The effects of chlorine dioxide and chlorine disinfections on genotoxicity of different biologically treated sewage wastewater samples were studied by umu-test.

Disinfection is an important step to guarantee the safety of the reclaimed water, and chlorine disinfection is the most common method.

The existing chlorine disinfection processes in water works were reviewed, including eight kinds of chlorine residuals model and three kinds of disinfection by-products model.

The dechlorination of disinfected secondary effluent with sodium thiosulfate was investigated.

However the problem of by-products of chlorination exists.

Based on existing problems in chlorine disinfection process,improvements were suggested from four aspects-setup of chlorination point,appropriately choice of chlorine dosage,mixing efficiency of chlorination,controlling measure of adding chlorine in order to enhance disinfection efficiency,reduce disinfection by-products and control production cost.

The Effects of Typical Nitrogenous Compounds on Haloacetonitriles Production and Chlorine Demand in Drinking Water Chlorination;

According to the analyses of negative effect of traditional chorine disinfection,this paper puts forward the improvement approach of using chlorine dioxide to replace it.