Bromate is a by-product of drinking water disinfection, which is potentially carcinogenic to humans. Therefore, in this study, the effects of hydraulic loading rate and the nitrate inhibition on bioreduction of bromate in the biofilm reactor were investigated. Two different flow biofilm reactors were used to reduce bromate and compare the removal efficiencies. The bromate removal efficiencies were found to be 86.6% with 8.1 mg/L of BrO₃ ^- influent at 48 h of empty bed contact time (EBCT) in the plug-flow biofilm reactor. The bromate removal efficiencies were 93.2% with 8.0 mg/L of BrO₃ ^- influent at 24 h of EBCT in the biofilm reactor with internal recirculation (20:1 ratio of recycle to influent flow). The bromate and nitrate removal efficiencies were 84.1% and 94.1% at 48 h of EBCT in the plug-flow biofilm reactor with 8.5 mg/L of BrO₃ ^- and 17.9 mg/L of NO₃-N influent, respectively. While the bromate and nitrate removal efficiencies were 79.9% and 94.5% at 24 h of EBCT in the recirculation biofilm reactor with 8.4 mg/L of BrO₃ ^- and 17.7 mg/L of NO₃-N influent, respectively. These results reveal that biofilm reactor with internal recirculation has a better BrO₃ ^- removal efficiency than that of plug-flow biofilm reactor. Furthermore, nitrate inhibits the reduction of bromate in the biofilm reactors.