由於工業與民生廢水未經妥善的處理，塑膠微粒逐漸累積在全世界的水域環境中，對於人體健康與環境會造成相當大的破壞。傳統從水體中去除塑膠微粒的方法包括物理、化學和生物途徑。物理過濾方法雖可達到較高的去除效率，但耗能大且成本高。利用化學方法絮凝塑膠微粒也很常見，但它們會造成二次污染的潛在威脅。生物途徑分為兩大類：生物降解及微藻吸附。生物降解可能會增加環境中非自然生物的存在，進而對海洋生態系統多樣性產生負面影響。而微藻表面的細胞外聚合物（Extracellular polymeric substances，EPS）能與塑膠微粒形成可自動沉降的異質團聚物，不需要消耗能量進行離心或過濾來收集。因此，本研究希望發展利用微藻移除塑膠微粒的技術，並建立一套量化移除效率的標準化流程。本研究項目包括（1）量化微藻有無長時間曝露在微粒中分別對多種塑膠微粒的移除效率，（2）利用SEM觀察微藻表面EPS的形貌變化，（3）測量微藻可溶性EPS的產量與移除效率是否有正向關係，（4）測量微藻及微粒表面電位對吸附效率的影響，（5）量測不同板材回收塑膠微粒的效率。
實驗結果顯示本研究所使用的柵藻能有效移除多種塑膠微粒，且本論文為第一個能對懸浮塑膠微粒進行計數，實現移除效率的準確量化的研究。使用的塑膠微粒材質包括聚苯乙烯（Polystyrene，PS）、聚甲基丙烯酸甲酯（Poly(methyl methacrylate)，PMMA）和聚乳酸（polylactide，PLA）。若將微藻長時間曝露在有微粒的環境下（預曝露），所有塑膠微粒的總移除效率均可高於85%，長時間的預曝露可將PS和PLA的總去除效率提高1.18到2.35倍。即使沒有預曝露，柵藻也能高效移除PMMA微粒（>90%）。SEM圖像顯示柵藻受到塑膠微粒刺激後，細胞表面顯著增加的EPS能促使微藻與微粒形成異質團聚物，而可溶性EPS產量與吸附在離心管管壁上的塑膠微粒個數成正比。此外，微粒的zeta電位結果顯示，越大的表面負電荷會使微粒與管壁間的排斥力增加，降低微粒吸附於管壁的效率，因此導致不同材質的微粒吸附量有所差異。最後，本研究發現在有可溶性EPS的情況下，PS微粒吸附固體板材的效率能提高1.27到2倍，而PMMA微粒無論有無可溶性EPS均可達到近100%的移除效率。此結果證實除了利用微藻與微粒形成異質團聚，可溶性EPS促進的固體吸附也能達到有效移除水中塑膠微粒的目的。

Due to the improper treatment of industrial and domestic wastewater, micro-plastics have gradually accumulated in the waterbody of the world, causing considerable damage to human health and the environment. Traditional methods for removing micro-plastics from waterbody include physical, chemical and biological approaches. Although the physical filtration method can achieve high removal efficiency, it consumes a lot of energy and is costly. It is also common to flocculate micro-plastics through chemical methods, but they pose a potential threat of secondary pollution. Biological pathways are divided into two categories: biodegradation and bio-flocculation/bio-adsorption. Biodegradation may increase the presence of non-natural organisms in the environment, which will have negative impacts on the diversity of marine ecosystems. On the other hand, the extracellular polymeric substances (EPS) on the surface of microalgae can form self-settling hetero-aggregations with micro-plastics, which does not require energy-consuming centrifugation or filtration to collect. Therefore, this study aims to establish the technology for removing micro-plastics using microalgae and a standardized process to quantify the removal efficiency. The tasks includes (1) quantifying the removal efficiency of a variety of micro-plastics, (2) using SEM to observe the morphological changes of EPS on the surface of microalgae, (3) measuring the soluble EPS and examining if there is a proportional relationship between soluble EPS yield and removal efficiency, (4) investigating the effect of microalgae and micro-plastics surface potential on the removal efficiency, and (5) investigating the facilitated removal efficiency of micro-plastics by soluble EPS coated solid surface.
The results show that Scenedesmus abundans effectively remove a variety of micro-plastics, and by counting the suspended micro-plastics, accurate quantification of the removal efficiency is achieved. The micro-plastics used include polystyrene (PS), poly(methyl methacrylate) (PMMA) and polylactic acid (PLA). When microalgae are exposed to micro-plastics for a long time (pre-exposure), the total removal efficiency of all micro-plastics can be higher than 85%. Prolonged pre-exposure increase the total removal efficiency of PS and PLA by 1.18 to 2.35 times. Scenedesmus abundans efficiently removes PMMA particles (>90%) even without pre-exposure to micro-plastics. SEM images show that the significant increase of EPS on the surface of S. abundans stimulated by micro-plastics promotes the formation of hetero-aggregations. The yield of soluble EPS is proportional to the number of particles adsorbed on the centrifuge tube wall. In addition, by measuring the zeta potential of micro-plastics, it was observed that a larger negative surface charge increase the repulsive force between the particles and the tube wall, reducing the efficiency of micro-plastics adsorption, and leading to differences in the amount of solid adsorption between different micro-plastics. Finally, the adsorption efficiency of PS particles on solid surfaces is increased by 1.27 to 2 times in the presence of soluble EPS, while the removal efficiency of PMMA particles reach nearly 100% disregarding the presence of soluble EPS. These results confirm that in addition to using microalgae to form hetero-aggregation, solid adsorption can also achieve the purpose of effective removal of micro-plastics in waterbody.

摘要-------------------------------------------i
Abstract---------------------------------------iii
致謝--------------------------------------------v
目錄--------------------------------------------vi
表目錄------------------------------------------ix
圖目錄------------------------------------------x
第1章 緒論-------------------------------------1
1.1 介紹---------------------------------------1
1.2 研究目的與規劃------------------------------2
第2章 文獻回顧----------------------------------3
2.1 塑膠微粒對環境及人體的影響-------------------3
2.2 從水體中移除塑膠微粒的方法-------------------5
2.3 使用微藻移除各種塑膠微粒---------------------8
2.3.1 微藻移除塑膠微粒的機制---------------------8
2.3.2 使用不同微藻移除各種塑膠微粒的適用性判斷----10
2.3.3 塑膠微粒對微藻生長的影響-------------------15
第3章 實驗方法與材料-----------------------------19
3.1 微藻培養------------------------------------19
3.1.1 固態培養----------------------------------19
3.1.2 液態培養----------------------------------21
3.1.3 微藻濃度檢測------------------------------22
3.2 塑膠微粒準備--------------------------------24
3.3 測量塑膠微粒移除效率-------------------------25
3.3.1 流式細胞儀--------------------------------25
3.3.2 使用未曝露微藻之微粒總移除效率--------------26
3.3.3 使用預曝露微藻之微粒總移除效率--------------27
3.3.4 微粒吸附管壁效率以及藉異質團聚移除效率-------28
3.4 測量二氧化矽微粒移除效率----------------------28
3.4.1 流式細胞儀---------------------------------29
3.4.2 使用未曝露微藻之微粒總移除效率---------------29
3.4.3 使用預曝露微藻之微粒總移除效率---------------30
3.4.4 微粒吸附管壁效率以及藉異質團聚移除效率--------31
3.5 SEM照片拍攝----------------------------------32
3.6 可溶性EPS產量測量-----------------------------32
3.6.1 萃取法-------------------------------------32
3.7 Zeta電位測量---------------------------------33
3.7.1 未曝露微藻及微粒之zeta電位測量---------------34
3.7.2 預曝露微藻及微粒之zeta電位測量---------------34
3.7.3 微藻及微粒隨pH值變化的zeta電位測量-----------35
3.8 測量塑膠微粒吸附板材效率-----------------------35
第4章 結果與討論----------------------------------37
4.1 微藻與塑膠微粒形成異質團聚---------------------37
4.2 有無預曝露之微藻移除塑膠微粒的總效率------------39
4.3 塑膠微粒吸附管壁效率以及藉異質團聚移除效率-------41
4.4 有無預曝露之微藻移除二氧化矽顆粒的總效率---------43
4.5 二氧化矽顆粒吸附管壁效率以及藉異質團聚移除效率----44
4.6 SEM拍攝下微藻表面EPS形貌變化--------------------45
4.7 有無預曝露之微藻可溶性EPS產量-------------------47
4.8 有無預曝露微藻及微粒之zeta電位變化---------------48
4.9 pH值對微藻及微粒表面zeta電位的影響--------------51
4.10 塑膠微粒吸附板材效率--------------------------53
第5章 結論與未來規劃-------------------------------59
5.1 結論------------------------------------------59
5.2 未來展望--------------------------------------59
第6章 參考文獻-------------------------------------61

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