New insights into microbial electrolysis cells (MEC) and microbial fuel cells (MFC) for simultaneous wastewater treatment and green fuel (hydrogen) generation

Hydrogen is the green fuel with higher eco-friendly and efficient vehicular fuel. In past hydrogen gas is derived from non-renewable resources. In recent years renewable resources are utilized for generation of bio-hydrogen gas. Hydrogen gas is preferably produced via electrochemical, photochemical, thermochemical and biochemical processes. Microbial fuel cell (MFC) and microbial electrolysis cell (MEC) are the notable systems used for hydrogen production from organic wastes and wastewater. This review mainly focuses on bio-hydrogen production from both MFC and MEC from wastewater. The mechanism, factors influencing the process, different types of MFCs, energy harvesting ways are signposted in this review. This review addresses on the difficulties in harvesting the energy as well as the economic aspect of harvested energy in detail. In MEC, microbial activity happens at anode and in electrode the hydrogen evolution occurs. Upscaling of the process is mainly influenced by the reactor design and microbiology. Performance of various catalysts on hydrogen evolution are discussed in detail. The scalability of integrating MFC and MEC needs to be decoded in near future for the better of hydrogen production and achieving sustainable development goals (SDGs).