碩士 / 國立中興大學 / 生物產業機電工程學系所 / 102 / The effects of microalgae post-harvest and its drying models were investigated. In this work, an airlift photobioreactor system for microalgae culture, equipped with a 100 liters tank, a temperature-reducing device, an airlift circulation device, and a movable illumination device, was designed and built. The efficiency of temperature-reducing, airlift circulation, and microalgae culture was tested respectively. The results showed that the temperature-reducing device could reduce the temperature in the airlift photobioreactor. Through the tests of airlift circulation efficiency, the cultivation solutions could be circulated thoroughly once within 26.5±0.8s at the aeration rate of 8 l/min respectively. The results demonstrated that the airlift circulation device enabled rapid circulation and mixture of liquids. The effect of microalgae culture by the newly constructed airlift photobioreactor was also tested, the results showed that Isochrysis galbana (CCAP 927/1) produced with cell density 817.22±53.86×104 cell/ml and the havest volume was 22.06±3.91 l a day, and proved with functions of cultivation and production.
Moreover, the concentration, the collection, and the cell viability after concentration of the two species of microalgae, Isochrysis galbana (CCAP 927/1) and Porphyridium cruentum (CCAP 1380/3) were determined respectively with the use of high flow rate and high speed centrifugal separator. The results suggested that the effects of microalgae concentration were unable to be shown by the high flow rate and high speed centrifugal separator within the adjustable relative centrifugal force (RCF) ranging from 1997.8G to 18616.7G. Comparatively, the effects of microalgae collection were more significant. The collection rate of Isochrysis galbana(CCAP 927/1) was 97.76% with the low RCF of 4843.3G, and the chlorophyll photosynthetic efficiency was 0.288 Fv/Fm, which showed that its cell viability after concentration was low. The collection rate of Porphyridium cruentum (CCAP 1380/3) was 92.44% with the high RCF of 18616.7G, and the chlorophyll photosynthetic efficiency was 0.619 Fv/Fm, which showed that its cell viability after concentration was of no significant differences.
Furthermore, microalgae hot-air drying models, discussing the drying rates and quality of microalgae after drying, were established. Samples of Isochrysis galbana(CCAP 927/1) and Porphyridium cruentum (CCAP 1380/3) were dried respectively in 35, 45, 55, and 65°C hot-air drying ovens after centrifugation. The content of crude lipids, the composition of fatty acids, the crude protein, the neutral detergent fiber (NDF) and the crude ash were analyzed to investigate the effects of temperature. Two control groups, freeze-drying and hot-air drying of 105°C, were compared and analyzed to the above experimental groups. The results indicated that no significant differences in individual fatty acids contents, the crude protein, the NDF, and the crude ash of Isochrysis galbana (CCAP 927/1) and Porphyridium cruentum (CCAP 1380/3) between the samples of 35 to 65°C hot-air drying and also to the samples of freeze-drying and 105°C hot-air drying were found respectively. However, the samples of Isochrysis galbana (CCAP 927/1) obtained the largest amount of crude lipids after treated with 35°C hot-air drying. In this study, the strong linear relationship between hot-air operating temperatures and drying constarts was observed through the establishment of drying models. Drying operating parameters with the lowest energy cost were obtained through the simulation for the hot-air drying process and the relation in energy cost of hot-air drying ovens with the use of drying parameters. The results could be offered for future reference to investigate the relationship between drying operating parameters and compositions of microalgae. Finally, variable costs of microalgae production, harvest, and drying were analyzed to efficiently reduce future mass production costs of microalgae with the results obtained.
| Identifer | oai:union.ndltd.org:TW/102NCHU5415006 |
| Date | January 2014 |
| Creators | Chun-Hsiao Liu, 劉俊孝 |
| Contributors | Chung-Chyi Yu, 尤瓊琦 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 131 |
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