Study On Optimization Of Drinking Water Disinfection Process

In the process of running water delivered to users from water plant, water flowing in the pipe net had been for several hours or even within a few days, Water in Large underground pipe network occurred complex physical, chemical and biological reactions. Some of the key indicators of water quality, such as residual chlorine, bacterial indicators and so on, occurred significant changes. Harmful bacteria and microbes propagated. They were harmful to human health. Thereby improving water quality in pipe network was an important part of improving water quality.Residual chlorine decay factors was studied by a static model of main water, confered chlorine and chloramines disinfection on biological stability. AR reactor dosing BAC water was taken as a dynamic model to study disinfection of microbial re-growth control. Then, General discussed the optimization of conventional disinfection process of drinking water.The residual chlorine decay experiment showed that chlorine decay rate constant was obviously influenced by temperature. The Kb value rose from 0.0311 to 0.1225 as the temperature increased from 10~℃to 30℃and the higher the temperature was, the faster residual chlorine in the water decayed. For the same water sample, the higher the initial concentration of chlorine was, the faster the free chlorine and total chlorine decayed. Residual chlorine decay and PH value had no significant correlations. The DOC and the Kb value had a strong exponential relationship.Despite the BDOC was increased during the chlorine disinfection process, the threshold requirements of biological stability was still met and chlorine decay rate in BAC effluent was significantly lower than the microfiltration water and raw water. The residual chlorine value could also maintained a high level after a longer residence time and the microbial re-growth was inhibited continually. BDOC change in chloramines disinfection process was similar to chlorine disinfection process. Biological activated carbon process was an effective means to ensure biological stability of drinking water. The residual chlorine in the effluent was 0.04mg/l when the chlorine dosage was 1mg/l. The suspended bacteria in the water was 6.30×10~3 and the bacteria in coupon was4.60×10~4 showed that the micro-organisms in the pipe network were not well controlled. When the chlorine dosage was 2mg/l and the residual chlorine in the effluent was 0.3mg/l, the bacteria number could be well controlled in two orders of magnitude.The disinfection byproducts, the amount of chlorine and biodegradable nutrient medium production could be reduced by making full use of front-end process on removal efficiency of the pollutant and dosing point of adding disinfectant as close as possible to the rear of water treatment process. Chlorine and water could be mixed adequately by choosing point of throwing chlorine reasonably, improving the setting of throwing chlorine pipeline, making full use of the hydraulic conditions of process piping and using mechanical agitation, elbow mixing, spray diffuser, pipeline mixer and other means.