title: A two-stage bioprocess for hydrogen and methane production from rice straw bioethanol residues.
abstract: This study evaluates a two-stage bioprocess for recovering hydrogen and methane while treating organic residues of fermentative bioethanol from rice straw. The obtained results indicate that controlling a proper volumetric loading rate, substrate-to-biomass ratio, or F/M ratio is important to maximizing biohydrogen production from rice straw bioethanol residues. Clostridium tyrobutyricum, the identified major hydrogen-producing bacteria enriched in the hydrogen bioreactor, is likely utilizing lactate and acetate for biohydrogen production. The occurrence of acetogenesis during biohydrogen fermentation may reduce the B/A ratio and lead to a lower hydrogen production. Organic residues remained in the effluent of hydrogen bioreactor can be effectively converted to methane with a rate of 2.8 mmol CH(4)/gVSS/h at VLR of 4.6 kg COD/m(3)/d. Finally, approximately 75% of COD in rice straw bioethanol residues can be removed and among that 1.3% and 66.1% of COD can be recovered in the forms of hydrogen and methane, respectively.
authors.affiliation: Department of Environmental Engineering, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan.
authors.forename: Hai-Hsuan
authors.initials: HH
authors.lastname: Cheng
authors.forename: Liang-Ming
authors.initials: LM
authors.lastname: Whang
authors.forename: Chao-Wei
authors.initials: CW
authors.lastname: Wu
authors.forename: Man-Chien
authors.initials: MC
authors.lastname: Chung
mesh_terms: D001483:Base Sequence; D019149:Bioreactors; D017931:DNA Primers; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D006859:Hydrogen / Q000378:metabolism*; D008697:Methane / Q000378:metabolism*; D012275:Oryza / Q000378:metabolism*; D016133:Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D000431:Ethanol; D006859:Hydrogen; D008697:Methane