Increasing power density and dye decolorization of an X-3B-fed microbial fuel cell via TiO2 photocatalysis pretreatment

Abstract

To improve the output power density of dye-fed microbial fuel cells (MFCs), which decreases with increasing dye concentration, a new strategy involving TiO₂ photocatalysis pretreatment of high content dye wastewater was proposed and demonstrated in this study. 200 mg L⁻¹ X-3B wastewater was treated using F-doped nano-TiO₂ under visible light for 2.5 h and then mixed into the substrate, and the maximum output power density (P_M) of MFC reached 392 mW m⁻². As a comparison, P_M was only 276 mW m⁻² when untreated X-3B wastewater was used as the substrate. About 42% power density was retrieved from the MFC fed with high concentration X-3B wastewater via prior photocatalytic treatment. Moreover, the decolorization rate of X-3B was also enhanced from 42% to 56.5% when combined with the photocatalysis process. The increase of power density after photocatalysis of X-3B was attributed to less electron consumption by decomposed X-3B, extra electron donors and mediators from produced intermediates as well as increased bacterial diversity in the anode chamber. These results demonstrated TiO₂ photocatalysis pretreatment as an effective and easy to implement technology for improving both the electricity harvest and pollutant elimination from wastewaters that contain concentrated hard-to-use biomass without specially acclimatizing or modifying MFC.