title: In-situ biogas upgrading with pulse H2additions: The relevance of methanogen adaption and inorganic carbon level.
abstract: Surplus electricity from fluctuating renewable power sources may be converted to CH4via biomethanisation in anaerobic digesters. The reactor performance and response of methanogen population of mixed-culture reactors was assessed during pulsed H2injections. Initial H2uptake rates increased immediately and linearly during consecutive pulse H2injections for all tested injection rates (0.3 to 1.7LH2/Lsludge/d), while novel high throughput mcrA sequencing revealed an increased abundance of specific hydrogenotrophic methanogens. These findings illustrate the adaptability of the methanogen population to H2injections and positively affects the implementation of biomethanisation. Acetate accumulated by a 10-fold following injections exceeding a 4:1 H2:CO2ratio and may act as temporary storage prior to biomethanisation. Daily methane production decreased for headspace CO2concentrations below 12% and may indicate a high sensitivity of hydrogenotrophic methanogens to CO2limitation. This may ultimately decide the biogas upgrading potential which can be achieved by biomethanisation.
authors.affiliation: Biological and Chemical Engineering, Aarhus University, Hangøvej 2, DK-8200 Aarhus N, Denmark.
authors.forename: Laura Mia
authors.initials: LM
authors.lastname: Agneessens
authors.affiliation: Biological and Chemical Engineering, Aarhus University, Hangøvej 2, DK-8200 Aarhus N, Denmark.
authors.forename: Lars Ditlev Mørck
authors.initials: LDM
authors.lastname: Ottosen
authors.affiliation: Biological and Chemical Engineering, Aarhus University, Hangøvej 2, DK-8200 Aarhus N, Denmark.
authors.forename: Niels Vinther
authors.initials: NV
authors.lastname: Voigt
authors.affiliation: Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, DK-9220 Aalborg, Denmark.
authors.forename: Jeppe Lund
authors.initials: JL
authors.lastname: Nielsen
authors.affiliation: Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, DK-9220 Aalborg, Denmark.
authors.forename: Nadieh
authors.initials: N
authors.lastname: de Jonge
authors.affiliation: Chemistry and Biotechnology, Danish Technological Institute, Kongsvang Allé 29, DK-8000 Aarhus, Denmark.
authors.forename: Christian Holst
authors.initials: CH
authors.lastname: Fischer
authors.affiliation: Chemistry and Biotechnology, Danish Technological Institute, Kongsvang Allé 29, DK-8000 Aarhus, Denmark. Electronic address: mvk@teknologisk.dk.
authors.forename: Michael Vedel Wegener
authors.initials: MVW
authors.lastname: Kofoed
mesh_terms: D056804:Biofuels; D019149:Bioreactors; D002244:Carbon; D019605:Euryarchaeota; D008697:Methane / Q000096:biosynthesis*
chemical_list: D056804:Biofuels; D002244:Carbon; D008697:Methane
keywords: Acetate; CO(2) affinity; H(2); Hydrogenotrophic methanogenesis; In situ biogas upgrading