Author, Institution: Bronius Žalys, Lithuanian Energy Institute
Science area, field of science: Technological Sciences, Environmental Engineering, T004
Research supervisor: Senior Researcher Dr. Kęstutis Venslauskas (Lithuanian Energy Institute, Technological Sciences, Environmental Engineering, T004)
Dissertation Defence Board of Environmental Engineering Science Field:
Prof. Dr. Egidijus Šarauskis (Vytautas Magnus University, Technological Sciences, Environmental Engineering, T004) – chairperson
Prof. Dr. Jonas Baltrušaitis (Lehigh University, United States, Natural Sciences, Chemistry, N003)
Senior Researcher Dr. Darius Jakimavičius (Lithuanian Energy Institute, Technological Sciences, Environmental Engineering, T004)
Chief Researcher Dr. Nerijus Striūgas (Lithuanian Energy Institute, Technological Sciences, Energetics and Power Engineering, T006)
Assoc. Prof. Dr. Alvydas Zagorskis (Vilnius Gediminas Technical University, Technological Sciences, Environmental Engineering, T004)
Dissertation defence meeting will be at the conference room at Lithuanian Energy Institute (Breslaujos 3 – 202, Kaunas)
The doctoral dissertation is available at the library of Kaunas University of Technology (Gedimino 50, Kaunas) and on the internet: B. Žalys el. dissertation.pdf
© B. Žalys, 2026 “The text of the thesis may not be copied, distributed, published, made public, including by making it publicly available on computer networks (Internet), reproduced in any form or by any means, including, but not limited to, electronic, mechanical or other means. Pursuant to Article 25(1) of the Law on Copyright and Related Rights of the Republic of Lithuania, a person with a disability who has difficulties in reading a document of a thesis published on the Internet, and insofar as this is justified by a particular disability, shall request that the document be made available in an alternative form by e-mail to doktorantura@ktu.lt.”
Annotation: This dissertation comprehensively evaluates the influence of pretreatment technologies applied to different biomass groups, including cattle, pig and poultry manure, alfalfa biomass, and winter wheat straw, on biogas production efficiency and environmental performance. Experimental anaerobic digestion studies, energy assessment, and life cycle assessment (LCA) were performed using the CML-IA and ReCiPe methodologies. Three pretreatment technologies were investigated: carbon dioxide (CO₂) pretreatment of manure, biological pretreatment of alfalfa using cattle rumen inoculum, and pretreatment of winter wheat straw with commercial biological products dominated by Trichoderma microorganisms. The results demonstrated that CO₂ pretreatment increased biomethane yield by 21.78%, 33.78%, and 28.76% for cattle, pig, and poultry manure, respectively, while also improving biogas quality. Biological pretreatment of alfalfa increased biogas yield by 12.1% and biomethane yield by 13.4%. Pretreated winter wheat straw achieved a 14.7% increase in biomethane yield. Life cycle assessment revealed that the highest biomethane yield does not necessarily correspond to the lowest environmental impact. The integrated ReCiPe assessment identified the most sustainable pretreatment technologies and demonstrated the importance of combining experimental, energetic, and environmental indicators to optimize biomethane production systems.
30th of October, 2026, 15:00
Conference room at Lithuanian Energy Institute (Breslaujos 3 – 202)
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