Revivability of fermentative hydrogen producing bioreactors

In this study we investigated the revivability of a continuous biological hydrogen producing reactor after a period of feed interruption. Before the feed interruption, the hydrogen production yield was 1.36 mol H-2/mol glucose with butyric acid and acetic acid as the main metabolic products. However, after feed interruption, butyric acid formation completely stopped and the hydrogen yield decreased to 0.29 mol H-2/mol glucose. Lactic acid, ethanol and acetic acid became the main metabolites after re-start up. Reduction of organic loading rate together with increasing the pH after the feed interruption resulted in an increase in the hydrogen yield to 0.7 mol H-2/mol glucose. The microbial community dynamics showed complete elimination of Clostridium affiliated strains and predominance of Lactobacillus affiliated strains after the re-start up of the reactor. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.