Effect of ozone on EOM and coagulation

Extracellular organic matter from algae affects particle coagulation, depending on the type of algae and the concentration of the extracellular matter. Ozonation of drinking water containing algae sometimes produces beneficial effects on coagulation. These benefits are often attributed to the extracellular organic matter (EOM) from the algae. This study focused on the properties of extracted EOM from three species of algae. Ozonation of EOM reduced its apparent molecular size and hydrophobicity. Ozonation also increased the functional group charge of EOM compounds but decreased the charge as measured by the colloid charge titration. Coagulation experiments with extracted EOM indicated that only small amounts were necessary to neutralize positively charged latex particles. Ozone produced no significant effect on EOM and thus did not affect coagulation of these particles. Alginic acid, a model EOM compound, was compared with the extracted EOM and behaved similarly to the high‐molecular‐size extracted EOM.