A review of sustainable hydrogen production using seed sludge via dark fermentation

In recent years, the production of hydrogen (H-2) via dark fermentation has become increasingly popular because it is a sustainable approach to produce clean energy. This review presents an overview with a critical analysis of the technical challenges in obtaining high H-2 yield through dark fermentation. Particular focus is given to the pretreatment methods that affect H-2 production. We observed that heat pretreatment is the most frequently applied and the most effective method of eliminating H-2-consuming bacteria (HCB) while preserving H-2-producing bacteria (HPB). The pre-dominant HPB species after pretreatment belongs to the genus Clostridium and hence the fermentation conditions are optimized according to their preference for H-2 production. Besides, we also reviewed fermentation conditions such as substrate, pH, temperature, oxidation-reduction potential (ORP), types of nutrient and inhibitor substrate, to obtain clearer insight on the influences of critical parameters in H-2 production. (C) 2014 Elsevier Ltd. All rights reserved.