臺灣博碩士論文加值系統

薄膜分離技術是現今回收微藻的方法，薄膜能有效地將微藻細胞分離，而其剩餘的培養基能回收利用，重新進行微藻養殖。本研究利用不同圓盤式薄膜(400B與400HB)過濾不同的藻類(螺旋藻及柵藻)，探討其最佳操作參數之可行性研究。利用薄膜分離技術能有效地把微藻細胞濃縮，但微藻細胞會附著於薄膜表面，進而造成通量下降，降低濃縮效率。所以，如何有效預防通量下降為本研究之探討方向。結果顯示，400HB的薄膜比400B的薄膜有更好的過濾效率，能由阻抗值與孔隙度得知。柵藻因其細胞尺寸較小，所以薄膜通量下降較螺旋藻來得慢，且利用洗淨方式能讓薄膜通量回復較螺旋藻來得高。薄膜阻塞原因在於破碎細胞中的多醣及蛋白質造成薄膜阻塞，故本實驗利用FTIR分析得證。實驗中發現過濾時加入曝氣系統能延緩通量下降約20%，而反沖洗是最有效率的洗淨方式。當過濾時，結合曝氣與反沖洗的方式能使薄膜通量達到完全的回復。

關鍵字:微藻、超濾膜、微藻濃縮

Membrane ultrafiltration (UF) method is a simply separation method which is usually used for microalgae harvesting. However, membrane fouling is an important problem that decreases the performance of microalgae harvesting. The aim of this research is study of different disc-type UF membrane filtrations (400B and 400HB) on harvesting of two different microalgae (Spirulina maxima and Scenedesmus obliquus), to investigate the optimum operating parameters for filtration-remediation process. Moreover, cause of membrane fouling was also studied in this research. The result indicated that 400HB membrane predominantly shows higher efficiency of membrane filtration than 400B membrane, corresponded with initial resistance, reversible resistance and irreversible resistance owning to higher porosity. Scenedesmus obliquus causes slower membrane fouling because of its smaller sizes and can be easily remediated than Spirulina maxima. The membrane fouling can also be caused by the polysaccharides and proteins from broken cells also not only for the cells, confirmed by FTIR study. It was found that fouling process can be temporized up to 20 % when applied aeration system during filtration process. Backwash cleaning method is the most effective cleaning method and the flux decline can be completely recovered when combining aeration with backwash cleaning method.

Keywords: microalgae, UF, harvesting

Table of Content
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Objectives 3
Chapter 2 Literature Review 5
2.1 Background 5
2.2 Microalgae 6
2.2.1 Application of microalgae 6
2.2.2 CO2 capture with microalgae 8
2.3 Membrane theory and technology 8
2.3.1 Membrane separation technique 8
2.3.2 Critical flux and initial resistance 10
2.3.3 Membrane harvesting for microalgae 11
2.3.4 Membrane fouling by microalgae 12
2.3.5 Energy consumption comparison 14
Chapter 3 Methodology 18
3.1 Materials and Apparatus 18
3.1.1 Cultivation system 18
3.1.2 Instrument and apparatus 23
3.1.3 Chemicals 24
3.2 Microalgae cultivation 27
3.2.1 Microalgae 27
3.2.2 Culture media preparation 29
3.2.3 Cultivation procedure 31
3.3 Membrane filtration 31
3.3.1 Membrane 31
3.3.2 Membrane filtration system 32
3.3.3 Membrane initial resistance 33
3.3.4 Flux-stepping 34
3.3.5 Membrane cleaning method 34
Chapter 4 Results and Discussion 36
4.1 Membrane characterization 36
4.1.1 SEM 36
4.1.2 Cause of membrane fouling 38
4.2 Microalga harvesting by membrane filtration 42
4.2.1 Blank test 42
4.2.2 Resistance of membrane 43
4.2.2 S. maxima harvesting 46
4.2.3 S. obliquus harvesting 63
Chapter 5 Conclusions and Recommendations 72
5.1 Conclusions 72
5.2 Recommendations 74
Reference List 75

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