Treating Wastes with Microbial Fuel Cells(MFCs) and Microbial Electrolysis Cells(MECs)

Two typical oxidized-status metals (Fe (III) and Cr (VI)) were studied as electron acceptors on cathodes in single chamber microbial fuel cells (SCMFCs) to explore novel sustainable technology for metal treatment in wastewater. The batch-mode tests indicated that the voltages of SCMFCs steadily increased with Fe(III) concentrations (10mg L-1, 30mg L-1, and 50mg L-1) and Cr (VI) concentrations (1mg L-1, 3mg L-1, and 10mg L-1). The maximum power density and current density reached at 658.34mW m-2 and 0.46mA cm-2 at 50mg L-1 of Fe(III), and reached at 419.31mW m-2 and 0.27mA cm-2 at 10 mg L-1 Cr (VI). The conversion efficiency of Cr (VI) and Fe (III) were high (>89%), and coulombic efficiency ranged 23-100% at different metal concentrations. Cr (VI) concentartion of 10 mg L-1 started to irreversibly inhibit SCMFCs. In addition, the open circuit potentials (OCPs) of anodes and cathodes well reflected the organic substrate removal in anode and metal reduction on cathode. Cathode liner sweep voltammetry (LSV) clearly showed the electrochemical activity increased with metal concentrations, and the cathode of Fe (III) had better LSV performance than Cr (VI). This study demonstrated high power generation of SCMFCs with metals as electron acceptors, and revealed the great potential of expanding MFCs for diverse waste treatment.