Effect factors of chlorine dioxide inactivation cryptosporidium andersoni oocyst in preoxidation process

The inactivation effects of chlorine dioxide (ClO₂) on inactivation of Cryptosporidium andersoni oocysts in aqueous solution were studied systematically. Several influencing factors including ClO₂ dosage, contacting time, temperature, pH, turbidity and permanganate index of the solution were investigated. The results showed that the inactivation rates of Cryptosporidium andersoni oocysts were affected by ClO₂ dosage and contacting time greatly, by temperature and turbidity slightly, and higher inactivation rate can be gotten at higher temperature. The effect of pH is slightly from 3.0 to 10.0. As to 10³ cell/ml Cryptosporidium andersoni oocysts, the inactivation rates of Cryptosporidium oocysts can reach to 95% when prolonging reaction time to 120min at 5mg/L ClO₂; as to 50cell/ml Cryptosporidium andersoni oocysts, contacting ClO₂ 30min with 3mg/L ClO₂ or 60min with 2.0mg/L, the inactivation rate can reach 100%. All of these provide reference for engineering application.