Determination And Removal Technologies Of Inorganic By-productsof Chlorine Dioxide On Purification Process

As a new disinfectant, chlorine dioxide has a good application prospect in the field of drinking water purification, but its inorganic disinfection by-products, namely chlorate and chlorite have certain heathy risk. In current domestic water plants using chlorine dioxide, professional knowledge level and economic ability is limited because of confining scale of them. There were less available daily methods for the determination of chlorine dioxide and its inorganic by-products; it also hinders researches about technology of risk control.This article is to solve the problems above determination methods and perfect the chlorite removal technology using ferrite as reducing agent. The methods were improved and evaluated based on the existing research, to make them be able to meet the demand of domestic chlorine dioxide using condition. Finally methods that was able to detect chlorine dioxide and its disinfection by-products easy and accurately.For the research about removal technology, which is used in the stage of coagulation by adding ferrous as reducing agent, dosing mechanism of system science were put forward. The effect of factors was analyzed by coagu-flocculation test. After the significant of factors was difinited, experiments were designed to explore the interaction effect between several factors and predict the optimum conditions. Results show that the optimum range of p H was 7.5-8.5, ratio of ferrous and chlorite was 1.8-2.3, concerntration of ferrous was lower than 7mg/L. Otherwise the interaction effect between these factors was analyzed by response surface method. The results showed that interaction effect was obverous between p H and ratio, concerntraion and ratio, p H and concerntrations. And optimum operating conditions were predicted by Box-Behnken mathematical model in response surface method, that p H was 8.18, ratio between ferrous and chlorite was 2.61, concerntration of ferrous was 4.59 and the adding position was later 11 min than chlorine dioxide.In a word, the improved methods were available for the determination of chlorine dioxide and its inorganic by-products in domestic plants. When chlorine dioxide is used as pre-oxidant, the removal technology of chlorite by ferrous was completed.