Dissertation
INVESTIGATING THE USE OF SELECTED HOMOACETOGENS: A UNIQUE BACTERIAL GROUP CAPABLE OF FIXING CARBON DIOXIDE INTO ACETIC ACID WITH HYDROGEN AS AN ELECTRON DONOR
Doctor of Philosophy (PhD), Washington State University
01/2020
Handle:
https://hdl.handle.net/2376/108393
Abstract
Homoacetogenic bacteria have the unique ability to metabolize H2/CO2/CO as a source energy to produce acetic acid as the end product. This gas fixing ability of Acetobacterium woodii was explored in three different objectives – increasing efficiency of acetic acid production by in-situ separation, methane mitigation from ruminants and biogas upgradation.
Autotrophic fed-batch fermentation of H2-CO2 by Acetobacterium woodii showed a production of 6.438 g/L acetic acid at 0.5 bar over pressure, over 10 days period. Amberlite FPA53 was selected as an ideal resin after performing detailed screening studies on six different types of basic anion exchange resins. Continuous in-situ extractive fermentation lead to production of 10.267 g/L acetic acid in 10 days giving higher yield of product and recirculation of media components without requirement of caustic base for pH maintenance.
Pure culture of Acetobacterium woodii and consortia from baby kangaroo droppings were used for bioaugmentation studies for methane mitigation. Both the consortia were unable to compete with rumen methanogens for H2. However, they showed complete utilization of low concentrations of H2 when methanogens were inhibited using BES. Since these acetogens could metabolize H2 in absence of methanogens for prolonged periods of time, they were considered as potential candidates for future studies combined with BES treatment.
Biogas produced by anaerobic digestion contains 20-30% of CO2. To increase the purity of methane in biogas, a preliminary research was conducted by developing an experimental prototype using pure culture of Acetobacterium woodii to sequester this CO2 by external addition of H2 . A gas mixture mimicking the biogas mix was used (CH4:CO2:H2, 33%: 22%:45%). An increase of ca. 96% in the purity of biogas was observed with simultaneous decrease of CO2 from 22% to 3.8% in 4 days, followed by increase in the purity to 99.71% by external addition of H2 in 8 days.
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Details
- Title
- INVESTIGATING THE USE OF SELECTED HOMOACETOGENS: A UNIQUE BACTERIAL GROUP CAPABLE OF FIXING CARBON DIOXIDE INTO ACETIC ACID WITH HYDROGEN AS AN ELECTRON DONOR
- Creators
- Supriya Charuhas Karekar
- Contributors
- Birgitte K Ahring (Advisor)Manuel Garcia Pérez (Committee Member)Xiao Zhang (Committee Member)Stephen Callister (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Systems Engineering, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 295
- Identifiers
- 99900581412801842
- Language
- English
- Resource Type
- Dissertation