Characteristics of the formation and toxicity index of nine newly identified brominated disinfection byproducts during wastewater ozonation

Ozonation plays an important role in wastewater treatment for reuse. However, the toxicity of wastewater treated with ozone considerably increases with bromide (Br − ) concentration >100 μg/L. Nine newly identified brominated disinfection byproducts (Br-DBPs) that are highly toxic in ozonated Br − -containing wastewater were found in our recent work, including 2-bromostyrene, 1-bromo-1-phenylethylene, 2-bromobenzaldehyde, 3-bromobenzaldehyde, 4-bromobenzaldehyde, 2-bromophenylacetonitrile, 3-bromophenylacetonitrile, 4-bromophenylacetonitrile, and 2,4,6-tribromophenol. In the present study, the formation and calculated toxicity index of the nine newly identified Br-DBPs were evaluated. The correlations between the water quality index and the formation of nine Br-DBPs were also analyzed. With the increase of ozone dosage, the concentrations of bromostyrenes, 3-bromobenzaldehyde, 4-bromobenzaldehyde, 2-bromophenylacetonitrile, and 2,4,6-tribromophenyl in the ozonated samples gradually increased. With the increase of Br − concentration, the concentrations of bromostyrene, 2-bromobenzaldehyde, and 2,4,6-tribromophenol gradually increased. With the increase of NH 4 + concentration, the concentrations of bromophenylacetonitriles gradually increased. Among the nine Br-DBPs, the bromophenylacetonitriles and 2,4,6-tribromophenol contributed the most to the cytotoxicity index, 2,4,6-tribromophenol and bromostyrenes contributed the most to the genotoxicity index, and bromophenylacetonitriles and bromostyrenes contributed the most to the oxidative damage index. The dissolved organic carbon levels strongly correlated with the formation of 3-bromophenylacetonitrile and 4-bromophenylacetonitrile, and the fluorescence I–V region intensity integral was correlated with the formation of 4-bromobenzaldehyde and 2,4,6-tribromophenol. The results of the present study clarified the formation potential of the nine widely existing newly identified Br-DBPs, confirmed the high calculated toxicity indices, and are of great value for future research on Br-DBPs.