Operational behavior of a hydrogen extractive membrane bioreactor (HEMB) during mixed culture acidogenic fermentation

Fermentative hydrogen production requires a continuous products-removal and effective upgrading steps to improve its general performance. Therefore, implementation of new technologies capable of achieving both requirements is essential. We present the operational behavior of a new process concept based on integration of membranes for gas separation and fermentation technology. This process, which we term as hydrogen extractive membrane bioreactor consists of coupling two dense polymeric membranes to a hydrogen producing culture. The process automatization of this system was essential to maintain the proper operational pressures in the membrane module and in the bioreactor-gas-phase. This system was able to extract and partially separate the hydrogen and carbon dioxide generated. The hydrogen partial pressure was reduced from 55.5 to 49 KPa, which means an increase of hydrogen yield of 16.3% (1.1–1.28 mol-H₂/mol-glucose). Simultaneously, the implemented system generated a final hydrogen stream 13% (v/v) more concentrated than a conventional process.