Date Published: March 29, 2012
Author(s): Yanmei Sun, Jincheng Wei, Peng Liang, Xia Huang.
Biocathode MFCs using microorganisms as catalysts have important advantages in lowering cost and improving sustainability. Electrode materials and microbial synergy determines biocathode MFCs performance. In this study, four materials, granular activated carbon (GAC), granular semicoke (GS), granular graphite (GG) and carbon felt cube (CFC) were used as packed cathodic materials. The microbial composition on each material and its correlation with the electricity generation performance of MFCs were investigated. Results showed that different biocathode materials had an important effect on the type of microbial species in biocathode MFCs. The microbes belonging to Bacteroidetes and Proteobacteria were the dominant phyla in the four materials packed biocathode MFCs. Comamonas of Betaproteobacteria might play significant roles in electron transfer process of GAC, GS and CFC packed biocathode MFCs, while in GG packed MFC Acidovorax may be correlated with power generation. The biocathode materials also had influence on the microbial diversity and evenness, but the differences in them were not positively related to the power production.
Microbial fuel cells (MFCs) utilize microorganisms as catalysts, which can promote biodegradation of organic matters and simultaneously produce an electrical current (Bond et al. 2002). In the past few years, researchers generally use chemical cathode MFC to remove the organic carbon in wastewater, but the cost of chemical cathode is high and it is easily lead to pollution. Currently, biocathode MFCs using microorganisms instead of common Pt as catalysts have important advantages in lowering cost, expanding function and improving sustainability. Therefore, biocathode MFCs as a new economical and environmentally friendly wastewater treatment technology has drawn more and more attentions (Huang et al. 2011). Although biocathode MFCs have many advantages, the current studies are still at laboratory level. The main challenge for their large-scale application is low power generation capability. Microorganisms are the core of biocathode MFCs. In the anode, microorganisms attaching on the electrode material and forming biofilm play an essential role in MFC generating electricity (Rabaey and Rozendal 2010), and in the cathode, the microbial catalytic efficiency plays a key role to improve the cathode potential and power output (Osman et al. 2010). Therefore, better understanding of the ecology of the microbial communities in the different reactors will be helpful to improve MFCs power production.
The maximum power densities of GAC, GS,CFC and GG packed MFCs showed a decreasing trend. The specific areas changed in the similar way as the power densities of MFCs with different cathodic materials. It indicated that the power density had positive correlation with specific area, which can be assured that high specific area is profitable for microbial attachment and biological catalytic processes.
The authors declare that they have no competing interests.