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 wastewater 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 compared with the MFCs started with clean and sterilized anodes. The power generation of MFCs increased with the anode areas (2–10 cm2), but kept a plateau for the anode area of 40 cm2. The MFCs with the clean anodes had lower power generation (268 mW/m2) than those with the pre-colonized anodes (801 mW/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.

► Biofilms growing on anodes and cathodes posed two-side effects on power generation. ► Thick biofilms reduced the power generation in a long-term operation. ► The MFCs with Pt-free cathodes achieved similar power generation as that with the Pt-based cathodes. ► The low-cost and stable operation of Pt-free biocathodes is promising for the real-world application.