Generation Study And Identification Of Haloacetic Acids In Chlorination Of Tannin

Chlorination is the leading disinfection mode in the system of urban drinking water. But, researchers found a series of nonvolatile chlorination by-product (HAAs) in drinking water, and it is confirmed carcinogenic to human in further research. The investigations shows that carcinogenetic risk of HAAs take more than 91.9% in total carcinogenetic risk of DBPs, furthermore the risk of HAAs is in an approximate linear trend with its consistency. Researches about HAAs has become more and more important, but researches in the past almost take humic and fulvic as subjects which have complicated structure and blurry molecular formula, so it is hard to probe into deeply the spanning mechanism of HAAs in chlorination. Thereby it is hard to control spanning of HAAs.Aiming at this situation, the research mostly does some research following: First, the method for determination of HAAs has been established according to US Environmental Protection Agency method 552.3(USEPA552.3), and it adopts liquid-liquid microextration combining acidity methanol esterification. Some improvements are made according laboratory condition to make laboratory process more convenient and effective.Following, this thesis takes tannin as research object for its abroad presence in nature and simple molecular constitution, analyzes and judges the HAAs generation in tannin chlorination process, reviews the rules of HAAs generation in reaction of tannin and chlorine in different water conditions, The results of experiments proves that HAAs generation has a high rate in anterior 8 hours of chlorination process, then the rate decreases. HAAs generation in reaction of tannin and chlorine is second-order reaction, toward tannin and chlorine, it is first-order reaction and the total reaction is second-order reaction. Though 24 hours, total HAAs generation has such a high concentration of 134μg/L/TOC. Total HAAs generation increases 72% at 25℃compared with 4℃,and DCAA increases 53%, TCAA increases 106%. Further, control conditions of HAAs generation in chlorination and crafts optimization are brought forward. At last, this thesis founds neural network (NN) model of HAAs generation...