Effective Inhibition of Bromate Formation with a Granular Molecular Sieve Catalyst Ce-MCM-48 during Ozonation: Pilot-Scale Study

The inhibition of bromate (${\mathrm{BrO}}_3^{-}$) 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 (${\mathrm{Br}}^{-}$) 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 ${\mathrm{BrO}}_3^{-}$ formation could reach 82–90% as the initial ${\mathrm{Br}}^{-}$ concentration varied from $200–800\mathrm{\mu g}/\mathrm{L}$ under typical water treatment conditions: aqueous ozone $\text{concentration}=2.0\pm 0.1\mathrm{mg}/\mathrm{L}$, $\mathrm{HRT}=10\min$, initial $\mathrm{pH}=7.7–7.9$, and $T=18\pm 2°\mathrm{C}$. 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 ${\mathrm{BrO}}_3^{-}$ 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 ${\mathrm{BrO}}_3^{-}$ formation during the ozonation process, and thus has potential applications to water treatment.