Characterisation of the formation of halobenzoquinone disinfection by-products in typical water sources at different water quality stages

As an emerging class of uncontrolled disinfection by-products, halobenzoquinones (HBQs) are 3 to 4 orders of magnitude more cytotoxic and genotoxic than regulated disinfection by-products. However, the formation of HBQs in different types of water sources is still unclear. In this study, 2,6-dichloro-1,4-benzoquinone (DCBQ) was selected as the representative species of HBQs to evaluate the formation characteristics during the chlorination of Yellow River diversion water, river water, south-north diversion water and mountain water. Principal component analysis and Pearson correlation analysis were carried out on the relationship between water quality characteristics and the formation of disinfection by-products in order to understand the formation potential of HBQs in each water source and the organic properties of disinfection by-product precursors such as HBQs. The results showed that different water sources have different capacities to form HBQs. The DCBQ formation potential (DCBQ-FP) of river water was the highest, followed by mountain water. The DCBQ-FP of Yellow River diversion water and south-north water diversion water was relatively the lowest. The DCBQ-FP was higher during the high temperature and high algal phase than during the low temperature and low turbidity phase. DCBQ precursors were mainly derived from algal-derived organic matter, low molecular neutrals (LMWN) during periods of high temperature and algal blooms. Aromatic compounds contribute significantly during the regular water quality period. The relationship with microbial metabolites (SMP) was high during periods of low temperature and low turbidity. As an emerging class of uncontrolled disinfection by-products, halobenzoquinones (HBQs) are 3 to 4 orders of magnitude more cytotoxic and genotoxic than regulated disinfection by-products.