Tangential flow filtration downstream processing

Clarification, or harvest, is typically the first step in downstream processing. During clarification, the cells, cell debris, and other particulates are removed from the cell culture broth, which contains the product. Clarification can be accomplished by depth filtration or by centrifugation followed by some form of filtration. Tangential flow filtration (ITT), sometimes also referred to as cross-flow filtration (CFF) is also used for clarification. Tangential flow filters are designed either in a flat sheet mode or hollow fiber mode. 

Dizon-Maspat, J., Bourret, J., D Agostini, A., and Li, F. 2012. Single pass tangential flow filtration to debottleneck downstream processing for therapeutic antibody production. Biotechnol. Bioeng. 109, 962-970. 

Figure 11.1.2. Block diagram containing additional steps in the production process for a typical intracellular product prior to downstream processing (TFF = tangential-flow filtration).

In this section, we will show the process of the construction of a mathematical model, step by step, in accordance with the procedure shown in Fig. 3.4. The case studied has already been introduced in Figs. 1.1 and 1.2 of Chapter 1. These figures are concerned with a device for filtration with membranes, where the gradient is given by the transmembrane pressure between the tangential flow of the suspension and the downstream flow. The interest here is to obtain data about the critical situations that impose stopping of the filtration. At the same time, it is important to, a priori, know the unit behaviour when some of the components of the unit, such as, for example, the type of pump or the membrane surface, are changed. 

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