Disinfection By-products Formation From Three Kinds Of Disinfectants

The population of China has more than1.3billion; everyday people need a lot ofdrinking water to meet the needs of their lives. How to guarantee the quality of the drinkingwater has become a major problem of improving people’s life. Disinfection by-products（DBPs） have been of great concern since they are carcinogenic and mutagenic. Manyinvestigations on sources of DBPs precursor and reactivity of different natural organic mater（NOM） have been reported, nevertheless, the impact of different bacterial on the productionof DBPs precursor in drinking waters has rarely been studied. This research choseEscherichia coli as the representative bacteria in drinking water. After disinfection, thereactivation of E.coli was balanced with the formation of DBPs.Nowaday, the major disinfection for drinking water in domestic and foreign countryincludes chlorine, chlorine dioxide, ozone, ultraviolet ray, and photocatalytic oxidation. Aschlorination has good disinfection effect, low cost, easy to use and easy to management, itwas used in almost99.5%waterworks in China, even94.5%abroad. However, with more andmore chlorined DBPs exposured, people began to seek other alternatived disinfection methods.This research selected chlorine, chloramines, and TiO₂/UV as the disinfectants, correlatedDBP formation with disinfection efficacy in order to identify the optimal dosage and contacttime for efficacious bacterial disinfection while minimizing DBP formation.The results showed that chlorine had a best effect in bacterial disinfection.1mg/L NaOClcould inactivate almost10⁷cfu/mL E.coli. When chloramines concentration was2.5mg/L, itcould also have a good effect in bacterial disinfection similar with chlorine. TiO₂/UVdisinfected the bacteria very slow, and the best concentration was0.1g/L.Chlorine produced DBPs, which reached at60μg/L, much more than the other twodisinfectants. Chloramines produced total DBPs at10μg/L while not any DBPs was detectedin TiO₂/UV processes.