title: Two-phase anaerobic digestion for production of hydrogen-methane mixtures.
abstract: An anaerobic digestion process to produce hydrogen and methane in two sequential stages was investigated, using two bioreactors of 2 and 15 L working volume, respectively. This relative volume ratio (and shorter retention time in the second, CH(4)-producing reactor) was selected, in part, to test the assumption that separation of phase can enhance metabolism in the second methane producing reactor. The reactor system was seeded with conventional anaerobic digester sludge, fed with a glucose-yeast extract--peptone medium and operated under conditions of relatively low mixing, to simulate full scale operation. A total of nine steady states were investigated, spanning a range of feed concentrations, dilution rates, feed carbon to nitrogen ratios and degree of integration of the two stages. The performance of this two-stage process and potential practical applications for the production of clean-burning hydrogen-methane mixtures are discussed.
authors.affiliation: Hawaii Natural Energy Institute, University of Hawaii, 1680 East-West Road POST 109, Honolulu, HI 96822, USA. mcooney@hawaii.edu
authors.forename: Michael
authors.initials: M
authors.lastname: Cooney
authors.forename: Nathan
authors.initials: N
authors.lastname: Maynard
authors.forename: Christopher
authors.initials: C
authors.lastname: Cannizzaro
authors.forename: John
authors.initials: J
authors.lastname: Benemann
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism*; D019149:Bioreactors; D050260:Carbohydrate Metabolism; D002244:Carbon / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D008697:Methane / Q000096:biosynthesis*; D009584:Nitrogen / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D002244:Carbon; D006859:Hydrogen; D009584:Nitrogen; D008697:Methane