Integrated biogas systems

dc.check.embargoformatEmbargo not applicable (If you have not submitted an e-thesis or do not want to request an embargo)en
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dc.contributor.advisorMurphy, Jeremiah D.G.en
dc.contributor.advisorLeahy, Paulen
dc.contributor.authorVoelklein, Markus
dc.contributor.funderSeventh Framework Programmeen
dc.date.accessioned2019-08-20T10:52:05Z
dc.date.available2019-08-20T10:52:05Z
dc.date.issued2019
dc.date.submitted2019
dc.description.abstractAn integrated biogas system is a synergistic cycle of processes sustainably recovering energy and nutrients by anaerobic digestion systems. It is a value adding sequence managing waste and biomass with a final gaseous by-product biogas or biomethane (a natural gas substitute). This thesis explored its core process, technology and strategies of biogas production and upgrading to biomethane. Various studies of this thesis highlight pathways to conduct and optimise anaerobic digestion at intensified conditions while improving reactor utilisation. An increase in substrate throughput and loading was attained by a pre-treating first stage hydrolysis reactor. The solubilisation of substrate provided upstream carbon dioxide segregation and high quantities of readily available liquid fermentation products. A downstream digester increased methane yields and enriched the methane content to levels of 71% of the biogas composition. Intensified conditions and mono-digestion of a single substrate such as food waste can exhibit deficiencies in essential nutrients and inhibition of methanogenic activity. Supplementation of undersupplied trace elements induced immediate recovery allowing stable digestion at loading rates as high as 5 g VS L-1 d -1 at mesophilic temperatures. An increase in temperature further improved degradation kinetics and stimulated higher biomethane yields at shorter substrate retention in grass digestion. In an integrated biogas system, biogas may be upgraded in conjunction with in-situ and ex-situ biological methanation strategies. The addition of hydrogen revealed positive effects on the methanogenic process. Adverse effects of elevated dissolved hydrogen concentrations on acetogenesis became evident in-situ. A biomethane with methane concentrations in excess of 96% successfully demonstrated the potential for gas grid injection at methane formation rates of 3.7 L per litre reactor volume per day. An approach, supplying gases continuously into a sequential ex-situ reactor system and steadily displacing the upgraded biogas, confirmed similar methane formation yields. A hybrid model, where an in-situ grass digester is followed by an ex-situ reactor suggested an alternative approach to conventional biogas upgrading. The contribution of this thesis is the successful demonstration of optimisation potential in novel and existing digestion systems. The employed biogas upgrading strategies proved to be efficient and suitable for gas grid injection.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationVoelklein, M. 2019. Integrated biogas systems. PhD Thesis, University College Cork.en
dc.identifier.endpage153en
dc.identifier.urihttps://hdl.handle.net/10468/8353
dc.language.isoenen
dc.publisherUniversity College Corken
dc.relation.projectinfo:eu-repo/grantAgreement/EC/FP7::SP3::PEOPLE/316838/EU/Advanced Technologies for Biogas Efficiency Sustainability andTransport/ATBESTen
dc.rights© 2019, Markus Voelklein.en
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectBiogasen
dc.subjectFood wasteen
dc.subjectBiological methanationen
dc.subjectGrass digestionen
dc.subjectTrace elementsen
dc.subjectThermophilic digestionen
dc.thesis.opt-outfalse
dc.titleIntegrated biogas systemsen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhDen
ucc.workflow.supervisorjerry.murphy@ucc.ie
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