Problem: The Geren Island Water Treatment Plant in Salem, Oregon, draws its supply from the North Santiam River. In 2018 that source had elevated concentrations of cylindrospermopsin and microcystin, which appeared earlier than in previous years.
Solution: Ozone was chosen as the best treatment option. The water goes through the primary slow sand filtration to remove cyanobacteria, a primary source of cyanotoxins. Remaining cyanotoxins are then destroyed by ozonation. Ozone also breaks down other contaminants that could impart taste and odor, improves secondary filtration, and reduces chlorine usage for disinfection. To optimize performance, ozone is forcefully mixed with source water. For
