自污水廠分離之微藻生化組成特性及其營養鹽利用之研究

Abstract

目前石化燃料的短缺危機，以及燃燒後排放大量二氧化碳造成的環境問題，開發低污染生質能源的需求迫在眉睫。微藻是生長速度快，無須占用耕地的微生物，同時在生長過程中能夠去除氮磷營養鹽，在適當的培養條件下還可累積不同比例的脂質、醣類與蛋白質，做為轉化成生質能源之原料。 以實驗室既有及自行從汙水廠放流水篩分出之微藻做為目標藻種，在BG11培養基中培養至快速生長期及穩定期，及另外以C. vulgaris與自行篩選之三株微藻，在人工合成廢水中額外添加有機碳源培養10天，觀測其生化組成(脂質、醣類及蛋白質)之特性，結果顯示微藻累積脂質與氮限制及壓力環境有關，醣類累積之差異則與本身藻種特性有關，培養基中之氮濃度，會直接影響其細胞累積之氮的比例，進而影響蛋白質含量的推算。 利用微藻去除氮磷營養鹽與產生質能源之應用，在與環境中其他微生物共存下之氮磷去除率皆接近100%，葡萄糖去除率也可達30%左右，在單純以合成廢水培養微藻的實驗中，C. vulgaris對於硝酸根之去除效率可達近100%，而7天的批次實驗中磷酸根的去除率為58.5%至88.0%，相較於有微生物共培養之實驗，推測培養基中含有有機碳，使環境中微生物與微藻共生，可促進微藻生長及去除氮磷營養鹽，使得氮磷營養鹽去除效率明顯高於單以合成廢水培養。 以水熱液化法(Hydrothermal Liquefaction, HTL)轉換微藻生物質產生物油，則因進料濃度以及體積不足，以及未找到最佳操作條件，故並無足夠產量進行分析，僅可確定經HTL反應後生物質大部分會轉為液相。

Due to the lack of the fossil fuel, new energy types are widely studied. Microalgae grow fast and do not occupy any arable land. As their growing, microalgae can consume the nutrients and help clean the water. Three microalgae strains were isolated from the local wastewater treatment plant in Taipei. Four strains from the culture collection and the three new strains were cultivated in BG11, respectively. The biochemical-compositions of these 7 microalgae are analyzed. Furthermore, synthetic wastewater is used as well in cultivating the newly isolated algae to get more details of their characteristics. The results from the 2 different culture media show that the protein contents are dependent on the concentration of nitrogen, and the carbohydrate and lipid contents are related to the limitation of nitrogen and the differences between the strains. The removal efficiencies of nitrate was good and phosphate were unobvious when the microalgae are cultivated in synthetic wastewater without organic carbon. On the opposite, the efficiencies are outstanding when the microalgae are cultivated with other microorganisms and glucose. The bio-oil was converted from microalgae biomass using HTL. The yield of the bio-oil is related to the operating conditions such as temperature, pressure and holding time.