title: Anaerobic bio-hydrogen production from ethanol fermentation: the role of pH.
abstract: Hydrogen was produced by an ethanol-acetate fermentation at pH of 5.0 +/- 0.2 and HRT of 3 days. The yield of hydrogen was 100-200 ml g Glu(-1) with a hydrogen content of 25-40%. This fluctuation in the hydrogen yield was attributed to the formation of propionate and the activity of hydrogen utilizing methanogens. The change in the operational pH for the inhibition of this methanogenic activity induced a change in the main fermentation pathway. In this study, the main products were butyrate, ethanol and propionate, in the pH ranges 4.0-4.5, 4.5-5.0 and 5.0-6.0, respectively. However, the activity of all the microorganisms was inhibited below pH 4.0. Therefore, pH 4.0 was regarded as the operational limit for the anaerobic bio-hydrogen production process. These results indicate that the pH plays an important role in determining the type of anaerobic fermentation pathway in anaerobic bio-hydrogen processes.
authors.affiliation: Department of Environmental Science and Engineering, Bio-Environmental Engineering Lab (BEEL), Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712, South Korea.
authors.forename: Moon H
authors.initials: MH
authors.lastname: Hwang
authors.forename: Nam J
authors.initials: NJ
authors.lastname: Jang
authors.forename: Seung H
authors.initials: SH
authors.lastname: Hyun
authors.forename: In S
authors.initials: IS
authors.lastname: Kim
mesh_terms: D000085:Acetates / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000254:growth & development / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000502:physiology; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration
chemical_list: D000085:Acetates; D000431:Ethanol; D006859:Hydrogen