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This paper reports on a study to establish the optimum coagulant for use in the Central Lake County Joint Action Water Agency's (CLCJAWA) ongoing Process Optimization Program. Liquid aluminum sulfate has been used for coagualtion at CLCJAWA since operations began in 1992. It has performed very well, resulting in an average finished water turbidity of 0.05 NTU in all Lake Michigan water conditions. However, voluminous alum floc create more sludge than other coagulant options and alum carryover onto filters tends to shorten filter runs. Additionally, finished water aluminum residuals have occasionally exceeded US drinking water aesthetics standards. Several different coagulants were evaluated in jar tests. These coagulants included: ferric sulfate; polyaluminum chloride; and, coagulant aid cationic polymers. Following the jar tests, a full-scale evaluation of each coagulant was conducted. The CLCJAWA facility is composed of three isolatable and identical treatment trains that allow side by side coagulant comparisons. Each candidate coagulant was tested for a minimum of four weeks. Comparisons were based on settled and filtered water effluent turbidity, filter run hours, sludge production, wash water consumption, organic carbon reduction, finished water aluminum residual, coagulant consumption, and overall treatment cost. Includes figures, appendices.

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Edition: Vol. - No. Published: 01/01/1999File Size: 1 file , 310 KB