An assessment of the UV/nFe0/H2O2 system for the removal of refractory organics in the effluent produced by the biological treatment of landfill leachate

Abstract The removal efficiency and mechanism of the ultraviolet/nanoscale Fe 0 /H 2 O 2 (UV/nFe 0 /H 2 O 2 ) system for refractory organics in membrane bioreactor effluent were investigated. The most effective removal of organics was achieved at initial pH = 3.0, H 2 O 2 dosage = 50 mM, nFe 0 dosage = 1.0 g/L, and UV power = 15 W, with a reaction time of 60 min. Under these conditions, the absorbance at 254 nm, chromaticity, and total organic carbon removal efficiencies were 65.13%, 79.67%, and 61.51%, respectively, and the aromaticity, humification, molecular weight, and polymerization of organics were all significantly reduced. The surface morphology and elemental valence analysis of nano zero‐valent iron (nFe 0 ) before and after the reaction revealed the formation of iron‐based (hydrated) oxides, such as Fe 2 O 3 , Fe 3 O 4 , FeOOH, and Fe (OH) 3 , on the surface of the nFe 0 . Refractory organics were removed by Fenton‐like reactions in the homogeneous and heterogeneous adsorption–precipitation of iron‐based colloids. At the same time, UV radiation accelerated the formation of Fe 2+ on the nFe 0 surface and promoted the Fe 3+ /Fe 2+ redox cycle to a certain extent, enhancing the removal of refractory organics. The results provide a theoretical basis for the application of the UV/nFe 0 /H 2 O 2 system to remove refractory organics in the effluent produced by the biological treatment of landfill leachate. Practitioner points The UV/nFe 0 /H 2 O 2 process is effective in refractory organics removal in leachate treatment. Humus in leachate was largely destroyed and mineralized by the UV/nFe 0 /H 2 O 2 process. Active nFe 0 material participated in the Fenton‐like process and was promoted by UV. The effects of nFe 0 material and UV introduction were investigated.