Efficiency of ozonation and O3/H2O2 as enhanced wastewater treatment processes for micropollutant abatement and disinfection with minimized byproduct formation

Abstract

Ozonation, a viable option for improving wastewater effluent quality, requires process optimization to ensure the organic micropollutants (OMPs) elimination and disinfection under minimized byproduct formation. This study assessed and compared the efficiencies of ozonation (O-3) and ozone with hydrogen peroxide (O-3/H2O2) for 70 OMPs elimination, inactivation of three bacteria and three viruses, and formation of bromate and biodegradable organics during the bench-scale O-3 and O-3/H2O2 treatment of municipal wastewater effluent. 39 OMPs were fully eliminated, and 22 OMPs were considerably eliminated (54 +/- 14%) at an ozone dosage of 0.5 gO(3)/gDOC for their high reactivity to ozone or center dot OH. The chemical kinetics approach accurately predicted the OMP elimination levels based on the rate constants and exposures of ozone and center dot OH, where the quantum chemical calculation and group contribution method successfully predicted the ozone and center dot OH rate constants, respectively. Microbial inactivation levels increased with increasing ozone dosage up to similar to 3.1 (bacteria) and similar to 2.6 (virus) log10 reductions at 0.7 gO(3)/gDOC. O-3/H2O2 minimized bromate formation but significantly decreased bacteria/virus inactivation, whereas its impact on OMP elimination was insignificant. Ozonation produced biodegradable organics that were removed by a post-biodegradation treatment, achieving up to 24% DOM mineralization. These results can be useful for optimizing O3 and O-3/H2O2 processes for enhanced wastewater treatment.