AWWA JAW18765

A Canadian utility's experience with chlorine dioxide treatment for the prevention of tastes and odors is outlined. The chief complaint was caused by the presence of chlorophenols, formed by naturally occurring organics. Chlorine dioxide treatment successfully eliminated complaints of this type but failed (even in combination with powdered activated carbon) to eliminate completely those complaints arising from urban runoff (hydrocarbons) entering the river upstream of one of the city's two major treatment plant sites. Although significant reduction of taste and odor problems was achieved with increased oxidative power, elimination of all complaints depends on implementation of fixed-bed activated carbon treatment. The occurrence of Giardiasis outbreaks since the institution of chlorine dioxide treatment is addressed. Includes 20 references, tables, figures.