Open Air Biocathode Enables Effective Electricity Generation with Microbial Fuel Cells

Abstract

The reduction of oxygen at the cathode is one of the major bottlenecks of microbial fuel cells (MFCs). While research so far has mainly focused on chemical catalysis of this oxygen reduction, here we present a continuously wetted cathode with microorganisms that act as biocatalysts for oxygen reduction. We combined the anode of an acetate oxidizing tubular microbial fuel cell with an open air biocathode for electricity production. The maximum power production was 83 +/- 11 W m(-3) MFC (0.183 L MFC) for batch-fed systems (20-40% Coulombic yield) and 65 +/- 5 W m(-3) MFC for a continuous system with an acetate loading rate of 1.5 kg COD m(-3) day(-1) (90 +/- 3% Coulombic yield). Electrochemical precipitation of manganese oxides on the cathodic graphite felt decreased the start-up period with approximately 30% versus a non-treated graphite felt. After the start-up period, the cell performance was similar for the pretreated and non-treated cathodic electrodes. Several reactor designs were tested, and it was found that enlargement of the 0.183 L MFC reactor by a factor 2.9-3.8 reduced the volumetric power output by 60-67%. Biocathodes alleviate the need to use noble or non-noble catalysts for the reduction of oxygen, which increases substantially the viability and sustainability of MFCs.

Microbial Fuel Cells, A Current Review

“…The reduction of oxygen at the cathode of MFCs is recognized as one of the current bottlenecks in power production [19,[130][131][132]. Oxygen is an ideal acceptor for use in a MFC due to its high oxidation potential, low cost and formation of water as its waste product.…”

“…The performance of a wet air cathode inoculated with a consortium of sludge and sediment microbes was increased through the interactions of the microorganisms on the cathode surface [131,139]. The use of a biocathodes has also been reported to reduce charge transfer resistance of the cathode from 188 to 17 ohms [140] and 40.2 to 12 ohms [141].…”

New applications and performance of bioelectrochemical systems

“…Direct biocathodes can be based on enzymes (Topcagic and Minteer 2006;Schaetzle et al 2009) or contain microorganisms that are attached to the cathode and that accept electrons from the electrode while reducing oxygen. This last type of biocathodes has been studied in salt water as well as in freshwater (Bergel et al 2005;Clauwaert et al 2007b). Although (bio)catalyzed cathodes have been shown to catalyze oxygen reduction compared to the plain material, the open circuit potentials are still low: in the range of 0.4-0.5 V vs NHE or sometimes higher, 0.65 V vs NHE (Clauwaert et al 2007b).…”

“…This last type of biocathodes has been studied in salt water as well as in freshwater (Bergel et al 2005;Clauwaert et al 2007b). Although (bio)catalyzed cathodes have been shown to catalyze oxygen reduction compared to the plain material, the open circuit potentials are still low: in the range of 0.4-0.5 V vs NHE or sometimes higher, 0.65 V vs NHE (Clauwaert et al 2007b). …”

Differences in Contaminants Removal Efficiency and Electricity Production in Disposing Leachate with Chemical-Cathode and Aerobic Bio-Cathode MFC

“…Clauwaert et al 9 realized that the reduction in oxygen at the cathode is one of the major bottlenecks of microbial fuel cells (MFCs). Freguia et al 10 found that the reduction in oxygen in the bio-cathode had improved as the anode effluent directly flowed into cathode of the double-chamber MFC.…”