9. Greenberg, A. E. , Ongerth, H.J . (1966). Salmonellosis in Riverside, Calif. Am. Water Work Assn. J. 52: 165-74. 10. Ross, A. I., Gillespie, E. H. (1952). An outbreak of water-borne gastro-enteritis and Sonne dysentery. Mon. Bull. Min. Hlth. and P.H.L .S. 11 : 36-46. 11. Levine, R. J. , Nalin, D. R. (1976). Cholera in primarily waterborne in Bangladesh. Lancet. ii: 1305. 12. Rosenberg, M. L., Koplan, J.P ., Wachsmuth, I. K., Wells, J. G., Gangarosa, E. J., Geurrant, R. L., Sack, D. A. (1977). Epidemic diarrhea at Crater Lake from enterotoxigenic Escherichia coli. Ann. Intern . Med. 86: 7 14-8. 13. Vogt, R. L., Sours, H. E., Barrett, T., Feldman, R . A., Dickinson, R. J., Whitherell, L. (1982) . Campylobacter enteritis associated with contaminated water . Ann. Intern. Med. 96: 292-6. 14. Neefe, J. R., Stokes, J. Jr. (1945). An epidemic of infectious hepatitis apparently due to a water-borne agent. JAMA. 128: 1063-75. 15 . Hopkins, R. S., Gaspard, G. B. , Williams, F. P. , Karlin, R. J., Cukor, G., Blacklow, N. R. (1984). A community water-borne gastroenteritis outbreak: evidence for rotavirus as the agent. Am. J. Pub/. Hlth . 74: 263-5. 16. Taylor, J. W ., Gary, G. W., Greenberg, H. B. (1981). Norwalk-related viral gastroenteritis due to contaminated drinking water. Am. J. Epidemiol. 114: 584-92. 17. Khuroo, M. S. (1980) . Study of an epidemic of non-A, non-B hepatitis: possibility of another human hepatitis virus distinct from post-transfusion nonA, non-B type. Am. J. Med. 68: 818-24. 18. Shaw, P. K., Bordsky, R. E., Lyman, D. 0. et al. (1977). A community-wide outbreak of giardiasis wit h evidence of transmission by a municipal water supply . Ann. Int. Med. 87: 426-32 . 19. Ritchie, L . S., Davis, C. (1948) . Parasitological findings and epidemiological aspects of epidemic amebiasis occurring in occupants of the Mantetsu apartment building, Tokyo, Japan. Am. J. Trop. Med. 28: 803- 16. 20. D'Antonio, R. G., Winn, R. E., Taylor, J.P. ( 1985). A water-borne outbreak of cryptosporidiosis in normal hosts. Ann. Intern. Med. 103: 886-8. 2 1. Houston, A. C . In: Chalmers, A. K. chr. (1912). Discussion on the varieties and significance of B. coli in water supplies. Br. Med. J. ii: 704- 16. 22. Bardsley , D. A. (1934). The distribution and sanitary significance of B. coli, B. lac tis areogenes and intermediate types of coliform bacilli in water, soil, faeces and ice-cream . J . Hyg . (Lond.). 34: 38-68.
23. Austin, B., Hussong, D., Weiner, R. M., Colwell , R.R. (1981). Numerical taxonomy analysis of bacteria isolated from the completed 'most probable numbers' test for coliform bacilli. J. Appl. Bacteriol. 51: 101-12. 24. Neefe, J. R., Stokes, J. Jr., Baty, J.B., Reinhold, J. G. (1945). Disinfection of water containing causative agent of infectious (epidemic) hepatitis. JAMA . 128: 1076-80. 25. Viswanathan, R. (Jan. 1957) . Epidemiology of the outbreak of hepatitis in Delhi (December 1955). ind. J. Med. Res. (Supp . No): 1-29 . 26. Wong, D. C., Purcell, R. H., Sreenivasan, M. A. , Prasad, K. M. (1980). Epidemic and endemic hepatitis in India: evidence for non-A, non-B hepatitis aetiology. Lancet ii: 876-9. 27. Neefe, J. R., Baty, J.B ., Reinhold, J. G., Stokes, J. Jr. (1947). Inactivation of the virus of infectious hepatitis in drinking water. Am. J. Pub. Hlth. 37: 365-72. 28. Lycke, E., Blomberg, J. , Berg, G., Eriksson, A., Madsen, L. (1978). Epidemic acute diarrhoea in adul ts associated with infantile gastroenteritis virus. Lancet. ii: 1056-7. 29. Mosley, J. W. (1967). Transmission of viral diseases by drinking water . In: . Berg, G. ed. 'Transmission of Viruses by the Wate Route'. Interscience, New York. 5-23 . 30. Chang, S. L. (l 986). Water-borne viral infections and their prevention. Bull. WHO. 38: 401 - 14. 31. Shuval, H. I. (1976). Water needs and uses: the increasing burden of enteroviruses on water quality. In : Berg, G. Bodily, H . L., Lennette, E. H., Melnick, J. L., Metcalf, T. G. 'Viruses in Water' . APHA, Washington DC . 12-25 . 32. Gamble, D. R. (1979). Viruses in drinking water: reconsideration of evidence for postulated health hazard and proposals for microbiological standards of purity. Lancet. i: 425-8. 33 . Hornick, R. B., Greisman, S. E. , Woodward, T. E., DuPont, H. L., Dawkins , A. T., Snyder, M . J. (1970). Typhoid fever: pathogenesis and immunologic control (first of two parts). N. Engl. J. Med. 283: 686-91 . 34. Ministry of Health . (1938). Report on a public local inquiry into an outbreak of typ hoid at Croydon in October and November i937. HMSO, London. 35. Kehr, R. W ., Butterfield , C. T . (1943). Notes on the relation between coliforms and enteric pathogens. Pub. Hlth. Rep. 58: 589-607. 36. Craun, G. F. (1978) . Disease outbreaks caused by drinking water. Water Poll. Cont. Fed. J. 50: 1362-74. 37. Eiden, J., Vo nderfecht , S., Yolken, J. H. (1985) . Evidence that a novel rotavirus-like agent of rats can cause gastroenteritis in man. Lancet. ii: 8-11.
A. G. STROM & J. A. CROCKETT Continued from Page 32 • by careful testing of raw water quality over all seasons, selection of the least costly adequate process(es) and adoption of relatively high process loading rates for the dry weather peak. Can lower capital cost processes such as direct filtration, clarifier only, or Sirofloc, be adopted? • selection of process and control system design which will minimise operating labour. Full plant utilisation is now possible and necessary and restriction of a plant to 20 hours per day is nonsense.
Implementation Thirty years or more ago, for water treatment plants in Australia, it was often a matter of the engineer calling tenders for a plant to give clean water, and requiring the tenderers to take raw water samples (which might , or might not, be appropriate) and provide the plant complete, or at least the parameters, the working dimensions and the eq uipment. With some waters, this was quite inappropriate, plants could be substantially over-designed, or they required heroic endeavours and agility on the part of the Contractor to produce the stipulated results. This 'Turnkey' approach has recently returned to fashion, the justification being the resulting 'single' responsibility. There is also a misconception that it saves on design costs. While it is true that some Turnkey plants have been installed at a low first cost, others have proved more costly as result of poor specifications. Since the primary consideration in selecting the accepted tender is the first cost, there is a great risk that life-cycle costs will be higher than necessary due to adoption of a poor design of lower-quality with a process which is high in operating and/or maintenance cost. In the Authors' view, implementation of water treatment should be preceded by proper evaluation of water quality and demands and should involve the preparation of a careful concept design, the writing of a clear specification of capacities, design parameters, standards and performances required, and an appropriate division of work between the different specialist con-
tractors. The cost of such an approach is not a major part of the final cost of the works. It gives the most success ful , lowest lifecycle cost plant and makes best use of the knowledge of specialist equipment contractors. Above all , it separates the critical evaluation of water quality and the most suitable process, from the selection of the lowest suitable tenders.
CONCLUSION Proper Water Treatment in Australia is still often regarded as an expensive luxury. This attitude is reinforced by the relatively high cost of many plants. In fact, considering the importance of water to health, well-being and enjoyment of life the cost of properly treating water, perhaps $50 per household per year, is small . We should be far more concerned about providing adequate quality than with avoiding the very moderate costs involved . Disinfection of all water supplies is essential but it becomes an imperfect, costly and consumer-unpopular process when the water is not fully treated. In addition to enabling proper disinfection without consumer reaction, water treatment also removes clay, manganese and iron , and the organic material which feeds growths in the reticulation mains. Proper treatment is the only way to ensure that a safe, palatable and pleasing water can be consistently delivered at the consumers tap. With most raw waters, disinfection without proper treatment is undesirable. Modern treatment processes are efficient and cost-effective provided they are designed and applied with a full understanding of the raw water concerned. Many modern plants have been overdesigned in capacity and process and in the present economic climate this is not satisfactory. Designers should be encouraged to keep costs down by careful investigation, sensible selection of design parameters and by staging the plant, either by adding to it or by uprating processes. Bypassing raw water at peak may well be a perfectly satisfactory and economical staging option if effective disinfection is maintained. A thoughtful approach is the best way to achieve the object of 'low cost' water treatment. WATER December, /987
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