An Integrated Coagulation-Sedimentation, O3-AOP, and Membrane Bioreactor (MBR) Hybrid System for The Degradation of Recalcitrant Organic Pollutants in Simulated Pharmaceutical and Resin Synthesis Wastewater

Abstract

The treatment of high-strength wastewater from pharmaceutical and resin synthesis processes, which contain recalcitrant organic pollutants and emerging contaminants, remains a major environmental challenge because of their high chemical oxygen demand (COD), low biodegradability, and toxicity. In this study, the performance of a laboratory-scale hybrid system integrating coagulation–sedimentation, ozone-based advanced oxidation (O3-AOPs), and a membrane bioreactor (MBR) for the removal of COD, phenol, and paraben from three simulated wastewater scenarios was evaluated. The system achieved overall COD removal efficiencies exceeding 95% across all the scenarios, with the highest removal (97.4%) observed in high-strength pharmaceutical wastewater (influent COD concentration of 4,398–4,750 mg L^-1). Phenol removal exceeded 98% in all the cases, while target parabens were reduced to below the analytical detection limit and were subsequently reported as nondetectable. Spatial attenuation profiling along the ozone contact column suggested a dual-mechanism behavior. The rapid pollutant attenuation observed in the lower section was consistent with radical-driven oxidation, whereas the enhanced removal in the upper section may indicate the contribution of additional processes, including possible physical stripping of volatile intermediates. The O3-AOP stage served as an effective protective barrier, reducing phenol concentrations to below the biological inhibition threshold before the wastewater entered the MBR. The findings demonstrate that the triple-integrated hybrid system provides an effective multiple-barrier treatment approach for complex industrial wastewater, offering high pollutant removal efficiency and substantially reducing the concentration of target cytotoxic and potentially endocrine-disrupting compounds.