Factors affecting hydrogen production in microbial electrolysis cell (MEC): A review

Microbial electrolysis cells (MECs) are emerging sustainable power generation technologies that can be used for biohydrogen production and wastewater treatment. The prospect for hydrogen gas as a vehicle fuel suitable for the environment is enormous. MEC serves as a reactor for producing biohydrogen by mixing MFC with electrolysis. MECs are the most sustainable, clean, and effective ways to produce biohydrogen. Effective aspects impacting H₂ production, including microbial culture, electrodes, membrane, and substrate, have been explored for greater comprehension of creating MEC technology-based hydrogen generation. The present issues with effective scale-up include the costly production expenses of microbial electrolysis cells, their significant internal resistance, methanogenesis, and membrane/cathode biofouling. This review examines the various operational parameters in optimization studies that influence overall hydrogen generation. This paper also presents strategies to overcome the constraints listed above by creating effective architecture, including several reactor designs, biological, and physical properties, and the use of various operational conditions for improved hydrogen production. This study summarizes recent developments and several other operating factors (organic loading, ionic strength, hydraulic retention time, applied voltage, etc.) that affect hydrogen production in an MEC system. The paper outlines the present technical difficulties and offers practical future ideas for addressing the constraints.