Applications of Bio-electrochemical Systems in Heavy Metal Removal and Recovery

Abstract

Heavy metals which are widely used in many industrial fields such as textile, electronics, metal, cosmetics have toxic and carcinogenic effects against living organisms and cause an increasing environmental and health problems due to their non-biodegradable properties. Therefore, many treatment methods such as membrane separation, precipitation, adsorption, coagulation/flocculation, and ionic exchange can be used for the removal of heavy metals from water/wastewater in order to comply with the strict regulations. Among these methods, bio-electrochemical systems (BESs) is a promising technology for the removal of contaminants as well as heavy metals and can be used for the generation of the energy from wastewater. BESs include anode, cathode, membranes, and external circuit in which microorganisms act as a catalyst on one or both electrodes. During the process, organic matters are biodegraded by electroactive biofilms at the anode to transport electrons to the cathode and heavy metal ions are reduced at the cathode to recover metal(loid)s. Reduced metal(loids) can be deposited on the cathode, precipitated or dissolved in the solution. The key operating parameters in bio-electrochemical processes are the concentration and type of the heavy metals, the amount of the applied voltage, type of the microbial community and membranes, the conductivity of the water/wastewater, the material types of the anode and cathode. This chapter provides the main definition of the heavy metals and the potential toxicity of heavy metals to the environmental life. It includes conventional heavy metal recovery technologies and the definition of BES as a promising novel technology. It also provides the applications of BESs for the recovery of heavy metals which is one of the main challenges and perspectives of BESs. © 2023 Elsevier B.V., All rights reserved.