Biohydrogen evolution in microbial electrolysis cell, a novel electrofermentation technology: Influence of reactor design

The electrofermentation (EF) technique links two major areas—traditional industrial fermentation and biochemistry—and involves the use of electrodes. It increases the microbial metabolism with the help of electron transfer during the fermentation process. EF gives rise to targeted biochemicals, increases product recovery, and decreases or limits the use of additives in redox balance. The microbial electrolysis cell (MEC) is a rising EF technology that helps in generating value-added chemicals including hydrogen by utilizing electron transfer. Wastewater consists of biodegradable natural matter; that is more and more being taken into consideration as a beneficial feedstock for the era of renewable power. Through investigations of recouping power from wastewater, MEC use has been discovered to be promising. However, this has been restricted to laboratory-scale experiments and comparatively premier operational conditions. Therefore, the sizable optimization of diverse parameters for MEC operation can be required for maximum applications. At the contemporary stage, the maximum restricting elements for a successful scale up are the massive inner resistance and excessive fabrication cost. This chapter discusses different operational factors during optimization that affect biogas production, which is relevant to research on physical and biological factors influencing MEC performance in terms of hydrogen production and wastewater treatment. This chapter presents an attempt to overcome these limitations by developing an MEC architecture using an efficient and economic separator, a cathode material that can be fed with different types of wastewater. Further, it includes recent developments on reactor design, manipulation at the bioelectrode for improved product output, and relevant composites for potential MEC application for a hydrogen evolution reaction (HER) and methane production on the cathode surface. Perspective is supplied with valuable information on the performance of the processes. This chapter will help readers understand the basics and recent updates on MEC-type EF along with various reactor configurations of MECs essential for integrated implementation.