High Power Recovery with Large-scale Multi-anode/cathode Microbial Fuel Cells Treating Wastewater

The lack of effective large-scale designs and inexpensive electrode materials has limited the real-world applications of MFCs. This paper aimed at addressing these problems by developing a multi-anode/cathode MFC and MnO2 (OMS-2) cathodes. The results demonstrated that the multi-anode/cathode MFC substantially increased the total power production of MFC since the average power density per anode/cathode channel did not significantly change when the MFC was operating with 12 and 4 channels (575 mW/m2 vs. 635 mW/m2) at an organic loading rate of 0.5 kg/m3/day. Meanwhile the power density increased from 300 to 380 mW/m2 as the organic loading rate increased from 0.19 to 0.66 kg/m3/day. MFCs achieved 80% of COD removal at HRT of 20 hours while the COD removal at HRT of 5 hours was 66% and fluctuated greatly with the shock in influent COD. MnO2 cathodes produced power density as high as Pt cathodes. A decrease in the power density (from 400 mW/m2 to 150 mW/m2) and an increase in Rin of MFCs (175 Ω to 225Ω) was observed due to the cathode fouling. Analysis revealed that the interior fouling was mainly caused by calcium precipitation (89%) and the exterior fouling was mainly caused by diffusion of sodium (83%) through the cathodes.