Collaborative Research: Shape Effects on Microorganism Removal by Microfiltration and Ultrafiltration Membranes

该奖项由美国国家科学基金会化学和生物分离项目颁发，支持从实验和理论两方面研究微生物大小和形状对膜排斥的影响。微滤和超滤膜越来越多地应用于食品加工、生物技术、制药工业和环境分离。这些先进的过滤技术在市政供水和废水处理中得到了普及，特别是在1993年密尔瓦基市隐孢子虫爆发之后。这是美国历史上最大的一次水传播疾病爆发，导致40多万人患病，50人死亡。尽管膜对这种寄生虫提供了几乎完全的屏障（传统的过滤技术不能），病毒和细菌可以通过它们，可能对人类健康构成威胁。MF和UF系统也用于药品、果汁、牛奶和其他产品的纯化和生产，其中无菌性是一个重要的考虑因素。矛盾的是，尽管微滤和超滤系统通常不能完全去除病毒和细菌，但控制微生物在它们之间运输的因素尚未得到很好的理解，特别是对于非球形生物。这就需要保守的膜设计和实现。此外，尽管棒状细菌和非球形病毒在供水系统中经常遇到，但以前对胶体通过膜的实验和理论研究主要集中在球形颗粒上。在这项工作中，将进行全面的理论和实验研究，以描述有助于微滤和超滤膜去除病毒和细菌的阻碍传输现象。重点将是系统和严格地确定微生物长径比的影响以及轴向和旋转佩莱特数对运输的重要性。将使用具有理想孔隙几何形状的轨迹蚀刻膜以及具有复杂多孔结构的商业相关相转化膜来检查许多杆状病毒和细菌在一系列孔径和跨膜压力下的过滤。一个严格的模型，结合布朗扩散和粒子排列与流动将被开发。这项工作更广泛的影响在于(i)培训克拉克森和休斯顿的一名高中科学/数学教师，（ii）与密理博公司的工业科学家进行交流，（iii）培训学生运用运输现象、生物技术和环境工程的原理进行跨学科和合作研究，（iv）支持本科生通过课程项目和暑期研究进行研究。（五）在同行评审的出版物和会议报告中传播研究成果。我们希望吸引来自休斯顿和波茨坦的各种K-12机构的参与者，特别是那些历史上少数民族学生团体的参与者。

This NSF award by the Chemical and Biological Separations program supports work to examine from both experimental and theoretical viewpoints the effect of microorganism size and shape on membrane rejection. Microfiltration and ultrafiltration membranes are increasingly employed in the food processing, biotechnology, pharmaceutical industries and for environmental separations. These advanced filtration techniques have gained popularity in municipal water and wastewater treatment particularly following the 1993 Cryptosporidium outbreak in Milwaukee, WI. This is the single largest waterborne disease outbreak in the history of the United States resulting in over 400,000 becoming ill and 50 deaths. Even though membranes present a virtually complete barrier to this parasite (conventional filtration techniques do not), viruses and bacteria can pass through them potentially posing human health risks. MF and UF systems are also employed during purification and manufacturing of drugs, juices, milk and other products where sterility is an important consideration.Paradoxically, even though microfiltration and ultrafiltration systems do not generally achieve complete virus and bacteria removal, the factors governing microorganism transport across them are not well understood, particularly for non-spherical organisms. This necessitates conservative membrane design and implementation. Further, previous experimental and theoretical studies of colloid passage across membranes have focused predominantly on spherical particles even though rod-shaped bacteria and non-spherical viruses are frequently encountered in water supplies.In this work comprehensive theoretical and experimental investigations will be performed to delineate hindered transport phenomena contributing to the removal of viruses and bacteria by microfiltration and ultrafiltration membranes. The focus will be on systematically and rigorously determining the influence of microorganism aspect ratio and the importance of axial and rotational Peclet numbers on transport. The filtration of numerous rod-shaped viruses and bacteria across a range of pore sizes and transmembrane pressures will be examined using both track-etched membranes with an idealized pore geometry as well as commercially relevant phase inversion membranes which have a complex porous structure. A rigorous model that incorporates Brownian diffusion and particle alignment with the flow will be developed.Broader impacts of the work lie in (i) training a high school science/math teacher in Clarkson and another at Houston, (ii) communications with industrial scientists at Millipore Corporation, (iii) training students to perform interdisciplinary and collaborative research applying principles from transport phenomena, biotechnology, and environmental engineering, (iv) supporting undergraduates to conduct research through course projects and summer research, and (v) disseminating research results in peer-reviewed publications and conference presentations. We hope to draw participants from a variety of K-12 institutions across Houston and Potsdam, particularly those with historically minority student bodies in several of these activities.