Transformation of bromide and formation of brominated disinfection byproducts in peracetic acid oxidation of phenol

Abstract Peracetic acid (PAA) has attracted increasing attention in wastewater treatment as a disinfectant. However, the transformation of bromide (Br−) during PAA oxidation of bromide-containing wastewater has not been fully explored. This study showed that Br− could be oxidized by PAA to free bromine which reacted with phenol to form organic bromine. At pH 7.0, more than 35.2% inorganic Br− was converted to organic bromines in 4 h. At acidic conditions, the conversion ratio was even higher, reaching 69.9% at pH 2.8. Most of the organic bromines were presented as bromophenols (i.e., 2-bromophenol, 4-bromophenol, and 2,4-dibromophenol), while regulated brominated disinfection byproducts (Br-DBPs, i.e., bromoform and bromoacetic acids) only accounted for a tiny fraction of total organic bromine. Similar results were observed when PAA was applied to natural organic matter (NOM) or wastewater in presence of Br−. The organic bromine yield reached 56.6 μM in the solution containing 0.1 mM Br− and 2 mg/L NOM initially. Among them, only 1.00 μM bromoform and 0.16 μM dibromoacetic acid were found. Similarly, regulated Br-DBPs only accounted for 28.3% of the organic bromine in a real wastewater effluent treated with PAA. All these data show that monitoring regulated DBPs cannot fully indicate the potential environmental risk of the application of PAA to wastewater.