Treatment of chromium (VI) wastewater with abiotic cathode and biocathode microbial fuel cells

The output voltage and reduction of hexavalent chromium (Cr(VI)) of abiotic cathode and biocathode microbial fuel cells (MFCs) with different initial Cr(VI) concentrations were investigated in dual-chambered microbial fuel cells. The results demonstrated that the output voltage and Cr(VI) removal ratio of biocathode MFC were higher than abiotic cathode MFC with different initial Cr(VI) concentrations (20, 28, 32, 36, 40, 44 mg/L). The maximum output voltage of biocathode MFC was 180.1 mV, which was 1.3 times of abiotic cathode MFC. With the gradual increase of initial Cr(VI) concentration, the difference of Cr(VI) removal between abiotic cathode and biocathode MFC was enhanced. Eventually, the Cr(VI) removal of biocathode MFC was 66.4% which was 55.1% higher compared with abiotic cathode MFC at initial Cr(VI) concentration of 44 mg/L. Except for the catalysis of electrochemically active bacteria on the biocathode, a smaller amount of non-conductive Cr(III) precipitation containing Cr2O3 reduced from Cr(VI) and attached on the surface of electrode was also a key factor for the superiority of biocathode MFC in output voltage and Cr(VI) removal aspects which was further confirmed by CV, SEM and EDX analysis.