THMs and HAAs Fotmation by Tryptophan during Chlorination Disinfection

Abstract

Wastewater reuse is an effective solution to water resource shortage problems, which commonly exists in urban areas. And disinfection is necessary to ensure the quality of the reclaimed water. Trihalomethanes (THMs) and haloacetic acids(HAAs) are two main disinfection byproducts(DBPs) in the water treatment process. Nitrogenous organic compounds are important disinfection byproducts precursors in the water. Tryptophan(Trp) is one kind of elementary amino acids, which are typical nitrogenous organic compounds. In this paper, the characteristics of THMs and HAAs formation from tryptophan under different chlorination disinfection conditions has been researched. The influencing factors were investigated, such as reaction time, initial concentration of tryptophan, chlorine dosage, pH and temperature. The results show that the yields of chloroform(TCM), dichloracetic acid(DCAA) and trichloracetic acid(TCAA) are all increased with the reaction time increasing, and the formation rates are all accelerated at the initial period; With the increase of initial tryptophan concentration, the yield of TCM, DCAA and TCAA are all increased at first and then reduced; With the increase of chlorine dosage, the yields of DCAA and TCAA both increased with ; The pH influences the formation of TCM and HAAs greatly. The yield of HAAs are low in the acidic condition and high in the conditions of neutral and alkaline conditions. The yield of HAAs is bigger at 20°C than other temperature.