開發貼附型微藻應用於油脂生產

Abstract

微藻具有生長快速、占地面積小等優點，所生產的油脂也具有做為生質燃料或食用油等多種用途。目前微藻之培養主要為開放池及光合反應器等懸浮培養模式，但其養殖濃度低，故需以沉降、離心等耗費大量時間及能源之採收方法收取藻體。微藻之貼附培養模式可利用刮取的方式取代傳統複雜的採收步驟，並具較高的光合效率、二氧化碳質傳效率及較低的水資源消耗等優勢。然而現有之產油藻株於貼附培養下的油含量較原懸浮培養低，一般低於10%以下。本研究之目的為篩選出兼具良好貼附能力及產油潛力之藻株，並透過對其特性之分析及貼附培養測試，來探討其以生物膜貼附系統培養之可能性。本研究由212株藻株中篩選並挑選出12株潛力藻株進行油脂分析及生長特性分析，包含油脂含量、油脂組成分、脂肪酸圖譜，及溫度、鹽度、pH值耐受性和異營能力等。並對3株貼附產油潛力藻株進行貼附培養，測試其於平面培養盤、靜止式斜面貼附反應器及靜止式直立貼附反應器之貼附效果。3株潛力藻株於貼附培養下之油脂含量最高可達藻體乾重的27至50%，遠高於文獻中之含量，顯示所篩選出之藻株於貼附培養下仍可保持高油脂含量，具有貼附生油脂之應用潛力。此外也測試了7種貼附材質之貼附性，選出貼附效果良好之材質進行旋轉式轉盤貼附反應器培養，發現不織布具有最佳之貼附效果，可應用於旋轉式貼附培養系統。本研究亦由31株貼附微藻中篩選出3株貼附生長快速且具高熱值之藻株，其熱值可達25 MJ/Kg以上，高於台電公司之煙煤、亞煙煤採購標準，灰分及硫分亦可低於採購標準之上限，具有應用為生物煤炭之潛力。

Microalgae have the adavantages of fast growing and less land requirement. The oil produced from microalgae can be used as biofuels and edible oils. Currently, the majority of microalgae cultivation processes are suspended culture systems include of open ponds and enclosed photobioreactors. However, the cell density is quietly low that need to use sedimentation and centrifugation methods to harvest microalgae cell in these systems. These processes are spending lots of time and energy. These complicated traditional harvest processes could be replaced by scraping in attached microalgal culture systems, which have other advantages like higher photosynthetic efficiency, higher CO2 mass transfer efficiency, and less water consumption. However, the microalgae currently used have low lipid contents when cultivated in attached systems compared to suspended cultivation. Therefore, the purpose of this study was to screen out the microalgae that have high attachment ability and high lipid content, then to analyze their properties and to check their situation under attached cultivation, assessing their possibility of cultivation in attached culture systems. This study got 12 potential microalgae strains from 212 isolates and investigated their lipid and growth properties which like lipid content, fatty acid profile, temperature andsalt tolerance, and heterotrophic ability. This study used 3 potential strains attached on filter membranes and cultivated in horizontal petri dishes, stationary inclined-photobioreactor, and stationary vertical-photobioreactor. The highest lipid content could reach 27%-50% under attached cultivation with the potentiality for oil production. Besides, this study got best biomass productivity by the non-woven fabric which tested from 7 kinds different fabrics in the rotating disk photobioreactor. This study also got 3 attached cultivated strains with high calorific value that higher than 25 MJ/Kg and low sulfur and ash content. The result shows that it could be biocoal by these potential attached cultivated strains.