Selection and optimization of biofilm carriers as high-effective microbial separator in microbial fuel cells

Four biofilm carriers including pyrite, manganese ore, ceramsite, and polyurethane sponge were used to construct microbial separators (MSs), while their performance in dual-chamber microbial fuel cells (MFCs) was evaluated. Polyurethane sponge and pyrite were superior biofilm carriers for MSs. The dense biofilm on the polyurethane sponge provides MS with optimal barrier capacity against dissolved oxygen and chemical oxygen demand. Pyrite's unique redox activity enhances proton transfer in MS and reduces ohmic resistance in MFC. The optimal thicknesses of polyurethane sponge MS and pyrite MS were 1.20 and 1.80 cm, and the maximum power densities of MFCs equipped with these two MSs were 14.62 and 11.21 W/m³. Using MSs as separators can significantly lower MFC manufacturing costs, particularly with polyurethane sponge MS at 3.52 $/m². Additionally, MSs demonstrated good regenerability. These results indicated that MSs based on pyrite and polyurethane sponge have the potential to be high-effective separators for MFC scale-up.