Research progress in dark microbial fermentation for bio-hydrogen production

Hydrogen deriving from bio-wastes or unused biomass is one of the most promising alternative energy carrier as a sustainable technology in the future.Dark microbial fermentation for the conversion of biomass to biohydrogen has being paid much attention in the world for its advantages of high hydrogen production rate,feasibility in the reactor design and process control,and possibility in integration with waste treatment.Progresses in dark fermentation for bio-hydrogen production achieved in recent years were reviewed in the present paper.In addition to the deeper understanding of the traditional hydrogen-producing bacteria,tools of modern biotechnology and bioinformatics were gradually adopted for the construction of the database of hydrogen-producing bacteria.In the respect of hydrogenase,not only were the related gene identification and the functional analysis important,but also was genetic engineering for improving hydrogenase paid attention.Concerning the combination of biohydrogen production with the waste treatment,many studies had focused on the effects of operating conditions and process optimization.Various wastes had been used for hydrogen conversion and a series of bio-reactors been designed.In addition,the feasibility and economic evaluation of the existing bio-hydrogen process was also discussed in the paper.Finally,new approach for bio-hydrogen in the dark fermentation was indicated.