The efficient treatment of mature landfill leachate using tower bipolar electrode flocculation-oxidation combined with electrochemical biofilm reactors

Mature landfill leachate contains high concentrations of organic and inorganic compounds that inhibit the performance of conventional biological treatment. Nowadays, few single treatment techniques could fulfill the requirements of cleaning mature landfill leachate. In this study, a tower bipolar electrode flocculation-oxidation (BEF-O) reactor and an electrochemical biofilm reactor (EBR) combine device was constructed to effectively treat mature landfill leachate. And the removal efficiency and mechanism of various pollutants using the BEF-O reactor were investigated. The BEF-O system with the current density of 100 mA/cm2 shows excellent treat-ment efficiency, which can roundly remove most pollutants (NH4+-N, COD and heavy metals, etc.), and increase the bioavailability of the effluent to facilitate subsequent EBR treatment. Benefiting from the metabolic stimu-lation and population selection effect of electric current on microorganisms, EBR has a denser biofilm, stronger anti-pollution load capacity, superior, and stable pollution treatment efficiency. More importantly, the combined device can reduce the concentrations of COD and NH4+-N from 6410 to 338 mg/L and 4065 to 4 mg/L, respectively, and has an economical energy consumption of 32.02 kWh/(kg COD) and 54.04 kWh/ (kg NH4+-N). To summarize, this research could provide an innovative and industrial application prospect technology for the mature landfill leachate treatment.

Automated summary

In this study, a combined device of tower bipolar electrode flocculation-oxidation reactor and electrochemical biofilm reactor was constructed to treat mature landfill leachate effectively. The BEF-O system showed excellent treatment efficiency, removing most pollutants and increasing the bioavailability of the effluent for subsequent EBR treatment. The combined device could reduce COD and NH4+-N concentrations, with low energy consumption.