Characteristics of chlorine dioxide eliminating Cryptosporidium oocyst in water

Abstract:

In order to extend the application of ClO2 in drinking water safety,the influences of ClO2 dosage,contact time,temperature and pH value on the killing effect of oocyst were investigated using fluorescent staining vital assessing method.SEM was used to study the changes of oocyst shaped in the sterilization process.The results show that the killing rate can reach 90% and 100% at the ClO2 dosages of 1.5 and 2.5 mg/L respectively when the contact time is 60 min.Higher killing rate can be obtained at higher temperature.The killing rate can increase from 54% to 70% when the temperature is raised from 5℃ to 30℃.The effect of pH value is not obvious.By comparing the SEM photos before and after sterilization,it can be found that ClO2 has great penetrability and does not destroy the oocyst surface but transforms the supporting structure.All the results indicate that ClO2 can be used to control Cryptosporidium oocyst in drinking water treatment and they provide a theoretical foundation for the engineering application.