transfer surfaces . However when evaporative cooling is used, as in wet cooling towers, evaporation of part of the water causes the concentration of dissolved salts in the remainder to gradually build up , and it is necessary to periodically blow down part of the water in the cooling water circuit to waste .

Water used for the conveying of materials does not have to be very pure either, but water for all other purposes will usually have to be so pure as to require pretreatment .

Wastewater from coal conversion

Wastewater falls into several classes : water from mining operations, water from conveying operations, blowdown from water treatment plants and cooling towers , and water separated from chemical reactors such as coal hydrogenation reactors . In general there will again be a hierarchy of purities, and waste from one part of the process may be used with little or no treatment in another part, e.g. blowdown from cooling towers could be used without further treatment for ash-sluicing operations . The material expected to provide the major treatment and / or disposal problems is effluen t from settling ponds from ash-sluicing operations, and effluent from chemical reactors. The effluent from the ash setting ponds will have a very high content of dissolved salts, whereas reactor effluents will contain emulsions or dispersions ot coal or oil , as well as more intimately di ssolved organic molecules such as simple organic acids, which will give them a high biological oxygen demand (BOD 5 ) .

THE PRESENT SITUATION IN THE LATROBE VALLEY River system

"The Latrobe Valley" is the name given to a broad, flat central valley running on an east-west axis and bounded by the Eastern Highlands to the north and South Gippsland Hills Mr. David G. Evans is Reader at Centre for Environm ental Studies of the University of Melbourne .

16

to the south (Figu re 1). The Latrobe River itself rises in the Eastern Highlands around Noojee and enters the Valley itself near Moe , wh ere the Moe River from the west and the Narracan Creek from the south join it. Thereafter it is fed by seven more tributaries from the Eastern Highlands to the north , and five from the South Gippsland Hills to the south .

At Sale , the Latrobe is joined by the Thoms.on River which rises on the northern slopes of the Eastern 'l'i ighlands , and finally it flows into the western end of Lake Wellington. This in turn discharges into Lake Victoria and hence through the compl ex Gippsland Lakes system into the sea through Lakes Entrance.

Coal deposits

.

Th e brow n coa l deposit s form a band mo stly south of th e Latro be Ri ver, abo ut 20 km wid e and running roughly 60 km fro m Ya ll ourn to Sale. Alt ogeth er four different sea ms are in vo lved , usuall y se parated by intru sions of sand and c lay Th e total thickness of coal is many hundreds of metres and the total resource is estimated at about 110,000 million tonn e, about 65 ,000 million tonne of which has been thoroughly proved. In turn 35 ,000 million tonne of these proven reserves are buried by 30 m of overburden or less, and as su ch are considered by the State Electricity Commi ssion of Victoria (SEC) and the Department of Minerals and Energy to be potentially recoverable , although by European standards wo uld be far hi gher (Allardi ce , Higgins and Spurri er 1976) .

Th e prove n reserves of 65,000 million tonn e fo rm about 20% of th e world 's proven reserves of brown coal and 3% of th e total wo rld 's proven reserves of all fo ss il fu els.

The SEC has opened four separate open-cut mines in these fields : Yallourn , Yallourn North , Yallourn North Extension and Morwell, the first and last of which are still being worked extensively to provide boiler fuel for power stations with a total installed capacity of 3000 MW and a further 750 MW und er co nstru cti o n. Ya ll ourn open clit produ ce s coa l for a bri quett e fac tory prod uc in g about a milli on tonn e of briqu ettes per year, one fifth of whi ch in turn is carboni zed to f orm bro wn coa l char, larg ely for ex port market s. Developm ent of a furth er coal fi eld at Lo y Yang near Traralgon is no w wel I advance d . Thi s will power a furth er 4000 MW of po wer station capac it y by so metim e in th e 1990's (M eldrum , 1976) .

Developm ent of water supply and effluent dispo sal systems

Early SEC developments at Yallourn took cooling water from the Latrobe River on a once-through basis , with fluctuations in the river flow being ironed out by building an impoundment at Yallourn . With the development of the 1600 MW Hazelwood power station on a new open cut at Morwell it became necessary to recool the water leaving the power station condensers , for reuse . This was achieved by building a cooling pond roughly the same area as the town of Morwell.

The latest power station , Yallourn West (700 MW built , 750 MW und er construction) uses conventional wet coolin¡g towers .

The proposal, after World War II, to build a town gas plant at Morwell operating on brown-coal briquettes led to th e passing of an Act of Parli ament (Victorian Government , 1953) to establish the Latrobe Valley Water and Sewerage Board (LVWSB) , with responsibility to provide town water for Morwell and Traralgon and industrial water for the SEC and the Gas and Fuel Corporation at Morwell , to provide for effluent disposal for the gasification project, and to restore and maintain adequate purity in the water in the Latrobe River WAT ER

,.-,, I

SCA LE

,,.•

'''

'', . .

10

0

20 km

--Ri ver

.

\

., ·'' , ',.

I

\

I

,I ' _._.,-\l - _,

"''

\

,.

' '.

,

I

I

LE GEN D

,.

- .

, , ' ... __ '

NIIN

Coa l meas ures Outfall sewer Boundary of Lat ro be River Catchment

Figure 1: The Latrobe Valley

(Latrobe Valley Water and Sewerage Board, 1955). The Board approached these tasks by various means, the major being: (i) Construction of an outfall sewer linking Yallourn, Maryvale (Austra lian Paper Manufacturers , APM), Morwell , Churchil l , Hazelwood and Traralgon to a treatment area at Dutson Downs between Lake Wellington and Lake Reeve , (ii) Construction of Moondarra Reservoir on the Tyers River, one of the northern tributaries of the Latrobe River, with pipelines supplying water to Morwell , Maryvale , Hazelwood , Churchill and Traralgon, (iii) Limitation of the pollution leve ls of discharges into the Latrobe River, the result being to require effluents to be purified to meet these requirements, or to be discharged instead into the outfall sewer . Table 1, which is an extract from LVWSB By-Law No . 7 (1969) , typical discharge limitations .

Table 1: Limitations on discharges into the Latrobe River (LVWSB, 1969) Characteristic or constituent pH Suspended Solids , ppm total dissolved solids , ppm B0D5, ppm

Lim itati on in the range 6-10 maximum of 30 maximum of 1000 maximum of 20

Present Water use (LVWSB 1955-1977) The use of water from the Moondarra Reservoir is at present dominated by the SEC and APM, with the current consumption being about 60,000 megalitres per year (ML/ year) . Since the mean annual flow for the upper Latrobe is about 570,000 ML/year this is only just becoming significant.

Some of the water used by th·e SEC and APM is treated after use and returned to the Latrobe further downstream , ;:ind the overa ll effect of present use on the lower reaches of the river

WATER

is probably negligible , at least in normal years . Because of contributions from the various tributaries the mean annual f low in the lower Latrobe , at Rosedale , is 940 ,000 ML/year.

Th e flow varies greatly with season and year : for example the record high flow at Rosedale in December 1934 was over a hundred times greater than the average"'rate and during March 1968 it fell to less th an on e fiftieth of the average.

Water quality varies considerably with distance downstream : for example , th e 1957-1977 average temperature of water entering th e Yallourn pondag e was 15 ° C; after receiving condenser water discharge from the Yallourn power stations the river temperature rose to 27°C, but by Rosedale i-t had again fallen to 20 ° C. Similarly the BOD 5 of water in the river downstream of the SEC Yallourn discharges was about 1.5 ppm; this rose to 2.5 ppm after rece iv ing treated wastewater from APM 's Maryvale mill , but gradually declined again to abo ut 1.5 ppm at Rosedale . In stantaneous values fluctuate with season and year , t ending to be worst in drought years ; e. o . in th e summ er of 1967 / 68 the temperature at Ya ll ourn ros e to 39°C and the BOD 5 at Rosedale rose to 6 ppm.

St eady chang es in wat er quality may be discerned over the 20 year period during which the LVWSB has been operat in g .

Fig . 2 sho ws that th e temperature of the river has been dropping as th e older pow er stations with once-through cond ens ers have been retired , the DO content has increased from 6 ppm to a health y 9 ppm , probably in response to the dro p in t emperature , th e BOD has increased from 1 ppm to about 2.5 ppm despite the elimin ation of many inputs with high BOD , th e pH has ris en slightly , the dissolved so lids co nt ent has risen by about 50 % and the suspended solids cont ent ha s appro ximately doub led . The river is currently in good shape , but if som e of th e above trends are allowed to co ntinu e it will not remain so .

17

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(a)

(J)

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~

!-

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20

6

-~

"'m

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t

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.'

~ m

8

10

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4

.,

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.,0

8

,: 0.

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300

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25 0

100

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0 1955

150

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~

100

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6

... ... ...

......

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1965

1970

19 70

1975

1980

Figure 2: Changes In mean annual values of water quality parameters In the Latrobe River over the past twenty years .

Open symbols are for measurements are Rosedale, closed symbols Brown Coal Mine Bridge (downstream of Yallourn operations of the SEC) .

50

1960

1965

Year beginning 1st July

...

1955

1960

1975

1980

(a) dissolved oxygen, ppm; (b) BOD5, ppm; (c) disso1ved solids , ppm ;

(d) temperature °C ; (e) pH; (f) suspended solids , ppm.

Year beginning 1st July Present effluent disposal (LVWSB 1955-1977) As mentioned prev iou sly , the LVW SB operates disposal system (fo r aqueous eff luents not pure enoug h for discharge into the Latrobe River (see Table 1). This consists of a pipeline from Morwell to Rosedale followed by an outfall channe l to the treatment area at Dutson Downs near the coast. The main pipeline is fed by branch pipelines from various towns and indu stries. This system has now reached its capacity and any new developments will require upgrading or duplication of the existing lines . The present major uses are: pulp and paper waste from APM , 8000 ML/year: domestic waste from towns and industries , 4000 ML/year, and industrial waste from Australian Char Pty . Ltd . , 200 ML/year. Until recently this system also handled saline effluent from the ash-sluicing operations of the SEC , but because of troubles with precipitation of in soluble sa lts this practice has now been suspended and a separate pipeline is under construction.

EXPECTED EFFECTS OF FUTURE COAL CONVERSION PROJECTS Scope of Future Developments In a seminar on "Brown Coa l in the Latrobe Valley Prospects and Prob lem s" in 1976, Urie est im ated possib le developments in power stations and coa l conversion in the Latrobe Valley by 2000 AD, as given in Table 2. At the time these seemed to be perhaps under-estimates (5 % per year growth rate in electricity use, and oil from coal to provide half of Victoria's oil requirements by the year 2000) , but in the light of a continued depression in the economy over the past three years we sho uld perhaps take them as upper limits . Urie estimates that the power station program outlined in Tab le 2

18

Table 2: Estimates of coal processing developments in the Latrobe Valley by the year 2000 (Urie , 1976) Output

Period

1. Power stat ion s Yallourn (1) Loy Yang Flynn

75°fJMW 4000 MW 5000 MW

1980-1981 1983-1992 1993-2000

2. Solvent-refined Morwell coal

1 Mt/ year

1983-1985

Coalfield

3. Syntheti c crude oil (2)

Loy Yang Maryvale Gormandale

100 000 Bbl / day (3) 50 000 Bbl / day 50 000 Bbl/ day

1990-1994 1995-1997 1998-2000

Notes (1) Present power station capac ity in Victoria is approximately 4000 MW .

(2) Present rate of oil use in Victoria is about 150 000 Bbl / day (7 Mt/ year).

(3) 100 000 Bbl / day is just under 5 Mt/ year.

would increase the present SEC net consumption of water from the Latrobe river to about 190,000 ML/year and the coal conversion program would require an addit ional 60,000 ML/ year. This total of 250 ,000 ML/year should be compared with the total average regulated supply of the upper Latrobe system of 570 ,000 ML/year. Clearly we shou ld look for possible alternative arrangements . Note, however , that the principal problem here is the power stations rather than the coal liquefaction plants .

Urie does not ment ion the effluent problem, perhaps because this has not so far proved difficult for power stations . As seen from Figure 3, the water and effluent flow sheet for the Loy Yang Power station (State Electricity Commission of Victoria , 1975) , only 8% of the water used appears WATER

\

20

Water vapour 58 000

low quality water 87 000

GASEOUS WASTES

power

high quality water 3000

4

.o

co, 1. 3

H20 2 .6

co, 0 .2

Wet

coal 4 .o

station

ash

fluegas

process heat

blowdown

1 I

to river 25 000

I

Wet

ash sluicing

ash settling pond

Saline effluent 7000

coal 4 .7

hydrogenation reactor Water

Undissolved ash residue

coal dryer

l.l

hydrogen produce r

Water 4.6

process cooling

Oil 1. 0

Figure 3: Simplified water flowsheet for 4000 MW Loy Yang power station (figures are ML/year).

as eff lu ents too impure for discharge into the river , most of this being saline eff lu ent from the ash ponds . If the same ratio holds for al l the power stations mentioned in Table 2, 15,000 _M Uyear of sa line effluent would have to be disposed of , wh 1ch 1s more than t he total capacity of the prese nt LVWSB outfal l sewer. Th e SEC is now building a separate efflu ent pipe lin e to the sea. ·Requirements of oil-from-coal plants The problems expected in supplying water to, and disposing of aqueous wastes from, the coal conversion plants suggested by Urie will now be examined. Figure 4 shows the coal, hydrogen and water required to produce 1 kg of oil , and the destination of all the material entering the system . The figures given here are based on the liquifaction of Loy Yang coa l as discussed in an earlier paper (Evans, 1976) . The coo ling water requirement is calculated to match the tota l requirement given by Urie, which is somewhat higher than that quoted in the U.S . literature (Magee, Jahnig & Kalfald eli s, 1977) and may be taken as an upper limit. It is assumed that the moisture from the coal used for process heat will leave boiler chimneys as water vapor, but moisture from the coa l used in the hydrogenation reactors could be recovered as liquid water in a separate high-pressure coal dewatering reactor at present being developed at the University of Melbourne for the Victorian Brown Coal Research and Development Comm ittee. In addition a smal ler amount of water formed in the hydrogenation reactors themselves from the oxygen in the coa l will also appear as liquid water. Both these streams will conta in organic contaminants and dissolved minerals from the coal, and, depending on the nature and concentrations of these contaminants , the wastewater might appear as effluents to be disposed of by an outfall sewer and final treatment plant or as a source of process water, after suitable on -s ite treatment.

Let us now consider the water supp ly problem revealed by Figure 4. As already noted the overall development program will require 60 ,000 ML/year of water for oil-from -coal plants .

However Figure 4 shows that only one fifth of this water need be of high purity , the remainder being required as cooling water. Thus providing that satisfactory means for disposing of used cooling water can be found, its initial quality is not critical. Moreover much of this cooling load is at higher temperatures than that in power stations, and in such cases it would be possible to use air cooling at a modest additiona l cost. Alternatively the designers could turn to cooling ponds rather than cooling towers to reduce the temperature of used cooling water to levels suitable for re-use . (Calculations by the author indicate that cooling ponds depend for their effect large ly on radiant emission into the cold night sky, rather than upon evaporation, as in wet coo ling towers .) It shou ld be noted that cooling ponds may also be used for power station coo ling wat er, as ha& already been demonstrated at Haze lwood , and should be co nsidered as an alternative in future power station deve lopm ents in the Valley .

Turning now to eff lu ent disposal: The hydrogenation reactors themselves will produce 0.3 kg of water per kg of oil produced, or 3000 ML/year. This will probably contain emulsified oil as well as phenols and soluble organic acids.

WATER

AQUEOUS WASTES

2 .0 to river

3.0 to ri ve r (or sewer?)

0 .3 to rive r (o r sewer?)

Figure 4: Mass balance for the hydrogenation of Victoria brown coal (all figures shown are f~r the production of a unit mass of synthetic crude oil).

Depending on the economics this wastewater could be discharged to the outfall sewer after emulsion breaking, or after further tre~tment , probably by biological methods , be re-used· as coo lin g water.

The larger quantity of water from the dewatering reactor poses an interesting problem: as well as emu lsion s and small organic molecules it will contain fine suspended coal and dissolved minerals . Moreover the quantity is so great (32,000 ML/year compared with about 12,000 ML/year being handled by the present outfall sewer, and with the total water requirement for the development of 60 ,000 ML/year) that its treatment and reuse must be given a high priority.

Prel iminary tests on eff lu en,ts from the dewatering process have shown that the level of dissolved minerals may be the greatest barrier to water reuse (Brown , 1977) . The dewatering process leaches _most of the sodium, part of t he magnesium, part of the calcium , most of the ch lorid e and part of the su lph ate out of the coal (Murray & Evans, 1972; Brown, 1977) . Even for typical Loy Yang coals with low levels of all of these ions , water recovered from the process is likely to have dissolved solids contents exceed ing• 1000 ppm, the present upper limit for discharge into the Latrobe River.

This problem could be avoided by removing the coal mo_isture b_y evaporation rather than by pressure dewatering , as 1s done 1n present power station practice in the Valley . The '."'ater from the coal would then enter the atmosphere, and the inorga_n1cs wou!d end up in the ash produced by burning or gas 1fy 1ng the insoluble residue from the hydrogenation reactor . Th is ash would be sluiced away by water to form sa line effluent, which in turn-would be discharged to the sea via a specia l outfall sewer, as mentioned earlier. The concentration of inorganics in this effluent would be far higher than it w~uld be in aqueous effluent from a coal dewatering plant', but its volume would be correspondingly lower. The advantage of thi s approach is that it uses known methods and experience. The disadvantages are the waste of energy in evaporating coal moisture (requiring an extra 0.3 kg of coal for every kg of coal converted to oil) and the loss of the ab ility to use thi s water constructive ly in the process.

POSSIBLE STRATEG IES Th e Latrobe River is the key to the water supply and was tewater disposal for all present and proposed future in dustri es in the Latrobe Valley, including future pow er stat ion s and oil-fro m-coal plants. The upper Latrobe system has a mean annual flow of 570,000 ML/year, from which Vall ey towns and the SEC and other industri es currently draw nearly 100,000 ML/year.

Cont inued on Page 23

19

ALCOHOL MANUFACTURE - WASTE WATER TREATMENT C. S. Barnes and E. J. Halbert INTRODUCTION If alcohol (more correctly known as ethanol) is made in Australia for use as a motor fuel, the quantities will be very large in comparison with present production. By 1985 about 2 million kl of absolute alcohol will be required to provide a 10 % blend with the petrol expected to be used then. By comparison the present production capacity is less than "100 000 kl/year.

This capacity comes from three distilleries in Melbourne, ::iydney, and Sarina in North Queensland , all owned by CSR Limited , and a small distillery at Bundaberg in Queensland.

The largest , with capacity of 50 000 kl is at Sarina and it is of some interest that it was built in 1926 with the intention of making power alcohol from cassava. By the time it commenced operating molasses was the cheapest and most convenient source of fermentable material, and cassava has not been used for alcohol production in Australia. However cassava has again come into prominence with the granting of research funds through NERDDC to study fuel alcohol production . An important component in the grants is a study of waste disposal from a cassava alcohol factory.

All distilleries operate on molasses which is still the cheapest substrate available. Over 300 000 tonnes , or more than half the Australian production is used with remainder going in to animal feeds , yeast production and export sales .

If all the molasses produced in Australia were converted to alcohol it would provide less than 1 % of future motor fuel requirements .

The Sarina distillery with a capacity of 50 000 kl/year is the largest in Australia and is large by world standards. There is one of comparable size in Japan and only four in Brazil with greater annua l production. In that country most distilleries are based on cane and operate about 6 months per year. By 1980 it is planned to have 195 distilleries operating with a total production of over 4 million kl. At present over '.2 million kl of absolute alcohol are used in petrol in BraziI1 ,2,3 It seems that a practical limit to the size of a distillery is set by the economics of transporting raw materials to it and wastes from it . If fuel alcohol is to be made in quantity it is more likely that a number of small distilleries wi ll be built rather than few large on.es. In this respect ethanol production differs from other alternative fuels such as methanol, liquified coal, or shale oil, all of which would be made in large plants.

ALCOHOL PRODUCTION The present method of production of alcohol in Australia is by batch fermentation and continuous distillation . There are several variations between different distilleries but the basic processes are similar . For each large fermentor of 100-300 kl capacity an inoculum is prepared beginning from a laboratory culture and building up through a series of stages increasing in volume each time approximately by an order of magnitude .

Final ly the large fermentors are prepared by di luting molasses about 2½ times with water. Fermentation is complete in 24-48 hours after addition of the inoculum . Recyc le of yeast promotes fast reaction.

This fermentation technology has not changed for several decades. New disti ll eries may use more advanced systems involving continuous fermentation , but the savings to be made in cost of production are small. The ambitious Brazilian programme is staying with conventional technology.

Dr. C. S. Barnes is Research Manager of the Distilleries Group of C. S. R. Limited and Mr. E. J . Halbert is a Research Chemist.

20

The main energy consumption and operating cost after the raw material is for distillation, since the whole fermented solution must be heated to distil the alcoho l from it . One aim during fermentation therefore is to obtain the highest possible alcohol concentration in the fermented solution .

Yeasts can usually tolerate 10-12% alcohol, but these concentrations are achieved at the cost of slower rates and less complete conversion of sugars . In practice therefore 8-9% is commonly attained.

The dilute alcohol solution resulting from fermentation must be concentrated in a stripping column and further concentrated to the 95% azeotrope in a rectifying column.

For blending with petro l it is desirable to have anhydrous alcohol and a third distillation employing a ternary azeotrope with benzene or some other azeotroping agent is essential.

WASTEWATER PRODUCTION The major waste from the distillery is the effluent from the first or stripping column . It is called dunder in Australia, and elsewhere is known as sti llage, slops, vinasse, or vinhoto . If a 50 000 kl/a distillery uses molasses as substrate it can operate most of the year provided molasses storage is available. A cassava distillery also should be able to operate most of the year. In this case alcohol will be produced at 7 kl/hand waste at 80kl/h to give a total waste water volume of 600 000 kl/a, i.e'. in one year it would form a lake 1 metre deep covering an area of 60 hectare .

If a distillery were operating on a self contained basis in conjunction with a growin.g sugar crop and a processing mill , it would be able to operate for on ly six months of the year, as does the Australi an sugar industry now and the Brazi li an alcoho l industry . This is due partly to variations in carbohydrate content of the crop , but also to the inability of harvesting machines to operate during the wet season.

In this event, for the same annual output th'e capacity of the distil lery must be doub led and the lake of dunder will be filled at the rate of 150 kl/h.

Waste water is produced from the other distillation col umns and from various other factory op8rations such as wash water from the fermentors and floors . Much of this cannot be returned to process . It amounts to about 50 % of the volume ot the dunder and cannot be reused . wnIIe tnls extra water would increase the size of the lake to nearly 100 ha it is relative ly free of contaminants in comparison with dunder and its disposal wou ld not be d ifficu lt.

WASTE WATER COMPOSITION The compos ition of waste wi ll depend on substrate to some extent , but the difference is not as great as might be expected. Cane juice, for example, has most of the components of molasses, but at a lower concentration. When cane is crushed the juice is concentrated to promote crystallisation of sucrose which is removed . All the remaining solids co nstitute molasses which is formed in the proportion of 1 tonne per 5 tonnes sugar . Some chemical changes occur due to the boiling but these are relatively minor. Amino acids react with reducing sugars to form Maillard condensation products which condense and polymerize , and some of the reducing sugars are cara melised to high molecular weight dark compo unds .

The eff lu ent form a molasses distillery would be expected to have about tour or tive times tne concentration or soIIas man would be produced from a distillery operating only on cane juice or hydrolysed starch . However the difference is not likely to be one of simple proportionality because of the need to add nutrients to pure carbo hydrate substrates. This is not necessary with molasses .

WATER

The composition of molasses is variable but appro xi mately 20 % water and 80 % Total Solids (Table 1). Of the solids all but the sugars will remain in the waste water along with added nutrients and substances produced by the yeast.

TABLE 1

Total sugars : sucrose glucose & fructos e unfermen table sugars Ash K Mg Ca SO Cl Gums Organi c Acids Other organic matt er

50 % 30 % 18 % 2% 10 % 5% 0.5% 0.3% 4% 10 % 3% 7%

Typi cal analyses of dist i llery waste are shown in Table 2.

TABLE 2

Molasses pH SG T (ex proce ss) â&#x20AC;˘ C BOD mg / L CO D mg / L Dissolved soli ds % Sus . solids % Tot. so lids % Ash % Organic matter %

4.8 1 05

SUBSTRATE Cane Cassava 6 4 5 Juice ¡ 3.7 - 5.9

go¡

45000 11 3000 10 1 11 3 8

20000

6-11 2-3 4.6 - 8

2.2

Dunder from molasses is a rich brown to black colour with a pleasant smell. There is little precise knowledge of the composition . It contains the non-fermentable substances of the substrate, yeast metabolites, and yeast cell contents .

These include gums , and many substances of plant origin .

Much has high molecu lar weight, but must be highly po lar because, except for cellular material , most of the organic matter and salts are in solution. Rem6val of suspended solids reduces BOD by only 1 % .

The ash is mostly composed of the inorganic components of plant sap , it is therefore rich in potassium , magnesium , and trace elements. Calcium is introduced during the sugar processing. The predominant anions are sulphate and chloride. There is not much phosphate but a small amount of nitrogen (ca 0.2% on total solids} is present .

It is of some interest that the concentration of calcium sulphate is several times its solubility in pure water as occurs in other salt solutions of high concentration . It fol lows that sulphate ion cannot be reduced by lime treatment and fi ltration in the usual way.

The insoluble matter is most ly yeast cellular material of little value as a protein source . It is possible to isolate whole yeast cells of reasonable quality by centrifugation , but this must be done prior to distill lation. The economics are not good because the high liquid content of the isolate means that alcohol is lost unless additional processing is undertaken to wash the cells . If this is done there is a further cost due to distillation from the more dilute alcohol.

WASTE WATER DISPOSAL

On the basis of volume of liquid product , the major output from a distillery is its waste water. In a molasses distillery this also contains more than half the total solids of the input to the process . The economics of operating a distillery and even of maintaining its existence are dominated by the need to find a method of disposal which is environmentally satisfactory. The feasibi lity of establishing a new facility will depend on the same factor . Additiona lly, because so much of the raw materia l and process costs are spent on material which ends up as waste , it is hoped that this waste might be put to some good use .

WATER

The main difficulty in disposal is created by the organic matter. As noted it is pleasant smelling, and at least to cattle is sufficiently attractive for them to drink when fresh . On standing it quick ly putrifies and becomes 01,tectionab le. The very high BOD when added to a confined waterway depletes dissolved oxygen with effects on aquatic life . The quantity of BOD is so great that removal is most expensive. The 50 000 kl/a distillery being considered would produce BOD equivalent to the domestic sewage from a city of 1 mil lion inhabitants .

In the past , the first aim in dunder disposal has usually been to get rid of the organic matter in the cheapest possible way , because there is no useful product which can be made from it. In the city distilleries in Australia , the waste is neutralized , cooled and discharged to the sewer . In North Queensland it is sprayed on to 500 hectares of land . Neither method is entirely satisfactory .

(I) Discharge to Streams

Historically the solution was simple . To obtain the large volume of process water necessary to operate a distillery required the factory to be located on a river. Having taken water from the stream there was no hesitation in returning it after use.

This method was universal until a few years ago un less the factory was in a city and could use the sewerage system. It is sti ll used in most third world countries and by the one molasses based distil lery in the UK . In most countries including Brazil it is illegal to discharge to rivers, but unofficially, it is condoned in many instances , because of the difficulty in providing alternatives . In Australian laws for discharge to streams are strict , The Clean Waters Regulations 1973 in Queensland lays down a limit for BOD 5 of 20 mg / L. (II) Discharge to a Sewer

A fuel alcohol factory is un likely to be located in a city . If it were , the effluent would be unwelcome in the sewers . The high BOD level would impose a difficult burden upon a treatment works and wou ld probably resu lt in anaerobic conditions in the sewers with odour and acid corrosion problems . Sulphate ion in sewage , promotes the formation of H2S. (Ill) Discharge to the Ocean

While the high BOD is undesirable in streams or close inshore , there is nothing intrinsically t9xic in the waste if it is sufficient ly diluted . On the contrary, if could be expected to have a fertilizer effect when sufficiently dispersed by ocean currents.

Disposal by a pipeline or barging to a suitable location would be an acceptable and cheap method of disposal. Given sufficient dispersion, sea water can easi ly accommodate high BOD and low pH without eutrophication . Dispersion from a pipeline is achieved by using sparge pipe orifices which will create diffusion over an appropriate area . Discharge periods can be limited if necessary to the ebb tide .

From some Japanese distillers the waste is first concentrated and then barged to sea.

OV) Aerobic Digestion Distil lery wastes have the reputation of being resistant to biological methods . However my col leagues have shown that thi s is not so . Using a suitably conditioned activated sludge and with appropriate nutrients it is possible to remove about 95 % of the soluble BOD in 24 hours.

The process is not very attractive because about half the BOD is converted to a sludge which is not easily concentrated , handled or disposed of.

In common with all aerobic treatments there is considerable operating expense in supplying air to the digester. With such a high initial BOD its reduct ion by 90% sti ll leaves a residual level which would not be acceptable for addition to a stream . Accordingly further treatment would be required, possibly by second stage diges.t ion.

21

We did not cost the process accurately , but believe that for a distillery of the size being considered the capital cost of a treatment plant would be about $6M, with an operating cost greater than $1 .6M/year to give a cost per kl alcohol of $75.80 . This would be an additional 30 % to the selling price .

(V) Submerged Combustion

In some countries , high BOD aqueous wastes from paper manufacture are degraded at 300-400°C and 100 MPa. The process is exothermic and can generate steam . A small plant has been operating several years in Tasmania .

We have not pursued this to any extent because the plant required is very expensive . For the distillery being considered the capital cost of the combustion plant could be around $12M or close to the cost of the whole distillery .

(VI) Incineration

The ultimate method for disposing of BOD is by incineration . It could be expected that the ash obtained would then have some value as a fertilizer .

In J~pan where regulations concerning discharges to rivers and coastal waters are exceptionally strict , this is perhaps the only acceptable method . It has been used in Brazil but was abandoned 30 years ago on economic grounds.

Before the organic matter can sustain combustion it must be concentrated to a 60% solution . Under appropriate conditions in an open chamber or fluidized bed , combustion can t.hen be sustained and sufficient heat generated for the initial concentration . The operation requires multiple effect evaporators which are prone to scaling . Cleaning with caustic soda is required daily. Combustion temperatures must be accurately controlled because over-heating causes fusion of the ash to an insoluble glass useless as a fertilizer. lncinceration plant is expensive. It is estimated that for a distillery half the size being considered plant cost would be of the order of $5M .

(VII) Ultrafiltration

Concentration of dunder organic matter could be effected if the organic components were retained by a membrane which allowed the passage only of salts . Because a significant proportion of low molecular weight organic matter is present , a membrane with a cut-off at molecular weight 1000 would be needed .

With capilliary tubes in the laboratory reasonably satisfactory concentration is possible, but such processes are notoriously difficult to scale-up . Our experience with pilot scale membrane filters has been universally discouraging.

Despite clarification of dunder by filtration or centrifugation the inevitable result was blocking after a few minutes operation.

WASTE WATER UTILIZATION

With so much of the input to the factory going out in the waste it is natural that considerable effort has been put into finding uses for this waste. No s_ingle organic component of any vaiue can be isolated and attempts at utilization fall into rour categories - stock feed , fodder yeast , fertilizer and biogas .

(I) Stock Feeds

Although cattle drink it neat , the amount of dunder that can be consumed in this way is small because the high salt content causes scouring.

However there is some nutrient value in the organic components and they have a reputation for containing unidentified growth factors . When concentrated to a molasses consistency dunder has the additional property of being a good binding agents for feed components .

A small amount (possibly about 7000 t/a) is used in this way, but the market is limited because stock feeds are not in wide-spread use in this country.

(II) Fodder Yeasts

Although the alcohol producing yeast Saccharomyces cerevisiae has exhausted the molasses of nutrients , the more cosmopolitan Candida yeasts can grow on dunder.

22

Under cond itions of strong aeration C. utilis can produce signi f icant quantities of yeast acceptable as a high protein feed additive . This has been examined , but the BOD is reduced only to 50 % so there still remain~ a substantial disposal requirement . Of course , as with any biological treat ment , the process would require additional fermentor capacity about as great as that used for alcohol product ion . There would also be a substantial power requirement for the aeration and more complex control than is needed for the anaerobic formation of alcohol. Nitrogen and phosphorus are needed to achieve yeast growth .

Our costings suggested that if a market and right price could be found this product could almost be produced economically . The final disposal requirement would be considerable and the likely gains would not cover the total di sposal co st . The process is operated in Taiwan, but not elsewhere .

(Ill) Fertilizer

Th e main elem ent of value in dunder is po tassium. It may be recovered along with the magnesium and other el ements in th e ash from incineration , but it is not easy to isolate from the original solution . Some double salts and organic compl exes of potassium have a sufficiently low solubility to precipitate or crystallise from aqueous solution , but they do not form in dunder.

To obtain fertilizer value it is best to apply the whole dunder to the treatment area when the value of the organic matter as a soi l conditioner also is obtained. This is the method reportedly most common ly used in Brazi l 3 ¡4 â&#x20AC;˘ In theory , when an autonomous distillery is concerned , that which has been taken from the soil is being returned and there should only be advantages . In practice there are many disadvantages .

Of the three major fertili zer elements N, P, and K , dunder is defi c ient in N and P which must be supplemented if an imbalance is not to occur . These are the two expensive el ements . If fuel alcohol is being considered , nitrogen is the highest energy input in the agriculture of cane and it would be an advantage if it could be recycled more effectively .

Application also is difficult. Pipelines can be laid for irrigation close to the distillery but more distant sites can only be serviced by tanker . These can only operate on crops before they have grown to any extent , and while they are operating they consume liquid fuel causing a reducti,on in effective yield . The tankers used in Brazil hold 15 kl therefore to remove 2000 kl from the distillery each day would require 133 truck- loads . If operating for 6 months per year 266 truck loads per day would be shifted.

The Brazilians claim the method is ~ conomi c for molasses alcohol waste water . With cassava or cane juice the concentration of potassium is lower and the economics are doubtfu l.

(IV) Anaerobic Digestion

With high organic loadings anaerobic digestion offers a prospect of return from the product ion of methane in usable quantiti"S . A number of research publications have appeared 7-9 ,but no industrial application to distillery waste is known. In this process several groups of microorganisms reduce the organic component to fatty acids which are broken down by a second series of organisms to methane and carbon dioxide. Given enough time , up to 95 % of the BOD can be removed . The gas has a heating value of 25 MJ / m 3 and with the high organic content of dunder from molasses , could supply the fuel needs of a distillery . Juice from cane or cassava tubers has less waste organic com ponents and could supply perhaps about 30 % of the requirements of a distillery .

Even with 95 % BOD removal the effluent will have a residual BOD of over 2000 mg/l and will require some add itional tr~atment , e.g. by aerobic digestion, if it must be discharged to a waterway .

Although attractive because of the gain in energy there are a number of costs which must be met . As it is usually operated , anaerobic digestion is a slow process requiring retention times of several weeks for complete breakdown .

WATER

With the large flows from a distillery this would mean the provision of digestor capacity many times the fermentor capaci t y required for alcohol production . Dunder is rich in sulphate ion which is reduced under anaerobic conditions to sulphide . It is not necessary to remove this before the gas can be burnt , but sulphide is inhibitory to methanagens and it may be necessary to remove it to achieve breakdown in a reasonable time .

We have a research programme currently looking for ways to increase the rate of the anaerobic degradation . One way is to use thermophilic organisms which operate at 55 ° C rather than the normal 35°C . Dunder is in a favourable condition for thermophilic operation, because it leaves the process at 80-90 ° C. Another way to increase the rate of reaction is to pass the solution being treated up a packed column . Other new configurations such as fluidized beds are being examined .

CONCLUSION Disposal , or preferably , utili zation of distillery effluent is a key factor in the operation of a distillery whether it be for potable , industrial or fuel alcohol. If fuel alcohol is produced, the quantities of effluent which must result will be so great they could well drown the whole venture if satisfactory disposal methods are not found . This is an aspect which is worthy of more attention than it is receiving.

REFERENCES 1. Bell ott i, P. V. Petrobras and its Participation in the Al cohol Programme, Petro and Quimica , April 1979.

2. Yand , V., and Trindade, S.C. Brazils Gasohol Program, Chemical Engineering and Processing, April 1979, p.11 .

3. de Oliveira , E.R. Ethanol: Renewable Fuel for Brazil , F.O. Licht 's International Molasses Report , 15, No . 21 /22, 1978.

4. Brieger, F.O. The Distribution of Distillery Slops in Sao Paulo , Brazil. Sugar y Azucar, Jan . 1979, p.42 .

5. Monteiro, C.E. Braz ilian Experience with the Disposal of Waste Water from the Cane Sugar and Alcohol Industry. Proc. Biochem . November 1975, p.33.

6. Jackman, E.A. Dist ill ery Effluent Treatment in the Brazilian National Alcohol Programme. The Chemical Engineer, April 1977.

7. Ono , H. Discussion paper following Utilisation of Materials Derived from Treatment of Wastes from Molasses Di stilleries . T.R. Bhaskaran , in Proceedings of Int. Cont . on Water Pollution Research Vol. 2. Advances in Water Pollution Research. Ed . J.K. Baars , 1965, 100-104.

8. Roth , L.A. & Lentz, C. P. Anaerobic Digestion of Rum Stillage. Can. Inst.

Sci. Technol . 1977, 10 (2), 105-108.

9. Sh ea , T.G., Ramos, E., Rodriguez , J. & Dorian , G.H. Rum Distillery Slops Treatment by Anaerobic Process. Environmental Protect ion Technology Seri es. EPA 660/ 2-74-074 July 1974, 83-85 .

ML/year to Melbourne from the Thomson Dam (Ministry for Conservation 1977) .

(2) Diversion of treated sewage from Melbourne to the Latrobe Valley . The Southeastern tre!tment plant at present produces about 80,000 ML/year.

(3) Recovery of coal moisture by replacing evaporative drying with pressure dewatering . This could release 32 ,000 ML/year from oil-from -coal reactors and a further 90 ,000 ML/year if applied also to coal used for process heat in these plants and also to future power stations.

With the high content of dissolved minerals the overall system would have to be quite different from the present , in which water is blown down from cooling towers and discharged into the river with a dissolved solids content below th e discharge limit of 1000 ppm of dissolved solids .

(4) Reduction in the evaporative cooling load. The two main poss ibilities here are the use of air cooling and cooling ponds . The tec hnology and costs of the former are well established , and it becomes a matter of balancing the ex tra cost involved against the saving in water . (As is apparent from proposals (1) and (2) above , the cost of augmenting the available water supply could be high).

Although th e use of cooling ponds is well established, it is by no means certain how they operate, but see the Author's earlier comment. Evaporative losses could be much less than for wet cooling towers. Careful investigation is warranted .

(5) Transport of coal to the sea ·coast for conversion there to electricity and oil. The cooling load could then be met by using sea water. The cheapest method of transport would be by slurry pipeline . Probably the best system would be to treat the coal by pressure dewatering at the coal field, using water as the heat transfer medium . This causes the coal particles to shrink and the coal surface to become hydrophobic rather than hydrophilic, with rejection of about 70% of the coal moisture as liquid water (Murray & Evans, 1972). The dewatered coal would then form a slurry in its own rejected moisture and could be transported by pipeline to the coast without the addition of extra water. The semi-dry coal would then be separated from the slurry by conventional methods and fed to power stations and oil-from-coal plants, and the residual water discharged into the sea after appropriate treatment .

These five proposals offer a variety of options to set alongside the alternative of accepting the gradual deterioration of the upper Latrobe, and probably also the Lakes . The first requires water otherwise available for other purposes , but the remaining four open up entirely new proposals for conserving water, and in some cases for dealing with effluents . ~

Continued from Page 19 12,000 ML/year is effluent too polluted for return to the river and about 35 ,000 ML/year is lost by evaporation in wet cooling towers. To partly offset this the SEC currently adds to the river about 13,000 ML/year from its pumping operations in the Morwell open cut. The overall effect on the river at present is not great: a small decrease in flow, a small increase in dissolved solids , and a somewhat larger increase in suspended solids .

However future power station and coal liquifaction developments over the next 20 years could increase the annual net water requirement to 250,000 ML/year, nearly half the mean annual flow . As most of this will be lost by evaporation, the overall result wi ll be an increase in dissolved and suspended solids and in BOD5. Clearly this could have a radical effect on the Latrobe River itself , and possibly also on the Gippsland Lakes system into which the river discharges. To develop strategies to deal adequately with this potential problem would require an extensive analysis of the whole system , which is beyond the scope of the present paper. However the following possibilities are clearly worthy of further investigation: (1) Diversion of some of the water from the upper Thomson River, at present intended for Melbourne , to the Latrobe Valley. Present plans involve diversion of about 150,000 WATER

REFERENCES Allardice , D.J., Higgins, R.S. & Spurrier, P.L. 1976. Future Utilization of Victorian Brown Coal , Paper presented to Fourth National Chemical Engineering Conference, Effective Use of Hydrocarbon Resources, Adelaide, The Institution of Engineers, Au stralia , Canberra. l:lrown , ::i.H., 1\/77. Tne I reatao11Ity or l:lrown v0aI uewaterlng Effluent, M.Eng. Sc. Thesis , University of Melbourne.

Evans , D.G. 1976. Conversion of Brown Coal to 011, Proc. RAC/ Vol . 43: ~90 .

Latrobe Valley Water and Sewerage Board 1955. First Annual Report.

Latrobe Vall ey Water and Sewerage Board 1955-1977. First to Twenty Third Annual Reports .

Latrobe Valley Water and Sewerage Board 1969. By-Law No. 7.

Magee, E.M., Jahnig, C.E . & Kalfaldells, C.D. 1977. The Environmental Influence of Coal Liquefaction , Coal Processing Technology, Vol. 3, American Institute of Chemical Engineers, New York.

Meldrum, I.W. 1976. Future Developments for Electricity Generation, Brown Coal in the Latrobe Valley, Prospects and Problems, Glppsland Institute of Advanced Education, Churchill. 31 -40 .

Ministry for Conservation, 1977. Glppsland Regional Environmental Study, Report of the Desk Study, Ministry for Conservation , Melbourne.

Murray, J.B. & Evans , D.G. 1972. Thermal Dewatering of Brown Coal, Fuel, 290-296 .

State Electricity Commission of Victoria 1975. Loy Yang Project - Statement on Environmental Effects, Submission to the Parliamentary Public Works Committee Inquiry.

Urie, R.W. 1976. Brown Coal Development - Possible Planning Scenarios , Brown Coal in the Latrobe Valley - Prospects and Problems, Glppsland Institute of Advanced Education , Churchill. 6S-94.

Victorian Government 1953. Latrobe Valley Water and Sewerage Act No. 5742.

23

CONFERENCE CALENDAR 1980 February 4-8, Adelaide A .W.W .A. fourth Summer School.

February 15th, Woflongong, N.S.W. Symposium , Industrial Use of Wat er and the Environment.

February 22nd, Sydney Symposium Pumps and Pumping (see adv.) .

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March 17-19, Surfers Paradise Course on Upgrading Wastewater Treatment Plants (see advt.). Uni Q'ld.

April 14-18, Adelaide Engineering Conference. I. E. Aust .

April 15-19, Oxford, England Int ern atio nal symposium on application of recent developments in hydrological forecasting to the operation of water resource syste ms . IASH , WMO , UNESCO .

May 12-16 , Adelaide

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June 23-27, Toronto, Canada Int ernational Water Pollution Control Federation confere nce and ex hibition .

July , Melbourne Environment sy mpos ium . I.E . Aust .

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July 7-16, Sydney Course on Municipal Wastewater Treat ment . Uni. of N .S.W. July 14-18, Townsville Groundwater recharge conference.

AWRC. July 14-24, Edmonton, Alberta Third international sy mposium water/rock interaction. Alberta searc h Council.

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July 21-25, Uni. of ClermontFerrand, France Third WMO scientific conference on weather modification . WMO. August 18-22, Brisbane Seventh Australasian hydraulics and fluid mechanics conference. I.E . Aust .

September 1-4, Paris Thirteenth international water supply co ngress and exhibition. IWSA .

November 4-6, Adelaide Hydrology and Water Resources Sympos ium . I.E. Aust.

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CONVENTION MAIL For correspondence on any aspect of the Eighth Federal Convention the mailing address is now: P.O. BOX94, ROCKLEA, O'LD. 4106.

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AWWA- N.S.W. REGIONAL CONFERENCE The 1980 Regional Conference will be held at Goulburn in the College of Advanced Education over the weekend 7th to 9th March .

Papers should include: Use of Asbestos Cement in the Water and Wastewater Industry .

Construction of Pejar Dam. Water and Wastewater Use and Treatment in Abbatoirs.

Commissioning of Lower Molonglo Water duality Control Plant.

Water and Wastewater Treatment at the Woodlawn Copper Mine.

.,

THE HYDROLOGY AND WATER RESOURCES SYMPOSIUM 1979 Copies of the Proceedings of the Hydrology and Water Resources Symposium are now avai lab le from th e In st itut ion of Engineers , Austral ia, at a cost of $24.00 per copy in c luding postag e. The publication co ntain s 47 papers , including 7 papers from the Workshop on Land Management and Water Issues in South Western Australia , and 1000 word summaries of the 17 poster presentations o n water resources issues which were displayed during the Symposium.

Cheques made payable to " The In stitution of Engineers , Australia " shou ld be sent to the In stit ution 's offices at 712 Murray Street , West Perth , Western Australia , 6005.

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