This progress report by the Filtration Com. of AWWA summarizes the state‐of‐the‐art related to the backwashing of granular filters and suggests research needs to the AWWA Com. of Research.

This paper provides an overview of the results of a study undertaken to provide a basis for predesign evaluation of the effectiveness of options for treatment of municipal surface waters in the province of Nova Scotia. Seasonal samples of raw water were obtained from the fall of 1992 through the fall of 1993 from five sites. Results were compared with a Nova Scotia Department of Health data base of randomly collected samples. For project samples, strong relationships were evident between raw water total organic carbon (TOC) and both colour and trihalomethane formation potential. Laboratory batch tests, supported by plant results, indicated that percentage removals of TOC increase with raw water TOC, and that settling-filtration was more effective than direct filtration for waters with higher raw TOC concentrations. Results of solids settling tests were consistent with TOC results. A treatment optimized for TOC removal also ensured removal of colour. TOC removals by dissolved air flotation followed by filtration exceeded removals by direct filtration or settling-filtration, based on laboratory bench tests, particularly at sites with higher values of raw TOC. Colour removal by dissolved air flotation was consistently higher at all sites. Key words: enhanced coagulation, trihalomethane precursors, total organic carbon, surface water treatment, dissolved air flotation.

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A description and comparison of five water treatment systems and supply sources—located in Sydney, Australia; Manila, Philippines; Springfield, Mass.; Rochester, N.Y.; and Long Island, N.Y.—are used as the basis for a discussion of tailoring the design of treatment facilities to local conditions. Water quality, existing treatment facilities, the supply source and method of regulation, climatic conditions, labor intensive design versus automation, equipment maintenance, cost of chemicals, emergency measures, and waste‐solids disposal are considered as they relate to the process train and other considerations relevant to the system.

Translations of specific articles from the Journal American Water Works Association are available in Spanish, and may be purchased through the AWWA order department. Filtration, cast iron pipe, developing countries, chlorine residuals, and vandalism are topics covered in these articles.