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

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 mu M in the solution containing 0.1 mM Br- and 2 mg/L NOM initially. Among them, only 1.00 mu M bromoform and 0.16 mu M 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.

Automated summary

Peracetic acid (PAA) has been widely used as a disinfectant in wastewater treatment, but its oxidation of bromide-containing wastewater has not been fully explored. This study found that PAA can oxidize bromide ions to form organic bromine compounds, such as bromophenols. Regulated brominated disinfection byproducts (Br-DBPs) only accounted for a small fraction of the organic bromine formed. Monitoring regulated DBPs may not fully indicate the potential environmental risk of PAA application in wastewater treatment.