Bromate formation in bromide-containing waters irradiated by gamma rays

The formation of bromate, a classified potential carcinogen, is of great concern when disinfection processes are used for treating high-bromide drinking waters. Bromide-containing aqueous solutions with various addi- tives were irradiated by 60Co γ source. With a 2.0 kGy irradiation of N2O-saturated solutions at initial bromide concentrations of 180.2 μg 1-1,416.9 μg 1-1,663.1μg 1-1 and 823.9μg 1-1.79.5%, 84.0%, 87.3% and 88.3% of bromide ions were transformed to bromate, respectively. Addomg CO32-/HCO3 or NO3 ions into N2O- saturated bromide solutions, the amount of bromate ions formed decreased with increasing concentrations of the additives. On the other hand, the bromate concentration was all below the detection limit of 1 μg 1-1 when- ever N2O was not added to quench eaq and -H. The results indicated that ＂7-rays irradiation could be used as a disinfection process, instead of ozonation, to comply with upcoming more stringent regulations, especially in waters containing high concentrations of bromide.