Impact of process loading on TFF microfiltration

Tangential flow filtration (TFF) microfiltration is one of the choices for clarification of mammalian cell or microbial cell culture in the biopharmaceutical industry. Unlike ultrafiltration, TFF microfiltration is limited by a maximum throughput or capacity obtainable under a given set of operating condi­tions.

We recently published an article "Impact of Process Loading on Optimization and Scale-Up of TFF Microfiltration," in which we highlighted the dependency of load­ing limits on operating permeate flux in flux con­trolled TFF microfiltration processes. Microfiltration processes operating at low permeate flux can reach higher concentrations com­pared to high permeate flux. The article shows that the final solid concentration dominates the maximum design capacity of microfiltration filter sizing at the selected constant per­meate flux. Therefore, measurement of the solid content (% PCV) of the feed solution helps to estimate the final achievable solid (or volumetric loading) limit of a certain microfiltration step.

The loading limits (% PCV) of microfiltration processes are expected to change with feed (particle size and type) and filter interaction. In this study, both the lysate and whole cell yeast showed similar combined cake-complete plugging mechanisms when a V-screen 0.1 µm microfiltration filter was used, and the loading limit (% PCV) for lysate (smaller size particles) and whole cell yeast (larger size particles) was determined to be 30% and 55% respectively.

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