Ultrasound, Hydrogen Peroxide, and Persulfate in Hybrid Advanced Oxidation Processes(AOPs): A Comparative Study for the Reuse of Sewage Treatment Effluent

Abstract

Objectives As the variety and quantity of recalcitrant pollutants such as pharmaceuticals, pesticides, endocrine disruptors, and cosmetic products discharged into water bodies steadily increase, the need for AOPs following biological wastewater treatment processes is growing. In this study, we compared the Total Organic Carbon (TOC) removal capabilities of conventional AOPs, ultrasound, hydrogen peroxide, and persulfate-based multiple AOPs on the final effluent of S wastewater treatment plant. The study also evaluated the feasibility of wastewater reuse by examining the optimal operating conditions of the applied AOPs. Methods The removal characteristics of TOC were investigated based on reaction time, US frequency, and oxidant dosage for the following conditions: ultrasound (US) alone, individual treatments with hydrogen peroxide (H2O2) and persulfate (PS) as oxidants, combined US/H2O2 and US/PS dual AOPs, and a US/PS/H2O2 multi-AOPs system. Results and Discussion Only US oxidation treatment at 80 kHz for 60 minutes resulted in a 14.4% TOC removal efficiency. Individual treatment with H2O2 at 174 mM showed 69.2% removal efficiency, while persulfate oxidation treatment at 43.5 mM showed 13.8%. The PS/H2O2 oxidation treatment showed 68.5% removal efficiency at 174 mM H2O2 and 0.52 mM PS, and an 85.3% removal efficiency at 2.08 mM PS and 350 mM H2O2 conditions. Under the same 80 kHz ultrasound conditions, the combined US and other oxidant treatment resulted in an increased TOC removal efficiency: 87.8% for US/H2O2 at 174 mM H2O2, and 81.9% for US/PS at 43.5 mM PS. Additionally, the multi-treatment with US, PS, and H2O2 showed a removal efficiency of 87.0% at 2.08 mM PS and 350 mM H2O2, and 91.1% at 174 mM H2O2 and 0.52 mM PS conditions. Conclusion In this study, among the AOPs, the oxidation treatment with US/PS/H2O2 exhibited the highest TOC removal efficiency at 91.1%. The integration of chemical oxidants with US demonstrated significant improvement in TOC removal capabilities, with PS showing superior performance at the same concentration conditions among the utilized chemical oxidants in the multi-AOPs. Although H2O2 also displayed commendable TOC removal abilities, its oxidation efficiency was lower at low concentration injections, whereas higher concentrations of H2O2 injections proved to be more effective in oxidation.

Keywords

• aops
• ultrasound
• hydrogen peroxide
• persulfate
• toc