Occurence and Control of Bromate in Aqueous Media

Bromate salt is an oxidizing agent that has been widely used as a food additive, but now the use of bromate is restricted to low level because of its mutagenicity and carcinogenicity. Potassium bromate was weakly mutagenic in Salmonella typhimurium TA100, TA102, and TA104 in the presence of metabolic activation, though the compound proved to be negative in TA98, TA1535, TA1537 and TA1538. It also demonstrated genotoxicity in some microbial tests. Potassium bromate or its radical derived from reduction seems to induce lipid peroxidation in producing oxidized DNA damage to the target. Bromate ion also exists in drinking water produced during ozonation of bromide-containing water. WHO guideline for drinking water quality recommended bromate concentration below 0.025mg/l and the U.S. government determined the maximum bromate concentration as 0.010mg/l in regulation, which leads the application of ozonation to be reconsidered. In Japan, 0.127mg/l of bromate ion was produced in experimental ozonation plant and the maximum of bromate ion (0.03mg/l) was detected in drinking water treatment plant. Bromate can be produced with water of high bromide concentration and must be controlled in treatment plant of high ozone dosage. New activated carbon reduces bromate though the activated carbon used for several months showed no reduction of bromate. Reduction of pH and ozone dose is most available technology for reducing bromate. Bromate is also detected in sodium hypochloride as a disinfectant and chlorinated water. Contaminated river water contained bromate up to 0.009mg/l, possibly discharged from permanent-wave neutralizing agent. Environmental bromide and bromate contamination should have a potential importance.