Bromate ion removal by HEEB irradiation

Proposed drinking water regulations will specify a maximum contaminant level of 0.01 mg/L for bromate ion (BrO₃⁻). This study used high-energy electron-beam irradiation to remove BrO₃⁻ after formation, when other control strategies are not as effective. BrO₃⁻ was reduced to bromide ion (Br⁻), with bromine (HOBr/OBr⁻) as intermediate. A dose of 60 krads was sufficient to reduce 70 percent of BrO₃⁻ from an initial concentration of 100 µg/L. The presence of electron scavengers such as hydrogen peroxide and nitrate significantly reduced BrO₃⁻ removal, whereas the addition of the OH radical scavenger such as t-butanol did not affect the removal of BrO₃⁻. This indicates that aqueous electrons (eaq⁻) are mainly responsible for BrO₃⁻ destruction. The presence of natural organic matter decreased BrO₃⁻ reduction efficiency. The reaction of eaq⁻ with various bromine species in water was used to model and simulate experimental data for the destruction of BrO₃⁻. Computer model predictions were in fairly good agreement with the experimental results.