Possibility analysis for bromate generation during running ozone-biological activated carbon process

Laboratory and pilot scale experiments were carried on to assess the formation of bromate during ozonebiological activated carbon(O3-BAC), and further to provide practical parameters for drinking water treatment with low risk of excessive bromate. The effects of initial bromide concentration and oxidation condition on bromate formation were studied, and bromate removal capability of the O3-BAC was also evaluated. Results showed that the concentration of bromide ion and ozone exposure level(Ct value) could impose a positive impact on bromate formation. Under the same value of Ct, an increasing ozone concentration would enhance the formation of bromate at about 200%. Raw water from Nanjing reach of the Yangtze River was treated by O3-BAC process, and the results showed that bromate was not detected in the effluent. Moreover, bromate removal was rarely observed in the BAC process, therefore bromate control measures should be mainly took in the ozone phase rather than in the subsequent BAC process.