Effective inhibition of bromate formation with a granular molecular sieve catalyst Ce-MCM-48 during ozonation: Pilot-scale study

The inhibition of bromate (BrO₃ ^-) formation during ozonation with a novel granular molecular sieve catalyst, Ce-MCM-48, was investigated in pilot-scale under simulated practical conditions by varying the initial bromide (Br-) concentration, total organic carbon (TOC) content, aqueous ozone concentration, water pH, and hydraulic retention time (HRT). The results indicate that the inhibition efficiency of Ce-MCM-48 for BrO₃ ^- formation could reach 82-90% as the initial Br- concentration varied from 200-800 μg/L under typical water treatment conditions: Aqueous ozone concentration=2.0±0.1 mg/L, HRT=10 min, initial pH=7.7-7.9, and T=18±2 °C. The extension of HRT from 10 to 20 min and pH variation in the range of 6.0-9.0 had insignificant impact on the inhibition efficiency of BrO₃ ^- formation. Compared with ozonation alone, the catalytic ozonation could achieve almost the same efficiencies for TOC removal and Escherichia coli inactivation. A long-term continuous operation experiment for 33 days demonstrated that the granular catalyst Ce-MCM-48 possesses not only a high efficiency, but also a large treatment capacity for minimizing BrO ₃ ^- formation during the ozonation process, and thus has potential applications to water treatment.