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 adsorptionprecipitation 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.

Leachate treatment via electrocoagulation–coal‐based powdered activated carbon process: Efficiencies, mechanisms, kinetics, and costs

“…In order to treat landfill leachate, a number of traditional chemical and physical processes have been suggested, such as adsorption with different adsorbent (Detho et al, 2021; Elgarahy et al, 2023; Kumara & Dayanthi, 2023; J. Liu et al, 2024; Salama et al, 2022), ion exchange with various resins (Aziz et al, 2020; Bashir et al, 2010; Scandelai et al, 2020), reverse osmosis (Bouchareb et al, 2022; Folino et al, 2024; García‐Pacheco et al, 2022), electrocoagulation (Guo et al, 2022; Hamid et al, 2021; R. Li et al, 2017; Ogedey & Oguz, 2024), electrochemical oxidation (Tang et al, 2022; Vocciante et al, 2021; Zhao & Zhao, 2021), fenton processes (Crispim et al, 2022; Feng et al, 2022; X. Li et al, 2018), advanced oxidation processes (Kanmani & Dileepan, 2023, Shuo Li et al, 2022, Y. Liu et al, 2022), dissolved air flotation (Adlan et al, 2011), and coagulation/flocculation (Lessoued et al, 2017; Reddy et al, 2022; Zakaria et al, 2022).…”