AWWA WQTC62393

This study evaluated ozonation as a polishing step for removal of cyanotoxins during drinking water treatment. Key functional groups (double bonds and neutral amines) of these cyanotoxins determine their toxicity and their susceptibility to attack by ozone. Under the conditions of drinking water treatment, pH 6-8, ozone and hydroxyl radicals were most reactive with Microcystin-LR > Cylindrospermopsin > Anatoxin-a. The order of reactivity determined by chemical kinetics was confirmed in water from Lake Greifensee (Switzerland) and Lake ÄyhÖnjÄrvi (Finland), in terms of the ozone dose necessary for toxin oxidation. Hydroxyl radicals enhanced toxin oxidation in the case of Lake Greifensee, and the fraction of the toxin oxidized by hydroxyl radicals was largest for Anatoxin-a > Cylindrospermopsin > Microcystin-LR. Includes 16 references, figures.