AWWA WQTC52963

The general goal of this project was to develop an improved understanding of theinteractions between natural organic matter (NOM), calcium, particles, and coagulants and, based on this knowledge, develop improvements in coagulation processes. It was hypothesized that interactions of calcium ions with NOM may lower the demand for conventional metal coagulants (alum, ferricsalts), thereby reducing sludge production and perhaps increasing precursor removal. The specific objectives of the study were: to determine the effect of addition of calcium on coagulant demand; to determine the effect of calcium addition on the removal of disinfection byproduct precursors; if beneficial effects occur, to determinethe conditions under which these effects are produced; and, if beneficial effects are observed, develop recommendations for possible applications in practice. Includes 10 references, tables, figures.