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Development of a Biomass-to-Methanol Process Integrating Solid State Anaerobic Digestion and Biological Conversion of Biogas to Methanol
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Development of a Biomass-to-Methanol Process Integrating Solid State Anaerobic Digestion and Biological Conversion of Biogas to Methanol. |
| 개인저자 | Sheets, Johnathon Patrick. |
| 단체저자명 | The Ohio State University. Food, Agricultural and Biological Engineering. |
| 발행사항 | [S.l.]: The Ohio State University., 2017. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2017. |
| 형태사항 | 319 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-05B. Dissertation Abstract International |
| ISBN | 9781687948601 |
| 학위논문주기 | Thesis (Ph.D.)--The Ohio State University, 2017. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-05, Section: B.
Advisor: Martin, Jay. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | Solid-state anaerobic digestion (SS-AD) can be used to convert abundant, low moisture feedstocks, such as switchgrass, to methane (CH4)-rich biogas. However, biogas is a gas under ambient conditions, and impurities need to be removed before it can be upgraded to other products. Integration of SS-AD with biological conversion of biogas to methanol could provide an environmentally friendly method to convert renewable feedstocks to liquid chemicals.The first project showed that limited air exposure had a minimal effect on SS-AD of switchgrass, and thermophilic conditions (55째C) improved biogas yields (102-145 L CH4 kg VSadded-1) compared to mesophilic (37째C) (88-113 L CH4 kg VSadded-1). Net energy analysis of a theoretical "garage-type" SS-AD reactor suggested that positive net energy could be obtained at elevated total solids contents (= 20% TS).A new methanotroph strain (Methylocaldum sp. 14B) was isolated from the digestate of a mesophilic SS-AD reactor. Strain 14B successfully converted biogas to methanol using phosphate as a methanol dehydrogenase (MDH) inhibitor and formate as an electron donor. The maximum methanol concentration (0.43짹0.0 g/L) and CH4 to methanol conversion ratio (25.5짹1.8%) were obtained using strain 14B suspended in NMS medium containing 50 mM phosphate and 80 mM formate a biogas:air ratio of 1:2.5 (v/v).Abiotic gas-liquid mass transport of O2 in a trickle-bed reactor (TBR) packed with ceramic balls was two times higher than an unpacked TBR. The results suggested that the TBR enhanced gas oxidation compared to shake flasks. Maximum methanol productivity (0.9 g/L/d) in the non-sterile TBR was obtained at 12 mmol formate and 3.6 mmol phosphate and a biogas:air ratio of 1:2.5. Operation under non-sterile conditions impacted the microbial community of the TBR.A mathematical model that considered mass transport and gas consumption kinetics was used to generate results that were similar to selected semi-batch data from the lab-scale TBR. The results from a theoretical large scale TBR model suggested that maximum methanol yields (18 g/L) could be obtained at high gas velocities, high methanotroph cell density (40 kg cells/m3), and elevated pressure (up to 3 atm), because they improved gas solubility and uptake kinetics.Techno-economic analysis was used to compare the feasibility of biogas upgrading technologies at a large-scale biogas production facility (5900 Nm3/h, 5,000,000 sft3/d). Biogas cleaning via pressurized water scrubbing (PWS) for compressed natural gas production had the highest net present value, followed by purified biogas production, biological methanol production, and thermochemical methanol production. Biological conversion had slightly higher methanol production costs than thermochemical conversion because of lower methanol production rates. Sensitivity analysis indicated that costs could be reduced if methanotrophs are modified to have higher gas oxidation rate, gas conversion, and methanol tolerance. The cost of electron donors need to be reduced to enhance economic feasibility.These results from this research indicate that an integrated process consisting of SS-AD of switchgrass and biological conversion of biogas to methanol is technically feasible. The knowledge obtained from these studies could be used to assist in the optimization and scale-up of SS-AD and biotechnologies for biogas valorization. |
| 일반주제명 | Alternative energy. Environmental science. |
| 언어 | 영어 |
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