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

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 (O₃) and ozone with hydrogen peroxide (O₃/H₂O₂) for 70 OMPs elimination, inactivation of three bacteria and three viruses, and formation of bromate and biodegradable organics during the bench-scale O₃ and O₃/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 gO₃/gDOC for their high reactivity to ozone or ^•OH. The chemical kinetics approach accurately predicted the OMP elimination levels based on the rate constants and exposures of ozone and ^•OH, where the quantum chemical calculation and group contribution method successfully predicted the ozone and ^•OH rate constants, respectively. Microbial inactivation levels increased with increasing ozone dosage up to ∼3.1 (bacteria) and ∼2.6 (virus) log₁₀ reductions at 0.7 gO₃/gDOC. O₃/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 O₃/H₂O₂ processes for enhanced wastewater treatment.