Microalgae biocathode coupled polyvinylalcohol proton exchange membrane for performance of recirculation honeycomb microbial fuel cells

Microbial fuel cells (MFCs) are a renewable energy technology that has garnered global attention for their ability to transform wastewater into electricity while also purifying the water. Honeycomb microbial fuel cells (HMFCs) in recirculation mode represent an innovative approach to integrating a honeycomb structure into an MFC to achieve uniform influent flow, thereby enhancing mass transfer and electricity generation. Numerous commercialization hurdles, notably the high cost of Nafion membrane, render MFCs financially inaccessible for wastewater treatment applications. Furthermore, employing harmful chemicals as reducing agents in cathodes and Pt-based cathodes is impractical for scaled-up systems because of the high costs involved. A novel attempt has been made to use microalgae as a photosynthetic biocatalyst in the cathode in conjunction with low-cost, polyvinyl alcohol membranes (PVA) against Nafion-117 for simultaneous bioelectricity generation and wastewater treatment of domestic wastewater-fed HMFCs. The results show that crosslinked PVA-based HMFC achieves a maximum power density of 42.95 ± 0.12 mW m⁻², an open-circuit voltage (OCV) of 700 mV, and a peak current density of 329.0 mA m⁻², with the lowest ohmic resistance of 26.64 ± 0.33 Ω, outperforming Nafion and neat PVA (NPVA). Furthermore, crosslinked PVA exhibits a COD removal rate of 86 ± 1.6 % by Day 30. While OD₆₈₀ value of 3.46 ± 0.05 reflects the cell growth of the microalgae. These findings suggest that crosslinked PVA is a promising proton exchange membrane (PEM) material for MFCs, with potential benefits for future MFC applications.