Treatment of Dark Fermentative H2 Production Effluents by Microbial Fuel Cells: A Tutorial Review on Promising Operational Strategies and Practices

Deriving biohydrogen from dark fermentation is a practically suitable pathway for scaling-up and envisaged mass production. However, a common issue with these systems is the incomplete conversion of feedstock as a result of which, a process effluent with notable organic strength is left behind. The main components of dark fermentation effluents are volatile fatty acids that can be utilized by integrated applications involving bioelectrochemical systems, particularly microbial fuel cells (MFCs) to generate electrical energy. In this work, MFCs deployed to treat dark fermentative H₂ production effluents are assessed to take a look into the current standing of this specific research area and address what MFC design and operating features (reactor configuration, mode of operation, anode surface and reactor size) seem favorable towards improved working efficiency (e.g. power density, Coulombic efficiency, COD removal). Furthermore, promising technological implementations are outlined and suggestions, conclusions for future studies for this field are given.