j 1ssN 0310 - 03s1
Official Journal of the AUSTRALIAN WATER AND WASTEWATER ASSOCIATION
IVol. 4, No. 4, Dec. 1977 Registered for posting as a periodical -
Filte_r9ak;.. a new dimension in effluent treatment Wherever there is industry or dense population, there is also effluent. Effluent which if left untreated would turn our rivers , lakes and harbours into vast cesspools, no longer capable of selfpurification and unable to support life. The process involved in a biological treatment plant is provided by nature itself - micro- organisms which feed or, organic waste, reconstituting , stabilising and finally purifying it. Fixed growth reactors in a treatment plant simply accelerate nature' s process; creating an environment in which microorganisms can survive in far greater numbers than they would in the natural environment by providing them with a continuous supply of oxygen and a medium in which they can live and breed.
In the past, the use of rock as a med ium was established practice. But today, pla stics have enabled the development of Filterpak ÂŽ - adding a new dimension to effluent treatment. As a random packed medium for fixed growth reactors it offers many advantages . The geometric design provides a much greater surface area to volume ratio enabling it to accommodate the maximum number of microorganisms. The larger voids ensure a fast flow rate and transfer of oxygen and make it less prone to channelling or blocking. Thus it not only greatly increases efficiency but also drastically reduces malodours. Moulded from a quality plastic, Hostalen PP (polypropylene), Filterpak "' has high mechanical strength yet is extremely lightweight so it is possible to increase the height and capacity of media reactors without the need for expensive foundations.
F1lterpa k ~ ma de fr om Hos ta ten PP provide a breedmg ground for m 1cro - orgamsms natures own punf1e rs.
For further information on Filterpak ~ please contact Hoechst Australia Limited, 606 St. Kilda Roi d, Melbourne 3001 . Tel: 51 0321 Name Company Address
"I Postcod e
'----------------~ Hoechst Filterpak :!' made under exclusive licence arrangement in South Pacific and areas in South East Asia by A.H.I. Chemical Engineering Services to Mass Transfer Limited United Kingdom .
Chairman: C. D. Parker Committee: G. R. Goffin M. B. Cureau F. R. J3ishop R. L. Clisby Joan Powling B. S. Sanders A.G. Longstaff W. Nicholson J. H. Greer A. Macoun G. R. Scott Publisher: Editor: A.W.W.A E. A. Swinton
BRANCH CORRESPONDENTS CANBERRA A.C.T.: A. Macoun, P.O. Box 306, Woden, 2606. NEW SOUTH WALES: G. R. Scott, James Hardie & Coy. Pty. Ltd., P.O. Box 70, Parramatta, 2150. VICTORIA: . M. Smith, Ministry of Water Resources and Water Supply, 9th Floor, 100 Exhibition St., Melbourne, 3000. QUEENSLAND: L. C. Smith, 24 Byambee St., Kenmore, 4069. SOUTH AUSTRALIA: R. L. Clisby, C/- E. & W. S . 13.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, . 3 Johns Place, Nightcliff, Darwin, 5792. Editorial Correspondence: E. A. Swinton, Box 310, South MelJ:>ourne, Vic. Or to State Correspondents. Advertising Enquiries: Mrs L. Geal, C/- Appita, 191 Royal Par., Parkville, 3052. Phone: (03) 347-2377.
IISSN OJ10 - 0J67l
Official Journal of the IAUSTRALIAN'"'NATER AND )
Vol. 4, No. 4, December 1977
CONTENTS Editorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Association News . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sewage as a Resource in Australia?
- I. C. Sandford .............. ~ . . . . . . . . . . .
Major City Water Supplies - B. P. O'Connell. . . . . . . . . . . . . . . . . . . . . . . . .
Waterborne Disease - Dr. Peter A. Wood. . . . . . . . . . . . . . . . . . . . . . .
The Evaluation and Upgrading of Existing Treatment Plants
- J. L. Bristow. . . . . . . . . . . . . . . . . . . . . . . . . . .
Industry News . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cont erence Calendar . . . . . . . . . . . . . . . . . . . . . . . . .
INSTRUCTIONS TO AUTHORS Artlcles should be of original thought or reports on orlglnal work of Interest to the members of the A. W. W.A. In the range 1000 to 5000 words. Diagrams or photos would be appreciated. Full Instructions are avallable from Branch correspondents or the Editor.
COVER STORY The Gold Coast City Council has augmented its water purification plant capacity from 70 to 140 Ml/day to meet the requirements of the rapidly expanding urban development of the Gold Coast. The augmentation programme included additional sedimentation and filtration units, chemical feeding and control equipment totalling $1 ,000 ,000. The front cover depicts the flocculation and sedimentation equipment installed by GATX-Fuller Pty. Ltd. in a 5 megalitre tank built by Klaus Huebner. The system is an updated version of the original tank which has given excellent service since it was installed in 1968.
Handles Water Beautifully Applications
"Len" Anthracite can be used :
Specific Gravity: 1.40-1 .45 Acid Solubility: ' 1.0% (max) Effective Size: Type 2 0.85-0.95mm Ty~e 3 0.50-0.60mm Uniformity Coefficient: 1.4 Voidage: 55%
D To increase the capacity and efficiency of existing filtration equipment
D To reduce the capital cost of new equipment
D For filtration of Alkaline Water: Caustic Acid Solution, Boiler Water and Oxidised Chemicals.
Distributed in Australasia by Kembla Coal & Coke Pty. Limited Box 1770, P.O. Wollongong, N.S.W. 2500. Telephone (042) 28 7455 Telex: 29172
When it comes to conservat~n many people simply use words . Some others take action-positive , constructive , meaningful action. The Associated Tree Farmers Scheme launched by Associated Pulp and Paper Mills in 1975 is an outstanding example . It is a practical programme that even improves on nature . There are three major objectives-to contribute to the conservation o'f Tasmanian forests; to demonstrate to farmers that with proper management , tree farming is a valuable alternative to traditional land uses , and to increase the future supply of wood fibre , Tasmania 's most important raw material. Associated Tree Farmers is a partnership in conservation for the benefit of individua l landowners, Associated Pulp and Paper Mills , Tasm ania itself and in the end all Australians. Associated Pulp and Paper Mills is contributing finance and management knowhow to ensure the reafforestation of private forest lands whic h, after harvest, could otherwise be lost forever as forest. As one of the Associated Tree Farmers members , Mr. Harold Davey, put it: "It is certain that in many cases reafforestation would not take place but for the Tree Farmers Scheme. This responsible attitude by Associated Pulp and Paper Mi lls must surely refute criticism of woodchipping in itself. If criticism is to be made , it has to be made towards the farmers who do not take advantage of this scheme . It is a service to the farming community that has no legal ties but only an undertaking that when a new crop is to be so ld Associated Pulp and Paper Mills has an opportunity to quote for the timber. "This property is open for , inspec tion by anyone interested and I wish to thank Associated Pulp and Paper Mills for the scheme and for being able to take advantage of it." This is conservation,in action . While others talk, Associated Pulp and Paper Mills is helping to grow better forests for the future benefit of us all .
grow better than words
Associated Pulp and Paper Mills Limited Austral ia's fine papermakers Partner in Assoc iated Tree Farmers
~ ,ooo .,.~,~ Â· and Storage ,~ - - - - - - - -
THE PARBURY HENTY RANGE OF WATER PURIFICATION EQUIPMENT INCLUDES:
SIMONACCQ DISC FILTERS The Simonacco Rotary Vacuum Disc Filter provides co ntinuous filtration of chemical slurries, mineral co ncentrates, sewage sludges, etc., and can be adapted to a wide range of industrial applications. Available with discs 1.8 m diameter up to 6 discs (24 sq. m) and with discs 3.96 m diameter up to 14 discs (266 sq . m).
MANOR FILTEA PRESSES Manor Engineering Co . Ltd. equipment is supplied by Parbury Henty for sedimentation , thickening, filtration, chemical handling , pumping, elutriation, flotation, sewage and industrial effluent purification. Manor fully automated presses of the type illustrated have extensive uses for materials on short filtration cycles and having good cake release characteristics.
â&#x20AC;˘ SIEBTECHNIK CENTRIFUGES The Siebtechnik Decanter is a screenless centrifuge, in which the solids are conveyed from the large to the small diameter against the centrifugal force. The worm acts as a conveyor as well as a regulating element, and its field of application inr,ludes materials which are too fine for the screening centrifuge, provided the solids have an adequate sedimentation rate, such as flotation concentrates and waste water.
PAR BURY HENTV & CO. PTY. LTÂˇD.
MINING DIVISION 6
1 Lincoln Street, Lane Cove, N.S.W. 2066 Telephone 428 3533
FEDERAL SECRETARY: P. Hughes, Box A232 P.O. Sydney South, 2000. FEDERAL TREASURER: J. H. Greer, C/- Melbourne & M.B,.W., 625 Lt. Collins St., Melbourne, 3000. BRANCH SECRETARIES :
Canberra, A.C .T . D. Henley, P.O. Box 306, Woden, A.C.T., 2606
New South Wales: P.J. Mitchell, C/- Envirotech Australia Pty. Ltd., P.O. Bo?< 220, Artarmon, 2064. Victoria: R. Povey, Cl- 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: R.J. Fimmel, P.O. Box 356, West Perth, 6005.
Conservation is fashionable "CONSERVATION" is the fashionable cry in today's society indeed it becomes the by-word in much of our controversy, both political and social, yet the public at large cannot, or will not, accept the need to conserve our most important raw material WATER. Because it cannot be mined, exported, taxed or demonstrated over, the public ignore the issue. Yet the greatest user of water is the industrial machine which supplies the consumer with the vast array of commodities which make life comfortable. When the consumer pays for his own water usage, he also pays for the indu strial consumption with every article he buys. Water thus becomes an essential manufactured goods, and management must the economics of continued purchase of purification and re-use of used water. Like air, out - its capacity for re-use is infinite.
component in all now look closely at new water, or the water does not wear
In some industries and municipal applications, potential cost saving is high, and capital cost readily recouped. In other industries , where process water is governed by health regulations, savings are more moderate, but by-product reclamation then becomes a considerable economic incentive. This great land of ours is blessed with most of the commodities required for man's comfort. The technology of good resources management is also available in abundance. It must then be an essential of our Association to play its part in improving public understanding of the urgent need for the conservation , re-cycl ing and management of this most basic of our resources. ,. Allan Pettigrew, Councillor for Queensland Federal Vice-President.
Tasmania:: P.E. Spratt, Cl- Fowler, England & N e w t o n , - - - - - - - - - - - - - - - - - - - - - - - - - - " " ' 132 Davey St., Hobart,Âˇ 7000. Northern ,Territory: A. Wade, Cl- Dept. of Construction, Mitchel I St., Darwin.
Thanks to the Queensland Branch for organising contributions to this issue.
Requests for Appllcatlon Forms for Membership of the Association
shou ld be addressed to the appropriate Branch Secretary .
Membership is in four categories: 1. Member- qualifications suitable for membership In the Inst. of Engineers, or other suitab le professional bodies. 2. Associate-experience In the W. & W.W. Industry, without formal qualifications. 3. Student. 4. Sustaining Member-an organisation Involved In the W. & W. W. Industry wishing to sustain the Association.
el . ASSOCIATION 路 NEWS VICTORIA The third annual regional conference was held at Thornton in Central Victoria from 21st to 23rd October, 1977. The theme of the conference, "Inland Water Management" was most appropriate in 路 view of the dry conditions prevailing throughout the State. Morning technical sessions were attended by 43 members and several wives. It is pleasing to see such interest being taken in these conferences . The 9ombination of business and pleasure in pleasant surroundings and amiable company is obviously a winning combination. Summer seems to be the season for relaxation for branch members. Following the weekend conference, the years activities were brought to an end with the annual dinner dance at the City and Overseas Club . Bob Swinton may have found himself a permanent job as master of ceremon ies; some of his ideas for the Monte Carlo were "novel" and involved interesting reactions!
SOUTH AUSTRALIA An expanded programme of Branch Meetings has been arranged for the 1978 Session , details of which are as follows :Friday 24th February - Joint meeting with the Hydr9logical Society of South Austral ia on the "Hydrology of the Blue Lake, Mount Gambi~r". This paper wi ll be presented by: G. F. McIntosh (E .&W .S. Dept.) P. C. Smith (Dept. of Mines) J. Turner (C .S.I.R.O .) Wednesday 26th April - Visit to the newly commissioned Hope Valley Water Treatment Works. Friday 30th June - "The relevan.ce of the LANDSAT programme to Water Resources Management" , by K. R. McCloy , S.A. Institute of Technology . " Industrial Wednesday 26th July Waste Charging", by Officers of the Melbourne & Metropolitan Board of Works . Friday 15th September - "Encephal iti s - the Mosquito Contro l Programrnii" by Dr. Dann Russe ll , Dept. Public Hea lth and R. Laughlan, Waite Agricu ltural Research Institute. Friday 27th October - "Treatment of Winery and Distillery Wastewate(i;", by H. E. Hicks and M . C. Sanders , E.&W.S. Dept . Friday 24th November - Lad ie's Night to be addressed by Mr. Warren Bonython . 8
QUEENSLAND The Queensland Branch r. :1.s held two successful meetings recently . These areWednesday, 23rd November, 1977 at the Majestic Hotel , Brisbane . Mr. Ian Sandford of Gutteridge, Haskins and Davey, Melbourne, spoke on the topic of " Sewage as a Resource in Australia" . Mr. Sandford described the various available methods of sewage being utilised as a resource with a most interesting sei of slides of operational plants . Friday , 27th January, 1978 at the Kin dler Theatre , Q.I.T. Brisbane. Dr. David Stansel of Envirotech, Salt Lake City, U.S.A., gave an afternoon's session on the subj ect " Carousel Biological Oxidation Systems". Dr. Stensel 's talk was illustrated by a number of slides, graphs and diagrams, which provided those in attendance with up- to - date theoretical and practical information on the subject. As mentioned in the September issue of "Water" , we are undertaking an "Operators Forum " to assist treatment plant operators to solve their problems in everyday operation. Queries and questions should be addressed to: "Operators Forum" , cl- P.O. Box 129, Brisbane Markets, Qld . 4106 . The 8th Biennial Conference programming is progressing steadily and the Queensland Committee has tacitly approved the Gold Coast as the venue for the 1979 conference . Further details will be available later. The Queensland Branch 1978 programme has not been finalised at this time , and will be done so at the next comm ittee meeting . Details will be avai lab le in the next issue of "Water".
WESTERN AUSTRALIA The Perth Entertainment Centre Restaurant never entertained a happier bunch of folks than those A .W.W.A .'s dining, wining and talking all but shop at their annual " Do" on December 7th. Near to half the branch members attended and, with their ladies and visiting N.S.W. members made up a group to take on al l subjects from the Lynch Affair to "the other cricket". The "Do" , always a success, has earned a permanent spot on the W .A. A.W.W.A .'s ca lendar. The Branch Committee is very pleased that after 5 years the membership has at long last passed the magic 100, a goal for which they have been striving for some time. Now that this milestone has been reached it is hoped that more rapid growth of the Branch will occur.
NEW SOUTH WALES 1. A film evening was held in October. Suitable clean and dirty (water) movies were shown. Prior to their screening, the D.K. Thistlewayte Memorial Prize was presented to Mr. J. A. Munro. 2. On Monday, 17th November, at our
November General Meeting , Mr. Ian Cookman of John Taylor & Son , Consulting Engineers , delivered a paper " Designing for Control and Operational Re liability of Sewerage Treatment Works". Mr. Cookmc1n 's paper discussed factors to be considered in formulating design philosophy for control systems. 3. The Branch Xmas Dinner was held at the North Syd路ney Leagues Club on Thursday, 1st December. Ninety happy people enjoyed a sumptuous smorgasbord . Complaints were heard that there was too much food and the plates were too small, necessitating frequent trips back to the a. serving tables . 4. The N.S.W. Branch commenced act ivities early in 1978 with two site inspections on the evening of 25th January. The visit to Kraft Foods Ltd. Yeast Extract Plant was carried out with considerable enthusiasm, particularly by one member who seemed to think its prime function was to produce little cel ls for the brewing industry. To more junior members, including your correspondent , it brought back memories of kindergarten days and vegemite sandwiches . Following our visit to Kraft we congregated at Austral Bronze Crane Copper Ltd . and our over-enthusiastic member somehow again managed to assoc iate yeast and the brewing industry with the pickling process . At that stage , we decided to adjourn to Dimitri'ii Bistro for vegemite sandwiches and pickling liquor. Our drive for new members is continu in g in the new, year. We are particularly keen to contact organisations interested in becoming sustaining members. Our hard-working treasurer, Jim Oliff , has spent considerable time in exp laining our firfancial balancing act to the Committee members and he is encouraging our membership SubCommittee to greater efforts . The NSW Branch Regional Conference for 1978 will be held at Terrigal from 17th to 19th March . The avenue for th is Conference will be the very popular Florida Hotel.
NEW EDITOR We must apologise to both readers and contributors for the extreme lateness of this issue. In late 1977, Barrie Murphy had to relinquish the position of Honorary Editor due to pressure of work and a Management Course . Bob (E. A.) Swinton agreed to take over . There was a hiatus in between (def. Chambers " a gap, a chasm , a break in 路 continuity : a place in a manuscript, etc, where something is missing " ). We will do our best to catch up through 1978, and we thank the W.A. contributors who have already filled our next issue.
SEWAGE AS A RESOURCE 路IN AUSTRALIA? By I. C. Sandford, B.E. (Chem.) (Hons.), M.Eng.Sc., M.I.E. (Aust.) Senior Chemical Engineer, Gutteridge, Haskins & Davey Pty. Ltd. 1. Introduction: The use of sewage as a resource Is about the reuse of the water, nutrients and energy contained In It. Hopefully sewage reuse not only conserves Increasingly scarce resources but also results In reduced costs for the treatment and disposal of sewage. It Is possible to consider the movement of materials In the ecosystem In two separate ways. (Fig . 1). In nature the loop Is closed with a natural balance being mantalned. An unnatural balance may develop when there Is uncontrolled addition of material s and waste material to the ecosystem, often resulting In pollution which may be visible, and always resulting In a waste of the resources . The nature and composition of sewage has been widely 路studied, and has led to a thorough documentation of Its composition , Its rates of production from various sorts of communities and the factors within each community contributing waste. (Tab les 1 and 2). Thus It Is possible to quite accurately assess the water resource potential, nutrient potential and energy potential of sewage. Further, the knowledge of the factors making up the sewage of a community may enable segregation of various wastes (If required) for specific reuse proposition s. Sewage treatment Is notoriously variable In the removal efficiencies of various pollutants. Not only Is there a wide selection of processes to choose from, but due to great variations In the way they may be operated, the efficiency of a process can, and does, vary enormously. (Fair, Geyer and Okum (1968) , Fair and Geyer (1954) ). This then makes planning for the use of sewage difficult but does provide a selection of processes which could be used for a variety of
FIG. 1 COMPARISON OF NATURAL AND UNNATURAL NUTRIENT PATHWAYS
UNNATURAL NATURAL reuse schemes, as often quite different standards are required for each reuse proposal.
2.0 Sewage Reuse It has already been Indicated that sewage Is a much studied substance. By selection and operation of any one of the large numbers of sewage treatment processes, It Is possible to match the process with almost any specific reuse proposition, whether It be for water reuse, energy reuse or nutrient reuse. For a hypothetical community of 100,000 Australian people It Is possible to estimate t~e value of Its sewage components . (Table 3) (After GHD (1976) ).
TABLE 1. VALUES FOR .SOME PARAMETERS OFTEN DETERMINED IN RAW SEWAGE. Except pH, all values as mg/I.
.c >< rn
~ Q) I- .c
u!? c:ns ..0 ::, rn c.
C: C. Q) C:
路 - Q) Q) C: Q) ....
Total solids Dissolved solids Suspended solids pH B.0.0 .5 C.0.0. T.O .C. Albumlnold-N Ammonlacal-N Comblned-N N03 -N N02-N P04-P
590-792 450-524 140-268 7.0-7.5 230-400 110-165 10-22 17-29 27-51 <0.05 9-21
1309 1163 146 7.6-8.2 340-390 670 186-247 16-23 41-53 57-76
322-640 240-382 82-258 400-650 6.0-7.0 6.8-7.5 75-276 400-800 159-436 1000-1800 550 30 45 4-35 76 0.03 0.04 16
1484 1174 7.5 250
25-1250 120-1380 2.1-8.1 6.4-10.6 53-450 52-665
150 19 27 46 0.2
5-38 12-90 17-128
6-55 9-50 15-105
100-550 6.3-7 .8 96-368 6-28 20-48 26-76
350-1200 250-850 100-350 100-300 250-1000 100-300 8-35 12-50 20-85 0 0
TABLE 2. DOMESTIC WASTEWATER ANALYSES Average contribution in grams/capita/day -
B .O .D.
3.2 2.3 2.5 2.1 3.2 0.9
0 .31 0 .42 0.49 0 .60 0 .72 1.50
0.04 0.42 0.82 0.13 2.1'5 0.27
0 0.01 0 .005 0.02 0.20
Water event Bath/shower Kitchen sink Dishwasher Garbage disposal Clothes washer Toilet-Faeces
3.1 8.3 12.6 10.9 14.8 4.3
3.3 15.3 0 .5 12.2 8.8
2.2 4 .1 5.21 15.8 11.0 6.5
0 .9 6.2 1.1 20 .0 3 .4
[a) From Witt et al (1974) for wastes from four households in
• by recharge of depleted underground aqulflers, or as hydrological barriers In such aqulflers • to maintain the flow of streams with low flows, caused either by seasonal patterns or control of the natural river flow • as process water for Industry (e.g. either used directly In the process or as cooling water) • In a "two pipe" system to households, with the reclaimed In a dry country such as Australia the Item of highest va lue water used only on gardens of course Is water. When substituted for first grade water It • as potable water. has an estimated value of $700,000 per year from 100,000 Each reuse proposition will require Its own water standard people. However, the approaching energy crisis must affect and the cost In producing such a standard will govern the the value of methane (I.e. the energy content of sewage) the economies of the project. Water reuse Is already widely nitrogen and phosphorus when used as fertilizer, and practised In Australia. (Table 4) . (After GHD (1976) ). possibly even the value of sludge when used as a soil conditioner. It can only be that sewage will become a more To govern and control the use of reclaimed water In valuable commodity. Australia , each State has produced Its own approach to the problem . (Table 5). (GHD (1977)). The presence, or lack of a 2.1 Water Reuse particular reuse standard, generally reflects that state's need Water may be, and has been, safely reused In a variety of for water, and the areas where the need Is greatest . Thus Tasmania, a water-rich state, has no standards for the use of ways viz: reclaimed water at all whilst N .S.W., a moderately water-rich • By Irrigation of suitable crops and pasture • by Irrigation of municipal grounds such as parks, street state, has extensive standards. Victorian standards are verges and community areas such as golf courses, schools currently being Investigated . Specific examples of reclaimed and playing fields water use In Australia are at Broken HIii where It Is used for garden watering and slag heap TABLE 3. stabilization, Montara Vi'neyard at Ararat where it is used for vine irrigation POSSIBLE RESOURCES :IN SEWAGE FROM 100,000 PEOPLE by the trickle process, Townsville golf Resource Amount Value Form course for fairway irrigation, Glenelg area in Adelaide for parkland irrigation, 7000MI 8.· $700,000* As town water supply replaceWater Kambalda for r,ickel industry process ment on parks, etc. water, Anglevale vineyard for vine b. $ 20,000 As pasture Irrigation water. irrigat ion, Werribee and Dutson Downs a. $ 20,000 600 ooom 3 As town gas. for pasture irrigation, and for general Methane b. $ 20,000 As electricity. municipal use throughout much of $ 20,000 300000 m3 Cost of oil (If prepared from fuel so uth western Western Australia. oil). Whilst not an exhaustive list it does indicate the range of reclaimed water $ 40,000 100tasP As equivalent super phosphate. Phosphorus $ 17,000 As equivalent commercial reuse already practised in Australia. 400 t as N Nitrogen fertiliser. The reuse of some 17% of Australia's. ? , $ 2,000 Soll conditioner. 200 t Sludge wastewater compares favourably with less than 2% of that available for reuse Thus possible resources in sewage amount to $8.2/capita . in U.S.A., but quite unfavourably with • Based on average costs. Marginal value in dry areas could be 4 times this. Israel where about 86% is reused as indicated in Table 6. TABLE 4. INCIDENCE OF RECLAIMED WATER USE IN AUSTRALIA Clearly those factors which govern NT SA NSW VIC WA a the potential for the use of reclaimed water are climate, soil type , effluent Effluent Reuse q.uality, crop requirements and potential health problems . Of course, 30 5 5 - Pasture climate is usually the dominant factor. 1 1 - Vine growing Much has been written on the problems 1 1 2 Trees experienced with the use of reclaimed Sportsground water and those generally !:)ncountered 12 8 10 18 16 (Including golf courses) are soil clogging, uncontrolled 1 Mine waste revegetatlon seepage , trace element problems House garden (either too little or too much), 2 (two pipe system) salinity/SAR problems, ultimate disIndustrial posal problems and health problems. None recorded in Tasmania (GHD (1976 and 1977)) . Use of
Wisconsin . Sample numbers ranged from 6 for garbage disposal to 69 for toilet flushing. [bl From Bennett et al [1974) for wastes from "severa l homes" in Colorado. [c) M. M. B. W. personal communication (1976) for wastes from three households of M. M. B. W. officers .
TABLES. SUMMARY OF REGULATIONS CONTROLLING USE OF RECLAIMED WATER IN SOME AUSTRALIAN STAT,,FS (1976).
USE OF RECLAIMED WATER
A. Irrigation of crops not for direct human consumption, I.e. Industrial Crops).
Irrigatio n of crops eaten cooked (Incl. fish culture) .
C. Irrigation of crops eaten raw.
Primary treatment Secondary treated essential. Free of gross effluent so l Ids; sign iflcant removal of parasite eggs.
Efficient Primary sedlmentat ion.
Secondary Treatment .
Secondary treatment essential, and sand flltratlon and disinfection may somet imes be required. Also to be free of gross solids, with significant removal of parasite eggs and bacterla, with no chemicals present that lead to I underslrable residue In crops or fish.
Pastures and fodder crops irrigated by chlorinated secondary effluent only . Animals not perm ltted to d rl n k effluent.
An adequately steri lised secondary eff luent. (Co liform organism < 2.2/100 ml.)
Surface irrigat ion : Secondary treated eff luent. Spray irrigation : Fl occulated , fi ltered and disinfected eff luent , to fecal coliforms: < 100/100 ml (mean) < 200/100 ml (90% ile)
Secondary treatment and Not allowed at all. disinfection essential. Sand filtration may sometimes be required. Less than 100 Coliform organi sms 100 ml In 80% of samples, and no chemicals that lead to undesirable residue In crops or fish.
Not al lowed at all.
No pathogenic bacteria or virus. <2.2 co liform organlsms / 100 ml.
D. Recreational Use (no Secondary treatment contact allowed). essential. Disinfection may sometimes be required . Free of gross solids, significant removal of parasite eggs and bacteria.
Disinfected Secondary eff luent; fecal coliform: < 1000/100 ml (mean) < 2000/100 ml (90% ile) For landscape impoundments, requirement is secondary eff luent only .
E. Recreational Use (I.e . Secondary treatment, body contact allowed) sand filtration and disinfection essential not more than 100 coliform organisms/ 100 ml In 80% of samples, and no chemicals that lead to irritation of skin and mucous membranes .
Disinfected filtered and flocculated effluent, fecal coliform : < 100/100 ml (mean) < 200/100 ml (90% ile)
F. Industrial Use
H. Municipal Use (potable) (aquifer recharge).
Secondary treatment essential. Sand flltration , nitrification, chem lcal clarification, ion exchange and disinfection may sometimes be required. Free of gross so lids, significant removal of parasite eggs, effective removal of bacteria, some removal of virus.
G . Municipal Use (non- Secondary treatment potab le) (restricted and sand fi ltration landscape Irrigation). essential. Free of grosssolids, sig nificant removal of parasite eggs and bacteria. Controls over taps, etc.
Disinfected secondary eff luent; fecal co liform : < 1000/100 ml (mean) <2000/100 ml (90% ile) Public access allowed on ly when dry .
Ch lorl nated secondary effluent. Special controls over taps, etc., and no public access during watering, only when dry.
TABLE 8. REUSE OF MUNICIPAL WASTEWATERS BY CROP IN ISRAEL
· Quantity of wastewater reused m 3/day %
45,680 19,500 10,075 9,130 4,900 1,250 5,150 95,685
Field crop Citrus Pastures Fodder crops Orchards and vines Fish ponds Other crops Total
Recently algae product ion has been examined as a potential for cont roll ed cult ivation . (Caldwell Connell (1975)). However, there are harvest ing problems and perhaps cultivation of macrophytes would be more appropriate. (Figure 3). They are extremely productive (Table 7) and thus are most attractive fro m t he unit production point of view. Using reclaimed water containing fertilizer, then production should be even higher than th at reported, which Is In the range 7-15 dry tonne/h a. (Boyd 1974). Alternatively the growth of fish In such pond s (and Its subsequent conversion to say, f ish meal) would be very productive . (Allen (1969, 1951)), Hickl in g (1961 , 1968)), (Mann (1965)), (Le Gren (1969)). FIGURE 3
MACRO PHYTE PRODUCTION
Ref. : Schmidt and Clements, 1975.
reclaimed water in the arid areas of Australia is popular, and at Kambalda it is used at a cost of 26.5c/kl, which compares very favourably with the Scheme water cost of $1.49/kl. (GHD, 1976). One concept worthy of further development Is that emp loyed In Townsville for irrigation of a golf course. Here an adjacent rising main provides the source of sewage, and a smal l carousel type treatment plant produces rec laimed water for use on the fairways. (e.g. Figure 2). Fig. 2
DIVERSION OF SEWAGE FOR EFFLUENT REUSE
Auxiliary Treatment (B) Plant
Effluent for reuse
The prob lems envi saged from such nutrient reuse projects are main ly econo mic and health. It needs to be carried out on a large scale before It becomes economically attractive. Health restrict ions will limit the usefu lness of the product, and certain ly preclude Its use for human consumption . However, use as stock feed etc. , would be Ideal.
;Sludges I I
Auxiliary Treatment (A) Plant
Main Municipal Treatment Plant
'I Ecosystem type
Effluent for reuse
Aqulfler recharge Is a most promising area for the use of rec laimed water. It is widely practised In the U.S.A. at Bay Park, Suffock County, Flushing Meadows, Water Factory 21, Santee Whittier Narrows, St. Peterburg and Fresno. As well It is In use In Israel In the Dan Region and In Holland . In Australia the interest is currently academic with pilot schemes In W.A. and a proposed pilot scheme at Boneo, Victoria. (Australian Groundwater Consultants (1977)). The great advantage of this process Is that In Its passage down to the aqulf ler t he rec laimed water undergoes very efficient tertiary treatment, producing a final reclaimed water of potentiall y exceptional quality. 2.2 Nutrient Reuse Of course this Is often an Integral part of any reclaimed water use programme. Whilst the main value may be the water, the nit rogen and phosphorus content of the water stimu lates the growth of grass, crops, etc. and Imparts a definite ferti lizer value to the reclaimed water. However, the nutrients may be of use In their own right. Examples wou ld be:• Algae growth In rec laimed water, which would be harvested for cattle feed, or perhaps utilised In place by aquaculture . • Macroph yte production, which coul d be used for paper product ion, energy production, single cell protein (SCP) production. • Growt h of specific energy crops such as cassava, sugar beet, trees, etc. Such crops wou ld then be converted to liquid f uels, such as methyl or ethyl alcohol. • Use of the nutrients during treatment to produce waste bio logical sludges, wh ich have their own unique values, say as soi l conditioners. 12
TABLE 7. LIKELY ANNUAL AVERAGE NET PRIMARY PRODUCTIVITY ON FERTILE SITES Values as tonne/ha/year. After Westlake (1963)
Approximate organic productivity*
Arid desert Temperate lake: Phytoplankton Temperate po lluted lake: Phytoplankton Temperatre submerg ed macrophytes Tropical su bmerged macrophytes f Temperate agricultu re: Annuals t Tropical ag ric ultu re: Annuals Tropical ag ricul t ure: Perennials or reed swamps
1 2 6 6 17 22
• It should be emphasized that organic productiyity is not the same as useful crops . t Values given by Morrison (1961] for average yields of alfalfa hay and corn silage in the U.S.A . were 4.5 and 5.0 tonne/ha, respectively, rising to 8 and 10 with good management.
2.3 Sludge Reuse There is nothing more certain than the fact that all sewage treatment plants product varying quantities of sludge (Table 8).
Sewage sludge Is variable In composition but has a high protein content and a wide range of minor constituents, making It an exce llent soil conditioner. (Anon (1 966)) . The major components of raw sludge are protein, grease, crude fibre, eth er so luble material, llgnln and ash. After digestion the major components are protein, crude protein, ash and lignin. Conventionally , sludge has been disposed of by dumping and latterl y by Incineration . However, Its value has now become more wi dely recognised and schemes to use It as a synthetic so il , to produce compost, and even as a potential pyrolys is feed-stock have been investigated . However, pyrolysis alone is only of academic interest, due to relatively low nett energy production and the problem of large volumes
TABLE 8. SLUDGE PRODUCED BY DIFFERENT SEWAGE TREATMENT PROCESSES
After Metcalf and Eddy (1972). (Values transposed to metric) Based on a sewage flow of 385/1 per capita per day and 300 mg/I _suspended solids. Sludge Treatment process
Primary sedimentation Undigested Digested in separate tanks Digested, dewatered on sand beds Digested, dewatered on vacuum filters Trickling filter Chemical precipitation Dewatered on vacuum filters Sedimentation , activated sludge Undigested Undigested, dewatered on vac . filters Digested in separate tanks Digested, dewatered on sand beds Digested, dewatered on vac . filters Activated sludge Wet sludge Dewatered on vacuum filters Dried by heat driers Septic tanks, digested Imhoff, digested
6900 1480 2700
Dry solids I/c/d
3.35 1.66 0.25 0.36 0.85 5.89 1.61
1.10 0.54 0.16 0.12 0.28 1.94 0.55
7.85 1.56 3.14 0.47 .95
2.61 0.57 1.02 0.51 0.33
281 281 168
20 .1 1.50 0.31
7.3 0.54 0.08 0.34 0.19
270 270 270 97 83
of aqueous effluent produced. The process of anaerobic digestion, suitably upgraded with more modern techniques, is probably still the best simultaneous producer of energy and treater of sewage solids. TABLE 9. NUTRITIONAL VALUE OF ACTIVATED SLUDGE COMPARED WITH THAT OF FISH MEAL AND WHEAT BRAN Values as percentage dry weight. From Plllal et a/, (1967).
Constituent Organic matter Nitrogen Crude protein Fats Crude fibre Inorganic matter Calcium Phosphorus Vitamin 8.12
Activated sludge 67.8 6.0 37.5 6.0 9.8 32 .2 1.5 1.3 73.5*
Fish meal Wheat bran 73.7
55.7 8.6 1.2 26 .4 8.2 7.2
16.2 3.5 11 .4 5.5 0.1 1.1
*As ug/100g Sewage sludge dewatered to about 25-30% solids Is only just auto-combustive when Incinerated . In the U.S.A. about 25% of al l sewage sludge is Incinerated (1.3 x 106 ton In 1974) and by 1985 this Is expected to rise to 40% and 4 x 10 6 ton. However, whether these expectations are In fact reached, will probably depend on the cost of energy and air pollution legislation. Incineration of sludge along with refuse (in a ratio of 1:20) is more attractive, and sufficient extra heat may be produced then to provide economic power generation. REFERENCES: ANON. (1966) . Anaerobic Sludge Digestion - Manual of Practice No. 16 J. W.P.C. Fed. 38, (10, 1683-1702, 38, (11), 1840-1858, 38, (12), 1925-1943. ALLEN, G.H. (1969) A Preliminary Bibliography of the Ut/1/satlon of Sewage In Fish Culture. FAO Fisheries Circular No 308 . FRI/C308, Rome. ALLEN, K.R. (1950) . The Computation of Production In Fish Populations. N.Z. Sci. Rev. 8, 89. ALLEN, K.R. (1951) . The Horoklwl Stream: A Study of a Trout Populat ion. Fish. Bull. N.Z. No. 10 1-231. AUSTRALIAN GROUNDWATER CONSULTANTS PTY. LTD. & GUTTERIDGE, HASKINS & DAVEY PTY. LTD . (1977) . Proposal for Study of Wastewater
90 90 57 396 396
57 34 34 34 22 150 150 106 106 64 64 64 102 102 102 37 31
Perhaps for too long there has been little consideration of the value of sewage . It is interesting that its reuse potential is realised mainly in the arid countries, a trend which is likely to spread to more western countries as population rises and the cost of water pol lution prevention rises. Any energy shortage could acce lerate this trend. However, it should be possible to take th is one step further, and ful ly uti lise the valuab le components of sewage together with the often extensive resources allotted to its treatment. One such way would be to use the treatment and treated wastewater to produce liquid fue ls. The water and nutrients wou ld be used for the cultivation of energy crops such as cassava, sugar beet or corn . The treatment complex would then be a resource recycling site, with the water, nutrient and energy content of sewage being assimilated with solar energy and then recycled as a very versatile liquid fuel. An excellent example would be at Werribee . Vic ., where there is already an extensive irrigation area .
Reclamation by Ground lnllltratlon. At Boneo, Using Effluent from the South , Eastern Purification Plant. March. Reclaimed Water Comm ittee. BENNETT, E.R., LINSTEDT, K.D. and FELTON, J.T. (1974) . Rural Home Wastewater Characteristics. Proc. of the Nat. Home Sewage Disposal Symposium. 74-78. BESIK, F. (1973). Multistage Tower-Type Activated Sludge Process for Complete Treatment of Sewage. Water and Sewage Works . 120, (9), 122-127. BOYD, C.E. (1974). Utilisation of Aquatic Plants. In: D.S. Mitchell (Ed .) Aquatic Vegetation and Its Use and Control. Unesco, Paris. CALDWELL-CONNELL (1975). Report on Field Testing of Algae. Harvesting Process under Summer Conditions. Report to Department of Environment Housing & Community Development. Celdwell-Connell Enpineers Pty. Ltd., Melbourne. FAIR, G.M. & GEYER, J.C. (1954) . Water Supply and Wastewater Disposal. WI iey, New York. FAIR, G.M., GEYER, J.C. and OKUN, D.A. (1968). Waler Purification and Wastewater Treatment and Disposal. 2. WIiey, New Yorll. GUTTERIDGE, HASKINS & DAVEY PTY. LTD. (19716) . Planning for the Use of Sewage. Report for the Department of Environment Housing and Community Development. Canberra, 3 vols. May. GUTTERIDGE, HASKINS & DAVEY PTY. LTD . (1977a) . Strategies Towards the Use of Reclaimed Water In Australia. Report to Reclaimed Water Committee, Victoria . GUTTERIDGE, HASKINS & DAVEY PTY. LTD. (1977b) . Planning for the Use of Reclaimed Water In Victoria. Report to the Reclaimed Water .;ommlttee, Victoria. HICKLING, C.F. (1961). Tropical Inland Fisheries . Longmans, London. HICKLING, C.F. (1968). The Farming of Fish. Pergamon Press, London . LE CREN , D. (1969) . Estimates of Fish Populat ions and Production In Small Streams In England. In: T.G. NORTHCOTE (Ed .) Symposium on Salmon and Trout In Streams. Institute of Fisheries, University of British Columbia, Vancouver. MANN, K.R. (1965) . Energy Transformations by a Popu lation of Fish In the River Thames. J . Animal Ecol. 34, 253-275. METCALF & EDDY, INC. (1972) . Wastewater Engineering: Collect/on, Treatment, Disposal. McGraw-HIii, New York . PAINTER, H.A. (1971). Chemical, Physical & Biological Characteristics of Wastes and Waste Effluents . Ch. 7 In: LL CIACCIO (Ed.) Water and Water Pollution Handbook. Marcell Dekker, New York . PILLAI , S.C., SRINATH, E.G., MATHUR, M.L., NAIDU, P.M.N. & MUTHANNA, P.G. (1967) . Activated Sludge as a Feed Supplement for Poultry. Wat. Waste Trt. 11, 316-320 and 322. SCHMIDT, C.J., and CLEMENTS, E.V. (1975). Demonstrated Technology and Research Needs for Reuse of Municipal Wastewater. Environmental Protection Technology Serles , EPA-670/2/-75-038. U.S. Environmental Protection Agency, Cincinnati, Ohio. VALLENTYNE, J.R. (1974) . The Algal Bowl, Lakes and Man, Department of the Environment, Fisheries and Marine Science, Miscellaneous Special Publication 22, Ottawa. WESTLAKE, D.F. (1963). Comparisons of Plant Productivity. Biol. Rev., 38, 385-425. WITT, M., SIEGRIST, R. , and BOYLE, W.C . (1974) . Rural Household Wastewater Characteristics. Proc. of the Nat. Home Sewage Disposal Symposium. 79-88.
"MAJOR CITY WATER SUPPLIES" B.P. O'Connell, B.E., M.I.E.Aust. Chief Engineer and Manager, Department of Water Supply and Sewerage, Brisbane City Council Water has always been suspect as a carrier of disease . Throughout the ages , the waterborne diseases such as cholera, typhoid fever and the multiple dysenteries have taken their toll in tragic numbers . The virtual elimination of these diseases from water used for human consumption in the modern cities, has been one of the proudest achievements of the water supply industry . The protection of wells and watersheds, construction of water treatment plants to remove turbidity and colour (along with these many of the pathogenic organisms from the raw water) and finally the disinfection of the treated water by chlorination or other means, has meant to the City dweller the virtual elimination of waterborne disease. This achievement has been due in no small measure to the use of chlorine as a disinfectant in urban water supplies. All of these measures are under challenge. The spread of urbanisation, the lack of suitable timber and the requirement for recreation facilities, has meant that catchments may no longer be virgin but required for other purposes . The use of chlorine too, is being challenged for its part in the creation of compounds which may present some hazards to consumers . The International Standards for Drinking-Water published by the World Health Organisation states (page 9) -
"Water intended for human consumption must be free from organisms and from concentrations of chemical substances that may be a hazard to health. In addition, supplies of drinking-water should be as pleasant to drink as circumstances permit. Coolness, absence of turbidity, and absence of colour and of any disagreeable taste or smell are of the utmost importance in public supplies of drinking-water. The situation, construction, operation, ·and supervision of a water supply, its distribution reservoirs, and its system must be such as to exclude any possible pollution of water". In Brisbane these standards must be applied to a water supply system supplying 850,000 people in a semi-tropical climate. The Metropolitan Water Supply and Sewerage Acts, Part IV, Section 40, states "The Board shall as far as prac14
ticable afford and distribute to all persons entitled to receive it under this Act, a constant supply of pure water for domestic purposes in the prescribed manner". Measures taken to ensure that water distributed to its consumers complies with these requirements are as follows. SOURCES OF SUPPLY
The main source of Brisbane's supply is the Brisbane River. Water is impounded in the Somerset Dam and Lake Manchester, and released as required to flow 130 km and 22 km respectively to the weir at Mt. Crosby. Storage at the treatment works is small, being 2200 Ml against a maximum consumption of 771 Ml/d in 1976-7.
BRISBANE WATER~ST EM
t. i, ti., ,, •• ~ ......
,,_ u , tr vo>Htiu
100 to 1000 per ml. A count of 10 to 100 coliforms per 100 ml is normally obtained on a membrane filter. After heavy rainfall with consequent increase in surface run-off, these figures may increase one hund redfold . This level of contamination very early convinced the authorities of the necessity for disinfection. The intermittent use of chloride of lime wa - commenced in 1924; continuous chlorination using liquid chlorine in 1930, and chloramination in 1935. Samples for bacteriological examination are collected each shift from the raw water, sedimentation basin outlets, clear water storages, and from the outgoing trunk mains . Sedimentation removes 50-00% of the organisms. After filtration, a fully automatic chlorination unit doses a 4:1 ratio of Cl2 and NH3 to a set residual chlorine level. Bacteriological samples are collected each shift from raw water, sedimentation basin outlets, clear water storages and outgoing mains . The count is reduced to less than 10/ml and coliforms to less than 1 / ml. A chlorine residual of 1.2-1 .8 mg/I is normally sufficient for the distribution system . DISTRIBUTION SYSTEM
North Pine River Dam supplies 15% of Brisbane's water at the moment. It is a terminal reservoir from an unprotected catchment feeding direct to the treatment works. TREATMENT
Treatment at Mt. Crosby and North Pine is by chemical addition, coagulation, f locculation , sedimentation, filtration, correction to pH and disinfection with chlorine and ammonia . Characteristics of the treated water show an average of Turbidity 1 Jackson unit Colour 2 Pt/Co units Suspended Sol id s O mg/I Total Diss. Sol id s 350 mg/I pH 7.3 to 7.5 Due to the open nature of the catchment area and the use made of the Brisbane River above the Treatment Works, the raw water contains a moderately high concentration of bacteria. Total plate counts range from
Having introduced , a satisfactory water into the system, it must then be maintained in this state. At this stage the likely points of contamination are:a) the servici reservoir b) repairs to burst mains c) connections of new mains d) in situ cement lining of existing mains e) defective hydrants, etc., within the system . Thirty-four service reservoirs are used, varying from 0.5 to 90 Ml capacity and more 90 Ml storages are proposed . They pose a threat to water quality, due to dissipation of chlorine, possible pollution by birds and animals, and vandalism . Some years ago bacterial sampling upstream and downstream demonstrated this danger. All reservoirs had previously been roofed to avoid algal growths in the subtropical conditions with high nutrient levels, but protection against birds and rodents was not always ideal. The measures were strengthened , e.g. : stainless steel mesh replaced the old bird wire. Human access can be gained only over "man-proof" fences, up external entry pipes or by mean s of ropes, but the possibility still exists. The answer appears to be to construct reservoirs
with an integral concrete roof , with all entry ports accessible only by motorised ladder. To compensate for dissipation of chlorine and to counteract potential pollution, a policy of secondary chlorination of some of the storage reservoirs has been adopted in recent years. The first installations used liquid chlorine but the danger of vandalism led to the use of sodium hypochlorite solution. Tanks are safe storage and the metering pumps are rugged and relatively inexpensive. Where chlorine usage is large and security is adequate, liquid chlorine is used. The aim of the dosage is to restore the chlorine level to approximately that in the inflow. Extensive testing was carried out at each reservoir before arriving at the most satisfactory dose. Too large a dose results in the production of nitrogen trichloride and the consumer consequently receives the maximum amount of annoyance and the minimum of protection . Too low a dose simply wastes chemical because no significant protection results. Whereas the average trunk main chlorine residual is maintained at approximately 1.0 to 1.5 p.p.m., the average storage reservoir residual is 0.8 p.p.m. It is found that this level produces an average distribution residual of 0.5 p.p.m. MONITORING
To check on the efficiency of the primary and secondary chlorination, the City Chemist's Laboratory maintains 260 sampling points throughout the distribution area. These are grouped into trunk main , reservoir and distribution samples. Where possible, samples are collected by samplers who are especially trained for this work and carry out no other duties . They record the time of collection, temperature, pH and chlorine residual of the sample, plus any abnormality which comes to their notice. At present, sampling points vary from domestic taps to specially installed sampling cocks at all points . A programme of supervision and re-education of the samplers is undertaken to keep them aware of their responsibilities . to the Samples are returned laboratory as quickly as possible . Difficulties have been encountered in maintaining the samples at a low temperature . Ice boxes were used, but it was found that melting ice-water became heavily contaminated and led to contaminated samples. Dry ice or refrigerator "brick~" appear to be the answer to this problem. Samplers are now supplied with station sedans rather than utility trucks, and this has improved the keeping qualities of the samples and reduced the risk of dust contamination. On receipt at the laboratory, samples are tested with a total plate count and a coliform count by membrane filter on a suitable medium .
Particular care is necessary while service reservoirs are under repair. Replacement of roof structures leaves the reservoirs at least partially uncovered for many months at a time. Potential contamination results from dropping building material into the water, the use of workboats and rafts, illegal swimming by children, faecal contamination by birds and rodents and the growth of algae. To counter these contingencies, the chlorination rate is increased so that a residual of 0.8 - 1.0 p.p.m. is maintained and workmen are instructed to be as careful as possible . Frequent samples are collected from these open reservoirs to check the level of bacteria and algae and the concentration of chlorine, and visual inspections are made. When work is completed, the reservoirs are drained, thoroughly cleaned, filled with chlorinated water for 24 hours, tested bacteriologically and only reconnected when tests are satisfactory . A similar practice has been adopted when bringing new reservoirs on line. A new concrete reservoir may have a very high chlorine demand, reducing a chlorine residual from 10 p.p.m . to 0.5 p. p. m. in 24 hours, whereas an old reservoir may require only 1.5 p.p.m . The chlorine absorption is particularly noticeable, of course, in filling the first third of the reservoir as the floor surface is a very big factor. The most satisfactory practice is to add sufficient hypochlorite for one-third of the volume into the first foot of water, then continue filling . For structural reasons, the reservoirs are filled over three days, so chlorine levels can readily be checked . The water is released only after bacterial testing. Repairs to broken mains can involve little testing because of the time factor. Repair gangs have had to be educated on the necessity for cleanliness and hygiene. Practices such as using the main as a scour to drain the excavation trench must be rigorously eliminated. Education together with a thorough cleaning of new fittings is found to be satisfactory in preventing gross deterioration in quality. Such contam ination as does occur can then be easily overcome by the chlorine residual maintained in the system. New installations must be thoroughly cleansed and the procedure involves cooperation between construction maintenance and testing staff. Stringent instructions are issued to staff and a special sampling programme instituted for the testing of new work . The instructions state that all pipes and fittings must be stacked well clear of any possible contamination from sullage and must be thoroughly hosed out before leaving the Depot. Before laying, all parts must 1 be re-inspected and hosed , if necessary , to remove any foreign matter. After being laid, the main is scoured, charged with water containing 10 p.p.m. of chlorine , all valves and hydrants are worked, then allowed to
stand for 24 hours . The main is then scoured until chlorine cannot be detected above that concentration already in the system. Samples are collected from special ferrules inserted during installation . Very large trunk mains are swept clean , scoured and charged with water containing 50 p.p.m . of chlorine injected by a chemical feed pump. After standing and scouring, bacteriological tests are carried out prior to connection. In the event of tests proving unsatisfactory, the new mains may be rescoured and, if necessary, rechlorinated. The programme of in situ cementlining of existing mains poses time problems because consumers are disconnected for an average period of 26 hours. The contractof ' s primary aim is to insert a good lining as quickly as possible . Because of the large number of openings, contamination from sources such as septic effluents may occur, especially in wet weather. Precautions have involved the demonstration to Contractors of the dangers involved , insistence on the sealing of all open ends not being immediately worked on, chlorination of tools used in the process and the use of highly chlorinated water for the preparation of the cem . nt. Samples are collected as soon as possible after completion of the cement lining . CONCLUSIONS
Institution of this complete proprimary chlorination, gramme of secondary chlorination, enclosure of service reservoirs , and the thorough cleansing of all units introduced into the system , with the whole controlled by a rigorous scheme of, sampling and testing, has enabled the Brisbane authorities to cons istently maintain the treated product water within the requirement of the United States Public Health Servic~ Standard. It is considered that as far as practicable, the Revised World Health Organisation Standard for treated water is met . Although the Maintenance Engineer Water Supply is responsible for the quality of the water in the distribution system, the City Chemist is responsible for all aspects of water treatment at Mt . Crosby, and North Pine, and all sampling and analyses , bacteriological and chemical, throughout the system . The minimum water rate in Brisbane today is $65 .12 per year. Three quarters of the more than 220,000 consumer properties are rated on the minimum , so the actual cost to most of Brisbane's households is $1 .25 per week - or 18 cents per day . The price of a small can of Coca Cola is 22 cents. Due to the size of our operation , the cost of the protection of our supply, including the cost of all analysts, samplers, chemicals, etc. , is less than half a cent per consumer property per day . A small price to pay. 15
WATERBORNE DISEASE Dr. Peter A. Wood, Sen. Lecturer in Microbiology, Department of Paramedical Studies, Q. I. T. Introduction
Waterborne diseases, often in the form of a full-blown epidemic, have been common in the history of mankind from the earliest times . Medicos, engineers, microbiologists and chemists have made considerable contributions to the fight against these diseases , and the greatest achievements made in controlling their spread have been the improvements in methods of sewage disposal and the provision of pure water supplies. The danger of contamination of drinking water with crude sewage cannot be over-emphasized because it contains all the agents that cause Âˇinfectious disease in man - bacteria, viruses, protozoa, intestinal worms and so on. Of these, the most important to modern society are - cholera, typhoid fever, bacillary dysentery and infectious hepatitis . These are too often considered no longer a danger in our Australian way of life, but our complacency should be shattered by the repetitive occurrence of reports of outbreaks of just such diseases in our community. These intestinal infections share a number of important properties. 1. The human intestine acts as the major reservoir and source of all these pathogens . Hence, it has been the contamination of drinking water with human sewage that has been responsible for all reported waterborne outbreaks. 2. The infective dose in all instances is relatively small, being measured in the hundreds for the bacteria and but one infective vlrlon for hepatitis. Hence , one accepts that primary, secondary and possibly even tertiary treatment of domestic sewage drastically reduces the pathogenic load, but the only safe effluent will be one which is completely sterile. This of course is not feasible economically and very seldom warranted. 3. None of these organisms possess special adaptations such as spores or pigments which would protect them from the forces of stream purification . Hence, their survival in water is limited, although it will vary greatly with a whole host of parameters such as temperature, organic load, pH, light penetration, salinity, competition for food, predators and so on. 4. Possibly the most important property shared by these pathogens is their ability to produce asymptomless carriers i.e. people who show no outward sign of the disease but who sporadically shed large numbers of the organisms in their
faeces. This condition may persist for months and even years after contact with the disease agent, and it is these people in this modern age of fast transport that pose a constant threat of introduction of the disease to new areas. Description of diseases CHOLERA:
In its most severe form, cholera is an acute diarrhoeal disease characterized by the loss of massive quantities of fluid and electrolytes from the body . If it remains untreated , it may result in cardiovascular collapse and death in 1 to 2 days . The causative agent is a small , slightly-curved, rod -s haped bacterium called Vibrio cholerae. The species is divided into two slightly different biotypes - Classical and El Tor - both of which can cause the disease. Of the greatest concern to us at the moment is the El Tor variety , as it was this that was isolated from the Beenleigh area and is the one that is currently spreading around the world. It was first recognized in 1938 when it was isolated from Mecca pilgrims who were held in the El Tor quarantine station on the Sinai Peninsula, but it was believed to have originated in the islands of Indonesia. In the last 20 years there has been a spread north to Russia and China, west through India, the Middle East, the African continent and Europe, east to New Guinea and the Pacific Islands and now, it would appear, south to Australia. This El Tor variety is more resistant to the pressures of the environment and tends to cause much fewer cases of severe cholera than the Classical type. It is these two properties which are responsible in large part for the current r spread of the disease into new communities. El Tor acts rather insidiously in that it causes a high proportion of mild infections and, most importantly, a large number of asymptomatic carriers. These carriers may continue to shed the organism in their stools some 30 to 40 days after contact , and so, with the emergence of rapid air transport, we no longer can remain complacent to the possible presence of this organism in our community. It is here, it will continue to "hitch -hike" into the country with overseas travellers, and so we must protect our people by adequate and efficient treatment of sewage and drinking water. In the past we have tended to believe that cholera was limited to those developing countries with grossly inadequate sanitation, but please
observe our own community - how many of our homes are connected to a sewerage system? How many of them receive-on iap adequately-treated drinking water? How difficult would it be for a cholera organism introduced by a carrier to get Into a community's drinking water either by direct faecal contamination or by seepage from a septic tank? May I suggest that there are many areas where the potential for outbreak exists. I think it is important to realise that man is the only natural reservoir of the cholera organism and although there have been reports of the organism being shed by domestic animals in close contact with families suffering from the disease, their presence in these animals has been transient and persisted only as long as it was present in the household. Drinking water contaminated with human faecal matter remains the main vehicle of spread, but vegetables washed in such waters, and shellfish harvested from polluted areas have also been involved. Person to person contact is not normally a major means of spread . The organism, if swallowed, is highly sensitive to the acid secretions of the stomach, but should it reach the intestine, it will grow and multiply and secrete an enterotoxin which will propagate the onset of disease. It is well to note the conditions that exist in the intestine for it is these which will reflfct most closely those which will foster persistence of this organism in our environment. Firstly, the temperature is approximately 37Â°C and so lower air and water temperatures will adversely affect the organism ; secondly, the salty, alkaline liquids of the intestine, rich in organic matter, closely correlate with conditions that exist in highly polluted tidal estuaries and it is in these areas that the organism may persist for some 4 to 6 weeks before succumbing to the forces of self purification. Should the pH of the water be reduced from the alkaline side of neutrality (pH 8.0 to 8.5) to the acidic side (pH 5.5 to 6.0), viability will be greatly reduced. The organism does not produce spores or contain pigments which would afford added protection, and so one could expect a rapid die-off in clean streams or in sewerage plants . They are sensitive to chlorination (2-3 p. p. m., 10 min . contact) but may be protected by particles of organic matter if present. One of the major objectives in controlling an outbreak is to prevent the continual reinforcement of numbers in the water with more recent loadings from carriers or victims.
TYPHOID FEVER: The causative agent of typhoid fever is Salmonella typhi, a smal I rod-shaped bacterium, which inhabits the human intestinal tract. Characteristically the history of a case of typhoid fever reveals an onset of disease some 10 to 14 days after exposure to infection. The onset is usually insidious as the early symptoms are often vague . Diarrhoea is commonly absent, but abdominal tenderness, headache, fever and delirium become prominent. It must be remembered that this type of fever is in fact a septicaemic infection with widespread involvement of tissues throughout the body. In a small number of convalescents, the typhoid bacillus persists in the body for over a year and many of these persons continue to be carriers for the remainder of their lives . Besides these individuals , asymptomatic carriers may also occur, and so it is not difficult for the organism to be spread from a patient or carrier to other people via water, food or direct contact. The infection is usually brought into Australia by visitors to this country or by holiday makers returning from areas where typhoid fever is still endemic . The occurrence of typhoid fever has drastically reduced since water supplies have been subjected to filtration and chlorination , but there still remains an inherent risk in eating raw shellfish such as oysters or mussels that have been harvested from contaminated river estuaries or bays . The need to chlorinate waters used for cooling in the canning industry has been exemplified by the Aberdeen outbreak of 1964 in which canned meat was contaminated by river water which was sucked through "leaky" joints during cooling . The typhoid bacillus, like cholera, has no special adaptative measures to overcome stream purification. It is closely related to the accepted faecal indicator bacteria and exhibits a similar persistence and die away pattern . BACILLARY DYSENTERY: Bacillary dystentery is caused by members of the genus , Shigella, which like Salmonella are small rod-shaped bacteria. On a few rare occasions , epidemics have been traced to captive monkeys, but human cases and carriers remain the important source of infections . The symptoms of the disease may vary from a mild transitory diarrhoea to severe attacks accompanied by fever, vomiting and profuse , bloody diarrhoea. It is said that the prevalence of bacillary dysentery will reflect the hygienic standard of a country or a community , and hence it is often endemic in institutions and lower socioeconomic urban communities . Usually the disease is spread from hand to mouth, but there have been occasional epidemics recorded in which the cause of the outbreak has been
traced to water supplies. In these instances , chlorination had not been instituted or had been defective. Such water-borne outbreaks are usually spectacular in the Âˇ large number of people simultaneously infected , and in the speed with which they can be terminated when the water supply is adequately treated . The mild and often fleeting nature of the illness associated with Shigella infection frequently results in the person infected continuing to engage in his daily labour and leisure pursuits; hence he remains in circulation as a. dispenser of the casual organism . One important point emerges from a study of the outbreaks that have occurred and that is that a majority have been traced to a single infected individual whose excreta have been discharged , not to the sewerage system of a community , but to an individual cess pit, septic tank , well or drinking water supply . However, occasionally they have arisen from accidental breaks in water treatment systems , contamination of a well supply of flooding, inadvertant cross c onnection o f contaminated water pipes with potable water supply lines , or through sewer line seepage . Like V. cholera and S. typhi, the survival of Shigella bacteria in the water environment is limited by many ecological factors . The organisms are very poor competitors and are relatively sensitive to strong aeration and pH values which are neutral to slightly acid . Hence there is a rapid die-off Âˇ during passage through activated sludge . In an estuarine environment , shigellae were quite resistant to the osmotic effects of sodium chloride, but survival was dependent upon temperature in that it was greatly extended by low temperatures. Of particular note Is that the organism is easily controlled by chlorination. INFECTIOUS HEPATITIS: This di;sease is characterised by feve r, weakness, general "off-colour" , abdominal pain and jaundice and is caused by the infection of the intestinal lining of Hepatitis A virus . It is essential that one realises that viruses outside the living host are essentially dead - they can neither grow nor multiply - but are simply a small packet of nucleic acid within a bag of protein . Hence, their ability to survive in the environment differs markedly from that of bacteria . It is most unwise to assume that waters receiving a sewerage effluent will be free of hepatitis virus even if such waters are shown safe by bacteriological means . Normally, the acid secretions of the stomach and the proteolytic enzymes of the bile act as effective barriers to most viruses gaining access to the small intestine. However, hepatitis virus is an exception , and it is the most important human viral disease transmitted by water .
Many common source outbreaks of this disease have been traced to massive and sustained cd'htamination of water supplies with sewage, e.g . the 1955 Delhi outbreak involving some 28 ,000 cases . However, shellfish growing in contaminated waters and vegetables spray-irrigated with sewerage effluent are also often implicated. The practice of spray- irrigation may also create an aerosol problem in that the viral particles may be disseminated by wind over large distances in the fine water droplets. The viral particle is very small , being only some 30 nm in diameter, is relatively stable outside the human host, and is particularly resistant to chemical disinfectants, e,.g. it is 10 to 15 times more resistant to chlorine than most bacteria . On reaching the intestine , the viral particle will invade the intestinal lining but may take some 20 to 30 days to bring on the full onset of disease. In the meantime, the slightly "off-colour" infected person may be shedding mill ions of viral particles into the environment, and it is this stage of the disease which offers greatest opportunity for contamination and spread . The long period of incubation and the large number of mild cases make it difficult to trace the source of infection but an explosive outbreak would tend to incriminate the water supply. CONCLUSION
There are a number of indicators which could aid the linking of a disease outbreak with a polluted water supply. 1. Outbreaks due to po,lluted waters are usually explosive , because large numbers of consumers in the area of supply are exposed simultaneously. 2. The unidirectional flow of water from the catchment ~ rea to the consumer often provides an obvious link in the caÂˇuse and effect sequence. 3. The affected population can often be associated with a particular branch of the distribution system , or to the use of a particular source of supply while other sources remain uncontaminated . 4. When neighbour.Ing communities which are utilising the same food and milk supplies, but have a different water supply , escape the outbreak , suspect polluted water. Finally, it is to be noted that the recovery of a pathogen from water indicates that it is already circulating in the general population, and in sanitarily advanced countries such as ours, these diseases may often be acquired by routes other than polluted drinking water. The low proportion of waterborne infection in our country is a tribute to the effectiveness of our water purification methods, the isolation of water catchment areas from sewerage plant outfalls, the regular monitoring of our water supplies and possibly a large slice of "good Aussie luck". 17
THE EVALUATION AND UPGRADl~G OF EXI-STING TREATMENT PLANTS by J. L. Bristow, B.Sc., ARACI, AAIM . Partner, M. A. Simmonds & Bristow, Water and Wastewater Consultants, Brisbane
I. WATER SUPPLIES
PLANT EVALUATION Water quality standards are becoming increasingly stringent , particularly with regard to bacteriological quality. The World Health Organisation has defined prime standards for bacteriological quality and toxic constituents , but they have set dual standards for, constituents which affect potability i.e.: maximum desirable and maximum permissible concentrations. In Australia, the Water Resources Council have issued the Australian Water Quality Criteria, compiled by Hart , and the States have set legal standards . The need for upgrading an existing water treatment plant is more often one of improving its performance rather than its output . There are usually four stages which must be assessed .
structure . There are standard criteria available for comparison with the unit under test . The 'salt test' described by Camp and others is a valuable tool in pinpointing weaknesses in sedimentation tank performance . It provides data on the timing of the first trace to the outlet i.e. short circuiting and the time to maximum concentration - the average detention time. It is also possible to calculate the Dispersion Index and the 'efficiency of displacement'. The degree of 'tailing' of the salt indicates dead areas which trap the salt for long periods. Dye tracers are invaluable for following short circuiting systems, and fluorescein can be used to advantage. With the information above , it should be possible to determine if it is possible to modify the existing basin or if it' will be necessary to duplicate or enlarge the plant to cope with the flow rate~.
Chemical Addition and Flocculation
This is the first stage of treatment of the raw water. It is necessary to determine that the most efficient coagulant is being applied and at the correct dose rate . The coagulant must be homogeneously mixed with the water to ensure that all the water is treated . The coagulant must be effectively mixed so that all the colloidal particles are flocculated. The correct paddle speed must be selected to achieve the optimum result . Flocculating basins should act like mixing basins and yet , to perform their f unction best, they should have a plug flow. Older designed flocculation basins invariably mix too well and measurable volumes of water remain in the basin to mix with fresh water entering . A better design incorporates mixing paddles with their driving shafts parallel to the flow of treated water. The paddles provide good mixing but there is a definite plug flow effect for new water entering the flocculator. Sedimentation
Once the water has been coagulated, the floe so formed is removed by sedimentation. Sedimentation tanks are of two main types, horizontal flow and vertical flow . Upflow basins can be circular or square . Horizontal basins are invariably rectangular, unless they have been adapted from some other 18
Filter performance will be judged from past performance results in terms of effluent quality, length of run and the pattern of head-loss build-up . This information should be coupled with informat ion on the filter sand-bed condition, both before and after' backwash, the percentage of mudballs present , the quality of silt and the sieve analysis . In the case of short filter runs, a microscopic examination should be made of a surface scraping from the filter bed to show the presence, or otherwise, of filter clogging algae or diatoms . Sterilisation and Neutralisation
This final stage of treatment ensures the chemical and bacteriological quality of the water. Without adequate sterilisation , it is not possible to ensure the bacterial quality of the consume(s' supply . Without adequate pre-treatment, it is more difficult for the chlorine to achieve safe sterilisation of the water. The chemical flocculation of the water and filtration both remove a large percentage of the bacteria and probably viruses, and the fewer organisms remaining in the filtered water , the more effective is the sterilisation stage .
The chlorine , besides maintaining a 'safe water', also helps to control slime growths and oth er organisms which appear in the water su pply from time to time . The presence of even minute amounts of iron and/or manganese in a supply can result in difficult dirty water can be probl e ms . Th e metal precipitated by bacteria which utilise organic compounds naturally present in the water, and which hold the iron and manganese in solution . In this way, the bacteria can concentrate the highly coloured hydroxides and produce dirty water problems of some magnitude. pH control or neutralisation simply makes the water less corrosive to both the steel and concrete structures in the distribution system . It consists of saturating the water with respect to calcium carbonate so that the tendency is to deposit calcium carbonate on these surfaces, instead of corroding or attacking the surfaces in some way . In some cases , the addition of alkali for pH correction may increase corrosive problems ih the distribution system . Where the pH value is above 8.3, and the water has a certain chloride: temporary hardness ratio , meringue dezvicification can become a severe problem. This form of corrosion produces enormous volumes of zinc hydroxy carbonate from certain brasses and galvanised components in the distribution system. Once this form of corrosion is started, it is difficult to stop even when the pH is reduced below 8.1 . UPGRADING OF PLANTS
When the data on plant performance has ceen collected, it should be compared with conventional design criteria, and a critical evaluation made to determine the loading on the plant . When considering the different ways of upgrading the plant in question, there is a certain amount of logic and commonsense required in making the final decision . Generally, decisions for upgrading water treatment plants are fairly straightforward . Once it has been established that the plant is performing as efficiently as possible then the quality of the final product determines whether the plant will have to be enlarged or not. There are one or two innovative measures which can allow
the capacity to be increased without complete duplication of the plant. The success or otherwise of these procedures may depend on the original design and on the degree of turbulence Âˇ created with the increased flow. Flocculation Laboratory and plant tests will establish the minimum time for flocculation. It is not possible to get proper clarification if the detention time is too short. Extra capacity can only be provided by enlarging the flocculation basin . PCI in England are investigating methods of achieving proper flocculation by velocity mixing through orifices . This technique will reduce the energy requirements for flocculation and another side benefit could be reduced flocculation time. There are no details of the process available at this time . Sedimentation Sedimentation tanks often perform poorly because of floe carryover, due to turoulence resulting from either temperature variations or poor design. With the advent of tube settlers and laminar platesettllng, it ls often possible to upgrade an upflow sedimentation basin by increasing t he rate of rise to as high as 6 m/hr. Inclined tubes will help to improve the settling performance, provided it is possible to eliminate turbulence and directional currents in Âˇ the lower portion of the basin . The use of these techniques also requires that flow rate increases be confined to small increment increases (less than 10% when related to the total flow) . Larger flow changes produce shockwaves which upset the settling characteristics of the basin, and result in poor quality settled water . Another method of upgrading is to consider converting the sedimentation basin to a dissolved air flotation unit. Overflow ratings using OAF can be greatly increased, in fact one manufacturer floats his 'floe' in the filter, filtering the water and removing the coagulated particles in the one vessel . Filtration Filter rates generally are fairly conservative , and many plants are designed to filter at 100 l/m2 /min. (2 gpm / sq . ft.). Filters will perform quite well filtering settled water with less than 5 mg / I suspended solids up to 150 l/ m2/min. (3 gpm/sq . ft .) and , if the settled water contains less than 1 mg/ I of suspended solids , it could be rated up to 220 I/m 2 /min . (4 .5 gpm/sq . ft.), and still produce acceptable quality water. For the same water quality, the length of filter run is basically proportional to the amount of water filtered . If the filter rate is doubled the length of run is halved. The Brisbane City Council were forced to use high 2 filter rates up to 220 I/m /min during the 1950's when the demand exceeded the design capacity of the filters . This was achieved without consumer complaints .
II . WASTEWATER TREATMENT QUALITY
With wastewater . treatment, the standard of effluent is not clearly defined . That is to say , standards are often set after giving due con sideration to the volume of the discharge, the dilution , and its effect on the receiving water . For domestic sewage, the most common standard which has been used is the British Royal Commission Standard for Sewage Disposal which was set in 1913. In England, they found that most sewage discharges were diluted at least 8 times In the receiving water . In this situation , th e authorities were prepared to accept an effluent quality measured in terms of two pollutants, BOD5 less than 20 and SS less than 30 . Since that time, it has been shown in practice that, except in special circumstances , this effluent standard has not greatly affected the environment. Today, regulating authorities require higher standards of effluent, particularly where the 8:1 dilution factor cannot be achieved . Again , there is a need for moderation . The trend in the United States was towards zero discharge to try and eliminate pollution of the environment. The authorities are beginning to realise the enormity and cost of such a task . The cost of treatment should always be taken into account , in terms of economics and the reliability of the process involved. PLANT EVALUATION
Some of the tests described above for a water treatment plant can be used when it comes to evaluating a wastewater treatment plant . However, most wastewater treatment plants make use of biological processes which have to be evaluated in a different manner. Primary and secondary clarifiers can be subjected to a salt test to check on th eir performance, but generally, wastewater treatment processes can be evaluated just as effectively by testing the raw untreated wastewater and the effluents from the various stages of treatment. The BOD5, suspended solids, pH and conductivity of all these samples will give an immediate indication of the efficiency of each unit stage . These performance detai Is can be.compared against the design criteria for the plant and , where any marked difference exists, further investigation and testing will be required to pinpoint t~e problem. In wastewater treatment, the location of the particular reason for poor plant performance is often speeded up by a visual inspection by the plant operator or .a qualified person . Once the cause ha:s been established, then it is relatively easy to suggest remedial measures. However, in some cases, the problem is not immediately obvious and an 'in depth ' study of the plant may be necessary.
Wastewater Flows When it is not immediately clear why the plant is not performing, or where it is suspected that design flows and BOD5 are being exceeded, it will be necessary to gather additional information. If flow-recorders are not available or are not operating , this information must be obtained by other means. Either by measuring pumping hours and pump flow or by installing a vee notch or rectangular weir and recording the height over the weir on a continuous basis . Measurements are required for at least 24 hours and, preferably, for at least one week . From this , peak and minimum flows can be observed and average daily flows calcu lated. Having established the pattern of flow , it may be necessary to collect snap samples at particular times, or composite samples, to determine the strength of the wastewater in terms of BOD, solids or any other suspended parameter which is known to be polluting the wastewater. The next step is to use the maximum and average flows recorded to evaluate theoretical detention times , weir overflow rates and/or upflow ratings, so these may be compared with conventional design criteria. Activated Sludge Plants
In the case of activated sludge plants, it is essential to determine not only wastewater flow and strength but detention times , suspended solids concentration of the mixed liquor and recirculation flow rate. The flow, BOD 5 and MLSS will establish the loading (F/M) on the plant. The loading and the recirculation rate will indicate the likelihood of achieving the required effluent quality. Dissolved oxygen concentrations of Jhe mixed liquor at various times and In various places in the aeration tank are essential. The SVI, or its equivalent, should be calculated to determine the settleability of the activated sludge . The activated sludge should also be examined under the microscope to determine what bacteria and protozoa are present . Activated sludge contains a specialised community of organisms whose dominant members are heterotrophic bacteria and saprobic protozoa present in the sludge floes and/or dispersed in the liquor (10). The protozoa feed on the bacteria, keeping their population young and healthy. Their presence is essential to the production of a high quality effluent. They only thrive under quite specific conditions of both pH and dissolved oxygen , and therefore their environment must be carefully control led . A well designed plant usually allows a wide range of operational conditions . An experienced person can often adjust these and improve the plant performance . However, it is necessary to obtain the 'feel' of the plant to know just what will happen when adjustments are made. 19
It is possible to gauge the degree of aeration and treatment with biological processes, by measuring the various forms of nitrogen present . Particularly , with sewage the nitrogen is normally present as ammonium nitrogen. In a fully aerated plant with adequate detention , the ammonia will be fully oxidised to nitrate. Over-aeration can produce very poor effluents because of bulking , in just the same way as underaeration. Care must be taken to distinguish between the two . It is also possible to arrange for nitrogen removal by denitrification of the nitrate to nitrogen gas. This is achieved by creating, alternately, oxygen rich and oxygen deficient conditions. Biological FIiters
Poor performance of blologlcal filters (trickling filters) can be attributed to a number of causes . The operator should make sure that the distributor system is functioning .properly . If all the flow is going through one section of the filter, very poor results will be observed . If any one section of the filter is allowed to dry out, the biological filter slimes, the 'heart of the system', will cease to be viable and again poor performance will be the result . Other less obvious problems can arise . Filter flies - Psychoda - can often reach plague proportions . Their larvae eat the biological slimes and reduce the efficiency of the filter accordingly . A careful inspection of the stones in the filter and the nearby surrounds should pinpoint this type of problem. Unpleasant odours sometimes emanate from the filter . This can be as a result of poor performance due to Psychoda fly or as a result of overloading of the filter, insufficient recycle flow and a number of other causes . Recent research seems to indicate the main cause is related to oxygen flux, that is the availability of oxygen for the biological flora of the filter. Oxygen deficiencies, even within the filter slimes, can produce odours and , as yet, not a great deal is known about the mechanism which determines whether the filter will smell or not. The biological filter also has its own specialised group of organisms somewhat different to the activated sludge groups. There are similar organisms but different species which adapted to the different are environmental conditions of the biological filter. UPGRADING OF PLANTS Wastewater Flows
The difference between wastewater treatment and water treatment is one of control. It is possible to regulate the flow of water to a water treatment plant. With wastewater, it is received at the plant and , unless there are holding basins, what comes through must be treated and processed . Equally, when there is no flow, there is nothing to
treat . This creates problems with biological treatment processes . With sewage in the larger towns and cities , there is a fairly cqntinuous flow, except between 1.00 a.m . and 5.00 a.m . , with two peak flow periods between 8.00 a.m. and 9.00 a.m. and 6.00 p.m. and 8.00 p.m. Very often , insufficient attention is paid to the periodicity of the wastewater flow, when designing 'packaged' activated sludge plants. The designer often considers the total daily flow and the BOD of the wastewater and designs the plant accordingly . The fact that the wastewater is produced over an 8 hour period is overlooked. Another oversight is the existence of a wet well or collection pit and pumps required to periodically pump the wastewater to the plant. The normal flow rate of the pump is often so great that it will pump a dc1y's flow in an hour. Where these pumps are installed to meet a future need, it would be better from a treatment aspect to install smaller pumps and add to the number used as the inflow increases. The pump capacity should be compatible with both the aeration tank and clarifier design . Wastewater Composition It is very unwise to design or supply a wastewater treatment plant without some indication of the composition of the wastewater. The designer is often in a difficult situation, being forced to design a plant for a factory which does not exist. It is not possible to get a sample of the wastewater! In fact, it is possible to obtain equivalent samples from other plants. Some attention to detail is necessary, to make sure the sample is equivalent and, in fact, it may be necessary to combine different effluents to produce the required wastewater . A miscalculation of the strength of the wastewater can result in overloading in the plant, due to a deficiency of oxygen or, due to an excessively high F/M ratio which makes it difficult to achieve the required effluent quality. Efficiency of Treatment Another area often overlooked is the treatment efficiency required of the plant to reduce the applied BOD to the required effluent quality . Normal sewage had a BODs /SS values of 250/350 mg/I. The effluent standard required is normally 20/30 mg/I. To reduce the raw sewage in one stage of treatment would require 92% reduction of BOD and suspended solids. Small packaged plants are often required to do this and , consequently, should allow quite low loading rates (F/M) . High efficiency units require close and careful control usually by a qualified and skilled operator. If the operator's time is divided between other duties then lower efficiencies of treatment are required to reduce the operator's responsibility. This usually means two or more stages of treatment.
There are also processes such as biological filters wh.4ch have a lower maintenance requirement than , say , activated sludge. When higher quality effluents are required , e.g. BOD/SS = 10/15 mg/I, then the reduction required increases to 96%. If the wastewater comes from a caravan park or a food serving establishment then the applied BOD can increase to 400 mg/I and more. The percentage reduction then increases still further. Efficiencies of this order are very difficult to attain . There must be very conservative loading rates if these plants are to operate effectively . It is preferable to avoid these high BOD reductions and opt for a multistage form of treatment. "' It should be remembered that anaerobic processes are efficient both in terms of BOD reduction and in terms of energy requirements . Careful design is required to provide safe operation, control odours and to provide versatility in plant operation. Anaerobic methods are most suited to the treatment of very high BOD wastewaters. The treatment efficiency of aerobic processes is related to energy costs . The greater the efficiency required , the higher the power costs. Plastic media filters are commonly used as 'roughing filte(s ' to reduce very high BOP's to more treatable levels . There can be odour problems with this form of treatment. Activated sludge is a highly efficient process and uses more power energy than the biological filters. Increasing the Capacity of the Plant Having progressed this far, it now requires a decision as to the best way of upgrading the plant in question . It has been assumed that the previous investigation has shown an overload situation. ~ Should the plant be duplicated? Can the extra capacity be supplied by building in an extra stage of treatment? What form should this treatment take? These are the difficult decisions to take . It can be made much easier when the designer is familiar with the different treatment techniques available and their various advantages and â&#x20AC;˘ disadvantages. Examples probably serve to provide the best illustration of the practical situation. EXAMPLES Treatment of Wastewater from a Tourist Facility A packaged activated sludge treatment plant was provided to treat this wastewater. Because the services provided were akin to the domestic household situation, only on a much larger scale, the designer assumed the applied wastewater was similar _ to domestic sewage . A single stage planf was provided to treat up to 9 m3 /d . (2 ,000 gpd) with a maximum BOD of 300 mg/I. Suspended solids were
considered to be of the same order of concentration . Because of the possibility of grease in the wastewater, a large grease trap was install ed on the kitchen discharge line. The effluent quality sought was BOD/SS = 20/30 mg/I. An investigation of the untreated wastewater showed that the design flow did not exceed actual flows, but that the assumed BOD strength of 300 mg/ I was gross ly in error. The average daily BOD was 1,850 mg/I with peaks up to 2,600 mg/I. The flow was mainly confined to a six hour period each day and , seasonal ly , the flow varied according to the number of tourists visiting the area . This is the worst possible situation for an activated sludge plant. The variation in load, both during the day and seasonally , would make it difficult to feed the act ivated sludge biota even ly to produce the maximum efficiency of treatment. The performance of the plant was really amazing. A reduction in BOD from 1,850 to 100 mg/ I represents a 95% removal rate. The designer inadvertently was asking for a 99% efficiency with an F/M value of 0.25 Kg BOD per Kg of MLVSS. In such a situation the F / M ratio would have to be less than 0.05. One proposal for alleviating this situation was to install a fully mixed holding tank prior to a biological filter as a first stage of treatment . This was to be followed by the activated sludge plant and a final lagoon to act as a buffer and accommodate variations in plant effluent quality, and the possibility of occasional plant breakdowns . This proposal was to cost substant ially more than the original installation. A form of anaerobic treatment was suggested, followed by disposal of the wastewater in absorpt ion trenches . The proprietor decided to try this anaerobic treatment method and has been very satisfied with the plant operation to date but no samples have been tested to check its performance . Treatment of Wastewater from a Take-away Food Complex
A packaged activated s ludge treatment plant was provided to treat this wastewater. Again, the wastewater from this complex was considered to be equivalent to domestic sewage with a BOD and SS of 300 mg/I. After problems of getting the plant to perform to the stipulated requirements, samp les of the untreated wastewater were co ll ected, and an analysis showed that , while the suspended solids were within the specif ication requirement, the BOD was much higher and about 550 mg/I. This plant was required to produce an effluent of BOD/SS equal to 15/25 mg/I which represents a 97% removal eff iciency . While the plant was generally capable of supp lying sufficient air to treat the wastewater
load , it was operating under difficulties . The wastewater fed to a wet well from where it was pump~d to the treatment plant. The fina l c larifi er was designed to handle a continuous flow of 25 m 3 /d or 17 .5 I/min. The wet well pump had a capacity of - 225 I/min . more than eight times the design capacity. If the pump operated for more than 3 - 5 minutes , solids were lost from the clarifier in the eff lu ent. An hour meter established that the pump worked 20 hours per months, that is less than one hour per day . Init ial ly , the electrodes were set so it pumped once per day. The situation was improved somewhat by adjusting the electrodes so the pump worked no more than 5 minutes per cyc le. The plant was operated successful ly for limited periods but continued to perform poorly because of an inexperienced operator. The problem · · was eventual ly so lved when the sewerage was extended and the complex was connected to the sewer. The packaged plant was shut down . A sat isfactory but disappointing end to a difficult problem . Assessment of a Pasveer Ditch Treating a Hi_gh BOD Wastewater
The wastewater had been treated for a number of years using a Pasveer ditch. There has been a gradual increase in the applied wastewater flow and the plant effluent had gradually deteriorated . An eva luation of plant performance was made and, at the same time , the daily wastewater flow . was measured. The plant was originally designed to treat the wastewater with a load equivalent to a population of 500 persons. It was now receiving a load equ ivalent to 2,500 persons . The investigation showed the average BOD,,5 was 700 mg/I with peaks to 1,900 mg/I during the morning . The dissolved oxygen concentrations in the aeration zone were almost not detectable. The effluent quality averaged BOD5 100 mg/I with peaks to 135 mg/I, a truly remarkable achievement . This represents an average reduct ion of 85%. To achieve an effluent BOD:SS of 20:30 mg/I, suitable for discharge to a river, the plant capacity must be increased 5 times. The best proposal seems to be a two stage process, with biological filters as the first stage, followed by an amp lified pasveer ditch system . The biological filter would be designed to reduce the applied BOD of 700 mg/I to 240 mg/I a 65% reduction . With this proposal, the ex isting Pasveer ditch would only need to be doubled to handle the present flow. Calculations indicated that the BOD would then be reduced to 15 mg/I. The load ing of this stage would then closely approximate loads being applied to other Pasveer ditch installations. The overall reduction required would then be spread over two stages of treatment.
Th is paper attempts to show that upgrading and improving plant .performance is not a simple procedure. It requires an in-depth study of the existing situat ion. It is advisable to consider treatment methods used in simil ar situation s and to discover how effect ively they operate. It is then necessary to decide which treatment process will be most effective in overcoming the existing problem , that is to say whether to en large all existing units or to add additional treatment processes . All the possibilities must be 'costed' to determine the best choice . The costs should include both ca . ital costs and operating costs and the client should indicate his preference for either high capital cost with a low operating cost or vice versa. In today's economic climate, it is difficult to know which is more preferable. The effectiveness of the proposed treatment should then be pilot plant tested to pinpoint any treatment problems caused by the particular wastewater composition and to confirm projected BOD removal efficiencies. Most reputable overseas industrialists and equipment suppliers would consider a pilot plant investigation an essential prerequisite to the successful installation of a wastewater treatment plant. The cost of a pilot plant can be regarded as an insurance against wasted expenditure on a 'white elephant' . ACKNOWLEDGEMENTS
The author wishes to thank Mr. Alan Simmonds who provided valuable help, information and advice during the preparation of this paper. REFERENCES
WORLD HEALTH ORGANISATION, International Standards for Drinking Water, 3rd edition 1971. AUSTRALIAN WATER & WASTEWATER ASSOCIATION SUMMER SCHOOL - CANBERRA 1973. Water and Wastewater Treatment. HART B. T. A Compilation of Australian Water Quality Criteria AWRC. Technical Paper No. 7 1974. KLE IN L. River Pollution Vol. 3 Control 1966. Butterworths . AMER ICAN WATER WORKS ASSOCIATION INC. Water Quality and Treatment 2nd editio n 1950, 3rd edition 1971. SIMMONDS M.A. Various Reports on ,Salt testing of Sedimentation Basins at Various Water Works in Queensland. TURNER M.E.D. Influence of Water Composition on the Dezincification of Duplex Brass Fittings Proc. Soc. for Water Treat. & Exam. Vol. 10 1961 Part 2 pp 162-79 . INTERNATIONAL ASSOCIATION FOR WATER POLLUTION RESEARCH POST CONFERENCE COURSE BIRMINGHAM 1974. Design Aspects of Biological Treatment. BLISS P.J . Principles of Biological Wastewater Treatment Symposium for Packaged Wastewater Treatment Plants. School Civil Eng. Uni. of NSW January 1977. CURDS C.R. & HAWKES H.A. Ecological Aspects of Used Water Treatment, Volume 1 1975 Academic Press. SCHROEDER E.D. & TCHOBANOGLOUS G. Mass transfer limitations on trickling filters JWPCF Vol 48 April 1976 pp 771 -75 .
AUSTRALIAN POLLUTION CONTROL SYSTEM STUDIED WORLDWIDE An Australian designed system . to control dust pollution in coal handling facilities is under study by Australian and world authorities . The system , now in successful operation at the new Port Waratah coal loader complex in Newcastle, has resulted in significant reduction of air pollution levels normally associated with such plants. It is likely to be instituted at other Australian coal handling facilities and overseas . The system, devised by consulting engineers Docker and Smith, and Planner West and Partners, uses a series of chemical sprays to form a biodegradable crust on coa l stock piles . The chemica l treatment is supported by a stream of water sprays which reactivate the crusting process if the coal surface is opened up during recovery for load in g into ships. The principal in charge of the research and development team (Mr. Ted West) said investigation had revealed that the trad itional method of watering down coal stock piles increased the likelihood of dust pollution. He said water alone tended to bring coa l fines to the surface , releasing them to the air as the pile dried off . The concept of introducing a micro-agg lomerating chemical to the coal as it travelled on conveyor belts from the receiving station to open air storage had proved highly successful. Targets for air pollution control had been met and future targets were expected now to be feasible. The Port Waratah spray system is designed for flexibility of operation . It can be controlled manually or programmed to operate automatical ly when wind velocity exceeds predetermined rate . Mr. West said the surfactant chemical used to control dust levels did not harm the stored coal in any way .
MULTI-RANGE CHLORINE ANALYZER USES UNIQUE SOLID-STATE PROBE Novel new probe in DEL TA Scientifi,c's Model 2124 Chlorine Analyzer measures true sanitising power, because it responds to the various chlorine forms in direct proportion to their eff iciency as disinfectants. It provides fast and accurate tests in water supply, sewage and pollution contro l , industrial process and waste treatment, as well as swimming poo l and coo lin g tower water. The Model 2124 eliminates the comparator colour guesswork of matching . There are no operating costs because it needs no reagents . It covers ranges O - 1, 0 - 5, 0 - 10 ppm; can be adjusted to O - 0.5 and O - 20 as well. Accuracy of Âą 1 % full scale can be
More than 8 kilometres of Hardies Asbestos Cement pipe has be,en laid throughout the Port Waratah complex to feed a dust control spray system now under study by world authorities.
ma in tained even for wastewaters, even if intensely coloured or turbid . Various cable lengths available. Analyzer can be used anywhere, in laboratory or plant as well as in field. Recorder output is provided.
UNISEAL DECOMPOSITION VESSELS With Uni sea l, rapid quantitative acid and alkali pressure decomposition, digestion and/or dissolution of organic and inorganic materials can be achieved within 10 to 120 minutes at temperatures of 110-180Â°C and pressures of up to 1200 psi. It is this pressure build-up within the crucible wh ich accounts for the speed with wh ich comp lete disintegration takes place , even of compounds most difficult to decompose by other means. Unisea l is made of Teflon-lined
stainless steel. In countless operations it takes the place of expensive platinum ware , which has hitherto been mandatory for the digestion, decomposition , and dissolution of many substances. Uniseal's major advantage over more expensive platinum crucibles, dishes and boats is that undesired side effects such as contamination, reduction and alloying are avoided and volatilation losses are eliminated. , Uniseal 's dimensionally optimised Teflon-Teflon sealing area provides a simple yet ideal means of preventing volatilisation ~sses . The removable pouring spout minimises the risks of spillage and contamination during the transfer of the cup's corrosive charge . Moreover, the Teflon spout, snapped to the periphery of the crucible's rim, facilitiates safe, easy and quantitative transfer of the decomposed sample solution without the need for removing the Teflon crucible from the steel jacket. For further information on these two products , contact JOHN MORRIS PTY. LTD., P.O. Box 80, CHATSWOOD, NSW, 2067. Telephone: 407-0206 JOHN MORRIS PTY. LTD ., 9A Osmond Terrace, NORWOOD, S.A. 5067. Telephone: 42-5809 JM SCIENTIFIC PTY. LTD ., 2A Beaumont Street, VERMONT, Vic . 3133. Telephone: 873-2711 JM SCIENTIFIC PTY. LTD. 50 Campbell Street, BOWEN HILLS, Old. 4006. Telephone : 52-4072
CONFERENCE CALENDAR International Conference on Developments in Land Methods of Wastewater Treatment and Utilisation.
INTERNATIONAL WATER SUPPLY ASSOCIATION
KYOTO CONGRESS 2nd - 6th OCTOBER, 1978 A programme covering all aspects of water supply is being arranged. Further enquiries at this stage may be directed to any of our Federal Councillors, who have received a draft programme .
Organised by International Association on Water Pollution Research and University of Melbourne OCTOBER 23rd-27th 1978
I.A.W.P.R. 9th INTERNATIONAL CONFERENCE STOCKHOLM,SWEDEN 12th-16th JUNE, 1978 Themes: Advanced Wastewater Treatment Sludge Treatment Pollution by Urban Run-off Studies of Receiving Water
44 Koornang Road , Scoresby 3179 ~
Purpose of the conference
The use of land for the disposal of domestic, agricultural and industrial wastewater has been practised for many years. Recently, interest in these methods has intensified due to their generally low cost and energy requirements.
Telephone 763 8988
BOBY ANALYTICAL LABORATORY SERVICES
Developments and investigations are establishing much better understanding of the capabilities and limitations of these methods. The Melbourne and Metropolitan Board of Works has long-term experience with a variety of low-cost land processes , and investigations are currently being undertaken throughout Australia . The conference will provide a forum for (liscussion for those engaged in research concerning such processes and those for whom their adoption would appear appropriate .
Co Sponsors Australian Water and Wastewater Association Asian Regional Division of International Association of Hydraulic Research The Melbourne and Metropolitan Board of Works The University of Melbourne The Commonwealth Scientific and Industrial Research Organisation Division of Chemical Technology
Pettigrew Engineering Co. Pty. Ltd. Pollution Control & Water Treatment Engineers For Full Turnkey Projects 34 Reginald Street, Rocklea . 4106 Telephone: 275-3322 -
ALLAN PETTIGREW CONSULTANTS PTY. LTD.
Consultants in Pollution Control & Water Treatment P.O. Box 94 - ROCKLEA 4106 TELEPHONE : Private 200-1176 Business 275-3322
The A~~urn1 Aquasieve
For fibre recovery and pollution control • • • • • •
Reduces sewered waste and .. water pollution Recovers reusable solids to increase total product utilisation Requires minimal maintenance Rapidly pays for itself Installs easily in confined space~ Reduces capital outlay and operating costs
We are more than willing to demonstrate this unit to you . Ring, write or call personally - let's talk.
ANZIEL PTY. LTD. 3 Bowen Crescent MELBOURNE. 3004. Australia. Telephone 267-1333 Telex 31-308
32 Hastie Avenue MANGERE, AUCKLAND, NEW ZEALAND. Telephone 633-969 Telex NZ-2473
In Mechanical, Process and Biological Engineering Mechanical Engineering Grit removal plant Screening press and bagger unit Circul ar and rectangular sedimentation tank scrape rs Sludge consolidation tank thickeners, mixing tank stirrers Sludge drying bed mechanical lifters Sand bed lifters
Process Engineering Thermal and chemical sludge conditioning plants TC Incinerator for screenings Multiple hearth , fluidised bed, rotary drum slud ge incinerators Static grate incinerator Dissolved air flotation Carbon regeneration and absorption systems
Biological Engineering Standardised activated sludge plant for small populations of up to 20,000 persons Extended aeration plant, Aerobic sludge digestion. Diffused air activated sludge plant. Automatic control systems for activated sludge plant
.._, HAWKER SIDDELEY WATER ENGINEERING A di v isio n o f Hawker Siddel ey Bru s h Pty . Ltd .
Vic. 262-284 Heidelberg Rd., Fairfield, 3078. Tel. 489 2511 . i'lS.W. 12 Frederick St., St. Leonards , 2065. Tel. 439 8444 . QLD. 193 Mary St. , Brisbane, 4000 . Tel. 221 2155. W.A. 2 Ferguson Street , Kewdale , 6105. Tel. 68 7022 . N.Z. Goldfield, Takapuna. Auckland 9. Tel. 44 5294 . Hawker Siddeley Group supplies electrical and mechanical equipment with world-wide sales and service. Agents for Hawker Siddeley Water Engineering Ltd . (Templewood Hawksley Activated Sludge .)
MARTEK DIGITAL WATER QUALITY ANALYZER/CONTROLLER for multiparameter measurement and control and water and wastewater.
The Mark VII is a reliable portable Instrument for undertaking spot-tests, vertical profiles through water columns, bloassays, bore hole surveys, and long term measurement of water samples aboard floating laboratories, in water treatment and waste water facilities. It can also be used for In-situ measurements in water bodies such as rivers, reservoirs, ponds, lakes, coastal and inland waters, and sewage and industrial plant effluents. • Monitors up to four out of eight interchangeable water quality parameters and will control two parameters. • Accuracy ±1 % of full scale. • Controls - ON/OFF with single or dual set points; adjustable dead band ON/OFF; and proportional control. • AC or DC power operation with Internal rechargeable batteries. • Portable or installed, unattended use. • Rugged, splash-proof construction.
SELBYS SCIENTIFIC LTD.
New lab nephelometer! • • • •
EPA [USA] Approved Low Cost - $646 Direct Digital Readout Recorder Output
Monitek 's new Model 21 lab nephe lometer makes EPA- required turbidity measurements easy, fast and positive. You just load your sample, select one of three turbidity ranges (0-2 , 0-20, 0-200 N.T.U.) wi th a front panel switch, and read the value on a 2½ digit LED display-with 0.01 N.T. U. reso lution. In addition , the recorder output gives you a source of precise data for monitoring trends and rate changes , and for subsequent analyt ica l work. In short, the Monitek Model 21 is the most practical way to make fast, accurate turbidity measurements that satisfy the EPA. For details and a demo, ca ll or wri te.
Dun rose [S] Pty. Ltd. 763 HIGH STREET, KEW EAST 3102, AUSTRALIA Sydney TT13333 Telephones: Melbourne 859 6871
I rJl[)rJITEtf I MONITEK, INCORPORATED
"A Complete Range of Laboratory and in-line turbidity and sludge monitors".
END VIBRATING & STATIC SCREEN Rotostrainet PROBLEMS? The Rotostrainer@ screen is a new concept applicable to total effluent and in-process waste treatment. Properly used, it cleans itself, and will not blind. Influent passes through the slowly rotating screen. Solids ride over the top and are removed by a wiper. The large mass of falling influent continuously backwashes screen members.
The screen revolves smoothly and quietly at 10 R.P.M . It won't shake itself to pieces. And its rugged, stainless steel, all-welded construction requires no tension adjustments or periodic mainte·nance to keep it operating, trouble.free for months at a time.
TOO GOOD TO BE TRUE? THERE'S MORE .•• The high-capacity Rotostrainer@ screen (up to 2500 GPM) is less expensive than old-fashioned equipment to purchase. install, and operate. Its low head loss (36 inches) provides an easy fit, even in existing systems. It perfOfms better than traditional screens. It con tinuously procuces drier solids, 15 to 20% dry weight, down to fines as small as 0.01 0 inch . Its gentle action will not break up the solids it removes . And the Rotostrainer@ screen does all this while cleaning itself. Contact: WATER
WILLIAM BOBY & CO. (AUSTRALIA) PTY. LTD. 44 Koornang Road, Scoresby, Victoria, 3179 Telephone: 763 8988 . Telex : 31868 Also at: Sydney 93 0311 , Brisbane 229 5800. Adelaide 278 4135
Asbestos-cement pipelines-proper control of waste in the thermal power stations of N.S.W. The suitabil ity of asbestoscement pipelines for the transportation of water is well established ; and it is becoming increasingly apparent that this su itability extends to many other fluids as well. Since their installation at the giant Liddell and Munmorah power stations, Hardie's pipeline systems have economically conveyed over 10,000,000 tonnes of coal 's waste residue , in the form of slurried fly-ash, to environmentally suitable disposal areas. Investigations have shown that pipeline wear is virtually non -existent and little maintenance has been required. Because of the success of asbestos-cement pipelines at these stations - the two largest in NSW - the Electricity Comm ission has adopted similar systems for JH 359. FPM
the stations at Wallerawang , Vales Point, and at its newest station, Eraring. With over fifty years' experience of asbestoscement pipelines, Hardie's are making a significant contribution to the . production of power for Australia's most industrialized state . NOTE : Hardie's have prepared a special 12-page technical report on the giant power stations of N.S.W. For your free copy write to : Publications Department, James Hardie & Coy. Pty. Limited , Box ~ HARDIE'S 3935 G.P.O. , Sydney. 2001 PIPELINE SYSTEMS
James Hardie & Coy. Pty. Limited. Sydney, Melbourne, Brisbane, Townsville, Rockhampton, Adelaide, Perth, Hobart
OTough, flexible, leak-free nylon eleven tube up to 3" dia.also ideal for lining existing reticulation systems. DApproved brake hose and suzi-coils made to SAE 1402/G. D Money saving, nylon eleven, self store hose. D Safe, low maintenance nylon eleven air brake tube. OQuiet running, long-life graphite filled nylon eleven bushes. D Economical, easily installed vapour emission control and fuel lines. D Hydraulic hose made to SAE 100R7. D Hydraulic and pneumatic packings to 9" dia. D Bellofram rolling diaphragms. Just released ... D Custom bundled tube for piezometer and control systems.
II Flavell Pty Ltd
81-89 Tulip Street, Cheltenham, Vic. 3192 Telex AA31914 Melbourne 93 3321 Sydney 736 1933
Precision engineering in plastics and rubber.
lilE~T ~ S1-IARPLES
Study the basic features of a solid-bowl, continuous-discharge Sharples Super-D-Canter ÂŽ centrifuge.
Internal design and operating G level selected for optimum performance on sludge to be handled . Wide range of sizes. Torque overload release is simple and can be reset without tools. Provision for coagulant additions (interna l or external) where optimum use can be made of them. Selected hard surfacing provided where needed most - feed ports of conveyor, feed zone, discharge ports , housing , flight edges and faces of conveyor. All components designed to highe st standards for operation over a wide range (up to 3100 x G) of G forces. G level selected acco rding to type of sludge. Replaceable liners protect casing in solids-discharge area, and in the bowl opposite feed ports. One-piece , heavy, cast-iron base reduces vibration.
8 Conveyor and bowl-speed differential infinite ly controlled to optimize process performance. 9 Forced-feed oil circulating system is floor mounted and connected to the centrifuge by flexible connections. 10 Heavy-duty bearings , de signed for long life, support rotating assembly. 11 High throughput and cost/performance because of many internal designs and G levels available . Highest Sigma (pool surface area x G) availab le. 12 Tungsten -ca rbide feed-port inserts for long wear. 13 Heavy duty pl aneta ry gear boxes. 14 Automatic operational monitoring systems. 15 Tungsten -ca rbide tiles in beach area, if required , for particularly abrasive sludges.
The Sharples Super-D-Canter centrifuge is built to the highest standards with no-compromise design. Our philosophy is to give
water and wastewater treatment plants a cost-effective, rugged, and adaptable thickening and dewatering centrifuge.
,. As a result the Super-D-Canter centrifuge is not limited by design, materials of construction, or abrasion protection to operate only at low G forces. Optimum G force can be selected for lowest polyelectrolyte cost, driest cake, most effective power, and least wear and tear. Stainless steel construction reduces maintenance and provides long life. And hard surfacing technology includes the new replaceable sintered Stellite and tungsten carbide conveyor hard surfacing with up to 20 times the abrasion resistance of conventional materials.
SHARPLES-STOKES PTY. LTD. 99 RESERVE ROAD, ARTARMON, N.S.W. MAIL BOX 367, ARTARMON, N.S.W. 2064. PHONE: SYDNEY 439-3378. CABLE: PENNWALT, SYDNEY