Optimizing Hydrogen Production Through Efficient Organic Matter Oxidation Performed by Microbial Electrolysis Cells

Microbial electrolysis cells (MECs) represent a pioneering technology for sustainable hydrogen production by leveraging bioelectrochemical processes. This study investigates the performance of a single-chamber cathodic MEC, where a cation exchange membrane separates the electrically active bioanode from the cathode. The system was constantly fed with a synthetic carbonaceous solution, employing a working potential of +0.3 V vs. SHE and an organic loading rate of 2 gCOD/Ld with a hydraulic retention time of 0.3 d. Notably, no methanogenic activity was detected, likely due to the establishment of an alkaline pH in the cathodic chamber. Under these conditions, the system exhibited good performance, achieving a current density of approximately 115 A/m3 and a hydrogen production rate of 1.28 m3/m3d. The corresponding energy consumption for hydrogen production resulted in 6.32 kWh/Nm3 H2, resulting in a slightly higher energetic cost compared to conventional electrolysis; moreover, an average energy efficiency of 85% was reached during the steady-state condition. These results demonstrate the potential of MECs as an effective and sustainable approach for biohydrogen production by helping the development of greener energy solutions.