Study On Disinfection By-products During Chlorination And Chloramination Of Cyclops

Since1974, Rook et al detected from the chlorination of tap water to chloroform start growing concern of the safety of drinking water. Eutrophication problems with water have become prominently, the Cyclops pollution problems have become prominently. Cyclops has strong antioxidant activity and swimming, can penetrate the filter, often occur in the clean water tank and pipe network. Therefore, this study researched the formation of DBPs during the chlorination and chloramination of Cyclops metabolite solution and the formation influencing factors.The results showed that during the chlorination and chloramination of Cyclops metabolite solution could produce DBPs. Formation of carbonaceous disinfection by-products (C-DBPs) including chloroform (TCM), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), chloral hydrate (CH)1,1-dichloropropanone (1,1-DCP) and1,1,1-trichloropropanone (1,1,1-TCP), and nitrogenous disinfection by-products (N-DBPs) including dichloroacetonitrile (DCAN), chloropicrin (TCNM).Chlorination of Cyclops metabolite solution lead to the yields of TCM, DCAA, TCAA, CH and1,1-DCP increased with increasing time. DCAN and TCNM reached a maximum after36h and6h, respectively, and then decreased with increasing reaction time, and1,1,1-TCP decreased continuously with increasing reaction time. The amounts;of TCNM and DCAN firstly increased and then decreased with increasing chlorine dosage, and others monotonically increased with increasing chlorine dosages.Formation of TCM increased with increasing pH value. The amount of TCAA,1,1,1-TCP and DCAN decreased continuously with increasing pH from5to10. The formation of CH, TCNM,TCAA and1,1-DCP varied significantly with pH from4to10and the maximum yields of these DBPs occurred at pH6-7. Formation of TCM, DCAA and TCAA increased continuously with increasing temperature. The amounts of DCAN,1,1-DCP and1,1,1-TCP decreased with increasing temperature from10to30℃. Concentrations of CH and TCNM had maximum yields at20℃. This research shows the concentrations of DBPs decreased with increased ammonia concentrations.Chloramination of Cyclops metabolite solution lead to the yields of DBPs monotonically accumulated with the extension of time, in addition to1,1,1-TCP. TCM,1,1-DCP, DCAN and TCAA formation monotonously increased with higher monochloramine doses. The amounts of CH, TCNM,1,1,1-TCP and DCAA firstly increased and then decreased with increasing monochloramine doses.1,1-DCP was not detected when the monochloramine concentration below10mg/L. The TCM concentration increased with pH. The amount of CH,1,1-DCP, DCAA and TCAA decreased continuously with increasing pH from5to10. The formation of1,1,1-TCP, TCNM and DCAN varied significantly with pH from5to10and the maximum yields of these DBPs occurred at pH6-7. Formation of TCM, DCAA, TCAA and TCNM increased continuously with increasing temperature. The generation of1,1-DCP,1,1,1-TCP and CH had maximum yields at20℃. DC AN formation decreased with increasing temperature from10to30℃.Chlorination and chloramination of Cyclops metabolite solution shows that chloramine disinfection can effectively reduce the generation of DBPs. Such as TCM, CH, DCAN, DCAA and TCAA was significantly higher than that in the chlorination. Formation of TCNM,1,1,1-TCP and1,1-DCP slightly more than the generated in the chlorination disinfection, because1,1,1-TCP and1,1-DCP could hydrolysis in the present of free chlorine, therefore, they relatively stable in the chloramine disinfection.