Comparative performance of sustainable anode materials in microbial fuel cells (MFCs) for electricity generation from wastewater

Abstract

Microbial fuel cells (MFCs) are a promising technology to generate electricity from wastewater and reduce the organic content. Whilst there has been a significant enhancement in MFC efficiency arising from the introduction of novel materials and cell designs, challenges remain with respect to the performance, cost, and sustainability of anode materials. This paper reports the development of single chamber MFCs with a focus on novel, cost-effective, and recycled carbon-based anode materials, including Recycled Water Filter Block/Powder (RWFB/RWFP), Recycled Chopped Carbon Fibre (RCCF), Carbon Felt (CF) and Graphite Flexible powder (GFG). Anodes prepared from GFG were shown to provide high power density (342.8 mW/m2), followed by RCCF, CF, RWFP, RWFB and CF (77.6, 71.8, 59.0 and 57.9 mW/m2, respectively). Chemical Oxygen Demand (COD) reduction was measured initially and at day 30, with GFG anodes observed to remove 83% of the initial load, compared to RCCF, RWFB, RWFP and CF anodes, where COD reductions of 69%, 61%, 65% and 73% were observed, respectively. Electrochemical analysis and biofilm imaging confirmed recycled materials were colonised by microorganisms and performed to high standards. GFG offers significant promise as an anode material, with excellent performance supported by a reduction in capital cost of up to 90% in comparison to CF. The use of recycled carbon material as MFC anodes shows promise, but requires additional work to improve the stability and durability of systems to permit scale-up.