Development of electrocoagulation-based continuous-flow reactor for leachate treatment: Performance evaluation, energy consumption, modeling, and optimization

Abstract

This study investigated the performance of continuous-flow electrocoagulation (CFR-EC) reactor for aged landfill leachate treatment with a novel configuration of iron and aluminum electrodes to enhance the applicability of the process. The effects of the applied current density (ACD), initial pH, and hydraulic retention time (HRT) on the percentage removal of COD, TOC, BOD5, color, turbidity, and heavy metals (HMs) were modeled with Box-Behnken design (BBD). The results demonstrated that the models are significant (R2 0.97—p-value < 0.0029 and R2 0.92—p-value < 0.0001 for Fe and Al electrodes). COD, TOC, BOD5, and NH3-N removal were maximized at HRT 50 min (40.0 mL min−1) and pH 11 reaching 59, 64, 55, and 27%, respectively, by applying the ACD of 1.1 mA cm−2 in the CFR-ECFe reactor. The CFR-ECFe reactor presented a higher color (59%) and turbidity reduction (86%) than the CFR-ECAl reactor. At optimum condition, the removal percentages of HMs: Cr6+, Pb2+, As3+, Mg2+, B3+, Mn3+, Ni2+, and Ba2+ were 50, 70, 80, 99, 81, 99, 20, and 65%, respectively. The total process cost for landfill leachate treatment was 0.21 $/m3. The CFR-ECFe was an effective and affordable reactor for pollutant removal from landfill leachate.