Activated coke-based cathode to improve the efficiency of continuous up-flow constructed wetland-microbial carbon-capture cell

Abstract

This investigation evaluated the continuous up-flow algae-assisted constructed wetland-microbial carbon-capture cell (CW-MCC) with activated coke-based cathode for wastewater treatment and power recovery. The performance of CW-MCC–1 (with activated coke-based cathode and carbon-felt anode) was compared to CW-MCC–2 (with carbon-felt as cathode and anode), while operating under ambient conditions and fed with municipal wastewater. The CW-MCC–1 showed superior maximum power density (143.41 ± 7.09 mW/m³) than CW-MCC–2 (96.64 ± 3.54 mW/m³). The CW-MCC–1 also outperformed CW-MCC–2 for wastewater treatment by attaining an average COD, NH₄⁺–N, NO₃⁻–N, and PO₄³⁻–P removal efficiency of 92.5 ± 3.4, 87.7 ± 7.5, 78.3 ± 9.3, and 89.7 ± 6.7 %, respectively. Hence, the present investigation supports the application of activated coke-based cathode in CW-MCC for efficient wastewater treatment and power recovery. The improved oxygen reduction reaction (ORR) kinetics attributed to porous structure, presence of metal dopants, and elevated dissolved oxygen from algal cultivation in catholyte further advocate the application of activated coke cathode in CW-MCC.