Alkalinity and salinity favor bioelectricity generation potential of Clostridium, Tetrathiobacter and Desulfovibrio consortium in Microbial Fuel Cells (MFC) treating sulfate-laden wastewater

Abstract

Clostridium, Tetrathiobacter and Desulfovibrio species are identified as suitable biocatalysts for treating organic-rich and sulfate-laden wastewater. Results from this study show that the power generation was much higher under alkaline conditions, i.e., pH of 8 when compared to neutral and acidic conditions. The effect of salinity was studied by varying the sodium chloride concentration at (1.5, 3, 4.5, 6, and 7.5 g/L NaCl) in anolyte. The highest power density of 1188 mW/m³ was produced at a sodium chloride concentration of 6 g/L in the anolyte. Results from cyclic voltammetry and linear scan voltammetry analysis suggested the direct electron transfer mechanism favored by cyt_b and cyt_c, Redox peaks observed for the biogenic synthesis of sulfite and sulfide support the complete one-step mineralization of sulfate. Bioelectrochemical behavior of the selectively enriched microbial consortium confirms its use for the treatment of wastewaters high in salinity and sulfate concentrations.

Keywords: Bioelectricity generation; Consortium; Microbial fuel cells; Sulfate-reducing bacteria (SRB); Sulfur-oxidizing bacteria (SOB).