Progress in heavy metals-containing wastewater treatment via microbial electrolysis cell: A review

Microbial electrolysis cell (MEC) is a versatile bioelectrochemical wastewater treatment system. Metal, hydrogen, methane, acetate, ethanol, and other resources could be recovered from wastewater via MEC. It has been applied in integrating production capacity and pollution control for its significant superiority and potential in heavy metal-containing wastewater (HMW) treatment. The main points of this review are as follows: (1) An introduction to MECs, including their operating principles and voltage losses. (2) An overview of heavy metal ions removal: theoretical foundations and effects of various MEC configurations. (3) Research progress on heavy metal ions removal mechanisms, including cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd), among others. (4) Current challenges and prospects in heavy metal ions removal via MEC. Furthermore, this review expounds problems inherent in MEC as well as those strategies; it also discusses several future opportunities and needs for the utilization of MEC in practical.