Electrochemical treatment of bio-treated landfill leachate: Influence of electrode materials, current density, and sodium chloride concentration

Abstract

The landfill leachate harbors a substantial volume of pollutants necessitating their eradication prior to environmental release. In this investigation, the electrochemical oxidation of Biologically Treated Landfill Leachate (BTLL), following treatment via Upflow Anaerobic Sludge Blanket (UASB). This investigation delved into and compared with the impact of various operational parameters within the electrochemical oxidation process for both Ti/SnO₂-Sb₂O₃ and Ti/PbO₂ anodes—namely, current density, duration of operation, sodium chloride concentration, and cathode—on the efficiency of pollutant removal. Additionally, it employed response surface methodology to discern the optimal operational conditions for electrochemical oxidation of landfill leachate. The final experimental results indicate that under a current density of 50 mA/cm² and an electrolysis time of 4 h, the COD removal rates for Ti/SnO₂-Sb₂O₃ anode and Ti/PbO₂ anode were 79.48% and 92.31%, respectively, while the TN removal rates were 57.99% and 57.17%, respectively. Additionally, NH₄⁺-N was completely removed for Ti/SnO₂-Sb₂O₃ anode and Ti/PbO₂ anode. Moreover, the former exhibited superior sewage treatment effectiveness when Ni was used as the cathode compared to Pt and steel. Response surface methodology (RSM) identified anode-specific optima: Ti/SnO₂-Sb₂O₃ (34 mA/cm², 7.3 g/L NaCl) and Ti/PbO₂ (38 mA/cm², 6.0 g/L NaCl), both at 4 h, yielding COD removals of 93.6% and 97.2% (experimentally validated), respectively. This study provides novel theoretical support for the combined treatment of landfill leachate using biotreatment and chemical oxidation processes.

Graphical abstract

Keywords

Ti/SnO ₂-Sb ₂O ₃ / Ti/PbO ₂ / Biologically treated landfill leachate / Electrochemical oxidation

Highlight

	● Response surface methodology optimized parameters for maximal COD removal.
	● Ti/PbO2 presents better performance than Ti/SnO2-Sb2O3 for pollutants removal.
	● Both anodes completely removed NH4+-N, showing excellent nitrogen removal.
	● TN removal capacity is in the following order: Pt < Ni < Steel cathodes.
	● Ti/PbO2 promotes the highest COD elimination rate was 99.91%.

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