title: Application of an early warning indicator and CaO to maximize the time-space-yield of an completely mixed waste digester using rape seed oil as co-substrate.
abstract: In order to increase the organic loading rate (OLR) and hereby the performance of biogas plants an early warning indicator (EWI-VFA/Ca) was applied in a laboratory-scale biogas digester to control process stability and to steer additive dosing. As soon as the EWI-VFA/Ca indicated the change from stable to instable process conditions, calcium oxide was charged as a countermeasure to raise the pH and to bind long-chain fatty acids (LCFAs) by formation of aggregates. An interval of eight days between two increases of the OLR, which corresponded to 38% of the hydraulic residence time (HRT), was sufficient for process adaptation. An OLR increase by a factor of three within six weeks was successfully used for biogas production. The OLR was increased to 9.5 kg volatile solids (VS) m(-3) d(-1) with up to 87% of fat. The high loading rates affected neither the microbial community negatively nor the biogas production process. Despite the increase of the organic load to high rates, methane production yielded almost its optimum, amounting to 0.9 m(3)(kg VS)(-1). Beneath several uncharacterized members of the phylum Firmicutes mostly belonging to the family Clostridiaceae, a Syntrophomonas-like organism was identified that is known to live in a syntrophic relationship to methanogenic archaea. Within the methanogenic group, microorganisms affiliated to Methanosarcina, Methanoculleus and Methanobacterium dominated the community.
authors.affiliation: GFZ German Research Centre for Geosciences, Microbial GeoEngineering, 14473 Potsdam, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kleyböcker
authors.affiliation: GFZ German Research Centre for Geosciences, Microbial GeoEngineering, 14473 Potsdam, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Lienen
authors.affiliation: GFZ German Research Centre for Geosciences, Microbial GeoEngineering, 14473 Potsdam, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Liebrich
authors.affiliation: GFZ German Research Centre for Geosciences, Microbial GeoEngineering, 14473 Potsdam, Germany; Institute of Geological Science, Jagiellonian University, 30-063 Krakow, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Kasina
authors.affiliation: Chair of Chemical and Process Engineering, Technische Universität Berlin, 10623 Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kraume
authors.affiliation: GFZ German Research Centre for Geosciences, Microbial GeoEngineering, 14473 Potsdam, Germany. Electronic address: wuerdemann@gfz-potsdam.de.
authors.forename: H
authors.initials: H
authors.lastname: Würdemann
mesh_terms: D001673:Biodegradation, Environmental; D056804:Biofuels / Q000032:analysis*; D019149:Bioreactors / Q000382:microbiology; D017610:Calcium Compounds / Q000378:metabolism*; D003246:Conservation of Energy Resources; D005229:Fatty Acids, Monounsaturated; D008697:Methane / Q000378:metabolism; D064307:Microbiota / Q000502:physiology; D010087:Oxides / Q000378:metabolism*; D010938:Plant Oils / Q000378:metabolism*; D000074262:Rapeseed Oil; D012037:Refuse Disposal
chemical_list: D056804:Biofuels; D017610:Calcium Compounds; D005229:Fatty Acids, Monounsaturated; D010087:Oxides; D010938:Plant Oils; D000074262:Rapeseed Oil; C016538:lime; D008697:Methane
keywords: Biogas; Early warning indicator; Genetic fingerprinting; High organic loading rates; Microbial community; Reactor performance