Electrochemical and microbiological characterization of single carbon granules in a multi-anode microbial fuel cell
Caizán-Juanarena, Leire ; Servin-Balderas, Ivonne ; Chen, Xuan ; Buisman, Cees J.N. ; Heijne, Annemiek ter - \ 2019
Journal of Power Sources 435 (2019). - ISSN 0378-7753
Capacitive bioanode - Charge storage - Charge/discharge cycles - Granular activated carbon - Microbial community - Total nitrogen
Capacitive microbial fuel cells (MFCs) use bacteria on a capacitive anode to oxidize organics in wastewater and simultaneously charge the electrode. This study aims to gain knowledge on the performance of single activated carbon (AC) granules, which are used as capacitive bioanodes. To this end, a multi-anode MFC that allows the testing of up to 29 granules under the same experimental conditions is used. 2 types of AC granules (PK and GAC) and 3 different size-ranges (n = 8 each) are studied in terms of current production, biomass quantification, microbial community and charge storage. Additionally, charge storage of PK granules (n = 24) is determined for different charging/discharging times. Results show that total produced charge directly relates to biomass amount, which has a linear relation towards granule outer surface area. Small AC granules have higher volumetric current densities, which could be of interest for their application in up-scaled reactors. PK granules show slightly higher biomass and current production than GAC granules, while these latter ones show larger volumetric charge storage capacity. Similarly, it is shown that short charging/discharging times are needed to obtain maximum charge storage and current output. These findings are of importance to design and operate MFCs with capacitive properties.
Performance of single carbon granules as perspective for larger scale capacitive bioanodes
Borsje, Casper ; Liu, Dandan ; Sleutels, Tom H.J.A. ; Buisman, Cees J.N. ; Heijne, Annemiek ter - \ 2016
Journal of Power Sources 325 (2016). - ISSN 0378-7753 - p. 690 - 696.
Activated carbon - Bioelectrochemical system - Capacitive bioanode - Granular bed - Microbial fuel cell
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.