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Enhanced versus Optimized Multiple Objective Coagulation

TitleEnhanced versus Optimized Multiple Objective Coagulation
Publication TypeBook Chapter
Year of Publication1998
AuthorsEdzwald JK, Tobiason JE
Book TitleChemical Water and Wastewater Treatment V
PublisherSpringer Berlin Heidelberg

Enhanced Coagulation is a new regulatory requirement in the United States aimed at removing TOC by coagulation thereby controlling formation of disinfection byproducts. A multiple objective framework for coagulation, called Optimum Coagulation, is developed and contrasted to Enhanced Coagulation. The paper shows that this approach should be incorporated into Enhanced Coagulationstudies. Water utilities unable to meet Enhanced Coagulation Step 1 requirements must conduct coagulation tests to determine alternative TOC removals. For low alkalinity waters these tests must be done at a pH no greater than 5.5. The paper shows that while this is favorable for coagulation of NOM, it can cause residual Al and floc separation problems. Optimum coagulation pH for alum depends on water temperature and ranges from pH 6–7 for treatment of low alkalinity waters. Optimum Coagulation conditions are those that maximize pathogen (Cryptosporidium) removals, produce low turbidities and particle counts, and minimize residual Al.