Bromide's effect on DBP formation, speciation, and control: part 1, ozonation

Ozonation of high‐bromide waters at ambient pH will likely result in bromate concentrations that exceed the maximum contaminant level specified in the draft D–DBP Rule. The effect of variable ozone dosage and bromide concentration on the formation of organic disinfection by‐products (DBPs) and bromate were evaluated. Low ozone dosages resulted in oxidation of organic precursors, yielding decreases in the formation potential for total trihalomethanes (THMs), six haloacetic acids (HAAs), and total organic halide (TOX). Increasing the ozone dosage oxidized bromide to bromate, decreasing the bromide for incorporation into DBPs. Bromate concentrations were linearly correlated with ozone residuals. Changes in the bromine incorporation factors n and n' reflected differences in the resulting speciation of THMs and HAAs, respectively. Because TOX measurements based on chloride equivalence may underestimate the halogenated DBP yield for high‐bromide waters, a procedure is described whereby bromide and bromate concentrations were used to correct the TOX measurement.