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The paper describes the method that led to the design of the 1,500 Ml/day dissolved air flotation (DAF) water treatment plant for Boston's water supply. In particular, the topics of flocculation techniques, floated solids removal and DAF recycle as they relate to very large capacity plant design are covered in detail. The use of mathematical models, including computational fluid dynamics (CFD) software, to refine the design is described.

This article discusses a system design to minimize microfiltration membrane maintenance at the Westchester Joint Water Works in Mamaroneck, New York. Several cleaning steps were used to remove contaminants from membrane fibers and keep them free of fouling. Frequent air agitation, backpulsing, and deconcentration were used to remove solids from the fibers. More aggressive cleaning programs‐‐ maintenance and recovery cleaning‐‐ were used with chemicals to remove fouling. The wastes produced from each of these steps must be handled carefully and within the constraints of local utilities, available property, and capital/operational costs.