Power generation from wastewater using single chamber microbial fuel cells (MFCs) with platinum-free cathodes and pre-colonized anodes

The effects of biofilm growth on anode and cathode surfaces on the power generation from wastew- ater in single chamber microbial fuel cells (SCMFCs) were investigated in this paper. SCMFCs with the clean/pre-colonized anodes and the platinum-based/platinum-free cathodes were operated for 26 weeks. The pre-colonized (4-week colonization) anodes were tested with three areas (2, 10 and 40 cm2 ) and com- pared with the MFCs started with clean and sterilized anodes. The power generation of MFCs increased with the anode areas (2–10cm2), but kept a plateau for the anode area of 40cm2. The MFCs with the clean anodes had lower power generation (268mW/m2) than those with the pre-colonized anodes (801mW/m2) in the first week of operation. With the operation proceeding to 4–5 weeks, the power generation of the clean anodes and pre-colonized anodes became similar and stabilized at 470 mW/m2 . In terms of cathode performance, platinum-free cathodes (carbon cloth, surface area: 5 cm2 ) and platinum- based cathodes (Pt loading: 0.5 mgPt/cm2 , surface area: 5 cm2 ) were compared. The Pt-based cathodes had higher power generation (330 mW/m2 ) than those of the Pt-free cathodes (253 mW/m2 ) at the startup period, but the difference quickly vanished after a few weeks of operation. This study demonstrated that the advantage of the MFCs with the pre-colonized anodes and platinum-based cathodes disappeared after 3–5 weeks of operation due to the thick biofilm growth on anodes and the aerobic biofilm formation on cathodes. Pt-free cathodes with controlled biofilm growth are promising for low-cost materials, stable power generation and long-term operation of MFCs.