Tangential-flow module

Figure 12.5 Different membrane modules used in MD (a) a Lewis ceU, (b) flat-sheet or tangential-flow module, (c) hollow-fiber module, and (d) a thin channel module.

The factors to consider in the selection of crossflow filtration include the flow configuration, tangential linear velocity, transmembrane pressure drop (driving force), separation characteristics of the membrane (permeability and pore size), size of particulates relative to the membrane pore dimensions, low protein-binding ability, and hydrodynamic conditions within the flow module. Again, since particle-particle and particle-membrane interactions are key, broth conditioning (ionic strength, pH, etc.) may be necessary to optimize performance. 

The NF/LPRO pilot plant was supplied by Sepratech (Separation Technoloy, INC, US), and consisted of a feed tank, a pump and planar module, as detailed in Fig. 5. All studies were done using a low conversion rate (5%) and a high tangential flow rate ( 4 ms-1) in order to minimize the polarization concentration effects. The applied transmembrane pressures were in the range of 0-25 bar. The temperature was maintained at 25°C. 

The two sequentially connected modules are composed of Berghof mbular membranes, which allow a tangential flow through their interior. Each module is formed of 31 tubes of 10 mm diameter. 

Cross-flow The flow of fluid across a membrane surface, parallel to its surface or tangential flow. These modules have one irflet (feed) and two outlets (concentrate and permeate). This is in contrast to dead-end modules. 

Figure 17.11 Different flow schemes with radial and tangential inlet modules. (Volkmann...

Figure 15.3 Small-scale tangential-flow ultrafiltration module. (Courtesy Millipoie Corporation.)...

TABLE 15.2 Tangential-Flow Ultrafiltration Modules/Cassettes Suitable for Biopharmaceutical Processing S... 

Today most vims filtration is conducted in normal flow mode (Bohonak and Zydney, 2005). The main advantage of tangential-flow filtration is the ability to suppress cake formation and the consequent decrease in permeate flux. This results in much larger feed volumes being filtered (capacity) before the module needs to be cleaned. 

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