Study On Formation Characteristics And Removal Mechanism Of Disinfection By-products During Prechlorination

In this paper, it was first studied systematically that the production characteristics of disinfection by-products, trihalomethane and haloacetic acids, during prechlorination of two raw water in Shanghai and variation law of disinfection by-products in pipe network. Viewing from different molecular weight and hydrophilia and hydrophobicity of organic matters, the disinfection by-products formation potential in Shanghai drinking water after treatment by conventional processes was discussed in detail. On this basis, the removal of haloacetic acids by the processes of advanced oxidation, such as UV-H₂O₂ and UV-H₂O₂-O₃, and Fe reduction were first studied, which would offer new thinking or path for reducing disinfection by-products.The accurate and credible analysis method of haloacetic acids was established using the acidizing methanol as the derivating agent. The recovery ratios agreed with 6223 segment specification in American standard methods for the examination of water and wastewater 19th edition.The main types of HAAs formation potential in raw water from Huangpu River were DCAA, TCAA and DBAA. The most HAAs formation potential was formed by the organic matters whose molecular weight were less than 3×10³Da, and in the molecular weight interval, the DCAA and TCAA formation potential were main. In finished water of raw water from Huangpu River, the most HAAs formation potential were formed by the organic matters whose molecular weight were less than 1 ×10³Da. The main types of HAAs formation potential in raw water from Changjiang River were DCAA and TCAA, and the distribution of HAAs formation potential was uniform in five MW intervals. In finished water of raw water from Changjiang Rive, the most HAAs formation potential were formed by the organic matters whose molecular weight were less than 3×10³Da.Based on the study on the formation potential of strong hydrophobicity and weak hydrophobicity and hydrophilia organic matters in raw water from Huangpu River, it was discovered that trichlormethane was the main product after chloridizing strong hydrophobicity and weak hydrophobicity organic matters, the following was dichlorobromomethane. Dichlorobromomethane was the main product after chloridizing hydrophilia organic matters, the following were trichlormethane,...