Efficient Fenton/biological activated carbon filter process for treating landfill leachates

Abstract

The treatment of landfill leachates is considered to be one of the most difficult processes among organic wastewater treatments. This study aims to address the challenge of treating landfill leachates by developing a new combined Fenton/biological activated carbon filter process to efficiently treat organic matter, ammonia nitrogen (NH₄⁺-N), and chromaticity. Under optimal Fenton process conditions (pH 4, H₂O₂ dosage of 15 mL L⁻¹, n(H₂O₂) : n(Fe²⁺) = 4 : 1, and reaction time of 100 min), the removal efficiencies of COD, chromaticity, and NH₄⁺-N reached 75.05%, 98.32%, and 30%, respectively. Response surface methodology confirmed that the significance of influencing factors follow the order of pH > H₂O₂ dosage > n(H₂O₂) : n(Fe²⁺) > reaction time, with a verified COD removal efficiency of 74.36% (minimal error). For the SPC/Fe²⁺ process, optimal conditions yielded COD, chromaticity, and NH₄⁺-N removal efficiencies of 58.39%, 84.21%, and 20.30%, respectively. The BAC filter achieved effective COD removal (27.3%) and excellent NH₄⁺-N removal (61.90%). The Fenton/BAC combined process achieved a remarkable treatment performance for landfill leachate, with a COD removal efficiency of 81.86%, NH₄⁺-N removal efficiency of 73.33%, and chromaticity removal efficiency of 98.50%. Notably, the biodegradability index (B/C) of the landfill leachate increased from 0.31 to 0.51, confirming the synergistic mechanism of organic matter and NH₄⁺-N removal by BAC. This study innovatively constructs a Fenton/BAC combined process, quantifies the synergistic removal effects of adsorption-biofilm-microbial degradation by BAC on leachate organics and NH₄⁺-N, and clarifies the SPC/Fe²⁺-Fenton performance-cost trade-off, providing a new technical route for efficient leachate treatment. This novel combined process offers promising research directions and significant theoretical and practical value for efficient leachate treatment.