High shear-assisted extraction of lipid from wet microalgal biomass = 고전단 기반 공정에 의한 비건조 미세조류 바이오매스의 지질 추출

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The importance of microalgae as the potential source of biofuel and value-added products (omega-3 lipids, pigments) have led to the development of the microalgae-based biorefinery in recent years. For industrialization of microalgae-based biofuel production, development of energy and cost-efficient lipid extraction process is necessary. The conventional wet lipid extraction process composed of cell disruption and lipid recovery step required high energy consumption and solvent usage, and long process time, which reducing the overall economic feasibility. To overcome these problems, high shear-assisted lipid extraction method was proposed using a high shear mixer (HSM) for industrial microalgal strains, wet Aurantiochytrium and Nannochloropsis sp. These strains can achieve high biomass and lipid productivity with producing high amounts of omega-3 lipids (DHA and EPA). HSM can induce strong turbulence flow and high shear stress that cause strong dispersion and cavitation effects. The concentrated wet biomass was mixed with various organic solvent directly by using a HSM to enhance accessibility of solvent to lipids. The results showed that high shear mixing achieved high lipid extraction yield compared to conventional stirring without severe cell disruption. Furthermore, high shear mixer shows same lipid extraction yield for dry and wet biomass, which indicating that high shear mixing can overcome water barrier preventing mass transfer of solvent. Additional process optimization for Aurantiochytrium sp. was performed in large scale and achieved high lipid extraction yield (90 %) with low energy consumption (4.83 MJ/kg dry cell) and solvent usage (5.9 ml/g dry cell), which is lower more than 10 times than conventional methods developed for Thraustochytrids. In case of Nannochloropsis sp., it contained thick cell wall composed of cellulose and algaenan (hydrocarbon with various functional group) so that it was not enough to extract lipids with only hexane. Thus, we added alcohol and acid to solvent mixture and achieved high lipid extraction yield with short process time. In addition, acid played important role of convert polar lipids to free fatty acid, which increased lipid quality and prevents emulsion formation. Optimization of solvent composition and operating condition was resulted in high lipid extraction yield (83 % of total lipid and 94 % of EPA) with 30 % lower energy consumption (1.38 MJ/kg dry cell) and 7-times shorter process time (5 min), compared to the conventional methods for photoautotrophic microalgae. In conclusion, high shear-assisted lipid extraction process was successfully demonstrated to increase economic feasibility for the microalgae-based biorefinery. The high shear-assisted lipid extraction process was able to achieve high lipid yield with low energy consumption, solvent usage and short process time compared to conventional methods. For future work, development of a continuous system for microalgae lipid extraction process using in-line HSM and another downstream process that using biphasic system is recommended.
Advisors
Chang, Yong Keunresearcher장용근researcher
Description
한국과학기술원 :생명화학공학과,
Publisher
한국과학기술원
Issue Date
2019
Identifier
325007
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 생명화학공학과, 2019.2,[vi, 103 p. :]

Keywords

Microalgae▼anannochloropsis▼aaurantiochytrium▼aomega-3 fatty acids▼ahigh shear mixer▼awet lipid extraction▼aorganic solvent extraction▼aprocess optimization▼abiphasic mixing; 미세조류▼a나노클로롭시스▼a오란티오키트리움▼a오메가-3 지방산▼a고전단 믹서▼a습식 지질 추출▼a용매 추출▼a공정 최적화▼a다상 혼합

URI
http://hdl.handle.net/10203/264918
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=842469&flag=dissertation
Appears in Collection
CBE-Theses_Ph.D.(박사논문)
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