Membrane filters -- essentially, thin sheets of porous medium that act to remove certain particles suspended in a fluid feed that passes through the medium -- are in widespread industrial use, and represent a multi-billion dollar industry in the US alone. Major multinational companies, such as W.L. Gore & Associates and Pall Corporation, manufacture a huge range of membrane-based filtration products and have a keen interest in improving and optimizing their filters. Membrane filtration is used in applications as diverse as water purification; treatment of radioactive sludge; various purification processes in the biotech industry; the cleaning of air or other gases; and beer clarification. While the underlying applications may vary dramatically (gas versus liquid filtration; small versus large particle removal; slow versus fast throughput; rigid versus deformable particles), the broad engineering challenge is the same: to achieve finely-controlled separation at low power consumption. But membrane characteristics (and hence the filter's behavior and performance) are far from constant over the filter lifetime: the particles removed from the feed are deposited within and on the filter, fouling it and degrading its performance. The processes by which this fouling occurs are complex and depend strongly on several factors, including the internal structure of the membrane, the flow dynamics of the feed solution, and the type of particles in the feed (their shape, size, and chemistry affect how they are removed by the membrane). In this project new mathematical models are developed to simulate membrane filtration and fouling, allowing membrane design parameters to be tuned for optimal performance. Particular attention is paid to the role played by the details of the internal membrane morphology, so that detailed design guidelines can be formulated. Collaboration with an industrial partner (Dr. Anil Kumar of Pall Corporation) maximizes the chances that our theoretical results translate into industrial practice. Graduate students are involved in the work of the project.
This project studies flow and fouling in membrane filters, which are of significant interest for industrial applications. Working with a PhD student, the PI and her collaborator formulate new predictive mathematical models that describe two situations of practical importance: (i) Flow and fouling within pleated filter cartridges, and (ii) Membrane fouling models for internally heterogeneous membranes. In each scenario the team builds models that account for an arbitrary particle size distribution within the feed solution, and also for a distribution of membrane pore sizes. First-principles theoretical studies of these scenarios are of interest to others carrying out fundamental theoretical and experimental research on such systems, as well as to those seeking to extend the scope of current applications and improve manufacturing processes. An industrial colleague, Dr. Anil Kumar of Pall Corporation, collaborates on the project. An experimentalist, he shares his existing data with the team, generates new data as needed to test the models, and acts as industrial advisor. This interaction ensures that the project remains focused and that questions relevant to applications are identified and addressed. The experimental data help to determine appropriate ranges for unknown parameters in the models, and to test uncertain modeling assumptions.
