Study on control of disinfection by-products with chloramines and combined chloramines

Laboratory-scale test was carried out for some types combined disinfection process: short term free chlorine plus chloramines disinfection(Cl2+NH3),chloramines disinfection(NH2Cl),short term chlorine dioxide plus chloramines disinfection(ClO2+NH2Cl) and short term ozone plus chloramines disinfection(O3+NH2Cl).The result shows that use of alternate disinfectants can availably control the concentration disinfection by-products.In the case of the same influent,chloroform,dichloroacetic acid and trichloroacetic acid produced in chloramines disinfection process are respectively 71.8%～87.2%,58.2%～76.3% and 89.0%～96.8% lower than those in conventional free chlorine disinfection process.The disinfection by-product level in water that disinfected by ClO2+NH2Cl and O3+NH2Cls was remarkably lower than what was treated only by chloramines.Through the analysis of the carcinogenic risk of disinfection by-products,changing the disinfection process can significantly reduce the carcinogenic risk of chlorination.