AWWA PATH50803

This study was designed to extend previous findings for ozone inactivation of Cryptosporidium parvum to real-world conditions by evaluating seeded oocyst inactivation in 16 potable source waters, one filter backwash water, and one phosphate-buffered water with a continuous-flow ozone reactor. Inactivation kinetics were obtained using the linear form of the Chick-Watson equation to evaluate the animal infectivity data. Ozone is an effective disinfectant for inactivation of Cryptosporidium parvum, but the Ct product to achieve a target level of inactivation may be impacted by the temperature, the pH, and the turbidity of the water. Ozone inactivation appears to be enhanced if the pH of the water is at or below pH 6.5 and if the turbidity is low. The influence of water temperature on ozone inactivation kinetics appears to be greater than the effect previously demonstrated for Giardia lamblia and utilized in establishing the Ct tables for Giardia inactivation in the Surface Water Treatment Rule Guidance Manual. Includes 13 references, tables, figures.