Preozonation effects on coagulation

The effects of preozonation on interactions among coagulants, particles, an d natural organic matter were examined at bench scale through a series of j ar tests using different organic matter, pH values, and coagulants. When al um was used as a coagulant, preozonation hindered turbidity and dissolved o rganic matter (DOM) removal at the conditions tested. When cationic polymer s were used as the coagulant, however, preozonation led to small but statis tically significant increases in the removal of both turbidity and DOM. Whe n polyaluminum chloride was used as the coagulant for several natural water s, preozonation aided turbidity and DOM removal in one instance and hindere d removal of particles and organic materials in another instance. The autho rs hypothesize that preozonation reduces the surface charge of particulates , leading to better coagulation by charge neutralization.