從微藻提煉的生物燃料，是化石燃料和其他生物燃料的優良替代品。藻類生物燃料屬碳中性，因為微藻為光自養生物，能經光合作用吸收二氧化碳，並將之轉化成碳氫化合物和脂肪。碳氫化合物和脂肪可用以提煉生物燃料。此外，微藻可以吸收廢水中的污染物作生長的營養，同時作污水處理。 / 本研究項目的目的為透過下述方法，降低藻類生物燃料的生產成本，並提高藻株的脂肪含量： (1) 篩選可以在污水自養培育，並有高產油量的微藻菌株，(2) 以兩階段培養方法，用處理過的污水作培養，從而提高油脂產，(3) 透過微藻毒理測試，和水質化學分析，研究處理後的污水中影響微藻生長的污染物和有毒物質。 / 這個研究中使用從沙田污水處理廠收集的二級處理污水，其水質亦被研究。幾種微藻菌株分別為小球藻 (Chlorella pyrenoidosa)，叢粒藻 (Botryococcus braunii) 和微綠球藻 (Nannochloropsis oculata)，從鰂魚池水分離出的小球藻 (Chlorella sp.1)，及兩種從處理污水中分離出的小球藻(Chlorella sp. 2, Chlorella sp. 3)。微藻菌株分別在培養基和處理污水中培養，並比較在兩種情況下的脂肪，脂肪酸，碳水化合物，蛋白質含量，生物質量和總有機碳。結果發現，雖然經處理的污水中營養成分非常低 (<0.11 mg / L活性磷，<9.68 mg / L硝酸根，<0.5 mg / L鉀離子)，所有研究的微藻菌株都能存活。在兩階段培養法下，首先以「氮含量充足階段」(培養基)提高生物質量，然後以「氮含量不足階段」(經處理污水) 培養，培養成本可以降低，同時提高脂肪生產率。在兩階段培養法下，叢粒藻的脂肪生產率比在人工培養基和經處理污水高2.6倍和7.13倍。 / 沙田污水處理廠處理的污水水質良好，並無驗出有害重金屬，雙酚A(BPA)，四溴雙酚A(TBBPA)和2,3,7,8-四氯二苯並二噁英(TCDD)。從藻類產生的生物燃料將不含有重金屬。 / 在這個研究中的叢粒藻 (Botryococcus braunii)，微綠球藻 (Nannochloropsis oculata)和小球藻 (Chlorella sp.1)都可以容忍雙酚A(BPA)，四溴雙酚A(TBBPA)，二氯苯氧氯酚 (TCS)和2,3,7,8-四氯二苯並二噁英(TCDD)。他們可以培育在其他來源的經處理污水。 / 利用經處理污水於兩階段培養法，是一種新的、更經濟的增加微藻油脂產量方法，亦可以配合任何其他方法，以減低藻類生物燃料的製造成本。 / Biofuel from microalgae can be an excellent substitute of fossil fuel and other biofuels. Algal biofuel is carbon neutral as microalgae are photoautotrophic. Through photosynthesis, microalgae can capture and convert carbon dioxide to hydrocarbons or lipids which can be used for biofuel production. Besides, microalgae can use pollutants from wastewater as nutrients for growth, which can serve as a wastewater treatment process. / The aims of the project are to lower the cost of algal biofuel production and boost up lipid content of algal strains by (1) screen a microalgal strain that can be cultivated in treated sewage autotrophically and give high oil yield, (2) use two phase cultivation, with treated sewage as medium, to boost up lipid productivity, (3) investigate heavy metals and some organic pollutants that may exist in treated sewage and can affect algal growth by performing algal toxicity test and chemical analysis of treated sewage. / The secondarily treated sewage used in this project was collected from the Sha Tin Sewage Treatment Works. The quality of the secondarily treated sewage was monitored. Chlorella pyrenoidosa, Botryococcus braunii and Nannochloropsis oculata from commercial source, and Chlorella sp. 1 isolated from tilapia fish pond water, and two species of algae, Chlorella sp. 2 and Chlorella sp. 3, isolated from treated sewage were investigated. Microalgal strains are compared by investigating the content of lipid, fatty acid, carbohydrate, protein, biomass and total organic carbon when cultivated in culture medium and treated sewage. Results found that although nutrients in treated sewage were very low (<0.11 mg/L reactive phosphorus, <9.68 mg/L nitrate and <0.5 mg/L potassium ion), all the microalgae investigated could grow reasonably well. Using two phase cultivation, with an initial nitrogen sufficient phase (artificial media) for biomass production, followed by nitrogen limitation phase (treated sewage), cost of cultivation could be reduced and the overall lipid productivity could be increased. Under the two phase cultivation, the lipid productivity of Botryococcus braunii was 2.6 and 7.13 fold higher than cultivated in artificial medium and treated sewage respectively. / Treated sewage from the Sha Tin Sewage Treatment Works was in good quality without harmful concentrations of heavy metal and BPA, TBBPA and TCDD. The microalgae could not absorb or adsorb significant amount of the harmful substances and the algal biofuel produced would not contain heavy metals. All the microalgae investigated in this project could tolerate BPA, TBBPA, TCS and TCDD. They could be cultivated in treated sewage from other sources. / Two phase cultivation using treated sewage is a new way for increasing lipid productivity from microalgae economically and can be combined with any other means for producing algal biofuel with lowest cost. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Kwan, Ka Ki. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 104-113). / Abstracts also in Chinese. / Acknowledgements --- p.i / Abstract --- p.iii / 摘要 --- p.Vi / Table of Contents --- p.viii / List of Figures --- p.Xii / List of Plates --- p.Xvi / List of Tables --- p.xviii / Abbreviations --- p.xx / Chapter 1. --- General introduction / Chapter 1.1 --- Fossil fuel, the major energy source nowadays --- p.1 / Chapter 1.2 --- Disadvantages of using fossil fuel --- p.3 / Chapter 1.3 --- Biofuel --- p.5 / Chapter 1.4 --- Disadvantages of traditional biofuel production --- p.8 / Chapter 1.5 --- Characteristics of microalgae --- p.9 / Chapter 1.6 --- Biofuel from microalgae --- p.14 / Chapter 1.7 --- Nutrients for microalgae related to lipid production --- p.18 / Chapter 1.8 --- Current research on algal biofuel --- p.19 / Chapter 1.9 --- Two phase cultivation as a new way for lipid production --- p.24 / Chapter 1.10 --- Objectives --- p.24 / Chapter 2. --- Biofuel production under two phase cultivation with artificial medium and treated sewage / Chapter 2.1 --- Introduction --- p.26 / Chapter 2.2 --- Materials and Methods --- p.28 / Chapter 2.2.1 --- Algal strains collection and isolation --- p.28 / Chapter 2.2.2 --- Artificial culture media --- p.29 / Chapter 2.2.2.1 --- Bristol’s Medium (BM) --- p.29 / Chapter 2.2.2.2 --- Modified Bold 3N medium (MBM) --- p.31 / Chapter 2.2.3.3 --- F/2 medium (F/2) --- p.33 / Chapter 2.2.3 --- Water quality of treated sewage --- p.33 / Chapter 2.2.3.1 --- Chemical and biological condition --- p.34 / Chapter 2.2.3.2 --- Total organic carbon and total nitrogen (TOC/TN) --- p.35 / Chapter 2.2.3.3 --- Reactive phosphate --- p.35 / Chapter 2.2.3.4 --- Nitrate --- p.37 / Chapter 2.2.3.5 --- Ammonia --- p.39 / Chapter 2.2.3.6 --- Metal elements --- p.40 / Chapter 2.2.4 --- Cultivation conditions --- p.40 / Chapter 2.2.5 --- Growth monitor of microalgae in artificial medium and treated sewage --- p.41 / Chapter 2.2.6 --- Comparison of microalgae cultivated in artificial media and treated sewage --- p.42 / Chapter 2.2.6.1 --- Large scale cultivation --- p.42 / Chapter 2.2.6.2 --- Cell morphology --- p.43 / Chapter 2.2.6.3 --- Cell harvesting --- p.44 / Chapter 2.2.6.4 --- Dried biomass --- p.44 / Chapter 2.2.6.5 --- Lipid content --- p.45 / Chapter 2.2.6.6 --- Fatty acid profile --- p.46 / Chapter 2.2.6.7 --- Extraction of carbohydrates and protein --- p.48 / Chapter 2.2.6.8 --- Carbohydrate content --- p.48 / Chapter 2.2.6.9 --- Protein content --- p.49 / Chapter 2.2.7 --- Two phase cultivation --- p.50 / Chapter 2.2.8 --- Statistical analysis --- p.50 / Chapter 2.3 --- Results --- p.51 / Chapter 2.3.1 --- Water quality of treated sewage --- p.51 / Chapter 2.3.2 --- Nutrient contents in artificial medium --- p.54 / Chapter 2.3.3 --- Growth of microalgae in artificial medium and treated sewage --- p.54 / Chapter 2.3.3.1 --- Cell morphology and cell size --- p.57 / Chapter 2.3.3.2 --- Biomass --- p.59 / Chapter 2.3.3.3 --- Lipid content --- p.61 / Chapter 2.3.3.4 --- Fatty acid profile --- p.63 / Chapter 2.3.3.5 --- Carbohydrates content --- p.66 / Chapter 2.3.3.6 --- Protein content --- p.67 / Chapter 2.3.4 --- Two phase cultivation --- p.69 / Chapter 2.4 --- Discussion --- p.74 / Chapter 2.4.1 --- Water quality of treated sewage and nutrients in artificial medium --- p.74 / Chapter 2.4.2 --- Growth of microalgae in artificial medium and filtered treated sewage --- p.75 / Chapter 2.4.3 --- Microalgae cultivated in artificial media and treated sewage --- p.76 / Chapter 2.4.4 --- Two phase cultivation --- p.81 / Chapter 3. --- Possible toxic effect on algal growth from chemicals in sewage / Chapter 3.1 --- Introduction --- p.84 / Chapter 3.2 --- Materials and methods --- p.85 / Chapter 3.2.1 --- Analysis of dissolved metals by ICP --- p.85 / Chapter 3.2.2 --- Organic compounds --- p.86 / Chapter 3.2.3 --- Algal bioassay --- p.87 / Chapter 3.3 --- Results --- p.88 / Chapter 3.3.1 --- Dissolved metals and metalloids --- p.88 / Chapter 3.3.2 --- Organic compounds --- p.88 / Chapter 3.3.3 --- Algal bioassay --- p.91 / Chapter 3.4 --- Discussion --- p.97 / Chapter 4. --- Conclusion and future prospectives --- p.99 / Chapter 4.1 --- Summary --- p.99 / Chapter 4.2 --- Genetic engineering --- p.100 / Chapter 4.3 --- Further study --- p.102 / Chapter 4.4 --- Conclusion --- p.102 / Chapter 5. --- References --- p.104