Influence of Ultraviolet Light Coupled with Hydrogen Peroxide Treatment on Organic Nitrogen and Carbon Precursors and Disinfection By-Product Formation

Abstract

This study examined the relationships between organic matter composition and disinfection by-product formation potential (DBPFP) following water chlorination. Laboratory synthetic water with various compositions of organic carbon and nitrogen were treated with ultraviolet light, coupled with hydrogen peroxide (UV/H2O2), to assess the effects of UV/H2O2 on their DBPFPs. Biologically treated wastewater effluent and histamine dihydrochloride were spiked in the tested solutions to represent complex organic matter compositions and nitrogenated aromatic structure. It was found that carbon-containing precursors were relatively easier to mineralize by UV/H2O2 treatment than the nitrogen-containing compounds. UV/H2O2 processes successfully reduced the precursors of trihalomethanes and haloacetic acids (HAAs); however, the treatment efficiency was lower for N-nitrosodimethylamine (NDMA) precursors. It was also observed that the degree of precursor removal was reduced when raw water was contaminated by domestic wastewater effluents. In comparison to untreated water, UV/H2O2-treated water produced a higher ratio of HAAs than trihalomethanes after chlorination. This suggests that a higher fraction of hydrophilic compounds was obtained after UV/H2O2 treatment. Raw water impaired by wastewater effluent also altered the formation and species distribution of DBPs, because higher ratio of HAAs and brominated DBPs were observed.