Cryptosporidium inactivated by chlorine dioxide in water and disinfect mechanisms

The fluorescence staining method was used to study the effect of chlorine dioxide(ClO2) inactivating Cryptosporidium in water and affecting factors(ClO2 concentrations,inactivating times,pH values,temperatures,turbidities and organic contents).Then the scanning electron microscopy(SEM) and protein assay were used to investigate cell ultrastructures variation to shed light on the mechanism of inactivation preliminarily.It could achieve the optimum disinfection effect(the survival rate of less than 1%) when adding 3.0mg/L of ClO2 after 120min(pH=7.0,25℃ and turbidity 1NTU),the survival rate of Cryptosporidium cysts had a non-linear positive correlation with chlorine dioxide concentration and reaction time.The turbidity on inactivation effects was also found to be statistically significant in artificial water.With increases in turbidity,the inactivating effect decreased.Inactivating rate might rise with the temperature increasing.The inactivating capability was found to be stronger under acidic than that under alkalic conditions.In some extent,concentrations of organic matter could inhibit the disinfecting effect of ClO2.Examined by scanning electron microscopy(SEM) and protein assay showed that the cell surface was damaged,some cells started the cytoplasm leakage,and then caused Cryptosporidium death.