Bromate minimization during ozonation

A study of BrO3‐ and TOBr production during ozonation indicates that both can be controlled by decreasing HO· and HOBr/OBr‐ concentrations. Significant levels of both bromate (BrO3‐) and brominated organics, measured as total organic bromine (TOBr), form during ozonation of water containing bromide and natural organic matter (NOM). Ozonation of several ultrafiltration and reverse osmosis membrane NOM isolates leads to approximately 17 percent of the bromide converting to bromate and 7 percent to TOBr. Depressing pH or adding hydroxyl radical scavengers decreases BrO3‐ production but promotes TOBr formation. In the presence of NOM, hydrogen peroxide addition lowers TOBr formation and may increase or decrease BrO3‐ formation, depending on other water quality factors. Ammonia addition decreases both BrO3‐ and TOBr production. Both BrO3‐production and TOBr production decrease when the initial bromide concentration is decreased and the ratio of ozone dosage to dissolved organic carbon is lowered.