Spatial-type skeleton induced Geobacter enrichment and tailored bio-capacitance of electroactive bioanode for efficient electron transfer in microbial fuel cells

Microbial fuel cell (MFC) is a promising alternative to energy-intensive conventional wastewater technology. However, poor electron transfer efficiency, low coulombic recovery (CR), and high capital cost highly restricted its practical application. In this work, spatial electroactive biofilm is successfully developed on the carbonaceous skeleton derived from phenolic foam, which highly improved the bio-capacitance and Geobacter abundance of bioanode. Compared with carbon cloth (CC) anode, the optimal spatial electroactive biofilm (3DP_900) enriched the Geobacter abundance up to 56.8% from 17.2%, and obtained an extraordinary electroactive biomass loading of about 339 +/- 63 mu g cm(-2) and a remarkable bio-capacitance of about 3.4 F. In general, spatial biofilm highly reduces the barriers to electron transfer (R-ct) and mass transfer (R-d) in anodic substrate oxidation reaction and obtains the lowest R-ct of 2.0 +/- 0.2 0 and R-d of 35 +/- 3.3 Omega in 3DP_900, which also supports the highest power density at 0.347 +/- 0.027 W m(-2) and the highest CR at 69.2%. More importantly, due to its mature preparation technology, carbonized phenolic foam (2 cm thick pieces) reduces the capital cost of electrode preparation by three orders of magnitude from 1157.3 USD m(-2) of CC to 5.2 USD m(-2). Overall, this work offers an effective and scalable electrode to achieve high substrate utilization rate and energy recovery efficiency, and considers the economic cost of electrode fabrication for the further construction of pilot-scale MFCs equipment.

Automated summary

This study successfully developed a spatial electroactive biofilm that greatly improved the performance of the bioanode in microbial fuel cells. Compared with traditional electrodes, this electrode had higher coulombic recovery and lower barriers to electron and mass transfer. Furthermore, the electrode preparation technology used in this study significantly reduced the cost, making it more feasible for the construction of pilot-scale MFC equipment.