Investigation of advanced treatment for semiaerobic aged refuse biofilter effluent in landfill leachate via a UV-enhanced Fe0/H2O2 system

The Fe 0 /H 2 O 2 system, which is capable of removing organic matter from wastewater, suffers from limited efficiency because of slow Fe 2+ release and restricted Fe 2+ /Fe 3+ cycling. This study investigated the performance and mechanism of a UV-enhanced Fe 0 /H 2 O 2 system for the removal of organics in semiaerobic aged refuse biofilter (SAARB) effluent from landfill leachate, with HO • identified as the primary reactive oxygen species. UV not only initiates a homogeneous Fenton reaction through direct photolysis of H 2 O 2 and promotes Fe 2+ release from Fe 0 but also accelerates surface corrosion of Fe 0 to form more iron oxides, which react with H 2 O 2 in a heterogeneous Fenton reaction, thereby generating HO • at a faster rate. HO • preferentially reacts with organics containing chromophores or auxochromes, attacks humus with abundant conjugated structures, converts them into smaller organic molecules, and even achieves mineralization. Increasing the Fenton reagent ratio and dosage enhances the removal performance of the UV/Fe 0 /H 2 O 2 system, with optimal organic removal observed under acidic conditions. Ultimately, optimal conditions of the UV power (10   W), Fe 0 (2   mM) and H 2 O 2 (12   mM) dosages at pH 3.0 achieved 84.48% CN, 90.06% UV 254 , and 62.84% TOC removal. This study provides a feasible solution for achieving discharge standards for landfill leachate.