MEMBRO₃X, a Novel Combination of a Membrane Contactor with Advanced Oxidation (O₃/H₂O₂) for Simultaneous Micropollutant Abatement and Bromate Minimization

Abstract

Ozonation is a water treatment process for disinfection and/or micropollutant abatement. However, ozonation of bromide-containing water leads to bromate (BrO3–) formation, a potential human carcinogen. A solution for mitigating BrO3– formation during abatement of micropollutants is to minimize the ozone (O3) concentration. This can be achieved by dosing ozone in numerous small portions throughout a reactor in the presence of H2O2. Under these conditions, O3 is rapidly consumed to form hydroxyl radical (•OH), which will oxidize micropollutants. To achieve this goal, a novel process (“MEMBRO3X”) was developed in which ozone is transferred to the water through the pores of polytetrafluoroethylene (PTFE) hollow fiber membranes. When compared to the conventional peroxone process (O3/H2O2), the MEMBRO3X process shows better performance in terms of micropollutant abatement and bromate minimization for groundwater and surface water treatment. For a groundwater containing 180 μg/L bromide, a 95% abatement of the ozone-resistant probe compound p-chlorobenzoic acid yielded <0.5 μg/L BrO3–, whereas in the conventional peroxone process, 8 μg/L BrO3– was formed. In addition, the efficacy of the MEMBRO3X process was demonstrated with river water and lake water.