Sustainable microbial fuel cell functionalized with a bio-waste: A feasible route to formaldehyde bioremediation along with bioelectricity generation

Bioelectrochemical systems, especially microbial fuel cell (MFC), are gaining popularity owing to their eco-friendly and energy generation with bioremediation. Due to its unstable electrode material, MFCs have poor electron transportation and production. To increase electron transport and bacterial biocompatibility, better anode materials are needed. Waste palm kernel shell-derived graphene oxide (PKS-GO) and reduced graphene oxide (PKS-rGO) were used to produce the anode electrodes to increase electron transport. The MFC with the PKS-rGO anode generated more energy (24.47 mW/m2) than the PKS-GO anode (13.77 mW/m2). Similarly, the maximum current densities recorded for both anodes were 84.98 mA/m2 for PKS-rGO and 63.74 mA/m2 for PKS-GO. Additionally, the PKS-GO anode showed a 0.00015F/g specific capacitance (Cp) value, whereas the PKS-rGO anode had a Cp value of 0.00021F/g. The enhanced capacitance of the PKS-rGO anode may be due to redox enzymes on microbial cell membranes. The electrochemical impendence spectroscopy also showed a rapid transportation rate of electrons in the case of the PKS-rGO anode. PKS-GO's anode has 1240 ῼ internal resistance, whereas PKS-rGO has 232 ῼ. The secondary use of MFC in wastewater treatment was also taken into account. The PKS-rGO anode (87 %) is more effective in bioremediating formaldehyde (FA) than the PKS-GO anode (81.70 %). The sequence reveals a prominent species of Niallia circulans strain for the PKS-GO anode, and two dominant species for the PKS-rGO anode, Bacillus siamensis strain and Bacillus velezensis strain. A comparative overview shows the effectiveness of the material compared to previous studies. Critical challenges constraining progress in MFC power output enhancement and future perspectives are also included.