Recent development of double chamber microbial fuel cell for hexavalent chromium waste removal

Hexavalent chromium (Cr(VI) is a highly toxic and carcinogenic form of chromium (Cr) metal and can enter the environment through improper treatment of industrial wastewater. Investigations on the removal of Cr(VI) aims to produce a sustainable method to efficiently reduce Cr(VI) to Cr(III). Microbial fuel cells (MFCs) is a green technology driven by sustainable energy from biomass waste, which is ideal for the reduction of Cr(VI). Optimization of the MFC performance requires an understanding on the working principles of MFC. Therefore, this article provides a comprehensive review of Cr(VI) reduction in wastewater using the general MFC system, the plant microbial fuel cell (PMFC) system, the soil microbial fuel cell (sMFC) system, and hybrid MFC systems. In addition, factors that influences the efficiency of Cr(VI) reduction, namely the concentration and composition of wastewater, the organic substrates, the properties of the electrodes, the pH and the temperature of the electrolytes, the effect of aeration (oxygen content), the stability of the membrane/separator and, the microorganisms will be discussed. Finally, this review will outline challenges, future prospects, and strategies for a largescale development of double-chamber MFCs.