Tangential filtration

Tangential filtration is distinguished from conventional filtration, also known as dead-end filtration, by the fact that the main flow is tangential to the membrane surface (Figure 11.11). In dead-end filtration a fast drop in the permeate flux is observed due to cake formation over the filter... 

Schematic representation of dead-end filtration (A) and tangential filtration (B).

In tangential filtration, membranes are used as filter media. Membranes are defined as barriers of reduced thickness, across which physical and/or chemical gradients are established to facilitate the preferential migration of one or more components from a given mixture, promoting their separation (Klein, 1991). They are usually made of polymers or inorganic materials, such as ceramic or sintered steel. In the biopharmaceutical industry, membranes find various applications, such as production of water for injection (WFI), sterilization of culture media, buffer solutions and gases, separation of cells and cell debris, and purification and concentration of proteins. 

Tangential filtration of animal cell suspensions presents several advantages, such as easy scale-up, simple operation, and a permeate totally free... 

Bornaz, S., Fanni, J., Parmentier, M. 1995b. Filtration in hydrophobic media. 2. Triglyceride partition phenomenon as observed by tangential filtration of butter oil. J. Am. Oil. Chem. Soc. 72, 1143-1148. 

Figure 1.1 The abstract (a) and concrete (b) drawing of a tangential filtration unit.

The exit variables that present an indirect relation with the particularities of the process evolution, denoted here by Cj,l = 1,Q, are recognized as intermediary variables or as exit control variables. The exit process variables that depend strongly on the values of the independent process variables are recognized as dependent process variables or as process responses. These are denoted by y ,i = 1, P. When we have random inputs in a process, each y exit presents a distribution around a characteristic mean value, which is primordially determined by the state of all independent process variables Xj, j = 1, N. Figure 1.1 (b), shows an abstract scheme of a tangential filtration unit as well as an actual or concrete picture. 

Due to their high stiffness and brittleness, it is not possible to extend to ceramic membranes geometries applicable with organic membranes like spirals, which give rise to high surface volume ratios. The ceramic membranes used for tangential filtration are nsually multichannel tubes or, in some applications, honeycomb monoliths. A very attractive type of membrane is the ceramic hollow fiber with an external diameter of less than 1 mm and ceramic walls with a thickness of a... 

Two Minimate devices connected in parallel are used to regain a concentration of liposomes of 20 mM. Tangential filtration is continued immediately with this device with a flow rate of 100 mL/min until the volume in the reservoir is about 15 mL. 

Extrusion can be defined as paste flow and extrudate formation from ceramic paste [1]. A membrane support must provide a high mechanical resistance and permeability. Tubular configurations correspond to this criterion and are adapted to the tangential filtration. 

The idea to limit polarization and fouling during tangential filtration of biological fluid by fluidizing small inert particles inside a tubular ceramic membrane had been presented at the end of the 1980s [25]. More recently, based on advances in the development of more stable membranes with increased permeance, the possibilities for integrating membranes into gas catalytic reactors to achieve a major increase in... 

The cells were concentrated by passing through a Millipore cassette using tangential filtration flow system which utilized 15 square feet of 0.45 y membranes. The circulation rate was maintained at 6 liters per minute with an input pressure of 8 psi and an output pressure of 6 psi. 

The tangential filtration flow system concentrated the cell suspension greater than 20 fold using 15 square feet of the 0.45 p membrane. The filtrate flow rate was 1 liter per minute and the circulation rate was 6 1/min. Initial concentration of the cell... 

Bennasar,M.andTarododelaFuente,B.,ModeloftheFoulingMechanism and of the Working of a Mineral Membrane in Tangential Filtration, Sciences Des Ailments, 7 647-655 (1987)... 

The spectrophotometric determination of Fe(II), Fe(III), nitrate and nitrite ions in natural and wastewaters in a sequential injection system [298] is an interesting example of this innovation. In-line tangential filtration was performed prior to the sample insertion port as part of the sampling step. Particulate material was not aspirated towards the holding coil and several samples could be analysed without the need for frequent cleaning of the filtration unit. Analytical figures of merit were similar to those for the corresponding flow-based analytical procedure with manual sample filtration prior to flow analysis. 

Recently developed cell retention devices such as alternating tangential filtration (ATF) or an acoustic device (Biosep) can be fitted to existing bioreactors at contract organizations. 

Of course, filtering wine through a diatomaceous earth precoat follows this law. Although the principle is different, the same law also governs tangential filtration (Mietton-Peuchot, 1984), where the particles, concentrated along the membrane, behave like a cake. 

Fig. 11.14. Schematic diagram of tangential filtration 1, inlet of liquid to be clarified 2, high-pressure pump 3, module containing the filtration membrane 4, clarified liquid outlet 5, cooling system 6, adjustable outlet for the concentrate containing the impurities 7, circulating pump...

The first attempts to apply tangential filtration in winemaking relied on nltrafiltration membranes that were likely to trap not only particles in suspension, but also colloidal macromolecules. In particular, unstable proteins were intended to be eliminated from white wines. However, it very quickly became apparent that the analytical and organoleptic characteristics of white wines were subject to profound modifications under these conditions. 

Control Precoat and kieselguhr filtration Tangential filtration ... 

The first trials of tangential filtration showed that it had a major impact on wine composition. 

Gnerrero-German et al. [288] developed a new bioprocess for the purification of plasmid DNA from E. coli ferments nsing a hollow-fiber tangential filtration (as a pretreatment of the feed solution) and tandem anion-exchange membrane chromatography as a second step. 

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