Co-substrate facilitated charge transfer for bioelectricity evolution in a toxic blue-green alga-fed microbial fuel cell technology

This study has investigated the key contribution of sodium acetate as co-substrate on the performances of microbial fuel cells (MFC) during the conversion of a toxic blue-green algae (BGA) biomass into bioelectricity. Microcystis aeruginosa biomass was employed as a target substrate and sodium acetate (AC) as a co-substrate. Compared with MFC treated with BGA alone (MFC-BGA), the MFCs treated with BGA together with acetate (MFC-BGA-AC) significantly magnified the voltage output by 261.3%. Moreover, the addition of co-substrate extended the electric batch cycle by 253.1% and 7.9% compared with MFC-BGA-AC and its corresponding MFC treated only with AC (MFC-AC), respectively. The co-substrate strategy also enhanced the maximum power density by a factor of 3.53 MFC-BGA and 1.2 MFC-AC. It has also displayed the smallest charge transfer resistance of 12.01 Ω which was approximately 45.8% lower than that of MFC-BGA and even slightly lower than the control. Based on the transmission electron microscope results, the cell morphology was also less affected in MFC-BGA-AC. Thus, our new study revealed that the co-substrate could empower the bio-electrochemical active bacteria for toxin survival and make a crucial contribution in alleviating the internal resistance within the operating reactors, which consequently promote the transfer of the generated charges to the bio-anode for power production evolution. The current investigation will conspicuously help in paving ways toward sustainable clean energy production and durable wastes control in the aquatic environment. Graphic abstract