Removal of refractory organics from landfill leachate by in situ electrogenerated H 2 O 2 combined with an Fe 0 Fenton-like process

Abstract

Landfill leachate contains a large amount of refractory organic matter, which will cause harm to the environment if not appropriately treated. In this study, the refractory organic matter in landfill leachate has been treated by in situ electrogenerated H₂O₂ combined with an Fe⁰ Fenton-like process, aiming to explore a cleaner and more efficient process for leachate treatment. The results showed that the current, initial pH and oxygen flow rate have significant influences on H₂O₂ production. The current and oxygen flow rate are positively correlated with H₂O₂ production, and neutral conditions are more favourable. Under the conditions of a current of 200 mA, an initial pH of 7.0 and an oxygen flow rate of 0.3 L/min, H₂O₂ production reached 2.81 mM, the current efficiency was close to 80% and the highest removal efficiency of organic matter reached 40.70%. The absorbance at 280 nm (E₂₈₀) decreased from 0.1669 to 0.1180, and the ratios E₂₄₀/E₄₂₀, E₂₅₀/E₃₆₅ and E₃₀₀/E₄₀₀ in the UV and visible regions changed from 0.7825, 5.4492 and 0.2422 to 1.3135, 7.3745 and 0.2966, respectively. The maximum fluorescence intensities due to humic-like acid and fulvic-like acid substances decreased from 1275 and 1246 to 595.9 and 711.0, respectively. Spectral analysis further showed that the complex structure of refractory organic matter in the landfill leachate was obviously destroyed, and the relative content of humus decreased significantly. This study may provide a theoretical basis for the effective treatment of refractory organic matter in landfill leachate by in situ electrogenerated H₂O₂ combined with a Fenton-like process.