Effect of Contact Area and Shape of Anode Current Collectors on Bacterial Community Structure in Microbial Fuel Cells

Low electrical conductivity of carbon materials is a source of potential loss for large carbonaceous electrode surfaces of MFCs due to the long distance traveled by electrons to the collector. In this paper, different configurations of titanium current collectors were used to connect large surfaces of carbon cloth anodes. The current collectors had different distances and contact areas to the anode. For the same anode surface (490 cm(2)), increasing the contact area from 28 cm(2) to 70 cm(2) enhanced power output from 58 mW center dot m(-2) to 107 mW center dot m(-2). For the same contact area (28 cm(2)), decreasing the maximal distance of current collectors to anodes from 16.5 cm to 7.75 cm slightly increased power output from 50 mW center dot m(-2) to 58 mW center dot m(-2). Molecular biology characterization (qPCR and 16S rRNA gene sequencing) of anodic bacterial communities indicated that the Geobacter number was not correlated with power. Moreover, Geobacter and Desulfuromonas abundance increased with the drop in potential on the anode and with the presence of fermentative microorganisms. Electrochemical impedance spectroscopy (EIS) showed that biofilm resistance decreased with the abundance of electroactive bacteria. All these results showed that the electrical gradient arising from collectors shapes microbial communities. Consequently, current collectors influence the performance of carbon-based anodes for full-scale MFC applications.

Automated summary

This study investigated the effect of different configurations of titanium current collectors on the performance of carbon cloth anodes in microbial fuel cells (MFCs). The results showed that increasing the contact area and decreasing the distance between collectors and anodes can enhance power output. Molecular biology characterization indicated that the abundance of Geobacter and Desulfuromonas was correlated with the drop in potential on the anode and the presence of fermentative microorganisms. Electrochemical impedance spectroscopy demonstrated that biofilm resistance decreased with the abundance of electroactive bacteria. Therefore, current collectors play an important role in the performance of carbon-based anodes in MFC applications.