碩士 / 國立成功大學 / 化學工程學系碩博士班 / 98 / Recently, global warming has become a serious environmental concern. Microalgae have good photosynthetic capabilities for CO2 fixation. Now, they have been produced for many applications, such as production of natural pigments or polyunsaturated fatty acids (PUFAs), which are high value products. Due to their small size and low cell density, recovery of microalgae is a major challenge. Therefore, we use NaOH, which is low price, as a additive to harvest marine microalgae efficiently.
In this study, we find that controlling pH at 9.5 ~ 10.3 is effective in harvesting of marine microalgae, and the flocculation phenomenon involves the formation of Mg(OH)2. This result is different from the flocculation caused by reducing electrostatic repulsion forces between cells. In general, flocculation results from the electro-neutralization between electrolytic flocculant and surface charge of the cells. While the electrostatic repulsion forces decrease, the aggregation of suspended cells (usually, negative-charged cells repel each other) take place.
According to quantities of Mg(OH)2, the settling phenomena can be classified into three modes, gradient, interface and transition mode (GM, IM and TM). In this research, in order to compare the efficiency between different modes, we use image analysis to establish the linear correlation between biomass concentration and luminance and evaluate the variations of local biomass concentration. The results show that GM can harvest microalgae efficiently and be faster than the other modes, the usage of NaOH is less. In addition, after removing the most water by base processes, Mg(OH)2 can be dissolved by supplying some acids, such as HCl. Then, we can obtain purer microalgae by high-speed batch centrifugation to remove the residues and ions.
| Identifer | oai:union.ndltd.org:TW/098NCKU5063102 |
| Date | January 2010 |
| Creators | Chung-ShinLin, 林忠信 |
| Contributors | Wen-Teng Wu, 吳文騰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 88 |
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