title: Changes in microbial community during hydrogen and methane production in two-stage thermophilic anaerobic co-digestion process from biowaste.
abstract: In this paper, the microbial community in a two-phase thermophilic anaerobic co-digestion process was investigated for its role in hydrogen and methane production, treating waste activated sludge and treating the organic fraction of municipal solid waste. In the acidogenic phase, in which hydrogen is produced, Clostridium sp. clusters represented 76% of total Firmicutes. When feeding the acidogenic effluent into the methanogenic reactors, these acidic conditions negatively influenced methanogenic microorganisms: Methanosaeta sp., (Methanobacteriales, Methanomicrobiales, Methanococcales) decreased by 75%, 50%, 38% and 52%, respectively. At the same time, methanogenic digestion lowered the numbers of Clostridium sp. clusters due to both pH increasing and substrate reduction, and an increase in both Firmicutes genera (non Clostridium) and methanogenic microorganisms, especially Methanosaeta sp. (208%). This was in accordance with the observed decrease in acetic (98%) and butyric (100%) acid contents. To ensure the activity of the acetate-utilizing methanogens (AUM) and the acetogens, high ratios of H2-utilizing methanogens (HUM)/AUM (3.6) were required.
authors.affiliation: Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, 17003, Spain; Department of Environmental Technologies, University of Cadiz, Faculty of Marine and Environmental Sciences (CASEM), Pol, Río San Pedro s/n, 11510 Puerto Real (Cádiz), Spain. Electronic address: szahedi@icra.cat.
authors.forename: S
authors.initials: S
authors.lastname: Zahedi
authors.affiliation: Department of Environmental Technologies, University of Cadiz, Faculty of Marine and Environmental Sciences (CASEM), Pol, Río San Pedro s/n, 11510 Puerto Real (Cádiz), Spain.
authors.forename: R
authors.initials: R
authors.lastname: Solera
authors.affiliation: Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Micolucci
authors.affiliation: Department of Environmental Sciences, Informatics and Statistics, University Ca' Foscari of Venice, Calle Larga Santa Marta, 30123 Venice, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Cavinato
authors.affiliation: Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Bolzonella
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels; D003013:Clostridium / Q000235:genetics / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D008697:Methane / Q000096:biosynthesis*; D059013:Microbial Consortia / Q000235:genetics / Q000502:physiology*; D012722:Sewage / Q000382:microbiology; D018505:Waste Management / Q000379:methods*
chemical_list: D056804:Biofuels; D012722:Sewage; D006859:Hydrogen; D008697:Methane
keywords: Anaerobic co-digestion; Biogas; Biohydrogen; Organic waste; Thermophilic; Two phases