Water Journal June 1976

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Official Journal of the AUSTRALIAN WATER AND WASTEWATER ASSOCIATION jvol. 3 No. 2, June 1976 Registered for posting as a periodical -

Category 'C '.

Price $1 .00

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TheC I Paper yce The re-use of paper and paperboard collected from sources outside the industry has been a feature of the Australian paper industry since its beginnings more than a century ago.

A.P.M. Ltd ., Australia's largest producer of papers and paperboards for the packaging and building industries, is the largest collector and user of wastepaper in Australia.

The quantity collected is some 350 000 tonnes each year and this provides about 50% of the Company's total fibrous raw materials .

Wastepaper is collected from industries, warehouses, large retailers and supermarkets, offices, shops and households.

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The Community benefits from this recovery activity because a valuable resource is separated and collected, and disposal by other means is not required .

The material recycled by A.P.M. together with other new pulps, produces paper and paperboard to be used in the preparation , distribution and storage of many of the goods used by Australians.

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Australian Paper Manufacturers Limited

Head Office: 4 South Gate, South Melbourne. Vic. 3205.

Sales Offices in all State capitals.

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EDITORIAL COMMITTEE

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Chairman: C. D. Parker Committee: G.R. Goffin F.R. Bishop Joan Powling A.G. Longstaff E.A. Swinton J.H. Greer,

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M. Dureau L.C. Smith R.L. Cllsby B.S. Sanders W. Nicholson A. Macoun

Hon. Editor: A. H. Truman

Publisher: A.W.W.A.

BRANCH CORRESPONDENTS

CANBERRA A.C.T.: A. Macoun, P.O. Box 306, Woden, 2606.

NEW SOUTH WALES: M. Dureau, Envirotech Australia Pty. Ltd., 1 Frederick Street, A.rtarmon.

VICTORIA: A.G . Longstaff, Gutteridge Haskins & Davey, 380 Lonsdale Street, Melbourne, 3000.

QUEENSLAND: L.C. Smith, 24 Byambee Street, Kenmore, 4069.

SOUTH AUSTRALIA: R.L. Clisby, C/- E. & W.S. G.P.O. Box 1751, Adelaide, 5001.

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

TASMANIA: W. Nicholson, 7 Swansea Court, Lindisfarne, 7015.

NORTHERN TERRITORY: C/- N.R. Allen, 634 Johns Place, Nightcliff, Darwin, 5792.

Editorial Correspondence: Hon. Editor, A.H. Truman, C/- Davy-Pacific Pty. Ltd., P.O. Box 4709, Melbourne, 3001.

Or to State Correspondents.

Advertising Enquiries: Mrs. L. Geal, C/- Appita, 191 Royal Par., Parkville, 3052.

Phone: (03) 347-2377.

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03671

Official Journal of the !AUSTRALIAN WATER AND I

l'ASTEWATER ASSOCIATJQN i Vol. 3

No.2

June 1976

CONTENTS Editorial -

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Energy, Food, Population

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Association News Literary Review

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Treatment of Wastewaters from Inorganic Chemical Manufacturing Operations - I. G. Meller ..

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The Direct Filtration Process and Its Application to Sydney's Water Supply - G. R. Grantham and K. A. Waterhouse

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Ultrafiltration and its role in Activated Sludge Wastewater Treatment - P. Gebbie, A.G. Fane and C. J. D. Fell

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Conference Calendar

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Products, Projects and Personalities

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INSTRUCTIONS TO AUTHORS Articles should be of original thought or reports on original work of interest to the members of the A.W.W.A. and preferably not more tha11 5,000 to 7,000 words.

Full instructions are available from Branch correspondents or the Editor.

FRONT COVER Architect 's drawing of the Melbourne and Metropolitan Board of Works' Sugarloaf Water Treatment Plant situated 40 km East of Melbourne. The Treatment Plant is one of the major elements of a multi-million dollar complex designed to supply high quality filtered water to Melbourne's Northern and Western suburbs . It will operate in conjunction with a Pumping Stat ion on the River Yarra at Yering Gorge, East of Warrandyte, and the Sugarloaf Reservoir, now under construction, in which will be stored up to 95,000 megali tres of water drawn from both the Yarra and the Maroondah Aqueduct . Another Pumping Station will supply stored water to the Treatment Plant which will then deliver treated water by gravity through the lower section of the existing Aqueduct .

Up-to-date, but proven and reliable treat ment precesses have been adopted in this 450 megalitres per day plant. Soph ist icated automatic controls and instrumentation will reduce manning and supervision to a minimum .

Extensive landscaping , adoption ot a low profile tor all buildings and structures and reclamation of wash water on site will ensure preservation of the natural enviro nment to a high degree. See story "F il tered Water for Melbourne" page 23.

Whafs the performance ofaHumes pressure pipe after 40years of service? ~

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~_,~ 100 /

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It's bound to be better. We seldom have a chance to find how much, because pipes just continue to perform . Nobody digs them up, even to look at them.

In 1964, however, Violet Town Water Works Trust wanted to increase the operating pressure in a reinforced concrete line by about 40% . Made by Humes in 1926, these pipes were originally tested at a pressure of 540kPa . Exhumed nearly 40 years later, some were tested again . Pressures at failure all exceeded 1350kPa. Proved beyond all doubt , the pipes have since then been working at the increased pressure without fault.

This is no exception. Humes pres sure pip es laid before 1920 are still in operation at Traralgon , Kerang and Mitcham , to name some Vic tori an exa mples Pressures ranging

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from 240 to 750kPa - that's from 80 to 250 feet head. Pipes over 50 years old· Reinforced concrete pressure pipes improve with age . Manufac tu red at extremely low water/ cement ratios Of Well under 0.4 by weight, their compressive Strength is much higher than that Of typical Structural COnCrete it_ is in . the 70,000kPa range - which gives them excellent density makes , ..... them practically impermeable •..,and ensures a very long life • with a continuously increasing performance .

HUMES CONCRETED PLASTICS D STEEL VIC.: 17 Ragla n Stree t , South Melbourne, 3205.

Phone (03l 60 o221 N.S.W.: Park Road, Regent s Park, 2143.

Phone co2i 644 235 1.

1gi2r~~tt~tr Road, South Brisbane, 4101.

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S.A. : 78-82 West Beach Road, Keswi ck, 5035.

Phone (08) 297 1011 .

W.A. : Sa lvado Road . Wembley, 6014 .

3 ~~re2(i~:is~ a; ~1~ce , Hobart, 7000.

Phon e (002) 23 7431 . ' .

N.T.: Reic hardt Road , Winn elll e, 5789. ~ hone Darwin 84 3388.

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If For further information I on ultra high strength I

concrete pipes, ask the 11. man from HUMES...

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Please send me latest catalogue of Humes Pressure Pipes .

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HC5 15N

Handles Water Beautifully Application

Typical Specifications

For filtration of Alkaline Water: Caustic Acid Solution, Boiler Water and Oxidised Chemicals.

Specific Gravity: 1.40 -1.45 Acid Solubility: 1.0% MAX Effective Size: Type 2 0.85- 0.95 mm Type 3 (j',50- -0.60 mm

Distributed in Australasia by Kembla Coal & Coke Pty. Limited, 1 Castlereagh Street, Sydney.

Telex Kemcol AA20571

Telephone (02) 233 6222

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Pumps are our business Whether you want to supply wate r to - or de-water from a min e, instal l a fire fighting syste m, or handl e low volume, high pressure slurries, McPherson's have the pump for you. Pumps such as • th e all-A ustr ali an al l-metric Ajax International Series back pul lout pumps ; • th e Peerless ve rti ca l line shaft and submersib le turbin e pumps ; • Ritz submersib le twin flow pumps deve loped for the mining indu stry in sizes to 2,000 hp; and• the Seebe rg pos itive displa ce ment pumps are ju st a few of th e pumps manu fac tured and /or distributed by McPherson's Li mited Pump Di vis ion.

Mc Ph erso n's, with a nation al coverage by its branc hes and di str ibutors, provides co nve nient sales and se rvice faci lities to ass ist you before and after you purch ase your pump.

McPherson's Ltd. Pump Division Melbourne 699 3588 Sydney 516 1633 Brisbane 52 2233 Ade laide 46 0271 Pe rth 61 8888

6310MP/PON

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CONTROL

In Mechanical, Process and Biological Engineering Mechanical Engineering Grit removal plant Screen in g press and bagger un it Circu lar and rectangular sedimentation tank scrapers Slu dge conso li dation tank thickeners, mixing tank stirrers Sludge dry in g bed mec hani ca l li fters Sand bed lifters

Process Engineering Thermal and chemical sludge conditioning plants TC In cinerator for screen in gs Mu ltip le hearth , fluidised bed , rotary drum sludge in cinerators Static grate incinerator Dissolved air flotation Carbon regeneration and absorption syste ms

Biological Engineering Standardised activated sludge plant fo r sma ll popu lation s of up to 20,000 perso ns Extend ed aeration plant, Aerob ic sludge dig estion .

Diffu sed air activated sludge plant Auto matic contro l systems for activated sludge plant

.,,, HAWKER SIDDELEY WATER ENGINEERING A divis ion of H awker S idde ley Brush Pty . Ltd .

Vic. 262-284 H eide lb e rg Rd . F airf ie ld , 3078. Te l. 4 89 25 11 . NSW. 12 Frede ri ck St. St . Leonards, 2065 . Te l. 4398444 .

Old . 193¡ Mary St. Brisbane , 4000 . Te l. 22 1 2926 . W.A. 113 K ew St. Welsh poo l , 6106 . Te l. 6 1 79 44 .

Hawker S idd e ley Group suppli es mechani ca l , e lectrica l and aerospace equipment with wo rld -w id e sales a nd se rvice .

Agents for: Hawker S idde l ey Water Eng ineering ltd . (Te mple wood Hawks ley A c tivat ed Slu dge.)

6517 H S

choice!

donkin Frontrunners 1n gas compression and control

Two major Australian public authorities recently chose Bryan Donkin compressors for their new sewage treatment plants. The equipment is being installed at the South Eastern Purification Plant of the M.M.B.W. at Carrum, Victoria and the Lower Molonglo Water Quality Control Centre of the National Capital Development Commission in the A.C.T.

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.,Backed by over a hundred years of manufacturing experience, the Bryan Donkin Company is dedicated to continued development of gas handling technology.

For more information, contact the Australian machinery agents Hawker Siddeley Brush Pty. Ltd.

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HAWKER SIDDELEY BRUSH PTY LTD In co rpo rated in NSW

VIC . 262-284 Heidelberg Road , Fairfield , 3078 . Tel. 489 25 11 . N .S.W. 12 Frederick Street. St. Leonards. 2065. Tel . 431502.

QLD . 193 Mary Street , Brisbane , 4000 . Te l. 21292 6 . W.A . 11 3 Kew Street, Welshpool , 6106 . Tel. 617944 .

H awker Siddeley Group supp li es mechanical, electrical and aerospace equipment with world- w,de sales and service.

5760HSBD

Mono announce the only submersible sewerage pumps to be unaffected by disposable nappies., ordinary nappies., wet-strength fibres., pantyhose., and solids up to 6'diameter.

The Monta pumps, from 2 to 75 HP, with 3''. to 6" sol ids capacity, are completely self-clearing.

Other benefits include easy installat ion and ma intenance.

The pump is guided into position by a slide tube and the res ilient face on its discharge branch seals the connection wi th the discharge pedestal.

Call Mono 's Water and Waste Treatment Division for fu ll deta il s of how the Monta pumps can handle your sewerage prob lem.

C?MUGUC?@ (AUSTRALIA) PTY. LTD. Head Office and Works : "Mono House" , 338-348 Lowe r Oandeno ng Rd., Mordia ll oc, Vic . 3195. Phone: 90 5211.

Interstate Office s: NEW SOUT H WALES: Kirrawee, telephone 521 -5611 0 QUEENSLAND: Kedron, tel ephone 59-6466 SOUTH AUST RALIA: Flinders Park, te lep hon e 43-9754 0 WESTERN AUSTRALIA: Belm on t, te l ephone 65-5244 C TASMANIA: Moonah, telephone 28-0353 [] NORTHERN TERRITORY : Winnel lie, telephone 84-3099. Ali ce Springs, tele phone 2-2913 AGENTS IN : Papu a and New Guinea, In donesia, Fiji, The Phi l ippines . ~44-P-042

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FEDERAL SECRETARY: R.F. Goldfinch, P.O. Box 359, Canberra, 2601 BRANCH SECRETARIES: Canberra, A.C .T. D. Butters, Cl- Dept. of Housing & Construction Phillip, A.C.T., 2606 New South Wales: Dr. D.T. Lacey, 16 Fairy Dell Close, Westleigh, 2120.

Victoria: R. Povey, C/ - S.R. & W.S. Commission, 590 Orrong Rd., Armadale, 3143.

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

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

Victoria Square, Adelaide, 5000.

Western Australia: B.S. Sanders, P.O. Box 356, West Perth, 6005.

Tasmania: P.E. Spratt, C/ - Fowler, England & Newton, 132 Davey St., Hobart, 7000.

Northern Territory: N.R. Allen, 634 Johns Place, Nightcliff, Darwin, 5792.

THIS ISSUE We have to thank New South Wales for the papers and contribut ions form i ng this issue. For the September Journa l, Queensland wi ll be in act ion and other Branches in t urn w ill be provid ing the material for succeeding issues. In this fashion, Water w ill acqua int readers w ith activit ies in all States .

Editor.

EDITORIAL ENERGY, FOOD, POPULATION This was the theme of the 47th ANZAAS Congress, held in Hobart in May this year. It was thoroughly discussed at most of the Congress Symposia, as is evidenced by the titles: International Pol itics and World Food Supply, World Population, World Energy.

Australia and New Zealand as a Food Bowl?

Australia's Biological; Marine Resources.

Future Energy Resources, Energy and the Environment. These culminated in a final symposium entitled ... The Sustainable Society. An Attempt was made to consider the implications of the discussions for Australia today and into the future, particularly with reference to Australia's role as a trading nation, and as a member of the Economic and Soc ial Commission for Asia and the Far East.

The writerattended the Congress and was surprised to find that unlike many conferences which have discussed these ther:nes over the past fifteen years, starting with the Club of Rome's Doomsday predictions, the Congress displayed a cautious optimism. The World will learn to cope.

So far as Australia itself is concerned, the size of our future populations is already a matter for political decision rather than an inexorable expansion . In his Presidential Address, "Zero Popu lation Growth - Fact or Fiction?", Professor W. D. Barrie, of ANU, discussed his predictions published last year in the Borrie Report on demographic analysis and projection . Although there is room for a spectrum of interpretation, it would seem that, left to itself, Australia's present popu lat ion will only increase to about 17 millions, levelling out at this figure by the end of the century . This trend is evident in most of the "Western" nations, and is a function of the modern smaller fami ly ... in other words, Z.P.G. This is on ly 20% more than present population .. . hard ly a land developer's paradise.

However, there is the factor of migration. After 1945, Australians committed themselves to 1 % p.a. migration in order to "popu late or perish" . They did, in fact, achieve this level until the 1970's. However, in the last statistical year, 1975, for the first time there was actually a nett loss of migrants. If we desire a bigger population than 17 mi ll ions, we must step up migration again to make up the balance.

The question, therefore, is "what size of population do we really want?" This is a decision that can be made on social and econpmic issues only, because, so far as resources are concerned, there are very few real constraints . Only the supply of liquid fuels is in doubt In the foreseeable future. Even water supply, our own field of interest, which has been longcherished as the major constraint on growth, can hardl,1 be cited as such in view of forecasts such as these. There is ample water in Australia to support a much bigger population, though patterns of use - or abuse may have to be modified, both on the urban and agricultural scene.

All these are comfortable figures and forecasts. They leave unanswered two questions.

What of the rest of the World? Here again, cautious optimism seemed to be the keynote. A stable population of no more than three times the present was projected, attaining this level sometime in the next century.

The increase will occur mainly in South America and Asia, but w ith Africa supporting over four times its present population. That this will strain both the renewab le and the fossil resources of the planet is in no doubt, and the po li tical implications to this "lucky country" are obvious, but it was considered that on balance, the World could cope ... provided the energy problem could be solved.

Coming closer to home, and to our own field of endeavour, though Austra lia, if left to itself, may happily limit its popu lation, to, say, 20 million, th is does not resolve the problems of concentration. On present trends, most of the extra 6 millions or so will finish up in Sydney, Melbourne or one of the other major cities. The consequent effects on water supply, waste disposal and transport are already causing our engineers considerable headaches.

We may shake our heads over the population problems of Asia, but in our own way, we have to reso lve the population problems of our own cities.

E. A. Swinton, (Journal Committee member).

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ASSOCIATION · NEWS SEVENTH FEDERAL CONVENTION The 7th Federa l Convent ion of the Austra lian Water and Wastewater Association will be held in Canberra from Tuesday 20th - Friday 23rd September, 1977. " Public Reali ties and Aspirations in Water Management" will . be the t heme of the Convention and the venue wi l l be Noahs Lakeside Internationa l Hotel.

Persons wishing to present papers are asked to contact their Branch Secretary tor details . Further pre-registration inform ation wi ll be ann ounced at a later date.

NEW SOUTH WALES As predicted the Annual Reg ion al Conference was a rip-roaring success .

The Friday go lf tournament at wh ich almost every player won a pri ze set the scene for a sporty weekend .

Our president , Jack Knight , arrived late for the evening reception after having exhausted Dave Hickie and Bob Edwards on the squa~h courts and there were libellous stories of midnight swims , early morning surfs, il li cit fishing trips and even mixed saunas.

The conference papers were meaty and wel I presented and only one de legate dropped off to a noisy sleep .

On Sunday the Lions Club hosted a magnificent barbecue at the Mangrove Creek Pumping Station and we all went home resolving to meet again next year.

Despite a slip-up in the issuing of notices, over 40 members turned up for the 5th May Genera l Meeting at which Mike Dureau gave a paper on "Sludge Disposal - Problem of the ?O's" . Brian Stone, who had just popped in from Pasadena where he is Office Manager for James M. Montgomery suggested that we should consider pumping sludge from Malabar and North Head over the Blu e Mounta ins and this provoked a lively discussion .

On the 22nd May , The Hermitage Wine Company 's tasting rooms were rocked by the wassailing of 36 of our finest drinkers. If the amount of wine consumed and the loud laughter which echoed through The Rocks is any

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indication , the evening was a resounding success.

On a more serious note, Professor Ratcliffe from the Chemical Engineering Departing was guest speaker at the 8th June General Mee'ting and his topic was "T he Study, Promotion and Encouragement of Po llution Control of Natural Waters" .

Future Functions 21st July: Annual General Meeting 6.30 p.m. at the Water Board.

Papers wil l be presented by the winner and runner-up of the D. K. B. Thistlewaite Memorial Prize for the best paper in the field of the Association's activities prepared by a University student.

CANBERRA Dinner/Ladies' Night The first function of this type was held in May this year at the Ambassador Hotel and was addressed by Mr. Reg Go ldfin ch, the Federal Secretary of the A .W.W.A ., who gave an illustrated talk on the 1975 World Study Tour. Due to the success of the evening it is intended that a Dinner become a regular event on the Branch calendar.

Field Day An inspection of the Lower Molonglo Water Quality Control Centre was held on Saturday, 22nd May. The plant is now at a very interesting stage with considerable mechanical equipment on site and al I major structures underway .

Future Meetings It is hoped to hold a symposium meeting on " Water Research in the A.C.T." in July followed by the A.G .M. in September and a meeting coinciding with the 1.A.W.P.R. Conference in October .

SOUTH AUSTRALIA On Friday , 28th May , the Branch was given a joint address by Mr. S. Lewis, Environmental Officer, Department of Environme nt , and Dr. D. Steffensen, Biologist , Eng ineering and Water Supp ly Department. Both speakers dealt with environmental studies of Gulf St. Vincent.

Dr. Steffensen's study was undertaken when he was at the University of Adelaide .

Mr. Lewis out lin ed the results of a three year study started as a result of complaints from the public that firstly fish were being killed near the effluent discharge from the Glenelg Sewage Treatment Works , and secondly, a big increase in cabbage weed had all eged ly occurred near the discharge from the Bo l ivar Sewage Treatment Works.

Preliminary work established that two major sea grasses occur in the Brighton to Largs area and that there were large areas of the sea f loor devoid of grass .

The possible contributors to degrada-

tion examined includ ed nutrients, salinity , turbidity and suspended solids .

The resultant study established no association between land based discharges and sea grass degradation and also demonstrated a large degradation area in Largs Bay where there is no land based discharge at all.

At Bolivar, it was established that no apparent correlation ex isted between nutrient output and cabbage weed growth. It was conc lud ed that, in the Brighton to Largs area, sand erosion was · the basic reason for area grass degradation .

The conclusions of Dr. Steffensen's ind epende nt study were that at Glenelg smal l areas near the effluent discharge experienced a higher than normal sea grass growth rate but those areas subject to sea grass degradation were influenced by sand movement. At Bolivar, chemical and biological effects of effluent discharge on sea grass growth were inconsequential , degraded areas were influ enced by sand movement and alg ae growth seems to be associated with nutrient levels.

QUEENSLAND Don King-Scott Memorial Prize Last year the Queensland branch comm ittee decided to offer an annual award to the top graduate in the Diploma of Environmental Engineering course at the Queensland Institute of Technology . The specific purposes of the award are : (a) To perpetuate the memory of our inaugural President and Federa l Counci llor, the late Mr. Don KingScott, formerly Chief Engineer of the Local Government Department . (b) To further foster • in terest in the aims of th is association in encouraging young graduates in Environmental Studies.

Th is year's w~nner (completed course 1975) is Phil lip Williams aged 28 who obtained the B. Tech. (Civil Engineering) from the Queensland Institute of Technology in 1971 and L.G .E. 1974.

Phillip was formerly employed by the Main Roads Department and is now Senior Assistant Engineer with Beaudesert Shire Council.

0.1. T. Course In Environmental Engineering The Queensland In st itute of Technology has been running this course for approximate ly 6 years. The Diploma in Environmental Engineering is a three year part-time graduate diploma run by the Civil Engineering Department . It is open to graduates in engineering and covers the fields of water quality engineering , water resources, land waste disposal, air pollution and environmental systems management.

Further information may be obtained from Mr. Brian Rigden, Senior Lecturer in Environmental Engineering , Queensland Institute of Techno logy , P.O. Box 246, North Quay , Q. 4000. Telephone 221-2411.

FEDERAL COUNCIL The Federal Counci l of the Association is pleased to announce that as a result of discussions with Senior Officers of the American Water Works Association during the recent World Study Tour , our Federal Secretariat has been appointed agent in Australia for the American Water Works Association .

It wi ll now be possib le for members of our Association to participate in all the act iviti es and rece ive publ ications of the American Water Works Association in a simil ar manner to that which has operated for many years with the Water Pollution Control Federation.

Membership Applicatiol') forms are available from our Secretary . Appli cants for membership are required to pay their first year dues in advance : Active Member $28 .00 (Aust) Affiliate Member $14 .00 (Aust) Life Member $28.00 (Aust) $10 .00 (Aust) Retiree Student $12.00 (Aust)

Peter Tyler Peter Tyler Lance Bowen GeorgeGanf Bill Williams Arthur Haughey Peter Cul len John Weir Ian Lawrence/ Geoff Henkel David Mitchell Valerie May Frank Burns Lance Bowen Derek Cannon Ian Smalls

AWRC SYMPOSIUM ON EUTROPHICATION Following the completion of a 12 month study of eutrophication in Australian inland waters and the publication of the ensuing report as AWRC Technical Paper No . 15 (An Assessment of Eutroph ication in Australian Inland Waters) it was decided to arrange a sympos ium to discuss in detai I the resu Its of the study and highlight the more important aspects of eutrophication .

At the symposium, held in Canberra on 4-6 February, fifteen papers were delivered on key topics by leading eutrophication research workers from both government and academic institutions . A I ist of the speakers, together with the title of their papers, is given at the end of this brief note.

The symposium was most successfu l and pointed up the need for a regular exchange of views and experiences between research workers, administrators , eng in eers and water managers involved in the field of water quality . The wide range of backgrounds and disciplines of the participants ensured that a useful and informative discussion period followed the presentation of each paper.

Due to the obvious interest in the topic and the fact that many interesting and often little understood facets of eut rophic ation were discussed, it has been decided to publish the proceedings of the symposium . These are expected to be ava ilab le by August 1976.

Speaker Tit le of Paper Gavin Wood

Brief presentation of his report (AWRCT .P. No . 15)

Bill Williams

The basic concepts of eutrophication Biological problems Chemical problems Primary productivity Benefits from eutroph ication Natural and agricultural causes Urban causes Natural and agricultural contro l Urban control Control with herbicides/ harvesting Control by nutrient removal Control by destratification / aeration Chemical monitoring Bio logi cal monitoring OECD eutrophication studies in Australia Resume and general discussion

Relations were derived between alg al productivity and biologically available phosphorus , transported to the lakes.

Levels of sediment , nitrogen and phosphorus in the transporting streams were related to human activities in the watershed , this applied particularly to use of fertili zers . The economic effects of control of nutrients from both manures and fertilizers were assessed .

Social attitudes to problems of water quality , and ways in which the public and legis lature respond were also studied.

The study is, of course , specific to the c lim ate, geography and sociology of the area studied, which is predominantly dairy farming , but with a snowed-in winter season . However, the methodo logy developed in each ch apter is well argued , and should be helpful and stimulating to workers - present and future - who have to face up to similar problems in the various Australian environments .

It is written in a sty le which is primarily aimed at the scientific community, but which is perfectly intelligible to the interested layman , particularly administrators and policy makers .

A book which can be highly recommended , not only for profession als and administrators involved in these issues , but also for educational institutions with interests in environmental science and agriculture .

LITERARY REVIEW " NITROGEN AND PHOSPHORUS FOOD PRODUCTION , WASTE AND THE ENVIRONMENT" Ed . Keith S. Porter Published by Ann Arbor Science, Michigan [Copy from The Ramsay Group Educational Division $20. 00. ] This book is the result of an interdiscip lin ary research project performed within the College of Agriculture and Life Sciences , Cornell University, with inputs from the disciplines of agricultural economics and engineering , agronomy, limnology, sociology and systems analysis .

The study deals with the interwoven issues of maintaining agricultural efficiency and protecting the environment, by attempting to quantify the flows of nitrogen and phosphorous across the landscape . The core of the investigations was a highly detailed study of a specific watershed and 13 lakes in central New York State, the ground water on Long Island , and a study of the control of nitrogen in animal manure .

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A.W.W.A. WORLD STUDY TOUR 1975 The first section of the A.W.W.A .

World Study Tour in 1975 has been reported in detail by Reg Go ldf inch , the Honorary Federa l Secretary I Treasurer, in a 115 page report covering inspections in Hong Kong , Japan, San Francisco , Lake Tahoe , Santa Ana , Cal. , Reno , Nevada , Washington D.C . and culminating with the 48th Conference of the Water Pollution Control Federation at Miami , Florida .

Specific problems investigated include nutrient removal , water rec lamation , sa li ne water conversion , alum s ludg e recovery, sewage s lud ge treatment , rating stud ies .

Members interested in reading the report should write to: Mr. R. Go ldfin ch , Hon. Federal Secretary /Treasurer, A.W .W.A . , Post Office Box 359, Canberra City, A.C .T. 2601.

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Treatment of Wastewaters from Inorganic Chemical Manufacturing Operations Ian G. Meller, B.E.(Chem.)* Inorganic pol Iutan ts are more easily treated in concentrated solutions.

Occasionally two wastes may be segregated because one is more easily treated than the other two , or has much greater pollution potential. Treatment practices involve in-plant segregation of contaminated wastes from uncontaminated coo ling waters, which on average, account for 40% to 80% of total plant discharge volume (3) . On the other hand, blending of wastes is frequently practiced to take advantage of selfneutralisation, or to achieve dilution of a troublesome component . Possible ¡ synergistic or antagonistic effects of various components must be taken in to account in blending . Treatment practice has been we ll summarised by Taylor (2) . " In general, waste streams are initially segregated and kept segregated as long as high concentration and ease of treatment are an advantage . The various waste streams should be blended to achieve dilution when the advantages of segregat ion have been fully exp loited ."

The Current status of water use and discharge in inorganic industries is indicated by figures available from surveys in the United States (3). (Table 1.) It is estimated that between 10% and 20% of the process waste water discharge from the inorganic chemical industry is to municipa l sewer systems.

This represents approximately 8% oJ the tota l feed to municipal systems . The inorganic chemical indu stry has generally found that in-plant, separate treatment has economic advantages, particularly when sig nificant quantities of waste water are involved .

The level of treatment required for a contam in ant will depend on the limits imposed by legislative bodies for the appropriate receiving water . In the State of N.S.W., taking the case of the heavy

metal copper, maximum discharge level to restricted , protected and control led waters is currently 1 mg/ I. For discharge to sewer , the maximum level is 5 mg/I, whi le for stormwater channe ls, a maximum of .5 mg/I is imposed (and in addition , total heavy metals must not exceed 3 mg/I).

Equalisation, neutralisation, sed imentation and lagooning processes are the most widely used . The effluents are not amenable to biological degradation as a general approach to treatment , since contaminants are primarily dissolved or suspended inorganic materials .

The treatment methods utilised for removal of specific contaminants are discussed below. (i) Phosphate Industry The phosphate industry is a relatively large tonnage one, its products are essential for detergent and fert ili ser manufacture.

Waste streams are characteristically low in pH and high in phosphates and fluorides (the latter having their source in the phosphate rock). Forms of phosphorus present in the industry waste water are suspended colloids and the soluble polyphosphorus (consisting mainly of pyro- and tri-polyphosphates) which are building blocks for detergents and orthophosphates.

Chemical remova l by precipitation with inorganic coagulants (such as ferric or ferrous iron, aluminium or calcium sa lts) fol lowed by floccu lation with polyelectrolytes is the commercial method . It is characterised by extremely low equipment and maintenance costs .

Residual phosphorus levels, lower than 1 mg/I , can be obtained. No major compet itive processes ex ist. Typica l inorganic coagulants used for this

TABLE 1: WASTE WATER DISCHARGE

Inorganic Industry Alka li es Gases Pigments Chemicals Paints Fertilisers Herbicides Exp1osives

10

Total Discharge (Billion (U .S.) gals/yr)

364.1 80 .8 91 .5 468.0 6 .5 97 .4 Not ava il able 143 .1

Discharge to Municipal Sewer Systems (Billion (U.S.) gals/yr)

47 .2 2.7 1.0 42.6 4.6 0.3 Not available Less than 50 million ga ll ons

Percent to Municipal Sewers

13.0 3.3 1 .1 9.1 70 .8 0.3 .::35

purpose include iron chloride , iron sulphate, alum inium sulphate , sodium aluminate , and calcium oxide . It should also be mentioned that cationic flocculants can be toxic to fish if used in low solids systems.

Technologica l developments in phosphate removal have been discussed by Jones (4) .

An additional problem in the phosphate industry is removal of fluoride ion . Chemical precipitation from levels of reduces fluoride approximately 1700 mg /I to less than 5 mg/I (5). Fluoride ion has an affinity for tricalcium phosphate and is settled enmeshed in a precipitate. Other removal methods are considered in section (iv). (ii) Removal of Nitrogen from Waste Water

The forms of nitrogen most prevalent in waste waters and which require treatment are ammonia (as NH~) and nitrate (as N0 3 ). The most widely used removal methods for inorganic nitrogen include biological synthesis, and nitrifications, ion exchange and air and steam stripping . Adams (6) discusses these methods.

For ammonia removal , nitrification is genera ll y practiced. In nitrification, ammonia and some organic nitrogen compounds are converted to nitrate by the aerobic organisms Nitrosommonas and N itrobacter. Nitrification by the activated slud~e process has been applied successfu lly to ammonia concentrations as high as 500 mg/I. A high strength ammonia waste may be reduced to leve ls less than 5 mg/I by using a submerged filter for final nitrification/polishing . A sludge disposal problem exists . Nitrate removal will also be necessary.

Air stripping for ammonia removal • consists of raising the pH of waste water to high levels (10 .5 to 11 .5) and providing sufficient air-water contact to strip the ammonia gas from solution.

Very few ammonia stripping towers have been designed for treatment of waste waters , and genera lly, those in use are applied to treatment of low strength waste waters . Apart from the econom ical consideration, and the lack of a sludge disposal problem, the major advantage of ammonia stripping is the ability to control the process for selected ammonia removals . However, • Technica l Officer, Australian Paper Manufacturers, Botany, N.S .W.

I

I

severa l disadvantages are inherent to the air stripping process . Tower freezing and precipitation of metal salts may occur, particularly in colder climates. Extreme fogging conditions may be produced and formation of ammonium sulphate aerosols by reaction with sulphur dioxide may be a problem in industrial areas .

Ion exchange of ammonia-nitrogen has been made possible with the advent of cli nopt iloli te, a natural zeolite wh ich has a strong affin ity for ammon ium ion.

Applicability of clinopti lolite to indu strial wastes is subject to the general limitations of the ion-exchange processes. If suspended solids are present, then pre-treatment for removal is required, or the so-called resin-in-pulp method, in which the resin is introduced directly into the contaminated solution , must be used .

The presence of organic material and interfering ions may severe ly retard the effectiveness and useful life of the resins. Loading capacity is limi ted, and cost of operation high. Invariably, disposal of regenerant so lut ions is a problem. Adams (6) cites one novel ion-exchange removal process in the ferti li ser industry in which regenerant solutions are used to form a marketable by-product fertiliser.

Nitrate and nitrated compounds are very d ifficu It to treat by physical and chemical techniques, other than ion exchange, which is itself restricted to certain waste waters . Denitrification is the commercial ly accepted process for nitrate removal. In this process nitrate serves as a terminal hydrogen acceptor in the anaerobic microbial oxidation of organic compounds. Nitrate is reduced to harmless nitrogen. The process has been effectively applied to nitrate levels as high as 10,000 mg/I. Nitrate reductions of 90% are obtainable.

Currently, three denitrification systems , anaerobic activated sludge, anaerobic ponds and upflow anaerobic f ilters offer good reliability with variable economy. If not already present, a cheap external carbon source, such as methanol, must be added. (iii) Removal of Heavy Metals The occurrence of the more troublesome heavy metals in three large inorganic chemical industries groups is shown below: The heavy metals are, for the most part, responsive to conventional treatment methods, which include chemical precipitation , cementation , electrodeposition, so lvent extraction,

TABLE 3: HEAVY METALS REMOVAL

Concentration of Feed Solution (g / I)

Treatment Method Applicable

100to10· 20to 1 1 to 0.1 0.2 to 0

electrowinning cementation or electrodeposition lime precipitation, solvent extraction ion exchange, activated carbon

reverse osmosis and ion exchange (7) .

An important chemica l characterist ic of the heavy metals is the so lubili ty of the ir salts .

The most genera lly appl ied treatment method , particularly where complex chemical compounds are not involved and economic recovery is not a consideration, is precipitation with lime or limestone. The metals copper, zinc, iron , manganese , nickel and cobalt are removed by almost complete precipitation as the hydroxi de .

For cadmium, lead and mercury, effect ive removal may be ach ieved through add ition al incorporation of soda ash (precipitation of in so lubl e lead carbonate) or sodium su lphi de (cadmium and mercury sulphides) .

Where chromium is present it is usua lly in the hexavalent form and reduction to the trivalent form with sulphur dioxide, ferrous sulphate, or metallic iron is necessary before hydroxide precipitation is possible .

In general , chlorination may be needed to break-down complex organic metallic compounds before chemical prec ipitation.

Liquid so lid s separation may be accomp li shed after appropriate reaction time by thickening and filtrat ion, or centrifuging. In some instances the solids (ma inly a mixture of hydroxide, basic carbonate, plu s calcium sulphate and carbonate) have been sold for metal content but they frequently must be disposed of as landfill. The filtrate carries come sodium sulphate , but is often suited for repetitive re-use in many plant operations or for direct discharge to a d ilu ting stream or san itary sewer.

Ion exchange may be favourable economically where the regenerate is high in metal ion concentration and can be re-used rather than discarded . The limitations of ion exchange have been pointed out in section (ii), a lack of ion selectivity may be a further limitation .

Some metals found in waste s olutions can be recovered by electrodeposition techniques using so lu ble anodes . The method has been

TABLE 2· OCCURRENCE OF HEAVY METALS

'

Indu stry : Alka l is , Ch lorine, Mi sce ll aneous In organic Chemicals Fertiliser In dustry Source (7)

Al

• •

As Cd

• •

•

•

Cr

Cu

F

• •

•

•

•

Fe Hg Mn Pb

•

•

• •

•

•

•

Ni

•

Sn

Zn

•

• •

app li ed quite successfu lly to copper conta ining solutions . Another method providing high purity metal recovery is cementation . The metal bearing solution is contacted with the correct metal powder or scrap and wil I precipitate as a metallic "sponge".

Using zi nc dust as a precipitant for gold and silver from cyanide solutions is a widely used cementation process that has interesting potential for recovering small amounts of metals such as cadmium, mercury and lead from industrial wastes (7). Copper recovery on iron is wide ly practised .

So lvent extractio n can provide separat ion of a particular metal ion for wh ich a general recovery treatment may then be app li ed . The metal ion is complexed with an organic reagent and extracted from water into an immiscible organ ic phase . A continuous countercurrent mixer-sett ler system is usually used.

The method of reverse osmosis , involv in g fi ltration through semipermeable membranes , has generally only been app li ed where recovery is of a spec ifi c stream which can be re- used or where recovery of an extreme ly valuable metal is involved . Kaup (8) has discussed the various design factors in this re lative ly new technique . Eff ici ency of rejection increase with' the size and valence of the metal ions . Current applications include separation of chromate from cooling tower blowdowns; removal oftsulphates from acid mine drainage ; retrieval of gold, silver, platinum and other precious meta ls from electroplating so lu tions and rinses . Membrane foul in g is caused by const it uents of waste water common ly miscellaneous particulates, biological growth and scales caused by ca lc ium su lphate and carbonate , hydrates of iron oxides, also aluminium and silicates .

Activated carbon absorption has been used essentially as a final polishing operation to remove metals to trace amounts less than 1 ppm. The carbon is regenerated by heating in a rotary ki ln.

The vario us treatment schemes discussed above are practical only wit hin certa in ranges of metal concentration in the feed so luti on . For instance , processes that might be emp loyed for various feed concentrations of copper are: Perhaps the most controversial area in heavy metal pollution in inorganic chemicals manufacture has been that of

11

mercury in the ch lor-a lkali in dustry.

Due ot its abi lity to accumulate in the body, pressure has been on manufacturers for high levels of removal fro m plant waste liquor. Jones (9) has described problems in this industry, and systems of mercury removal in commercial app lication. Martin (10) has also reviewed modern technology for mercury removal.

As a spec ific case study, it is interest ing to note limitatio ns of removal methods d iscussed for mercu ry removal. The deposition of mercury by a more active metal (ceme ntat ion) e.g. alumin ium, copper, iron , zinc, is effective, but it subst it utes another metal in solution in usually more than an equivalent amount. Methods based on precipitation of mercuric sulphide suffer from the high toxicity and offensive odour of su lphid e reagents . Sorption of mercury on preformed metal sulphid es , e.g. iron sulphide , ca lcium su lphide, zinc sulphide , is an effec tive remova l ¡ method . Howeve r, the mercury in solution is replaced by anot her ion. Ion exchange methods are expe nsive and suffer from resin attrition and fou lin g due to suspended so lid s (graphite and carbon from electrodes, and dirt).

So lvent extraction of mercury has not been feasible due to lack of solvents.

Development of high molecular weight amines for solvent extraction of mercury (11) from brine so lu tions following successfu l appl icat ion s in nuc lear technology could lead to recovery of mercury in some marketable form. (iv) Removal of Cyanides, Fluorides and Sulphides Strong cyanide wastes are most successfu ll y treated by electrolyt ic decomposition (12) . Cyanide is broken down to carbon dioxide and ammonia with cyanate as an intermediate. Low to intermediate cyan id e is reported by this process and, either partial treatment or comp lete destruction, can be achieved as req uired. Chemical oxidation by ch lorination or ozonation is most approp ri ate for low cyanide wastes, whether carr ied over from the electro lytic decomposition process or as dilute rinse water wastes. Concentrations of cyan id e up to 30 mg/I have been successfu lly treated in acclimated aerobic biological treatment processes (13) .

Operating costs of the two chemical ox idati on treatment processes are equi val ent, alt hough capital costs for ozone treatme nt appear high in comparison to chlorin ation eq uipm ent costs. Ch lorination adds chlo ride ion s to the waste, and thus in creases both chl oride and total disso lved so lids content, while ozo nation has no residual effect of itself . To avo id formation of toxic HCN, strict segregat io n of cyanide wastes from acidic waste streams is essent ial.

12

Indu strial wastes , containing high f lu oride levels, require two-stage treatment. Lime precipitation removes fluor id e down to approximately 10 to 20 mg I I. Further reductions to the 1 mg/ I level are best achieved by activated alum ina (12). The units involved are essential ly the same as those used for ion exchange water softening, and the regenerate can be treated in the first stage lim e removal unit by rec ycling .

Removal of sulphides is genera lly through precipitation with metal ion s.

Gas stripping has also been used but there are air pollution problems associated with this method. (v) Disposal of Brines

Brin es contain so lu ble salts which do not break down , and are not subject to bacterial degradation. They result from rege neration of ion exchange resins , and from manufacture of a number of inorganic chemica ls, particularly soda as h.

Taylor (2) gives a typ ica l analysis of the waste stream from a soda as h plant.

The preferred practical so lution for hand ling such wastes has been discharge to surface waters where high dilution is available . Solar and applied heat avaporation ponds and deep well disposal have also been used .

Waste Water Treatment Costs An exhaustive investigation of capital and operat in g costs in the inorganic chem ica l indu stry has been summarised by Jones (1). A cost comparison of water treatment processes and t he genera l waste characteristics for which they are app li cab le, have been provided

by Eckenfelder (14) .

Operating cost approximately doubles in going from simple neutralisation treatment to complete treatment, involving demineralisation. Capital cost of deminera lisation p lants are approximately f ive times that involved in a simple neutralisation plant. However, a valid process cost comparison can be made only when benefits of possible re-use of water are accounted for.

FUTURE TRENDS The inorganic chem ica l industry continues to rely largely on naturally occurring raw materials . It is thus unlikely that characteristics of wastes produced wil l change . The most clear trend in treatment of inorganic effluent streams is that toward recyc lin g.

Ob jections from environment quarters for have resu lted in the need conside rab ly higher eff luent qual ity standards. In areas where eff lu ent is sewe red, municipal treatment costs have risen sharply. The econom ic feasibi li ty of recyc ling depends upon the net sav in gs effected by handling a smaller volume of water, after the cost of treatment the effluent for recycle has ber .; considered. Recycle streams are

best when contami nants are either low in content or easi ly removed , and industry quality requirements are flex ible .

Practices of brine and sludge disposal, particularly where a highly toxic contaminant is involved , will be placed under increasing criticism. For heavy meta ls, there is increasing pressure for legis lation to prov id e removal prior to ocean dumping or land disposal. A trend toward recovery of the contam inant s in some marketable or reusable form is expected . Ricci (15) has described severa l promising recent deve lopments for metal recovery from waste water.

A number of treatment innovations show good prospects in areas of problem contaminants, such as the phosphate industry (4) . Adiabatic gas flashing has appeal where air stripping has previously been used if the so lu te gas can be re-used in the process or recovered as a by-product (16) .

The most enco urag ing area of current deve lopment is that of the membrane process, particularly reverse osmosis.

Further development and improvement of ion specific electrodes will facilitate rapid measurement of individual pollutants and make possible a better control over the treatment process .

REFERENCES 1. Jones H. R., "Environmental Control in the Inorganic Chemical Industry", Pollu tion Contro l Review No. 6, Noyes Data Corporation Ltd. 1974.

2. Gurnham C. F., "Industrial Waste Water Contro l", Ch. 17, Inorganic Chemicals, by W. R. Tay lor, p305-323, New York Academic Press 1965.

3. "Chem ical Wastes : What's Ahead?", Water Wastes and Eng ineering Vol. 9 No. 5, pC6, May 1972.

4. Jones H. R., " Detergents and Pol lution", Pollution Control Review No. 7, Noyes Data Corporation .

5. Patton V. D., " Phosphate Mining and Water Resources", Industrial Water and Wastes Vol. 8, No. 3, 1124-33, May 1963.

6. Adams C. E., "Removing Nitrogen from Waste Water", Environmental Science and Technology Vol. 7 No. 8, p696-799, August 1973.

7. Dean J. G., Bosqui F. L., Lanouette K. H., "Removing Heavy Metals from Waste Water" , Environmental Sc ience and Technology 6, p521, June 1972.

8. Kaup, E. C., "Desi gn Factors In Reverse Osmosis", Chem. Eng. Vol. 80 No. 8, p46-55, 1973.

9. Jones, H. R., " Mercury Pollution".

10. Martin L. F. , " Industrial Water Purification", Pollution Technology Review No. 5, Noyes Data Corporation 1974.

11. Moore F. L. , "Solvent Extraction of Mercury from Brine Solutions with High-Mo lecularWeight Amines", Environmental Science & Technology Vol. 6 No. 6, June 1972.

12. Watson M. R., "Pollution Control in Metal Finishing", Pollution Technology Review No. 5, Noyes Data Corporation 1973.

13. Eckenfelder W. W. Jr., " Industrial Water Po lluti on Control", p130, McGraw-Hill 1966.

14. Eckenfelder W. W. Jr. , "Treatment-Cost Re lationsh ip for Industrial Wastes", Chem .

Eng. Prog. Vol. 67 , No. 9, p76-85.

15. Ricc i L. J., "Heavy-Metals Recovery Promises to Pare Water-C leanup Bills", Chemical Engineering Vol. 82, No. 27, p29-31, December 1975.

16. Wilson D. B. , Tsas H. Y. , "Waste Water Degassing by Adiabatic Flashing" Journal Water Pollution Contro l Federation, Vol. 46 No. 9, p2209-2214, September 1974.

•

l

The Direct Filtration process and application to Sydney's water supply

its

G. R. Grantham* and K. A. Waterhouse.

General The filtration of water by passing it through a bed of f in egrained media is one of the most basic of water treatment processes . Traditionally, within our life-span at least , filtration has been the fourth step in a treatment system involving coag ul atio n, flocculation , sett ling and fi lt rat ion .

This system has been widely used since the turn of the century with little change until such men as Bay li s, Hudson , Camp , Pitman and Conley began experim ents in the 1930's, 40's and 50's which led to better qual ity of water at lower costs by providing better pre-filter preparat ion and higher f il trat ion rates . The primary objective to provide a steady production of high -quality water w ith minimum operating and maintenance costs has not changed but the criteria for acceptab le water have been significant ly tightened to resu lt in a product now vastly superior to that produced as few as five years ago.

Direct Filtration One of the more recent imp rovements in filtration technology has been that of direct filtration . Direct filtration is the conventiona l four-step process with the second and third steps, flocculation and settling , left out . A chemica l coagulant , usually alum, and almost always a floestrengthening agent , usually a polymer, are added to the raw water with rapid mixing and directly app lied to the filter. The filter removes the strengthened pin-point floe along with the raw water turbidity to produce an eff lu ent turbidity wh ich readily meets the American Water Works Association 's recently adopted objective of 0.1 Jtu for filtered wate r. Thi s is usuall y do ne at filter rates in the orde r of 2.85 to 4.01 litres per second per sq uare metre and without apprec iab ly shortening fi lter runs or increas in g the amou nt of backwas h water required .

One may argue successfully that d irect filtration as defined above was a fore-runner of the rapid sand filtering process in that the old slow sand filters were operated with no flocculation or settl ing pretreatment and usually without any coagulant at all. There are major differences, of course , in the rates of f il tering, pre-f il ter preparation, design of the filter bed , method of bed cleaning and process contro l. The excel lence of water quality from the slow sand filters as regards tu rbidity and bacterial removals is usually matched by direct fi ltratio n but direct filtration sometimes fa ll s behind in co lour removal.

Applications of direct filtration are limi ted to waters hav in g low turbidity and co lour . Average turb idity of 10 Jtu or lower, and preferably lower than 5 Jtu , is needed for successful direct filtration . Short term peaks of 50 to 80 Jtu can be accommodated. Algae blooms do not seem to create any more of a problem in direct fi ltrat ion than in the convent iona l systems. Taste and colour removal by adding activated carbon ahead of direct filtration has been successfu l in the Southern Nevada Water System (Las Vegas) plant.

The advantages of direct filtration are obvious . There is a sig ni f ica nt savi ng in capita l costs by el im inating flocculation

and operation needed for the production of high qual ity water.

Multi-media FIiters Direct filtrat ion has been successfu l on ly with the use of dual or multi-media filters , the so-ca ll ed reverse graded fi lters. The single media fi lters do not provide the storage in the bed necessary to give acceptable length of filter runs before turbidity breakthrough occurs . Fi lters having 600 to 900 mm depth of coal 1.00 mm to 1.20 mm effective size and a uniformity coefficient not greater than 1.5, and a 200 to 300 mm depth of sand 0.45 to 0.50 mm effective size and uniformity coefficient of 1.5 have proven successful. There is considerable debate about mixing of the coal and sand in dual media f ilters . One group favours mixing because tests indicate less breakthrough. On the other hand, the sizing of media (coal size less than twice the sand size) for minimum mix in g has certa in other advantages, not the least of whi ch is less susceptib le to mu d ball formation in the mixed zone due to lower poros it y. lnterbed mixing can be m in imized by spec ifying appropriate sizes for coa l and sand . Backwashing the sand before adding the coal and removing the top 50 mm of the sand, which contains the fines , will reduce bed fines and mixing at the interface.

Filter Backwashing Backwashing design is equally as important as filter bed design. The backwash must consist of the conventional upf low of water at adequate rates aid ed by air scour or some kind of surface or inter- bed wash system . Air scour rates of up to 0.02 cubic metres per second per square metre should be provided and was h water rates sho uld be capab le of expandi ng the sand layer 40 percent and the coa l layer 25 percent. The backwash hydraulic faci lities should al low the operator some flexibi lity on the high side to take care of viscosity changes due to warm waters and t o be able to increase the rate if he wishes. Provision of 15.3 to 17.7 I/s m2 capacity for water and 0.02 m3/s m2 for air scour are recommended. Surface wash for deep dua l media filters is not very effective. A new design usinif Baylis type surface wash system utili zes longer vertical laterals with three sets of nozzles at different leve ls is sa id to be successful. The nozz les are located at top of expand ed sand bed, at top of expanded coa l bed and in between.

Pretreatment The preparat ion of the raw water for direct fi ltration is extremely important and there is no lead t im e to make changes . Fortunately the waters for which direct filtration is possible are those in which quality changes are gradual or can be predicted. Alum in amounts of about 1 to 2 mg/I per Jtu is fed into a rapid mix unit . The rapid mix unit should provide up to G = 800 sec¡1 energy with a variable speed mixer which can be controlled by the operator to give the optimum mix. The floe w ill be pin- po in t and difficult to see so the appropriate mix can be determined only by tests on pil ot or bench sca le, the criterion being length of fi lter run

and sedimentation tanks and equipment. The amounts of

before breakthrough. The relatively high energy mix results in

chemi ca ls and the res ulting vo lum es of sludg e are reduced materi all y and the ev id ence is at hand that the resulting so li ds in t he backwash water are eas ier to dewater. The d isadvantages of d irect filtration are it s limited app li cabi lity to relatively c lear waters and the more sophisticated control

a higher floe density (less water conta in ed in the floe partic le) wh ich makes a tougher f loe and one which is usua lly easier to dewater. Detention periods in the rapid mi x tank need not be longer than 20 to 40 seconds. In -line blenders with variable speed drives are gaining favour . Careful

* Respectively -

Director, Camp Scott Furphy Pty . Ltd. and Designing Engineer M.W.S. & D. Board, Sydney, N.S.W. 13

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plant has proceeded on the basis of the direct f iltration process.

The results of the pilot plant studies showed that Warragamba water containing turbidity of the order of 25 Hellige units would be successfully treated by direct filtration at rates up to 4.5 I/s m 2. Filter runs of 10 to 12 ho\JrS could be expected at this rate while considerably longer runs were obtained at lower filtration rates and / or turbiditi es. The use of a cationic polyelectrolyte as a primary coagulant gave longer filter runs than did alum .

North Richmond Water Treatment Works Design Criteria for these works are shown in Appendi x 'C' .

These works which draw water directly from the Nepean River, are at present being amplified to increase their capacity from 28 to 45 Ml/day . This is being achieved by (a) amplification of raw water and treated water pumping stations ; (b) conversion of the rapid sand filters to dual media filters including provision of air scour; (c) amplification of pipework ; (d) conversion of an existing circular horizontal flow sedimentat ion tank to a high rate upflow clarifier.

Items (a), (b) and (c) have been completed and item (d) is in progress . While the sedimentation tank is out of commission the plant is being operated as a direct filtration process . Alum is dosed into the raw water in the rising main from the river pumping station . The water is then applied directly to the filters without furthe r treatment , apart from the mi xing the flocculation which takes place within the inlet main .

The plant commenced operation in this manner on the 25th November, 1975, and has performed satisfactorily since that date. During this time raw water turbidities have varied from 6 to 25 Hellige Units and colour from 30 to 40 standard units .

The effluent from the filters has been of high quality, turbidities ranging from 0.1 to 2.5 Hellige Units and colour from Oto 10 units, the higher values being obtained just prior to backwashing . (See Figs . 1 and 2.) Due to the extensive rainfall over the period since 25.11 .75 the demand in the system has not been high and the filters have been operated at fairly low rates of between 1 and 2 I/s m2 depending upon the pumping rate. (See Fig . 3.)

Fig. 3 -

North Richmond W. T. W. Dual Media Filters .

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35

FiLiF.R PUN (H(iURS J

The f il ter runs have varied from 20 to 60 hours and backwashing has normal ly been initiated on eff luent quality rather than headloss . Backwashing is governed to some extent by operational constraints in that it is carried out only during the day shift. After an initial period backwashing has generally been carried out at approximately 48 hour intervals when the effluent turbidity has reached 2.0 to 2.5 Hellige units and the head loss is approx imately 0.45 to 0.6 m.

Operating Experience Operating experience at the pilot plants at Nepean and Warragamba , at North RichmondWaterTreatmentWorks and at the Warragamba Township Water Treatment Works, where dual media filters form part of a conventional treatment process , has shown that the following observations are generally applicable .

(1) The provision of air scour or other auxiliary scouring facilities is essential for proper cleaning of the filter bed .

Operation of both pilot plants and at Warragamba and North Richmond has shown that mud- ball formation occurs rapidly where a high velocity water wash is used alone .

(2) Operation at both pi lot plants showed that provision of adequate minimum mixing and detention time between coagulant addition and entry of the raw water to the filter bed handling of the floe produced is not required but it should not be pumped.

Polymers are usually required in direct filtration to toughen the floe to result in longer filter runs . The polymer in concentrations usually less than 1 mg/I is acfoed just ahead of the filter. Polymers are often also added in the last minute or so to the backwash water to "precondition " the filter. The choic e of polymer and the rate of feed are made by tests on pilot or bench scale .

Filter Control In the design of systems for control of higher rate f ilters, the use of continuous turbidity measurements, to signal when changes should be made or a filter backwashed , is recommended . The trend in dual media filters is to provide for measurement and recording turbidity of water at the interface between sand and coal and of the filter effluent .

This has several advantages in that proper interpretation of results can signal when backwash should be started, poor coagulation is occurring or for some reason filter rates have been changing abruptly . It is important that the rate of filtration be maintained as uniform as possible because rate changes invariably result in an increase in turb idity of the water, especially at the coal -sand interface. A sp ike in the recorded turbid ity results will indicate such a rate change.

The cause should be determined and elim inated - it may be a faulty or " hunting " rate controller .

Interface turbidity measurements allow the detection of the impending end of a filter run without allowing turbidity to in crease in the filtered water . When interface turbidity begins to in crease , and while the sand is still able to remove this turbidity , the filter should be backwashed . In the more sophisticated systems , this rise in in¥lrface turbidity is the. signal for automatic starting of the backwash sequence .

Interface and effluent turbidity measurements can be used to detect over and under-coagulation. In the case of overcoagulation , the interface and effluent turbidity will be the same low value indicating that all turbid ity is being removed in the coal layer. When the signal comes in that backwash is needed because of excessive head loss , the conclusion should be drawn that too much coagulant is being used. On the other hand , if the interface and effluent turbidity traces show similar fluctuations with effluent turbidity levels slightly timewise lagging the interface turbidity, undercoagulation is indicated. The coagulant dosage is not adequate to remove the turbidity which passes through the filter.

Operational Results Direct filtration has been applied to a limited extent since about 1964. Toronto began experiments with direct filtration of Lake Ontario water which have led to design and construction of a 327 MIid plant wh ich they c laim wil l save $4 .8 million compared to a conventional plant. The proposed date of comm issioning is May, 1976. The filtering rate w ill be 4.1 I/s m2 although tests were run as high as 7.8 I/s m 2. Polyelectrolyte and alum will be used.

Three smaller direct filtration plants have been operated in the Province of Ontario all filtering Lake Huron water. These are the Grand Bend , Port Elgin and Owen Sound plants all 15

built around 1964-5. Of these, the Grand Bend plant has had trouble with algae and have increased their coal size to 1.55 mm to obtain reasonable filter runs. The Port Elgin design was sand only for the filter media and trouble has been experienced with high effluent turbidity when fi lter rates exceed 2.45 I/s m 2. This plant is · being modified to add · sedimentation tanks which would appear to be a retrograde step. The Owen Sound plant operates well at 3.7 I/s m2.

The largest filtration plant in service now is the 760 Mild plant of the Southern Nevada Water System which supplies Las Vegas and other customers. The plant , completed in Nov., 1971 , filters Lake Mead water (Colorado River). The filters are dual media with 500 mm of 0.60 to 0.70 mm coal having uniformity coefficient of 1 .75 and 250 mm of 0.45-0.50 mm sand having uniform ity coefficient of 1 .5 all supporteo by 250 mm of graded gravel. Filtering rate is 3.4 I/s m2. The backwash is des igned for 15 I/s m2. Surface wash has proven unsatisfactory due to coa l plugging the ports. Al l plant hydraulics have been designed to provide 50 percent excess capacity. The waste washwater is clarified in an upf low c larifier with overflow returned to the plant and underf low dried on sand beds. Filter runs of 80 hours are obtained with raw water load ings of 1-3 Jtu. A 230 Mi ld direct fi ltration plant has been commissioned in November 1975 for the City of Springfie ld , Mass . This plant filters water from a western Massachusetts river which . for several months of the year yie lds water at or very near freezing temperatures . For this reason , the design has included a 30 minute floe preparation tank which wil l be used as needed . Fi lters are dua l media with 600 mm of coal 1 .0 to 1.1 mm , uniformity coefficient maximum of 1.5 and specific grav ity 1.4 to 1 .6. The sand layer is 300 mm of 0.45 mm size and uniformity coefficient of 1.6. The sand is supported by ceram ic tiles with Camp nozz les on 150 mm centres, Ai! Scour at 0.02 m3/s m2 and backwash to 17.7 I/s m2 have been provided . Backwash is fu lly automatic, actuated by filter eff luent turb idity or loss of head, whichever first exceeds the present va lue. A pilot scale test of alum and/or po lymer for coagu lant has indicated polymer is sign ificant ly cheaper for coagu lation . Doses of 1.4 to 1.5 mg/ I are expected to be used.

The construction cost of this plant is $5 ,388 ,000 U.S. for the 230 MI/ d plant or less than $24,000 per megal itre per day of capacity. The elimination of settling tanks saved about $2.5 mil lion .

TABLE 4: des ign criteria

Capacity (Meld)

Number of Filters

NEPEAN

PROSPECT

NORTH RICHMOND

21 .82 initial 36.37 ultimate

3180 In itial 3960 ultimate 4770 possible 24 initial (double units) 3.66 design

28.41 original 45.46 amplified

3 init ial

5 ultimate FIitration Rate (l/sm2) · With - (no.) of filters out of operation Backwash Rates Water Ifs m2 Airml/s m2 Chemical Treatment Al um (all In mg/1) Sod. Hydroxide Lime Sod . Si licate {as activated silica) Chtorine Pot. Permang .

Sulph. Acid HF sillclc Ac id Primary Polymer Filter Aid Polymer Chemical Mixing Time Filter Size

3.26 design

4.89 max .·

4.07 max .·

1 15.28

2 double units 15.28

0.015

0.02

4 - 15

10 · 30

2·7

12 · 75

4 original 4 amplified 3.91 design

13.04 original 15.28 amplified 0 original 0.02 amplified

8-50 1.5 - 5

1 · 2.67 1·2 1 · 2.5 0.8 · 1.2

, .3 0, 0.3

5.791 m dia.

4.572 mo/all

~

15 minutes 427 m2 (each double unit)

50 sec .

35.72 m2 2.66 m deep

Filter Media (all in mm) Gravel Coarse Sand Fine Sand

300/ 1.2 - 13.2 0

610/ 14 x 1½" original

150/4.75 · 9.5

30510.55 · 1.19

300/0.59 1.19

Anthracite

760/ 1.19-1 .69

90011.19 · 1.69

690/0.47. 0.67 orig .

300/0.59 · 1.19 ampl.

70011.19. 1.69 ampt.

0

u

lower rates. Chemica l dosage rates were critical and the provision ot adequate detention t ime between chemica l addition and entry to the fi lter bed was essential.

Construction of this plant is now complete and commission ing is in progress . As yet no operat iona l data is avai lab le.

Prospect Water Treatment Works

Nepean Dam Water Treatment Works

Design Criteria for these works are shown in Table 4.

As origina ll y designed these works provided for treatment in upflow c larifiers fo l lowed by dua l media filtration .

However , fol lowing extensive pilot plant stu~ies , a review of water qua lity records for the Board's major storage dams, and assessment of probable future water quality, Camp, Dresse r and McKee submitted a reco mmendat ion that the clarifiers be de leted from the schemE: 2 This recommendation was subsequent ly adopted by the Bocfrd and the des ign of the was essential. Requ irements wi ll vary and shou ld be determined tor each particu lar raw water.

(3) Addition of coagu lant should be on a continuous basis as pulsed f low has a detrimental effect on f ilter performance .

The output from chemical metering pumps should be wel l dispersed before addition to the raw water.

(4) The minimum depth ot anthrac ite which shou ld be considered in the app lication ot dual media filters to direct fi ltration is 600 mm whi le a depth of 900 mm is preferable .

The latter depth has given a better ba lance between turb id ity break through and deve lopment of al lowable head loss .

(5) Operat ion ot the dual media filters at Warragamba Dam has shown a significant decrease in bacteria removal.

Co l iform counts on the water before and after f iltration showed a 43 percent reduct ion compared with about 95 percent for the sand only fi lter medium . Norma l chlorinat ion after filtrat ion has adequately contro ll ed the additiona l load.

Design Criteria for these works are shown in Table 4.

The design of this plant was based large ly on the resu lts of pi lot plant studies carried out from August to October 19701.

The resu lts of this pilot plant study showed that water from Nepean Dam cou ld be satisfactori ly treated by direct fil tration at rates up to 4 I/s m 2 with · excellent reduc tion of turbidity co lour and iron . Fi lter runs of the order of 10 hours cou ld be expected at rates such as this whi le substantial increase in length ot run could be achieved at

References: 1. Pilot Plant Eva luation of Water Treatment by Direct Fil tration, by K. A. Waterhouse CIVIL ENG INEERING TRANSACTIONS INSTIT. OF ENG INEERS AUST . VOL .

CE16 No.11974.

2. Feasibility of Direct Fil tration Prospect Water Treatment Works by Camp , Dresser and McKee International Inc. March 1973.

SYDNEY WATER BOARD POLICY

In 1973 the Sydney Water Board adopted as a general pol icy that where raw water is drawn from a large storage dam which prov ides a considerab le retention period between the entry and draw-off points , treatment by direct filtration wou ld be investigated.

As a resu lt of this po l icy the Board has constructed one new direct filtration plant at Nepean Dam and two others , at Warragamba and Upper Cordeaux, are now in the initial planning stage. The out l ine design for a direct fi ltration plant at Prospect to treat the bu lk of Sydney's water has been comp leted by Camp , Dresser and McKee International of Boston . One existing plant at North Richmond is at present being operated as a direct filtration plant wh il e the pretreatment unit is ampl if ied .

16

!

Ultrafiltration and its role in Activated Sludge Wastewater Treatment

by Peter Gebbie,• A.G. Fane & C.J.D. Fell+ A review of the ultrafiltration (UFJ process and current applications are given, with emphasis on activated sludge (AS) wastewater treatment. Results from a 4.6 1/h AS. UF pilot plant, treating a synthetic sewage are presented, including fluxltransmembrane pressure drop data at varying MLSS. The process holds promise as a packaged sewage treatment process capable of producing an exceptionally high quality effluent.

1. INTRODUCTION 1.1 Ultra Filtration - theory Ultrafiltration (UF) is a pressure driven process using a semi-permeable membrane to separate molecular or colloidal materials from a liquid. It can separate molecular species on the basis of size, shape and chemical structure in the range 5,000 - 100,000 molecular weight.1 Unlike reverse osmosis (RO) systems, osmotic pressure effects are low in an UF System. As a consequence, operating pressures are considerab ly lower than the 4MPa required for RO systems.2 Membranes used are principally cellulose acetate or substituted aromatic types. Stavenger3 and Porter4 have quoted performance characteristics for commercially available membranes, and Griffith, et al5 have given a review of membrane types obtainable in Australia.

The asymmetric structure of UF membranes accounts for a high operating flux, which is influenced by the following : (1) apparent pore size of the membrane " skin " , (2) membrane type, (3) operating temperature (4) pH, and (5) nature of the rejected species.

All membrane processe, affecting a phase separation exhibit the phenomena of Concentration Polarization (CP).6 The separation of solute species from a solvent results in a local concentration of the rejected species at the membrane surface. This leads to the formation of a laminar gel-layer and a decline in flux is observed .

Operating flux obtained at the condition of CP is given by: J = k In CgiCs _ _ (1) where: J = solvent flux , 1/m2- hr, = mass transfer coefficient, k Cg = ge l-layer solute concentration at membrane wall, and Cs = so lute bulk concentration

1.e. a plot of J against log Cs will yield a straight line of slope - 2.303 k and intercept Cg. Since C9 is constant for a given solute species, this condition represents a limiting value of flux, i.e. is independent of trans-membrane pressure drop ( AP). It can be shown that the onset of the pressure independent region ("plateau") occurs at lower pressures for higher Cs and the onset of this region occurs at higher pressures for higher mass transfer coefficients, k, i.e. U. Thus the effect of CP may be reduced by estab li shing turbulent conditions and/or operating with a lower feed concentration, Cs. For turb ulent conditions, k may be found from the dimensionless Dittus-Boe lter equation , which on re-arrangement yields: u a.o0.67 _ _ (2) k = 0.023 d(1·8 l. v (a-0.33) where: d

= equivalent hydraulic diameter,

u =

average velocity across membrane,

p

= viscosity of the recirculation f luid , = the density of the recirculation liquid ,

v D

= solute diffusion coefficient.

u

= ulp = kinematic viscosity, and

This equation holds for flow in narrow, parrallel channels.

Values for the exponent "a" vary from 0.67 to 0.80 according to Blatt, et al7. Bhattacharyya, et alB quote a = 0.88.

Since from Equation 1, flux is directly related to k, Equation 2 ind icates a log-log plot of flux against U will yield a straight line of slope "a".

For the case when the gel condition is reached, solvent flux can be expressed by: p _ _ (3) J = Rm + Rg where:

J AP Rm

= = = Rg =

so lvent flux, transmembrane pressure drop, resistance of the membrane, resistance of the ge l layer.

Typically, Rg is >10 Rm and Equation 3 can be approximated by: J

= A P/Rg

_ _ (4)

Equation 4 indicates membrane flux obtained is proportional toAP. However, at a critical value of solute concentration flu x will decline, correspond ing to gel formation adjacent to the membrane surface. Any increase in AP causes the gel layer to thicken giving no further increase in flux .

For highly permeable membranes (100-200 l/m 2/hr), fluid velocities required to overcome CP effects are high. An optimum U of 3.0 to 3.4 m/s is typical9. For this reason, a recyc le UF loop is commonly employed in practical membrane sys' tems .

In spite of high recirculation velocities, the viscous gel-layer becomes less permeable, reducing flux and necessitating periodic shutdowns for cleaning . A gradual and irreversible decline in flux restored at the end of ~ ach cleaning cycle is often evident,10, 11, 12 1.2 Practical Ultrafiltration Systems

1. Membrane Configuration Generally three types of UF membrane module are currently avai lable: 1. Thin channel: units consist of cartridges mounted in a shell and tube, or modules of a parral lel plate design, e.g . " Ajax" and " Dorr-Oliver" IOPOR type modules.

2. • Large diameter tubular: process stream flows inside tubes of 1.3 to 2.5 cm diameter e.g. "Abcor'' and "Paterson-Candy International " type modules.

3. Hollow fibre: offers a high surface area to volume ratio using hollow fibres of 500um diameter to house process flow, e.g. "Amicon" type of modules.13, 14 2. Equipment Arrangement Practical configurations of UF units include: 1. Batch feed and bleed: as shown in FIGURE 1, 2. Continuous cascade: this arrangement is suitable where high flux is required.

• Member, Post Graduate student, School of Chem . Eng., U.N.S. W.; now Chemical Engineer, William Boby & Co. (Aust.) Pty. Ltd., SCORESBY, Vic. 3179. t Lecturer and Senior Lecturer respectively, School of Chem .

Eng., U.N.S. W., Kensington, N.S. W. 2033.

17

/UT£NTAT£

PROCESS BATCH

--P£.RM£AT£.

FE.CO

RE.CYCLE:

PUMP

PUMP -l()()kPa.

l00 kPa.

FIGURE 1: ultrafiltration batch feed and bleed process.

Both arran gements make use of a rec irculat ion pump providing pressure drop. This is an econom ical so lution to reducing power and pumping costs.

1.3 Ultrafiltration Applications The following include rec ent app lications of UF in the treatment of aqueous wastes.

1. recovery of electrophoretic paint drag -out,15 2. continuous fermentation applications,3, 4 3. recovery of metals from electrop lati ng waste streams, 9 4. recovery of latex po lymers,3, 4 5. removal and re-use of silver from photographic wastes, 5 6. co ncentration and dewatering of mil k. casein and protein procucts,4, 16 7. fractionation of lactose and protein from cheese whey and dairy eff luent,1 , 17 8. recovery of starch and co lloid s from potato and starc h waste,5, 18 9. reducing f ibrous and suspended matter from pulp and paper eff luent ,19, 20 10. dewatering powdered act ivated carbon prior to furn ace rege neration , 11 . laundry wastewater treatment,8. 21 12. so luble oi l treatment and recovery,22 and 13. sewage t reatm ent.3, 10, 23, 24, 25 UF generally is not app li cab le to the treatment of high flows of di lute, easi ly biodegradab le wastes having little recovery valu e.26 1.4 Role of UF in Activated Sludge Sewage Treatment Th ere are distinct ad vantages in combining a UF membrane separating system with activated sludge (AS) treatment of se wage: (1) large organic compounds cannot permeate the UF membran e, (2) slow ly metabolized organics are retained so increasing the reactor res idence tim e without in creasing hydraulic load· in g, (3) hind ered settling and sludge bulking limitat ions of norma l AS c larif ication are not a considerat ion using membrane separat ion , (4) a cons istent ly higher quality effluent may be produced, and (5) in areas of acute wat er shortage, high quality ultraf il · trate may be re-used as a secondary water source.

Higher Mi xed Liquor S.;spe nded So lids (MLSS) concentrations can be maintained in the aeration tank: 15,000-20,000 mg/1 as opposed to th e more common 3,000-5,000 mg/1 level. 1 Stavenger2 4 reports that MLSS have reac hed as high as 40,000 mg/1 in pilot AS/membrane stud ies. Hardt, et al25 found that simi lar MLSS concentrat ions cou ld be separated by an UF system . TABLE 1 summarises a comparison of process criteria for AS/U F, convent ional and extended ae ration (EA} AS treatment syste ms process in g 570 I/h of a wastewater.2 7

• Boby/PCI (Members of th e Portals Water Treatment Group) can offer tubular UF equ ipm ent for wastewater treatment and/or recovery app licat ions.

18

Savings in sludge aeration tank vo lume are immediately apparent.

PROCESS Conventional Extended PARAMETER AS/UF AS Aeration AS System Reactor Volume 1 2,663 3,423 13,694 Influent BOD, mg/1 250 250 250 System MLSS, mg/1 2,500 10.000 3,500 Load, kg BOD/kg MLSS.d 0.13 0.4 0.08 Reactor Dissolved Oxygen, mg/1 1.5 1.5 1.5 Mean Cell Residence Time, d 4.9 2-10 11 Re circulation Ratio, % 240 25 50-100 Hydraulic Detention Time, hrs.

4.7 6 24

TABLE 1: comparison of operating data fo r conventional, extended aeration AS and AS/UF treatment processes (567 LPH l/h). 27 Higher removals of BOD are possible using UF in conjunc· tion with AS treat ment. For a 90 % BOD removal by the AS process , membrane UF can re move an additional 90%, yield· ing an overall BOD reduction of > 99 %. The positive barrier presented by the UF membrane ensures removal of AS solids and waterborne pathogen s, chlorinat ion being emp loyed for possible virus inactivation .

We ismann, et aI10 have discussed the performance of UF to the treatment of raw sewage, trick ling filter effluent and contaminated water respectively. The basic f low-sheet is shown as FIGURE 2.

SL/JOG£ R£C'l'CL£

ULTRIIFILTRIIT£

AcTIViirco SL//00£ AERATION TANK

IHl"iUENT

Allt

t FIGURE WlT WELL

2:

As/11F TRCIITM£Nr PLANT FLLJW SH£t:T.

FIGURE 2: AS/U F treatment plant f lowsheet. ~

Sm ith, et al28 have al so discussed th e success of UF in separating AS solids from mixed liquor. More recently , Bemberis, et aI2 7 have surveyed successfu l Dorr-O li ver " lopor" app lications in the treatment of sewage and wastewaters. In all cases ultrafi ltrate (final effluent) was free of coliform bacteria and suspended solid s, and showed a BOD of 1-2 mg/1 .

Reuse of rec laimed ultrafi ltrate is thu s possible in view of its outstanding quality.

Of particular interest is the app li cation of AS/UF to treat sewage at Pikes Peak Co lorado.3, 29 A 3.2 kl/hr sk id mounted unit was used to demonstrate the feasibility of the process.

Stavenger3, 24 has detai led operating data for the plant. Sludg e wastage from the plant occurred every one to two month s and was considerably mineralized, requiring littl e additional treatment prior to disposal. A BOD removal of 99 % was achieved with 100 % remova l of E.coli and SS. Eff lu ent has been used as toilet f lu shing water since 1972. Prior to the adoption of this scheme, water had to be transported to thi s tourist area at a height of 4,250 m. Okey 26 has exam in ed thEl econom ics of AS/UF sewage treatment and has conc luded the process is attractive if intensive re-use of ultrafiltrate is intended. Weismann et aJ10 have conc luded there is a "cross-over" between 76 and 190 kl/d, when conven· t ional sewage routes become more econom ical. However, wate r avai labi lity problems may prompt the selection of UF based treatment.

Following the successful application of AS/UF to varied wastewater and sewage treatment problems, Dorr-Oliver have recently announced the Membrane Sewage Treatment (MST) system .30 The biological process flowsheet is basically that used in earlier trials. However, the UF separation stage has beem considerab ly altered.

2. EXPERIMENTAL 2.1 Pilot Plant Description In order to verify the suitability of AS/UF as a sewage treatment method, and to develop operating criteria and data, an investigation was initiated to estab li sh the following: (1) the variation of flux with transmembrane pressure drop (AP) for a range of MLSS concentrations, (2) the variation of flux with operating time.

(3) the quality of ultrafiltrate effluent, and (4) the effects of UF on the biological process.

PVC plastic tubing and fittings were used to fabricate the UF loop. A 240 I/min. APV stainless steel centrifugal pump (11), was employed to provide recirculation and two smaller JABSCO, 23 I/min . pumps (10) were used to pres. surize the loop to a maximum of 290 kPa. Flow from the recirculation pump was measured by a calibrated rotameter (12) and a throttled by-pass. Pressure gauges (14) AND (16) upstream of the ultrafilter and in the permeate line provided an indication of the system operating pressure and transmembrane pressure drop.

Permeate from the module was collected from the header and passed to a storage cylinder (17). A fraction of recircu lated sludge was bled from the UF loop and returned to the aeration tank (18). A heat exchanger (13), (concentric tube, Cu, 0.1 m2) was incorporated in the loop to provide temperature control of ± 2°c.

A synthetic sewage, based on Vegemite and Bonox was used as substrate feed to the AS plant.33 Characterist ics are shown in TABLE 2.

Parameter BOD

ss

COD O-PO 4 NH 3

.p -N

mg/1 Settled Synthetic Typical Settled Sewage Sewage 240-310 (270 av.)

60-100 470-560(500 av.)

3.2 12.0

TABLE 2: wastewater characteristics sy nthetic sewage.

FIGURE 3: schematic lay-out of the AS/UF treatment plant.

(1) (2) (3) (4) (5) (6) (7) (8) (9)

air filter air rotameter aerator headers sewage feed drum feed control valve and distributor aeration tank DO probe DO recorder mixed liquor take-off to UF loop

(10) (11) (12) (13) (14) (15) (16) (17) (18)

inlet pressurising pumps UF recirculation pump recircu lation rotameter heat exchanger modu le header and pressure gauge UF module and housing UF header take-off ultrafiltration collection return sludg e line

The description of a 4.6 1/h AS/UF pilot plant and operating results obtained are given be low.

FIGURE 3 is as chemat ic of the combined AS/UF treatment plant. A 1401 perspex aeration tank was constructed, (6). Compressed air was passed through a glass woo l and bead column (1) to remove oil, metered via a rotameter (2) and passed to a bank of large porous stone diffuser (3).

Dissolved oxygen (DO) levels within the aeration tank were monitored using Mackereth type DO probes (7), coup led to a Heath "Servo-recorder" (8), (Model: EV20B).31 Probes were located at the aeration tank inlet, mid-point and eff lu ent outlet following calibration. Synthetic sewage used was gravity fed into the aeration tank from a 220 1 storage tank (4), via a control valve and distributor (5).

A Dorr-Oliver " lopor XP24/2" 0.19 m2 UF Module was selected for trials in separating biological so lid s from AS mixed liquor. Data quoted by Dorr-Oliver suggested a nominal ultrafiltrate rate of 4.6 1/h at U = 2 m/s.32

100-150 130-190 100-150 7.0 25-30 of

Vegemite/Bonox

A batch "fill and draw" method was employed to "feed" an acclimatized starter culture of AS, and to allow MLSS to increase to 1000-2500mg/1 . DO levels in the aeration tank averaged 1.7 mg/1.

Soluble BOD of the effluent was approximately 30 mg/1 or a 90% BOD removal. Oxygen uptake rate tests showed an approximately constant rate of 20 mg/1 hr. Occasional sludge sett lin g tests (½ hr., Imhoff cone) were employed to monitor the condition of the sludge. A Sludge Volume Index (SVI) of 42 ml/g at a MLSS 2500-3500mg/1 was typical indicating rapid sludge settling .

2.2 Characterization of the Ultrafiltration Loop Flux characteristics of the new XP24/2 membrane were determined using tap water. The variation of flux with AP for U = 3.22. mis is plotted in FIGURE 4. ~ will be noted that ultrafiltrate flux varies linearly with AP. This plot indicates pure solvent flux expected for a given ilP. The UF loop was next coupled to the AS plant and Flux/ 6.P characteristics determined for AS mixed liquor at differing MLSS and recirculation velocities (U). Flux at each AP was measured by col lecting permeate over a ten minute period.

2.3 Operation of the Combined AS/UF Pilot-Plant Having established ultrafiltrate Flux/ AP and MLSS relationships, the performance of the combined AS/UF plant was examined continuously over a three day period.

A AP of 62 kPa was se lected so that permeate flow rate balanced the required feed rate. At this AP, feed rate resulted in a residence time in the aeration tank of 2.8 to 3.7 hours, corresponding to high rate operation with only moderate BOD removals possible. Due to low MLSS (1,770 mg/1) in the aeration tank, an ultrafiltrate flux of 60 1/m2/hr. was selected to ach ieve a reaso nable MLSS and to all ow suffic ient residence time for BOD removal.

Records of ultrafiltrate flux , temperature, AP, recirculation rate, air f low, feed rate and sludge return were made.

Ultrafiltrate was collected and analysed for BOD. SS, COD, NH3 -N, and O-PO 4 -P were determined on a composite sample. Influent substrate BOD was also determined.

O.P and U (2.7 m/s) were held constant during the experiment. Microscopic examination of AS, periodic oxygen uptake rate and settling tests were carried out to assess the effect 19

of prolonged recirculation within the UF loop on the biological process itself. MLSS was determined on completion of the run.

3. RESULTS AND DISCUSSION 3.1 Flux/Transmembrane Pressure Drop Data A typical plot of ultrafiltrate flux as a function of transmembrane pressure drop is shown in FIGURE 4.

At each U, ultrafiltrate flux increased with b.P. In all cases flux appears asymptotic to a "plateau value ", i.e. independent of pressure drop, according to Equation 1. Similar flux data for the ultrafiltration of AS at Pikes Peak has been reported by Stavenger.3 FIGURE 4 clearly shows the effect of U on ultrafiltrate flux .

It is noticeable that at a low U (Reynold's number), flux obtained' is considerably less than that at higher velocities (Equation 1 and 2).

.

~

~ 40

- 2·3

FIGURE 6: determination of k, and Cg,

120

MLSS 1630 0

160

t,,P,

too

ment with the literature is not unreasonable, especially for data at a MLSS concentration of 4,760 mg/1 .

MLSS species classified as " solute" include colloidal and macromolecular components as well as SS. If a plot of flux versus log (MLSS) is made, in accordance with equation 1, it is implicit that a relationship between Ca and MLSS exists, i.e.the MLSS is indicative of the whole of the rejected solute species; colloidal and dissolved. The justification for this assumption will be appreciated on examination of FIGURE 6 where a plot of flux against log (MLSS) (for varying U) does yield a reasonably straight line as indicated by Equation 1.

m9jL

200

PRESSURE DROP,

Joo

/rPa.

FIGURE 4: effect of transmembrane pressure drop and recirculation velocity on ultraflux; at constant MLSS concentration .

FIGURE 5 is a plot of permeate flux at a transmembrane pressure drop of 230 kPa as a function of U at different MLSS. Slopes obtained for plots of ultrafiltrate flux against U (at 230kPa) vary from 0.56 to 0.70. From Equation 2, agree-

3.2 Variation of Flux with Solids Concentration From equation 1. a plot of limitina (" plateau") flux versus log Ca will yield a straight line of slope -2.303 k and intercept C. In this instance Ca will represent the concer.tration of MLSS in the aeration tank. This plot is shown in FIGURE 6.

Plateau flux (when flu x is independent of .6.P) was estimated by extrapolation . Data at U = 1.68 mis is especially well described by a straight line plot. All intercept at a gelfayer concentration of 65% w/w SS. Blatt, et al 7 have discussed concentrations of rejected solute prior to gelation and for colloidal dispersions suggest a value of Cg of 5-60% w/w is typical.

3.3 Decay of Ultrafiltrate Flux With Time Ultrafiltrate flux was observed to decline at 2.5 % ·per day over the three day continuous AS/UF run .

Longer runs will be necessary to determine more realistically the rate of decay of ultrafiltrate flux . Similar flux decline has been reported by Weismann, et aI10 in the treatment of secondary sewage effluent (from a trickling filter plant), and in the separation of AS from mixed Liquor using a Dorr-Oliver UF system.

Generally a build-up of inert solids accounts for gradual fouling of the membrane and resultant decay of flux .

3.4 Ultraflltrate Quality BOD of the ultrafiltrate is tabulated as a function of time, in TABLE 3. UF of the mixed liquor does not appear to have affected the BOD removal capabilities of AS.

MLSS <:> 890 mg/l A 1'JD " • 4-7&0

.3 VELOCITY,

,,

4

m/s 5

FIGURE 5: variation of ultrafiltrate flux with recirculation velocity, at a pressure drop of 230 kPa.

20

An average BOD removal of 86 % was achieved assuming the influent BOD to be reasonably constant at 275 mg/1 .

Reported data suggest a lil<ely BOD removal of 72%34, 35 fcir AS systems treating domestic sewage, at the stated conditions of BOD load and aeration time (F/M = 1.12 Kg BOD/~ MLSS.d, aeration time 2.8-3.7 hrs., MLSS 1770 mg/1) .

The higher removal of BOD achieved (86%) is expected from the AS/UF system because of better suspended and dissolved solids removal. Soluble BOD retained by the membrane is particularly important in explaining the higher quality effluent obtained.

TIME, days ULTRAFIL TRATE BOD , mg/1

0.03

0.11

0 .19

0.28

0.36

0 .90

1.03

1.40

1.90

2.03

2.24

2.91

3.08

45

39

28

20

13

40

33

26

36

14

24

41

24

TABLE 3: variation of ultrafiltrate BOD with time.

TABLE 4 lists other characteristics of ultrafi ltrate composite samp les.

CONC'N mg/1

CHARACTERISTIC BOD

t>t> ON COMPOS ITE COD ON COMPOSITE O-PO 4 -P NH 3 -N

38 (av.)

0 100 2.6 11 .2

TABLE 4: ultrafi ltrate quality.

It shou ld be noted that the ultraf il trate contains no SS. This is superior to eff luent from a well run EA or conventiona l AS plant.

Ultrafiltrate BOD is less than or equal to 30 mg/1 50% of the time (BOD remova l of 88.9 % ) and less than or equal to 46 mg/1 90 % of the time (or an 83 % BOD removal) .

3.5 Effect of UF on AS Population In all cases ciliated protozoa present prior to UF were qu ick ly destroyed, during AS/UF tria ls. The "c rysta l c lear" colour of s ludge supernatant was rep laced by a murky co llo idal appearance, suggesting severe rupture and homogenizat ion of some of the biolog ica l f loe.

The viab ility of the combined process supports the view that AS can withstand the deterioration of ci liate popu lation in the UF loop. 36 Period ic oxygen uptake rate tests made on s ludge in the aeration tank during UF showed a reasonably constant rate of 21.1 mg/1 hr. It would appear that UF has not great ly affected the respiration rate of AS. Hardt, et al25 reported a net decrease in oxygen uptake rate of AS fo llowing UF, although a 90-95 % COD reduction was achieved for the biolog ica l system (MLVSS = 20,000 - 50,000 mg /1). An overall COD remova l of 99 % was reported for the AS/membrane system.

4. CONCLUSIONS The fo ll owing may be conc luded from work during the course of this project: 1) current ultrafiltration theory appears to satisfactori ly describe the separat ion of sludge sol ids from activated s ludge mixed liquor, 2) for the ultrafi ltration of activated s ludge mixed liquor (us in g a Vegemite/Bonox based synthetic sewage) w ith a Dorr-Oliver XP24/2 lopor modu le, flux was found to vary with recircu lation ve locity to the 0.56-0.70 exponent, 3) a va lue of 65 % SS by we ight was estimated for Cg , the concentration of the ge l-layer, 4) ultrafi ltrat ion f lux for a three day continuous AS/UF run was observed to dec li ne at a rate of 2.5% /day, 5) an average BOD remova l over a three day continuous treatment run of 86 % was obtained. This is exce ll ent co nsidering the mode of operation of t he AS plant (high rate). A residence time of 2.8 to 3.7 hours, an average MLSS of 1,700 mg/1 and an average BOD loading of 1.12 kg BOD were used, kg MLSS .d

6) ultrafi ltrat ion does not appear to have affected the assim ilat ive capac ity of activated sludge, althoug h destroying higher micro-organism populations,

7) the combined AS/UF process appears to ho ld promise where a compact treatment plant, capab le of y ielding a high quali ty effluent, is required.

5. ACKNOWLEDGEMENTS The authors gratefully acknowledge assistance from the Facu lty of App li ed Science technica l and academ ic staff, U.N.S.W. Dorr-O liver (Aust.) Pty. Ltd. provided several XP24 UF modules, valuable advice from Harvey King & Steve Brady of Dorr is also acknowledged. The Authors appreciate the help of Jenny Clinton who typed th e manuscript."'

6. REFERENCES 1. Forbes, F.; " Role of ultratiltration in industrial effluent problems", Chemis try and Industry , 19 Jan 74, 47-48.

2. Kaup, E. C.; "Design factors in reverse osmosis", Chem, Eng; Apr 2, 1973, 49路 50.

3. Stavenger, P. L.; "Novel applications of industrial semi-permeable mem路 branes", 3rd Joint Me eting A.I.Ch.E. & Inst. Mex . de /ngenieros, Quimicos, Aug 30 -Sep 2, 1970, 1路20.

4. Porter, M. C.; "Ultrati ltration of colloidal suspensions", A.I.Ch.E. Symposium Serie s, 68, 120, 21-30, (1972).

5. Griffith, D. C.; et al, "Use of membrane processes in the treatment ot aqueous wastes", Proc. 1974 Aust. Waste Management & Control Cont.; U.N.S.W.; Jul 1974, 106.

6. Porter, M. C.; "Conce ntration polarization wit h membrane ultratiltration", Ind. Eng. Chem. Prod. Res. Develop; 11, 3, 241 (1972).

7. Blatt, W. F.; et al, "Solute polarizati on and cake formati on in membrane ultratiltration: causes, consequences and cont rol techniques", Membrane Science & Technology, ed. J.E. Flinn, Plenum Press, N.Y.; 1970, 47-97.

8. Bhattacharyya, D.; et al; "Membrane Ultratiltration: Waste treatment applica路 lion tor water re-use", In d. Water Eng. , Aug/Sep 75, 6-12.

9. Forbes, F.; "Considerations in the optimization of ultratiltration ", Chem.

Engineer, Jan 72, 29-34.

10. Weismann, B. J.; et al, "Performance of membrane system s in treating water and sewage ", A.I.Ch.E. Sympos ium Series, 64, 9, 285-290 (1968).

11 . Thomas, D. G. & Mixon, W. R.; "Effect of axial velocity and initial flux on flu x decline of cellulose acetate membranes in the hyper-filteration of primary sewage efflu ent", Ind. Eng. Chem. Prod. Res . Develop; 11, 3, 339-343 (1972).

12. van Allena, C.; "Cleaning non-cellulosic ul trafiltration membranes", Process Biochem; 26-29, Mar 75.

13. van Allena, C.; " Product ion scale ultrafiltration", Process Biochem, Oct 73, 7 & 30.

14. Anon, "Membrane processes for Pollution Control", Aust. Chem. Eng. , Aug 73, 21 -22.

15. Porter, M. C.; et AL, " By product recovery by ultratiltration", /hd. Wat Eng 'g; 8, 6, 18-24 (1971), 16. Leonard, F. B. & De Murley, J. S.; "Prof itable recovery of Pollutants", A/ChE Workshop on Indu strial Pro cess Design for Water Pollution Con trol, 3, San Francisco, Mar 31-Apr 2, 1970.

17. Muller, L. L.; "Whey utilization with membrane processes", 3rd Nat, Chem.

Eng . Cont. , R.A.C.I.: 1.Ch.E.; et al, Mildura, Aug 197i, T196-T197.

18. Bambridge, M.; et al "Starch was te concentration by ultrat iltration", 3rd Nat. Chem . Eng. Co nt., T1 98-T200.

19. McNamara, J. P., Private co mmun ication, Sep 1974.

20. Wiley, A. J.; et al , "Concentration of dilute pulping wastes by Reverse Osmosis and Ultrafi ltration ", 42nd Cont. W.P.C.F. Proc; Oct 5-10, 1969.

21. Bhattacharyya, D.; et al; ''Ultratiltration of Laundry waste constituents", J. W.P.C.F., 46, 10, 2372-2386 (1974).

22. Fletcher, P. V.; "Ultrafiltration "; Aust. Process Eng. Nov 1974, 43.

23. Samm on, D. C. & Stringer, B.; "Application of membrane processes in treatment sewage", Process Bioch em., 4-12, Mar 1975.

24. Stavenger, P. L.; "Putting semi-permeable membranes to work", Chem. Eng. Prog. , 67, 3, 30-36 (1971).

25. Hardt, F. W.; et al, "Solids separation by ultrafiltration for concentrated AS ", 42nd Con t. W.P.C.F. Proc; Oct 5-10, 1969.

26. Okey, R. W.; "Treatment of industrial wastes by pressure driven membrane processes", Industrial Processing wi th Membranes, ed. Laney & Loeb, Wiley & Son, N.Y.; 1972, 249-276.

27. Bemberi s, I.; et al, "Membrane sewage treatment systems - potential for comp lete wastewater treatm ent', 1971 Winter Mee ting Am. Soc. Agr. Eng. Proc; Dec 1971, (Paper 71 -878).

28. Smith, C. V.; et al , "Use of ultrafiltration membranes tor activated sludge separati on", Proc, 24 th Ind. Waste Cont; Purdu e Unive rsity, 1,300-13,100 (1969).

29. Anon, "new sewage technique tested atop Pikes Peak", Water and Wastes Engineering, 7, 11 , 54-55 (1970).

30. Dorr-Oliver, Inc; "Membra ne Sewage Treatment Employing Dorr-Oliver Process Technology (ac tivated sludge and ultrafiltration)", Dorr-Oliver, Inc; Stamford, Connec ticut, Sep 73.

31. Gebbie, P.; et al; "Construction & cal ibrati on of DO Probes", Water, 3, 1 (1976).

32. Dorr-Ol iver, Inc; " Ultraliltration Data Sheets " , Dorr-Oliver (Aust) Pty. Ltd.; Mar 1974.

33. Gould, B. W.;Assoc Prof.; School of Civil Engineering, U.N.S.W.: Priva te communication, Aug 1974.

34. Fair G. M. and Geyer, J. C.; " Water Supply and Wastewa ter Disposal " , Wiley and Son, N.Y.; (1959), 723.

35. Eckenfelder, W. W.; "Comparative bi olog ical waste treatment design", Proc .

Am. Society Civil Engineers, San. Division, SA6, 167 (1967).

36. Gebbie, P.; " The Application of an Ul tra fillration!Activated Sludqe Process to the Tratmen t of Wastewater ", M.App. Sc. Thesis, School of Chem. Eng. U.N.S.W., 1975.

21

Conference Calendar IAWPR SYDNEY 1976

6:

JOURNAL SUBSCRIPTIONS AUSTRALIAN WATER & WASTEWATER ASSOCIATION JOURNAL I enclose herewith the sum of $ .... ... (Austral ian) as prepayment for supply of the following issues of 'WATER ' -

INTERNATIONAL CONFERENCE

17-22 OCTOBER, 1976.

Registrations : The Secretariat Eighth Conference , I. A .W.P .R. Box 2609 G.P.O .

SYDNEY , N .S.W. 2001. AUSTRALIA

March o

June o

Sept. o

Dec . o 197-

Note:AII subscriptions conclude with the December issue , renewals are due by the end of February for a full year's subscription . Price , in cluding surface mail to al l countrLes, is $1.00 (Aust .) each issue, made payable to the A.W.W.A. - ' WATER '.

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

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

ENVIRONMENT '76 OCTOBER 8-13, 1976 EXHIBITION BUILDING, MELBOURNE

Mail this form to :

A. H. Truman Officially laun ched , March 3rd by the Chairman, Mr. A. Dunbav in Butcher, Deputy Director Victorian M ini stry for Conservation . Also announced were • an environmental project competition for Victorian schoo l students, • the awarding of an outstand in g enviro nmental painting for a 'major contribution in environm enta l protection ', • a new emphasis on 'sel lin g' environmenta l matters to the ge neral pub I ic , • newspaper (Melbourne Age) support w ith production and T.V. and radio adverti s in g of a spec ial supp lement , • a three day (Oct . 11 -13) Environment Conference .

A.W.W.A. MEMBERSHIP Request for Application Form for Membership of the Association To the Hon . Secretary , Australian Water & Wastewater Assoc ., Mr. R. F. Go ldfin ch, P.O. Box 359, Canberra City , A .C.T ., 2601 . . I, .. .. .. .... . .. .... .. .. ... .... .............. .. ... . .. ... . .. .. . .. ... . ...... .. .

(Name)

(Address) Membersh ip is in four categories .

1. Member - qualifications suitable for membership in the Inst . of Engineers , or other su itable profess ional bodies.

2. Assoc iate - ex perience in the W.&W .W. Industry, wit hout formal qualifications .

3. Student.

4. Sustaining Member - an organisation involved in the W.&W.W. Industry wishing to sustain the Association .

22

Pollution Control Engineering, Inc . , U . S.. A .

Have recently licensed

KEITH ENGINEERING to manufacture their range of

FLOTATION SYSTEMS for treatment of waste water in Australia and New Zealand For further details CONTACT:

KEITH ENGINEERING (SALES) PTY. LTD. 7 McPherson Street, Banksmeadow, N.S.W. 2019 Telex: AA-22815 Phone: 666-9042

FILTERED WATER FOR MELBOURNE

AUTOMATIC WATER SAMPLE COLLECTION/STORAGE UNIT rhe Philips PW 9810/00 is designed to automatically collect and store water samples on-site.

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Details from Philips , Sydney .

NEW SEE-FLO FLOWMETER The new SEE-FLO flowmeter from Acromet measures flow at pressures up to 250 p.s.i.g .

It makes poss ibl e laboratory determination of chemica l compounds in the collected samples , in addition to permament installation the PW 9810/00 is also useful in preliminary investigations to determine where permanent stations should be placed. As part of a network , it greatly improves long-term scientific investigation .

The PW 9810/00 is made up of two compartments ; a sample storage compar!ment and a refrigeration compartment. The sampled liquids are stored in 12, 21 polyethylene containers .

Four operating modes are possible:• liquid sampling proportional to an input signal related to parameters such as flow , level or conductivity , 20 ml samp les are extracted, initiated by a pulse generator , and a 2 I storage conta in er fi lled for a preset time of 30 , 60 , 90 or 120 minutes , • liquid sampling in relation to time , the same pulse generator is operated by an internally produced signal to fill a 2 I storage container over a preset time period , • liquid samp lin g proport ional to an input signa l (eg. flow) , but only when initiated by an alarm signa l,

The SEE -FLO offers among its many other advantages , the ability to view and measure with 2% accuracy and 1 % repeatability , flows of any gas , liquid or viscous material - even adhesives.

Pressure ratings up to 2500 p.s.i.g. are available in other models . They also meet MIL-S-901 B high impact shock requirements.

All SEE-FLO meters are calibrated to the requ irements of the specific application . Flow ranges for ½" to 8" pipe . Gases 28 to 5000 SCFM. Liquids 3 to 5000 GPM .

SEE-FLO is also ava il able with alarm switches for actuation of either flow failure or excessive flow rates.

For further information contact Acromet Pty. Ltd. , P.O. Box 491, Clayton. Victoria .

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The princip le structures, the four high-rate Boby/Graver Reactivator Solids Recircu lat ion type clarifiers and twelve Boby/P.C.I. Gravity Sand Fi lters, may be c learly distinguished in the Cover Picture.

Prior to coagulation of the discoloring matter the raw water will be dosed with lime , if necessary, to adjust its natural alkalinity and aerated if the water, as drawn from the depths of the Sugarloaf Reservoir, is deficient in oxygen . Capacity of the Plant may be doubled in future from the present 450 Megalitres per day by another stage built symmetrically about the rectangular inl et control structure .

Bulk supp lies of lime, liquid alum, coagu lant aid , chlorine and fluoride will be received and stored in an aesthetical ly designed building (right centre) and dispensed with the assistance of automated contro l.

The same building will house a workshop and store and a pumping station for the safe disposal of concentrated wastes and for the return to the treatment system of water recovered from filter backwas hin g and clarifier desludging . The five circular tanks for the collection of waste wash water and for thickening of sludge may be seen in the cover picture. These units, together with the chemica l station , will cater for a future normal throughput of~900 Ml/day .

Crit ica l fu nctions of the Plant and the automatical ly controlled pumping stations will be monitored by instruments, alarms and regular laboratory testing centred in the Administration Building, a fully air-conditioned complex containing comprehens ively equ ipped laboratory and educat ional aids in the form of animated disp lay of processes and a . theatrette for the enlightenment of both M.M .B.W. staff and the general public.

Credit for the convenient layout, attractive architecture and unique but reliable processes adopted, is vested jointly in the Me lbourne and Metropolitan Board of Works and William Boby and Company (Australia) Pty. Ltd. who have been awarded the contract for the functiona l design of both processes and layout and supp ly and installation of the treatment equ ipment at a contract amount of $7 ,735, 034.

Consulting architects to the Board for the Sugarloaf Project are R. S. Demaine , Russell, Trindle, Armstrong and Orton Pty. Ltd.

23

WASTE WATER TREATMENT

~

H.P. CRECORY has the answer . .. and the equipment! /

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,,

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Time-contro lle/operation of the Gregory Sewage Ejector provides a simple, completely automatic method of lifting up to 200 gal lons of raw sewage per minute without screening . No inaccess ibl e or submerged working parts, it adapts itself automatical ly to the in take flow. An odour-fre e c losed system giving troub lefree operation .... . . approved by authorities in Aust¡ ralia and New Zealand.

*Aust Patent No. 273099

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25

The UNOX SYSTEM is the direct oxygenation process developed by UNION CARBIDE. In the place of air, UNOX employs oxygen gas to improve significantly the activated sludge wastewater treatment process.

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2.000 ~alitres ofwastewater daily. have

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26

UNOX OZONATION SYSTEM-disinfects water following basic UNOX system treatment.

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FLOW M 3 /24 HOURS 25 40 65 90

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MAX . LOADING IN Kg. B.O.D./24 HOU RS 14 19 26

f

38 The unit is ideally suited for insta llatio n in industrial plants, hospita ls, construct ion and mining camps, co untry hote ls, motels and carava n parks and in residential commu nities from 25 to 650 persons . Simply in sta lled, it is high ly effic ient and may be moved from one site to anoth er. A descr ipt ive leaflet is ava il able.

PAR BURY HENTV & CO. PTY. LTD. MIN ING DIVISION 1 Linco ln Street, Lane Cove, N.S .W. 2066 Telephone 428 3533

27

PORTABLE ULTRASONIC MANHOLE MONITOR

UMM-12 The portable Ultrasonic Manhole Monitor UMM-12 measures material levels by beaming ultrasonic energy towards the surface of liquids. Using this "sonar- in-a ir" methods, the UMM-12 continuously records the level on a strip-chart recorder. As its name implies, the UMM -12 was specifically designed to measure the level of waste water in sewer lines and thus it is built to withstand the corrosive environment in manholes . But the instrument can be used for many other applications , which require the measurement of liquid material levels .

The UMM -12 is truly portable since it operates on rechargeable batteries from 7 to 12 days continuously on one charge .

The UMM-12 can be adjusted for various depths of flow with its unique Span Dial. The Span Dial allow s digital level calibration for any pipe size or channel depth from 3 inches to 100 inches in 1/10 inch increments. For examp le, an 18- inch depth in a channel would be reflected as 100% on the chart paper when the Span Dial is set to 18.0. The liquid level can be converted to volume of flow with a conversion table .

The UM M-12 requires little or no maintenance because it does not have any contact with the material. The instrument sets up qui.ckly and is easily moved to a new site .

STANDARD FEATURES • Fast, Easy Setup • Fiberglass Waterproof Enclosure (14" x 12" x 6") • Enclosure Includes Two Hooks and Handle For Easy Placement • Dial Adjustment For Adjusting To Different Spans (Flow Depths) 3 Inches to 100 Inches in 1/10 Inch Increments • Portable , Easily Carried to Different Locations • Strip-Chart Recorder With Adjustable Speeds

COMBINED INSTRUMENT SYSTEMS PTY. LTD. Registered Office:

17 THORNTON CRESCENT, NUNAWADING, VICTORIA, 3131

• • • • • • • • • • •

Meter Indicating O to 100% Readout Non-Contact Sensor, Encapsulated ifi Non-Corrosive Kynar Explosion-Proof Sensor As Rated By Factory Mutual Research Non-Corrosive Flexible Neoprene Sensor Cable in 20-Foot Lengths Quick Disconnect Fitting For Sensor Cable at Enclosure All Fittings Non-Corrosive and Rust-Proof Four Rechargeable, 4 .5 Amp Hours, 12-Volt Batteries Internal Battery Charger Activated By 110-Volt Plug-in Power Cord 115-Volt Plug-in Switch For Setting Fast Recharge or Float Recharge For Line Operation All Batteries, Meter, Recorder etc. In Enclosure

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Telephone: 174 7030, 174 7039 Telex: AA-31305 Poatel Adchu: P.O. BOX 80, NUNAWADING, VICTOIIA, 1111, AU111AUA

28

OPTIONAL FEATURES

11 1 ·. ~

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'

• Extra Battery Pack in Slide-in Holder Including External Charger • Viewing Window For Enclosure • Extra Sensor With 20-Foot Cable Assembly

SPAN DIAL

If clean water is an essential part of your process plant ... or the economic separation of suspended, entrained or dissolved materials such as chemicals, minerals, oils, spirits, etc .. .. then you need the specialised skills and equipment available from Permutit.

De-ionisers/ Filters Reverse osmosis

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Nobody treats water more cleanly than Permutit!

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IPERMUTITI The Permutit Company of Austra lia Pty. Limited A Subsidiary of THE PERMUTIT COMPANY LTD. ENGLAND .

A Memb er of the Po rtals Group Cnr. Wattle Road and Short Street , Brookvale, N.S.W. 2100 Telep hone: 93-0311. T elex: AA2 4742 Cables : Thepermutit, Syd ney.

P.O. Box 117, Brookvale, N.S.W. Australia 2100.

44 Koornang Road, Scoresby , Victoria Australia 3179 Telephone : 763-8988 Tele x: AA31868 50 Leichhard t Street, Spring Hil l, Queensland .

Australi a 4000 Telephone : 229-5800 T elex:

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pettigre'W water A COMPIETE SER~E

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POLLUTION CONTROL

SURVEYS AND CONSULTING

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PILOT STUDIES OF WASTEWATER

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DESIGN AND MANUFACTURE

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EXPER IENCE AND RELIABILITY INSTALLATION , TESTING AND COMMISSIONING CONTINUOUS AFTER-SALES SERVICE

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Pollutio·n Control for Small Business In addition to large scale pollution control systems for major industries, Pettigrew Engineerin·g Co. Pty. Ltd. also solves the pollution problems of small businesses by designing and producing suitable equipment within their budget capabilities.

PETTIGREW ENGINEERING CO PTY LTD 34 REGINALD STREET, ROCKLEA, OLD., 4106, AUSTRALIA TELEPHONE (07) 275-3322 - CABLES "PECOTRADE" PRINTED l!IY HEDGES

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IIELL PTY . LTD ., MARYBOROUGH VICTORIA