Optimization of the biogas production in manure- and sludge-based biogas plants

PhD defence, Friday 2 February 2018. Maja Nielsen.

2018.02.02 | Camilla Dalegaard Mikkelsen

Maja Nielsen

We are all talking about the climate changes and feeling the consequences of using fossil fuels, which has fostered an increasing interest for renewable energy. Anaerobic digestion catalyzes the production of biogas. Here different kind of waste streams are microbial degraded to methane - an energy carrier applicable in the existing energy infrastructure. Though being a common technology in Denmark, knowledge about the most efficient operation is still very limited. This also includes information about the microorganisms present in the reactors. During her PhD studies, cand.scient. Maja Nielsen examined strategies to optimize the production of biogas. She had a particular interest to identify and characterize the microorganisms catalyzing the biogas production. Using DNA-sequencing technologies, she has identified and characterized several novel microorganisms. The results plays an important to understand the link between optimum reactor performance and the presence and activity of specific organisms. She examined a large number of Danish biogas plants and found that the majority were operated at non-optimum conditions. However, introducing small temperature differences affected the biogas production positive. Maja Nielsen found wheat straw to be a very important co-substrate in manure as well as sludge based biogas plants. Her results led to the development of new guidelines to obtain the most efficient biogas production.

The PhD degree was completed at Institute of Engineering, Science and Technology, Aarhus University.

This résumé was prepared by the PhD student.

Time: Friday 2 February 2018 at 1300
Place: Navitas, room 04.047, Department of Engineering, Aarhus University, Inge Lehmanns Gade 10, 8000 Aarhus C
Title of dissertation: Effect of temperature and feeding for reactor performance and microbial community composition in anaerobic digestion
Contact information: Maja Nielsen, e-mail: maja.nielsen@eng.au.dk, tlf: +4530662313 
Members of the assessment committee:
Professor Sven G. Sommer, Department of  Chemistry, Bio- and Environmental Technology, University of Southern Denmark, Denmark Senior Lecturer Alex Enrich Prast, Department of Thematic Studies, Linköping University Associate Professor Anders Bentien, Department of Engineering, Aarhus University (chair) 
Main supervisor:
Senior researcher Henrik Bjarne Møller, Institute of Engineering, Aarhus Denmark
Co-supervisor:
Asssociate professor Lars Ditlev Mørck Ottosen, Institute of Engineering, Aarhus, Denmark
Product Manager, Caroline Kragelund Rickers, Technological Institute, Aarhus, Denmark
Language: The PhD dissertation will be defended in English


The defence is public.
The dissertation is available for reading at the Graduate School of Science and Technology/GSST, Ny Munkegade 120, building 1520, rooms 128-134, 8000 Aarhus C.

PhD defence
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Revised 19.02.2018