Study On The Controls Of By-products Of Chlorine Dioxide In Drinking Water By Using Combined Disinfection

Chlorine dioxide as a new disinfectant, has a good application prospect in the field of water drinking water, but the inorganic disinfection by-products has certain health risks, and the possibility of chlorite and chlorate are greater than the risk of health. There are clear limits in the standards for drinking water, so it is very necessary to exceed the standard of risk control. At present, there are water using chlorine dioxide preoxidation combined with sodium hypochlorite disinfection control disinfection by-products and good operation effect. But the control reason analysis, the operation parameter optimization, the suitable water quality condition and so on question is still in the fuzzy stage.Firstly, the two water plants to use chlorine dioxide disinfection method combined with other research carried out for 7 months. The research results showed that water using the method of composite chlorine dioxide pre oxidation + sodium hypochlorite disinfection process. Coagulation and sedimentation time generated mixed chlorite mainly from the process of clean water, the total chlorite proportion were 50.6% and 55.1%, is the main source of the reduction reaction of chlorine dioxide and water. Join the hypochlorous acid by chlorite has certain decrease, 8.1% of the total; chlorate was generated mainly from in water purification process of coagulation and sodium hypochlorite disinfection, accounting for the proportion of total chlorate is 41.2% and 52.7%, is the main source of the oxidation reaction of chlorine dioxide solution into, into the sodium hypochlorite and reaction and chlorine dioxide and water, respectively, accounting for factory water chlorate was 47.8%, 46.1%, 6.1%. The correlation between the production quantity of chlorine dioxide disinfection byproduct and the water quality condition is: total manganese, total iron and algae.Secondly, combined chlorine dioxide sodium hypochlorite as the focus of the chlorine dioxide disinfection by-product control technology research and optimization. By changing the dosage, reaction time, water quality, and the conventional process to determine the optimal operation mode and the applicable conditions. The results show that the combined use of inorganic by-products generated by the dosage and disinfection order affected the generation of chlorine dioxide per 1mg/L chlorine dioxide + sodium hypochlorite disinfection of the chlorite and chlorate were 0.551mg/L, 0.117 mg/L and 0.149 mg/L, sodium hypochlorite and chlorine dioxide 0.0699 mg/L; chlorine dioxide dosing point has little effect control of inorganic disinfection by-products, the chlorine dioxide dosing the process can reduce the amount of generation is arranged at the rear end, 21.2% chlorite; low concentration of chlorine dioxide is used as a pre oxidation, the general consumption completely in the precipitation process; sodium hypochlorite, chlorite and sodium hypochlorite reaction will be a small part of the. In order to reduce the chlorite content; pure chlorine dioxide + sodium hypochlorite disinfection, chlorate oxidation of chlorite from 52.2%, 26.1% from two Oxidation of chlorine dioxide, 21.7% from sodium hypochlorite into; for each additional unit of water quality conditions generate chlorite in order to reduce the pH(210 ?g) > Mn2+(201?g) > ammonia(76?g) >CODMn(33?g) >Fe2+(-95?g), including divalent iron increased the formation of chlorite; after the change of the membrane pore size, decreased by 18.8% chlorite formation, the conventional process of chlorate formation without obvious effect; using sodium hypochlorite combination produces chlorinated by-products, its generation most in the national standard limit value of 30% less than, belonging to the safe range.Finally, using three kinds of commonly used pre oxidation with chlorine dioxide combined with and comparing the control effect of inorganic disinfection by-products and applicability in the changes in the pH of raw water, ammonia nitrogen, CODMn, Fe2+, Mn2+ is obtained by orthogonal experimental method. Coupled with the chlorite control effect of sodium hypochlorite(46.1%) is a sort of Potassium Permanganate(28.7%) >hydrogen peroxide(25.2%). Control of sodium hypochlorite chlorite is the most obvious, but will increase 33.3% chlorate. Three kinds of pre oxidants in pH, ammonia, CODMn, Fe2+?Mn2+ changes can maintain control of chlorite, the sodium hypochlorite control of chlorite by pH value and Fe2+ influence, applicable to CODMn, Mn2+, ammonia large changes in raw water; Potassium Permanganate by pH value and Mn2+ influence for two Fe2+, ammonia nitrogen, CODMn large changes in the raw water; hydrogen peroxide by Fe2+ and Mn2+ influence for ammonia, CODMn, pH value of large changes in the raw water; three kinds of pre oxidants can strengthen the disinfection effect of chlorine dioxide, residual chlorine dioxide performance the amount of chlorine dioxide disinfection of 2h effluent after. The effect of the order of Potassium Permanganate > sodium hypochlorite> hydrogen peroxide.