The effects of electrode spacing and flow direction on the performance of microbial fuel cell-constructed wetland

• 4 different CW-MFC architectures are investigated.
• Simultaneous upflow–downflow regime reduces internal resistance by a factor of 1.7.
• CW-MFC maintains wastewater treatment performance of CW.
• Maximum power outputs of 0.278 W/m3 were obtained.

This study explores the potential to integrate microbial fuel cells (MFCs) into constructed wetlands (CWs) to concomitantly achieve power generation and advanced wastewater treatment with minimal construction and operating costs. Four 8.1L CWs incorporating MFC with different architectures/flow regimes were constructed to simultaneously treat swine wastewater while determining the best method to maximize the achievable power in CW-MFCs system. By placing the cathode at the air–water interface and burying the anode at a depth of 0.4 m the amount of dissolved oxygen (DO) at the cathode area is increased while ensuring the anode remains anoxic. By keeping the anode buried and placing the cathode directly above, the ohmic resistance is reduced. More significantly, when this arrangement was run with simultaneous upflow into the anode and downflow into the cathode, a maximum power of 0.276 W/m3 was generated. Thus the optimal configuration for scaling up study is obtained.

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