Efficacy of single-chamber microbial fuel cells for removal of cadmium and zinc with simultaneous electricity production

• Simultaneous high power generation and metal removal efficiencies can be achieved.
• The estimated MTCs of Cd and Zn for exoelectrogens have been determined.
• Incremental increase in heavy concentrations slow reduction in voltage output.
• Heavy metals were removed mainly through biosorption and sulfides precipitation.

Simultaneous high power generation (3.6 W/m2) and high Cd (90%) and Zn (97%) removal efficiencies were demonstrated in a single chamber air-cathode microbial fuel cell (MFC). The maximum tolerable concentrations (MTCs) were estimated as 200 μM for Cd and 400 μM for Zn. Increasing the concentrations of Cd to 300 μM and Zn to 500 μM resulted in voltage drops by 71 and 74%, respectively. Feeding the MFCs with incrementally increased Cd and Zn concentrations resulted in much slower reduction in voltage output. Biosorption and sulfides precipitation are the major mechanisms for the heavy metal removal in the MFCs.

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