碩士 / 大仁科技大學 / 環境管理研究所 / 98 / Microalgae, due to the advantages of higher photosynthetic efficiency, higher biomass production and faster growth compared to other energy crops, as a potential source of bioenergy has attracted wide attention. Microalgae are photosynthetic microorganisms that convert sunlight, water and carbon dioxide to algal biomass. There are several different types of bioenergy, such as biomethane, biohydrogen, bioethanol, and biodiesel, from microalgae can be provided. All microalgae contain proteins, carbohydrates, lipids, and nucleic acids in varying proportions. Many microalgae are exceedingly rich in lipid, which can be converted to biodiesel.
There are several factors influencing lipids of microalgae, such as light (quality, quantity), temperature, nutrient concentration, O2, CO2, pH, salinity, and toxic chemicals. The goal of this study was to understand the effect on the potential of biomass growth rate and the biodiesel productivity. Two phases of experiments were performed in this study. In the first phase the effect of growth stage on bioenergy production potential was conducted. Four factors including temperature, light intensity, nitrogen nutrient concentration, and carbon dioxide concentration were investigated using central composite design (CCD) in the second phase. The CCD methodology is a statistical method that uses quantitative data from appropriate experiments to determine operating conditions and to help to study the interactions between these factors simultaneously.
Results from the first phase experiments shows that the growth rate decreased with increasing cultivation time. It was observed that a very decease in growth rate was found between day 10 and day 20 of cultivation time. However, the lipid content and calorific value of biomass increased with increasing cultivation time. Both lipid content and calorific value of biomass were highest at the end of cultivation time. The lipid content of microalgae grown during day 31~50 was about three times that during day 0~10 day of cultivation time. The result might follow the general pattern that higher lipid content at low relative growth rate of algae. The lipid productivity was calculated by lipid content and growth rate. The highest lipid productivity was culture grown at the first 10 day of cultivation time. This result suggests that culture grown day 10 is the most favorable for biodiesel production under investigated condition.
The CCD methodology based on four variables was used to determine the effect of temperature, light intensity, nitrogen concentration, and carbon dioxide concentration on the bioerergy production potential in the second phase. Through analysis of the response surfaces derived from the results, light intensity and temperature were found to have the most significant effect on bioerergy production potential. The best results for laboratory scale tested on the potential of biomass growth rate and the biodiesel productivity were obtained at 25 ◦C with 92.5 μmol/m2/s of light intensity, nitrogen nutrient content limited (low 505 mg/L), and 12 mL/L/day dioxide carbon concentration.
| Identifer | oai:union.ndltd.org:TW/098TAJ05700011 |
| Date | January 2010 |
| Creators | Wei-Han Chen, 陳暐翰 |
| Contributors | Jen-Jeng Chen, 陳振正 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 99 |
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