Improving performance of microbial fuel cell while controlling methanogenesis by Chaetoceros pretreatment of anodic inoculum

• CE enhanced to 45% by using marine algae Chaetoceros as methanogen inhibitor in MFC.
• Control of methanogenesis magnified the power density by 477% than control MFC.
• Power density of 21.43 W/m3 was achieved by marine algae pre-treatment of inoculum.
• This pre-treatment increased bio-catalytic current and reduced internal resistance.
• Higher exchange current density and lower charge transfer resistance was observed.

Loss of substrate due to methanogenesis reduces Coulombic efficiency (CE) of the microbial fuel cell (MFC) significantly. Hexadecatrienoic acid present in the marine algae Chaetoceros inhibits the growth of methanogenic archaea. Influence of Chaetoceros pre-treated mixed anaerobic sludge on the electrogenic activity of MFC was evaluated. A MFC inoculated with Chaetoceros pre-treated mixed anaerobic sludge demonstrated maximum CE of 45.18%, with volumetric power density of 21.43 W/m3 and current density of 93 A/m3. Cyclic voltammetry indicated higher electron discharge on the anode surface due to suppression of methanogenesis. Tafel analysis also showed a higher exchange current density and a lower Tafel slope and charge transfer resistance, indicating advantage of this pre-treatment method in reducing the cell internal losses. A 60% reduction in specific methanogenic activity was observed in anaerobic sludge pre-treated with Chaetoceros; emphasizing significance of this pretreatment for suppressing methanogenesis and its utility for enhancing electricity generation in MFC.