AWWA JAW52375

The effects of preozonation on interactions among coagulants, particles, andnatural organic matter were examined at bench scale through a series of jar testsusing different organic matter, pH values, and coagulants. When alum was used asa coagulant, preozonation hindered turbidity and dissolved organic matter (DOM)removal at the conditions tested. When cationic polymers were used as thecoagulant, however, preozonation led to small but statistically significantincreases in the removal of both turbidity and DOM. When polyaluminum chloridewas used as the coagulant for several natural waters, preozonation aidedturbidity and DOM removal in one instance and hindered removal of particles andorganic materials in another instance. The authors hypothesize that preozonationreduces the surface charge of particulates, leading to better coagulation bycharge neutralization. Includes 12 references, tables, figures.