The performance of biochar waste-derived electrodes in different bio-electrochemical applications
Andrea Goglio, Arianna Carrara, Hager Galal Elsayed Elboghdady, Mirko Cucina, Elisa Clagnan, Gabriele Soggia, Patrizia De Nisi, Fabrizio Adani
Abstract
This work studied the performances of two ad hoc biochar-based cathode materials : one obtained from pyrolysis of the organic fraction of municipal solid waste (OW) and the other of wood chips (WC), in the context of three different bio-electrochemical reactors’ scope: MFC , MEC and MES . Cathodes were characterized through composition, pH, specific surface area and infrared spectroscopy ; then production of electricity, methane (CH 4 ), and volatile fatty acids (VFAs) from carbon dioxide (CO 2 ) was described, and finally the microbial community was explored through 16S rRNA gene sequencing. WC-based electrodes performed better than OW-based ones. WC (200 ± 25 mV) generated twice the amount of electricity compared to OW (100 ± 10 mV) in MFC modality. In MEC modality, WC achieved both higher CH 4 production and concentration (3.6 ± 0.7 mL per day, 73.2 ± 3.9 % v/v, respectively) than OW (3.0 ± 0.3 mL per day, 70 ± 8 % v/v, respectively). In MES modality, WC produced ten times more acetic acid (0.3 ± 0.13 g L −1 per day) than OW (0.03 ± 0.04 g L −1 per day). The better performance of the WC-biochar cathode was attributed to its higher Brunauer–Emmett–Teller (BET) value and its carbonaceous graphite-like structure. NGS analysis highlighted the presence of specific genera of microorganisms leading to the differential functioning of the systems.