title: High-rate thermophilic methane fermentation on short-chain fatty acids in a down-flow anaerobic packed-bed reactor.
abstract: In order to maximize the efficiency of methane fermentation on short-chain fatty acids, growth media containing acetic acid and butyric acid as major carbon sources were supplied to a thermophilic down-flow anaerobic packed-bed reactor. The organic loading rate (OLR) to the reactor ranged from 0.2 to 169 kg-dichromate chemical oxygen demand(CODcr)/m(3)-reactor/day, corresponding to a hydraulic retention time (HRT) of between 1.4 h and 20 days. Stable methane production was maintained at HRTs as short as 2 h (OLR=120 kg-CODcr/m(3)/day), with the short-chain fatty acids in the feed almost completely removed during the process. The apparent substrate removal efficiency, determined from the total CODcr values in the influent and effluent, was 75% at short HRTs. However, the actual substrate removal efficiency must have been greater than 75%, since a fraction of substrate was also utilized in microbial cell synthesis, and these cells were part of the measured total CODcr.
authors.affiliation: Group of Environmental Engineering and Bioengineering, Kajima Technical Research Institute, Chofu-shi, Tokyo 182-0036, Japan. tatara@kajima.com
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tatara
authors.forename: Akira
authors.initials: A
authors.lastname: Yamazawa
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ueno
authors.forename: Hisatomo
authors.initials: H
authors.lastname: Fukui
authors.forename: Masafumi
authors.initials: M
authors.lastname: Goto
authors.forename: Koji
authors.initials: K
authors.lastname: Sode
mesh_terms: D019342:Acetic Acid / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000254:growth & development / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D020148:Butyric Acid / Q000378:metabolism*; D018929:Cell Culture Techniques / Q000379:methods*; D019605:Euryarchaeota / Q000254:growth & development / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D005285:Fermentation / Q000502:physiology; D008697:Methane / Q000378:metabolism*
chemical_list: D005232:Fatty Acids, Volatile; D020148:Butyric Acid; D008697:Methane; D019342:Acetic Acid