Performance of single carbon granules as perspective for larger scale capacitive bioanodes

The use of high surface area electrodes, like carbon-based felt or granules, in Bioelectrochemical Systems is crucial for high volumetric current production. In case activated carbon granules are used, charge can also be stored in the form of an electric double layer in the pores, which has been shown to improve bioanode performance. So far, it is not known how much current can be generated by a single granule. In this study, we investigate the current production and charge storage behavior of a single carbon granule. Two types of activated carbon granules and one graphite granule are tested to find the untapped potential of granular bioanodes. A single activated carbon granule produces up to 0.6 mA, corresponding to 60 mA cm⁻³ granule volume at −300 mV vs. Ag/AgCl anode potential. Charge – discharge experiments show that capacitive granules produced 1.3–2.0 times more charge compared to a graphite granule with low surface area. When extrapolated to other granular systems, our study indicates that the current generated by granular bioanodes can be improved with several orders of magnitude, which could form the basis of an economically feasible Microbial Fuel Cell.