Continuous flow operation with appropriately adjusting composites in influent for recovery of Cr(VI), Cu(II) and Cd(II) in self-driven MFC–MEC system

ABSTRACT

A self-driven microbial fuel cell (MFC) – microbial electrolysis cell (MEC) system, where electricity generated from MFCs is in situ utilized for powering MECs, has been previously reported for recovering Cr(VI), Cu(II) and Cd(II) with individual metals fed in different units of the system in batch operation. Here it was advanced with treating synthetic mixed metals’ solution at appropriately adjusting composites in fed-batch and continuous flow operations for complete separation of Cr(VI), Cu(II) and Cd(II) from each other. Under an optimal condition of hydraulic residence time of 4 h, matching of two serially connected MFCs with one MEC, and fed with a composite of either 5 mg L⁻¹ Cr(VI), 1 mg L⁻¹ Cu(II) and 5 mg L⁻¹ Cd(II), or 1 mg L⁻¹ Cr(VI), 5 mg L⁻¹ Cu(II) and 5 mg L⁻¹ Cd(II), the self-driven MFC–MEC system can completely and sequentially recover Cu(II), Cr(VI) and Cd(II) from mixed metals. This study provides a true sustainable and zero-energy-consumed approach of using bioelectrochemical systems for completely recovering and separating Cr(VI), Cu(II) and Cd(II) from each other or from wastes or contaminated sites.

KEYWORDS:

• Microbial fuel cell
• microbial electrolysis cell
• metal recovery
• continuous flow operation
• appropriate composite

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grant Nos. 21377019 and 51578104