Lead(II) Removal at the Bioanode of Microbial Electrolysis Cells

Abstract Advanced treatment, such as tight membrane filtration and ion exchange, can be applied for Pb 2+ removal from wastewater but these methods are expensive with a high demand for electric energy and chemicals. Microbial electrolysis cells (MECs) are an emerging wastewater treatment technology and MECs can remove Pb 2+ by reduction and precipitation at the cathode and biosorption at the anode; however, reduction at the anode has not been reported. We investigated Pb 2+ removal mechanisms using lab‐scale MECs. Using an anion exchange membrane, independent Pb 2+ removal in the anode and cathode chambers was observed at various voltage applications, including open circuit, 0.3 V, 0.6 V, and 0.9 V. A substantial amount of metallic Pb (0. 10 ± 0.02 mg) was found on the graphite fiber anode. Also, the observed anode potential (−0.15 to −0.33 V vs. SHE) indicated sufficient driving force for Pb 2+ reduction at the anode for the Pb 2+ concentration of 0.1 to 2.5 mg L −1 . Inactivation of exoelectrogens using ethanol resulted in no Pb 2+ removal. The findings show that Pb 2+ removal is achieved by various mechanisms in MECs, including electrodeposition at the anode by exoelectrogens.