博士 / 國立交通大學 / 生物科技學系 / 100 / Microalgal cultivated in photobioreactor can be used for CO2 mitigation from waste gas and microalgal lipids can be converted into biodiesel. In this study, we screened and isolated microalgal strains with high potential for CO2 reduction and microalgal biomass production. In addition, we also designed an air-lift photobioreactor for high density microalgal cultivation.
First, the high growth potential microalgal cells were screened and isolated as a candidate for CO2 reduction and biomass production. Then, the low (i.e., 8 × 10^5 cells/mL) and high (i.e., 8 × 10^6 cells/mL) density of the microalgal cells inoculums for CO2 tolerance was evaluated. The results indicate that microalgal cells grew rapidly in a high-density culture with CO2 aeration. Thus, the strategy of increasing CO2 tolerance and cell density in the microalgal cultures was performed in this study. At the initiating stage of culture, the microalgal cells were grown and adapted to an enriched-CO2 (2%) environment. Then, the semicontinuous system was performed. The result shows that the microalgal cells can grow well even under the conditions of 10% and 15% CO2 aeration.
Then, for increasing biomass production and CO2 removal efficiency, the microalgal cells cultivated in the operation mode that culture broth was replaced by 1/4 (i.e., one-fourth volume of cultured broth was replaced by fresh medium at an interval of 2 days) and 1/3 (one-third broth replaced at 3 days interval) and 1/2 (one-second broth replaced at 8 days interval). The results show that the maximum biomass productivity could achieve 0.61 g/L/d in 1/4 of the culture broth recovered from the culture every 2 days. The CO2 removal efficiency was also evaluated because the high performance of biomass production and high density cultivation. The results show that > 60% of CO2 could be removed from the aerated gas which contains 10% CO2 under high density (approximate 5 g/L) cultivation.
Finally, the growth and on-site bioremediation potential of an isolated thermal- and CO2-tolerant mutant strain, Chlorella sp. MTF-7, were investigated. The biomass productivity of Chlorella sp. MTF-7 cultured indoors at 35 and 40oC was 0.32 and 0.24 g/L/d, respectively. The Chlorella sp. MTF-7 cultures were directly aerated with the flue gas generated from coke oven of a steel plant. The biomass concentration, productivity of Chlorella sp. MTF-7 cultured in an outdoor 50-L photobioreactor for 6 days was 2.87 g/L (with an initial culture biomass concentration of 0.75 g/L), 0.52 g/L/d. By the operation with intermittent flue gas aeration in a double-set photobioreactor system, average efficiency of CO2 removal from the flue gas could reach to 60%, and NO and SO2 removal efficiency was maintained at approximately 70% and 50%, respectively. Our results demonstrate that flue gas from coke oven could be directly introduced into Chlorella sp. MTF-7 cultures to potentially produce algal biomass and efficiently capture CO2, NO and SO2 from flue gas simultaneously.
| Identifer | oai:union.ndltd.org:TW/100NCTU5111114 |
| Date | January 2012 |
| Creators | Chiu, Sheng-Yi, 邱聖壹 |
| Contributors | Lin, Chih-Sheng, 林志生 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 110 |
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