碩士 / 大仁科技大學 / 環境管理研究所 / 101 / The energy demand for fossil fuel is globally increasing. However, extensive utilization of fossil fuels has led to global warming and environmental impacts due to the attributed increase in greenhouse gas emissions. Therefore,a significant interest was turning more attention to develop the new, clean, and sustainable energy sources in many countries. Microalgae, widely recognized as the feedstock for third-generation of biofuels. Have a higher biomass production and a faster growth rate than other energy crops.
Many microalgae are exceedingly rich in lipid content for producing biodiesel. However, the accumulation of lipid and increase of cell growth rate depend on diverse factors, including cultivation conditions, algal species, and growth environments. There are four major types of cultivation conditions for microalgae: photoautotrophic, heterotrophic, mixotrophic and photoheterotrophic cultivation. Although biodiesel is environmentally sustainable, it should be produced practically and economically. One of the methods to reduce costs of algal biomass is to integrate wastewater treatment with algae biomass production.
One of the dominant green algal species, Scenedesmus sp., was isolated from local constructed wetland and firstly cultured in autotrophic and mixotrophic growth to compare the biomass production. Carbon dioxide and piggery wastewater was served as the carbon and nutrient sources for the cultures, respectively. The kinetics on nutrient utilization and lipid accumulation under their respective optimal growth were then studied. The effects of nitrogen sources at similar nitrogen concentrations on cell growth and lipid accumulation of Scenedesmus sp. under autotrophic growth were also examined. For the mixotrophic growth, the effects of piggery wastewater content, incubation time, and biomass concentration on the growth rate, nutrient removal efficiency, and biodiesel production were examined by using a central composite design (CCD).
Preliminary results indicated that an appropriate composition of each source was beneficial for biomass production, 8 % (v/v) CO2, and 40 % piggery wastewater content for autotrophic and mixotrophic cultivation, respectively. The specific growth rate and lipid productivity obtained with autotrophic growth were slightly higher than those obtained by mixotrophic growth. Furthermore, cell cultured in nitrite nitrogen (NO2-) under autotrophic growth has a high lipid productivity and nutrient removal compared with those cultured by NH4+ and NO3- nitrogen.
Results from the CCD tests show that considtration of the experimental range, the most important factor for lipid productivity and nutrient removal is incubation time. The highest lipid productivity (25.23 mg/L.d) and nutrient removal were obtained at the following conditions: piggery wastewater content (50 %), biomass concentration (OD > 0.3), and incubation time (5-7 days). The mixotrophic cultivation not only produced biomass, but also could assimilate up to 78.56 % total nitrogen, 70.38 % total phosphorus, and 80.91 % COD from piggery wastewater, respectively. In conclusion, Scenedesmus sp. may be a potential strain for integrating piggery wastewater treatment with algae biodiesel production.
| Identifer | oai:union.ndltd.org:TW/101TAJ00700018 |
| Date | January 2013 |
| Creators | HUANG,YU-CHENG, 黃鈺鉦 |
| Contributors | CHEN,JEN-JENG, 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 | 179 |
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