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

Abstract

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 40cm2) and compared 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 470mW/m2. In terms of cathode performance, platinum-free cathodes (carbon cloth, surface area: 5cm2) and platinum-based cathodes (Pt loading: 0.5mgPt/cm2, surface area: 5cm2) were compared. The Pt-based cathodes had higher power generation (330mW/m2) than those of the Pt-free cathodes (253mW/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.