Research Of Controling Chloroform In Drinking Water Using Chlorine Dioxide Disinfection

Preparation of high purity chlorine dioxide using chemical method in laboratory and application of chlorine dioxide as disinfector in drinking water disinfection to control trichloromethane formation were investigated. Under high acidic condition reducing agent such as sodium sulfite, sulfur dioxide et al, could reduce sodium chlorate to produce chlorine dioxide, the factors which would influence content and purity of chlorine dioxide were discussed. Controlling chloroform in drinking water using chlorine dioxide as pretreatment disinfector was reported. Using chlorine dioxide as first disinfector followed by chlorine as secondary disinfector would decrease the concentration of chloroform in drinking water. Chlorination after chlorine dioxide pretreatment may be influenced by reaction time and temperature. Additionally, when the mixture which composed of chlorine and chlorine dioxide was used, with the content of chlorine dioxide in mixture disinfector increasing, chloroform in the sample treated by it may decrease obviously. The concentration of TOC(Total Organic Carbon) in water was decreased when pretreating samples with chlorine dioxide as disinfector followed by chlorine as secondary disinfector. Furthermore, the THMFP(Trihalomethane Formation Potential) in water also reduced, which indicated that chlorine dioxide could oxidize NOM(Natural Organic Matter) to remove precursor of trihalomethane, as the result of these reactions , the concentration of trichloromethane in water would decrease. Adding chlorine dioxide to raw water before flocculation the percentage of removing THMFP was higher than that after flocculation. Substituting chlorine dioxide for chlorine as pretreatment disinfector may control trichloromethane formation in drinking water.