Scalable microbial fuel cell (MFC) stack for continuous real wastewater treatment

A tubular air-cathode microbial fuel cell (MFC) stack with high scalability and low material cost was constructed and the ability of simultaneous real wastewater treatment and bioelectricity generation was investigated under continuous flow mode. At the two organic loading rates (ORLs) tested (1.2 and 4.9 kg COD/m3 d), five non-Pt MFCs connected in series and parallel circuit modes treating swine wastewater can enable an increase of the voltage and the current. The parallel stack retained high power output and the series connection underwent energy loss due to the substrate cross-conduction effect. With continuous electricity production, the parallel stack achieved 83.8% of COD removal and 90.8% of NH4+-N removal at 1.2 kg COD/m3 d, and 77.1% COD removal and 80.7% NH4+-N removal at 4.9 kg COD/m3 d. The MFC stack system in this study was demonstrated to be able to treat real wastewater with the added benefit of harvesting electricity energy.

► This study demonstrates the use of non-Pt MFC stack treating real wastewater.
► The stacks in series and parallel circuit mode were conducted at two ORLs.
► The parallel connection approached a maximum power density of 175.7 W/m2.
► The parallel stack achieved 83.8% COD removal and 90.8% NH4+-N removal.
► Such a tubular air-cathode MFC stack has high scalability and low material cost.