Ultraviolet‐enhanced Fe⁰‐activated H₂O₂ process for the removal of refractory organic matter from landfill leachate: Performance and mechanism.

The Fenton‐like process, utilizing zero‐valent iron (Fe0) and hydrogen peroxide (H2O2), is employed to degrade refractory organic matter in membrane bioreactor (MBR) effluent derived from landfill leachate. However, the rate‐limiting Fe2+/Fe3+ redox step diminishes treatment efficacy and generates substantial iron sludge. This study elucidates the mechanism by which ultraviolet (UV) irradiation augments the Fe0/H2O2 process for the removal of refractory organic matter in MBR effluent. The results show that the UV‐ enhanced H2O2 process effectively disrupts the aromatic structure of organic compounds, reducing molecular weight, degree of polymerization, and humification. Compared with the Fe0/H2O2 process, the removal efficiency of UV254, color number, and total organic carbon in the effluent treated by the UV/Fe0/H2O2 process increased by 24.16%, 14.62%, and 57.46%, respectively. Concurrently, the generation of iron sludge was reduced by 21.6%. This enhancement is primarily attributed to UV's ability to intensify the Fe2+/Fe3+ redox cycle and expedite the surface corrosion of Fe0, yielding more iron oxides. This accelerates the decomposition of H2O2, generating a higher quantity of •OH through both homogeneous and heterogeneous Fenton‐like reactions. The refractory organic matter is removed through the oxidation by •OH, as well as the adsorption and precipitation facilitated by iron‐based colloids. Practitioner Points: UV promotes Fe0/H2O2 process to degrade refractory organic matter in MBR effluent.UV promotes Fe0 to dissolve more Fe2+ and the redox cycle of Fe2+ and Fe3+.The dosage of H2O2 or Fe0 influences the treatment effect of the process. [ABSTRACT FROM AUTHOR]