| 摘要: | 生物反應器的產物除了微生物的細胞外，尚包含溶解的微生物產品(soluble microbial products，SMP)及細胞外高分子物質(extracellular polymeric substances，EPS)， 例如碳水化合物、蛋白質、多醣類或腐殖酸等，故薄膜過濾的機制相當複雜。然而，唯 有對此系統進行充分地解析，方能提高生化產品之分離效率，並基於所獲得的基礎成 果，研發高效能的薄膜過濾裝置。 在為期三年的研究計劃中，擬針對生物反應器含多成份之產物進行微過濾與超過濾 之微觀解析，了解薄膜之結垢機制，建立適用之操作準則，並研發適用於生化產品之高 效能薄膜過濾系統。在第一年的研究中，擬探討生化產物之微過濾與超過濾機制，針對 生物微胞、膠體粒子、溶解的微生物產物與細胞外高分子物質共存之懸浮液，探討過濾 中之薄膜結垢現象，其中包含解析蛋白質與高分子物質在薄膜內的吸附與阻塞、微粒子 在薄膜上之附著等。尤其著重在不同物質間的交互作用與其在結垢現象上所分別扮演的 角色，並探討如何善用操作條件控制結垢的型態與目標產物的透過率或選擇率，以提升 分離效率。 在第二年的研究中，主要擬探討薄膜特性(種類、材質、孔徑、親疏水性、薄膜表 面電荷等)對蛋白質之結垢機制與分離效率的影響。蛋白質會因為溶液環境或流動時受 到剪切力而形成聚集體，尤其更會因細胞外物質或溶解於溶液中的微生物產出物的存在 而有不同的形態，故其薄膜結垢機制亦變得相當複雜。本研究擬採用數值模擬、理論模 式推導與實驗進行三者並行的研究方法，針對不同種類與性質之薄膜，分析蛋白質進入 薄膜的孔洞中、附著在薄膜上或填入凝聚蛋白質堆疊所形成的孔隙中、以及結垢層的壓 縮作用等。並同時探討操作變數對蛋白質混合物之篩分效率之影響。 在第三年的研究中，擬將前兩年的研究成果，延伸應用至生化產品之薄膜分離模組 之設計上。對於含菌體細胞、蛋白質、多醣體、碳水化合物、塩類等多成分之生化混合 物，探討不同幾何型態的模組安排與薄膜設計對分離效率之影響。尤其著重在不同模組 之整合，試圖以最經濟、最有效率的複合式安排達成目標產物的分離與純化。並期能了 解在實際的應用系統中，如何進行模組的最佳化設計；以及針對生物反應器之產物，如 何以操作條件來控制薄膜結垢、過濾速度與分離效率。
The products of bioreactors consist of not only microbial cells but also soluble microbial products (SMP) and extracellular polymeric substances (EPS) which are composed of proteins, carbohydrates, polysaccharides, nucleic acid, lipids, and humic substances. Therefore, the mechanism of membrane filtration is very complicated due to the complex suspension. However, to understand the biofouling in membrane filtration is the essential step to enhance the separation efficiency and to develop high performance membrane filtration modules for bio-products. This proposal is a three-year-project and presents a task to attack the fundamental and technology involved in membrane filtration of bioreactor’s products. In the first year, the biofouling mechanism in membrane filtration will be analyzed on a microscopic viewpoint. The effects of operating conditions and suspension properties (such as pH and electrolyte concentration) on the filtration flux, membrane fouling, protein transmission, protein selectivity, etc., will be also studied by computational fluid dynamic (CFD) method, theoretical analysis and experimental analysis. In the second year, the efforts will be put on the effects of membrane characteristics (materials, morphology, pore size distribution, hydrophobicity, surface potential, etc.) on the separation efficiency of proteins. The effects of suspension properties on the protein coagulation and on the performances of membrane bio-filtration will be also studied. The compressibility of the filter cake formed by microbial cells will be also analyzed based on the filtration theory, colloid science and dynamic consolidation theory. In the third year, the results obtained in previous years will be extended to design and develop high performance membrane filtration modules. For the bio-product suspensions, the performances of bio-separation in different geometrical membranes and modules will be studied thoroughly. The optimal hybrid membranes and hybrid modules will be also design through CFD methods. |
