| description |
Microbial fuel cells installed in rice paddy fields (RP-MFCs) are able to serve as on-site batteries for operating low-power environmental sensors. In order to increase the utility and reliability of RP-MFCs, further research is necessary for boosting the power output. Here we examined several powdered iron species, zero valent iron (ZVI), goethite, and magnetite, for their application to increasing power outputs from RP-MFCs. Soils around anodes were supplemented with either of these iron species, and RP-MFCs were operated for several months during the transplanting and harvesting. It was found that power outputs from RP-MFCs supplemented with ZVI were more than double the outputs from control (not supplemented with iron species) and other MFCs, even after iron corrosion was ceased, and the maximum power density reached 130 mW/m2 (per projected area of the anode). Metabarcoding of 16S rRNA gene amplicons suggested that several taxa represented by fermentative bacteria and exoelectrogens substantially increased in MFC supplemented with ZVI. Results suggest that ZVI lowers oxidation/reduction potential around anodes, activates anaerobic microbes involved in the conversion of organic matter into electricity and increases power output from RP-MFCs. |