Bromide's effect on DBP formation, speciation, and control: part 2, biotreatment

Both bromo‐ and chloro‐substituted disinfection by‐products decreased significantly when a combination of ozonation and biotreatment was used. The effect of bromide concentration, ozone dosage, and biotreatment on the control of disinfection by‐products (DBPs) was evaluated. Although total trihalomethane precursors were better controlled by ozonation and the precursors of six haloacetic acids were better controlled by biological treament, the combined processes were effective for the control of all halogenated DBP precursors. Ozone's conversion of bromide to bromate and the chemical or biological oxidation of organic matter changed the ratio of bromide to dissolved organic carbon. Increases in this ratio increased the formation of some brominated DBPs, but these DBP increases were offset by the precursor oxidation provided by the combination of the two processes.