(313d) Practical and Economic Implications of Filter Fouling Models and Sizing Methodologies

Practical and economic implications of filter fouling models and sizing methodologies

Ranjeet Patil (ranjeet.patil@emdmillipore.com) ,Michael Felo (Michael.felo@emdmillipore.com)

Abstract:

 In pharmaceutical industry, membrane filters are typically sized by running filtration tests with small scale devices/filter discs at constant pressure. The flux decay data from these tests is used to estimate the required filtration area for manufacturing scale processes.  It is a common practice to use a filter fouling model to predict filter performance beyond small scale test throughput.  

Most popular filter fouling model used in biopharmaceutical industry is gradual pore plugging or standard blocking model. Over past decades, other filter fouling models and filter sizing methods have been proposed. In some cases, predictions derived from these models and methods have been shown to be more accurate than gradual pore plugging model.

Although certain models have been shown to be more accurate than others, using a different model for filter sizing may not necessarily translate to better process control and economic gains.  Actual pharmaceutical processes have a variety of feed steams with wide range of particle size distribution and employ different types of membranes. Marginal improvement in accuracy of prediction achieved due to a different fouling model may not translate to manufacturing scale due to aforementioned variables.

The objective of the proposed study is to understand the impact of using different filter fouling models and sizing techniques on filter sizing for manufacturing scale. In this study,

• ·         Accuracy of prediction of different fouling models and sizing techniques is determined at lab scale.
• ·         The small scale results are compared to a process scale device performance. .
• ·         Different feeds are used for filter sizing studies at lab scale to test the impact of feed variability on the accuracy of prediction.  
• ·         Different filter meterials (e.g. PVDF, PES) and filter constructions (e.g. single layer, multi layer) are evaluated at lab scale to understand the effect on the accuracy of predictions of different filter fouling models and sizing methods.
• ·         Cost analysis is conducted for a generic Mab process (15000L scale) to evaluate the potential cost savings due to different sizing models/methods.
• ·         Based on the results, an optimum filter sizing strategy is proposed.