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Filters and Filtration
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Prefilters are most commonly depth filter types and are generally constructed of nonwoven or melt-blown fiber materials such as polypropylene, polyamide, cellulosic, glass fiber, metal fibers, and sintered stainless steel (12). Normally, prefilter materials are constructed into mats by the random deposition of either individual or continuous fibers whose fixation is accomplished by pressing, heating, gluing, entanglements, or other forms. The pores of such filter constructions are rather random interstices among the fibers. Such pore-size distribution can be influenced by the thickness of the individual fiber or the compactness of the matrix. Therefore, prefilter types have a large variety and can be selected for many kinds of application.
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Published in Maik W. Jornitz, Theodore H. Meltzer, Sterile Filtration, 2020
Maik W. Jornitz, Theodore H. Meltzer
A prefilter with a pore size rating of 1 μm will be tried. Two possibilities are available: a 1 μm rated membrane cartridge and a 1 μm rated glass fiber depth medium. The membrane filter has the inherent advantages of greater surety of retention and nonfibrous construction. The nominally rated depth filter has the characteristic of high dirt-holding capacity. Since the application does not proscribe the use of fibrous medium, the glass fiber is chosen for trial.
Prefiltration in Biopharmaceutical Processes
Published in Maik W. Jornitz, Filtration and Purification in the Biopharmaceutical Industry, 2019
Another application into which depth filters are incorporated into a filtration step is prior to crystallization of the API. In this phase of the process, the depth filter is used as a prefilter to a membrane filter. Its primary purpose is to protect the membrane filter from fouling during the processing of the entire batch. This is usually performed using a lenticular cartridge configuration upstream of the membrane (Figure 1.16).
An effective, simple and low-cost pretreatment for culture clarification in tetanus toxoid production
Published in Preparative Biochemistry and Biotechnology, 2018
Lucía Avila, Osvaldo Cascone, Mirtha Biscoglio, Matías Fingermann
The linearizing plots calculated from data obtained during a representative filter sizing test are shown in Fig. 3. In this experiment, mean initial filtrate flux under constant pressure (0.3 Bar) through the 13.5 cm2 filtering device was 2.19 ml/min/cm2. Filtrate flux dropped during the 12.5 min of the test, achieving a final value of 0.66 ml/min/cm2. No significant changes were observed in TT content after clarification (Student t test, α < 0.05). As Fig. 3 shows membrane fouling dynamics in this experimental asset are better described in Standard blocking model. According to this model, pore volume constriction occurs after particle deposition on the walls, it can be concluded that particles in the supernatant are smaller in size than membrane pores. After linear-fitting of the experimental data to this model, scaling parameters for filtration were calculated. The filtrate volume at the moment when flow reaches 20% of its initial value (V80) was 42.92 ml/cm2. Then, for clarification at typical low-scale industrial TT production level (100 l culture harvest) 800 mg chitosan and 0.49 m2 area of filtering membrane would be required. Current commercially available 10-inch cartridges of the evaluated material have a surface of 0.6 m2. According to different authors who assayed 0.2 µm pore size microfiltration TFF membranes, processing 100 l fermentation broth would demand 0.45–0.7 m2 area of filtering cassettes.7,9–11 Clarification by depth-filtration would require two 0.11 m2 area depth-filter capsules of diatomite-cellulose combined media, together with a 0.6 m2 area of a 0.22 µm pore regenerated cellulose filtering cartridge.8