Important Role of Abiotic Sulfide Oxidation in Microbial Fuel Cells Treating High-Sulfate Wastewater

Microbial fuel cells (MFCs) have been considered as an alternative for the treatment and energy recovery of organic wastewater containing sulfate, which cannot be achieved via conventional anaerobic treatment processes. This study investigates the performances and mechanisms of two-compartment single-chamber MFCs treating sulfate-rich organic wastewater at the chemical oxygen demand (COD) to sulfate ratio of 1, 3, and 6 in MFC1, MFC3, and MFC6, respectively. The first compartments functioned as anaerobic bioreactors. In the second compartments where fuel cell apparatuses were installed, sulfide removal was 49.51 ± 57.74, 24.08 ± 13.74, and 15.69 ± 21.30 mgS2-/L in MFC1, MFC3, and MFC6, respectively. The maximum power generation amounts of 9.33, 1.79, and 1.41 mW/m2 were achieved in MFC1, MFC3, and MFC6, respectively. A higher sulfide concentration in MFC1 contributed to higher power generation in MFC1. The main mechanism of electrical generation in all MFCs was abiotic sulfide oxidation