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Entwicklung eines Prozesses zur oxischen mikrobiellen Elektrosynthese mit Kyrpidia spormannii unter besonderer Berücksichtigung der Prozesseffizienz
Citation Link: https://doi.org/10.15480/882.16022
Publikationstyp
Doctoral Thesis
Date Issued
2025
Sprache
German
Author(s)
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2025-10-07
Institute
TORE-DOI
Citation
Technische Universität Hamburg (2025)
With the help of microbial electrosynthesis (MES), carbon dioxide from industrial point sources can be converted into chemical energy storages under biocatalysis, using electricity generated from renewable sources. Anoxic MES processes are already being used in industry, for example
for the production of acetic acid or methane. However, the biomass yields are low and the range of products is limited. In contrast, oxic microbial electrosynthesis (oMES) enables the produc tion of more valuable products and biomass. However, biofilm-based oMES processes have so
far been insufficiently characterised, particularly with regard to their energy efficiency. There is a lack of studies analysing efficiency across different stages of biofilm growth. The influence of oxygen concentration on microbial growth, but also on the efficiency of the process, is not yet sufficiently understood. In addition, there is a lack of methods for continuous biofilm harvesting and investigations into the use of industrial flue gas as a substrate.
In this work, the oMES was operated with the Knallgas-bacterium Kyrpidia spormannii. The bioelectrochemical system used allowed non-invasive quantification of the biofilm using optical coherence tomography (OCT). This allowed to record growth kinetics, which determined the potential for the fastest biofilm growth at-375mV to-500mV vs SHE. Furthermore, the Coulombic efficiency could be determined over the process duration. It was 100% in the most efficient phase. At this point, no system-side electron losses occurred, meaning that oMES cultivation achieved the same efficiency as Knallgas fermentation, but without the disadvantage of handling explosive gas mixtures. By modelling biofilm growth, the oxygen demand for the current growth phase of the biofilm could be predicted, and electron losses resulting from oxygen reduction could be reduced. With 35,8kWh for the production of 1kg dry biomass, the energy requirement of the oMES process was also competitive with a two-stage Knallgas fermentation. A method was developed to harvest the biofilm via hydrogen bubbles. The biofilm was able to regenerate after being partially harvested. The harvested biomass had a protein content of around 62%. By adding a synthetic polymer, the initial growth phase of the biofilm until complete electrode coverage could be shortened. Finally, it was shown that the use of industrial flue gas as a substrate did not inhibit growth.
for the production of acetic acid or methane. However, the biomass yields are low and the range of products is limited. In contrast, oxic microbial electrosynthesis (oMES) enables the produc tion of more valuable products and biomass. However, biofilm-based oMES processes have so
far been insufficiently characterised, particularly with regard to their energy efficiency. There is a lack of studies analysing efficiency across different stages of biofilm growth. The influence of oxygen concentration on microbial growth, but also on the efficiency of the process, is not yet sufficiently understood. In addition, there is a lack of methods for continuous biofilm harvesting and investigations into the use of industrial flue gas as a substrate.
In this work, the oMES was operated with the Knallgas-bacterium Kyrpidia spormannii. The bioelectrochemical system used allowed non-invasive quantification of the biofilm using optical coherence tomography (OCT). This allowed to record growth kinetics, which determined the potential for the fastest biofilm growth at-375mV to-500mV vs SHE. Furthermore, the Coulombic efficiency could be determined over the process duration. It was 100% in the most efficient phase. At this point, no system-side electron losses occurred, meaning that oMES cultivation achieved the same efficiency as Knallgas fermentation, but without the disadvantage of handling explosive gas mixtures. By modelling biofilm growth, the oxygen demand for the current growth phase of the biofilm could be predicted, and electron losses resulting from oxygen reduction could be reduced. With 35,8kWh for the production of 1kg dry biomass, the energy requirement of the oMES process was also competitive with a two-stage Knallgas fermentation. A method was developed to harvest the biofilm via hydrogen bubbles. The biofilm was able to regenerate after being partially harvested. The harvested biomass had a protein content of around 62%. By adding a synthetic polymer, the initial growth phase of the biofilm until complete electrode coverage could be shortened. Finally, it was shown that the use of industrial flue gas as a substrate did not inhibit growth.
Subjects
Oxic microbial electrosynthesis
Kyrpidia spormannii
Hydrogen oxidizing bacteria
Energy efficiency
Coulombic efficiency
DDC Class
572: Biochemistry
660.2: Chemical Engineering
579: Microorganisms, Fungi and Algae
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