Filtration of liquids

Various types of filter media and the materials oi which they are constructed are surveyed extensively by Purchas Industrial Filtration of Liquids, CRC Press, Cleveland, 1967, chap. 3), and characterizing measurements (e.g., pore size, permeabihty) are reviewed in detail by Rushton and Griffiths (in Orr, op. cit., chap. 3). Briefer summaries of classification of media and of practical criteria for the selec tion of a filter medium are presented by Shoemaker (op. cit., p. 26) and Purchas [Filtr Sep., 17, 253, 372 (1980)]. 

Assume laminar flow of filtrate of liquid through the filter cake. Rate of filtration is usually measured as the rate at which liquid filtrate is collected. The filtration rate depends on the area of the filter cloth, the viscosity of the liquid, the pressure drop across the filter and filter cake resistance. At any instant during filtration, the rate of filtration is given by the equation ... 

Filtration of Liquids Depending on the specific electrochemical reactor type, the filtration rate of a liqnid electrolyte throngfi tfie separator should be either high (to secure a convective snpply of snbstances) or very low (to prevent mixing of the anolyte and catholyte). The filtration rate that is attained under the effect of an external force Ap depends on porosity. For a separator model with cylindrical pores, the volnme filtration rate can be calcnlated by Poiseuille s law ... 

Matteson, M. S. and Orr, C. Filtration Principles and Practice, 2nd edn. (Marcel Dekker, New York, 1987). Purchas, D. B. Industrial Filtration of Liquids, 2nd edn. (Leonard Hill, London, 1971). 

PURCHAS, D. B. Industrial Filtration of Liquids, 2nd edn. (Leonard Hill, London, 1971). 

A few other players in the nuclear membranes activity also developed inorganic membranes for the filtration of liquids. This was the case with Norton-USA who with the know-how of Euroceral developed MF membranes made of an 0-AI2O3 tubular support with an a-Al203 layer. The inner tube diameter was 3 mm and the outer diameter 5 mm. In 1988-1989, Norton also produced the multichannel membrane elements. These membranes produced by Norton are now sold by Millipore under the trademark Ceraflo . 

Technical Report No, 26, Sterilization Filtration of Liquids, Parenterals Drug Association, Inc. 1998. 

Adsorption of t-PA to process equipment surfaces consisting of either stainless steel or glass was minimized by adding the detergent polyoxyethylene sorbitan monooleate (Tween 80) to the serum-free culture conditioned media at 0.01% (vol/vol). The equipment was also rinsed, before use, with phosphate buffered saline (PBS) containing 0.01% Tween 80. Hydrophilic, plastic equipment was used whenever possible. All buffers were sterile filtered. Sterile filtration of liquids and gases is usually carried out using 0.2 or 0.45 Jim filters. 

Sterilizing Filtration of Liquids, technical report no. 26. Parenteral Drug Association (1998). 

Figure 2.34 Particle capture mechanism in filtration of liquid solutions by depth microfilters. Four capture mechanisms are shown simple sieving electrostatic adsorption inertial impaction and Brownian diffusion...

Membrane polymeric materials for separation applications are made of polyamide, polypropylene, polyvinylidene fluoride, polysulfone, polyethersulfone, cellulose acetate, cellulose diacetate, polystyrene resins cross-linked with divinylbenzene, and others (see Section 2.9) [59-61], The use of polyamide membrane filters is suggested for particle-removing filtration of water, aqueous solutions and solvents, as well as for the sterile filtration of liquids. The polysulfone and polyethersulfone membranes are widely applied in the biotechnological and pharmaceutical industries for the purification of enzymes and peptides. Cellulose acetate membrane filters are hydrophilic, and consequently, are suitable as a filtering membrane for aqueous and alcoholic media. 

TR 11 Sterilization of Parenterals by Gamma Irradiation, 1988 TR 13 Fundamentals of an Environmental Monitoring Program, 2001 TR 22 Process Simulation Testing for Aseptically Filled Products, 1996 TR 26 Sterilizing Filtration of Liquids, 1998... 

Fig. 7 Manual bubble point test set-up. (Reprinted from Technical Report No. 26, Sterilizing Filtration of Liquids 1998 by PDA.)...

Candle FilterS Tubular filter elements contained in a matching vessel are known as candle filters. The actual filter vessel may contain one or more filter candles, and may be used as pressure or suction filters for the filtration of liquids and gases. A particular advantage offered is that candles may readily be changed to different types, to suit particular requirements or applications. A typical candle filter is shown in Fig. 11. Materials of candles are selected to fit a particular process. 

Purchas, D.B. 1967. Industrial filtration of liquids. Cleveland, OH CRC Press. 

MF has also made its debut in the Japanese soft drink industry for the filtration of liquid sugar. Figure 2.55 is a flow schematic for two parallel plate and frame backwash systems to remove yeast from the liquid sugar. The parallel lines permit backwashing without interruption of the process flow stream. 

Sterile filtration of liquids and gases is now virtually always done using mem brane filters. The first U.S. patent for membrane filters was filed in 1922 and pertained to cellulose acetate membranes. A wide range of membrane filter media are now commercially available to suit various applications cellulose esters, polyvinylidinefluoride, polytetrafluoroethylene (PTFE), and polyhexam-ethyleneadipamide (nylon 66), separately or as laminates with polyethylene, polypropylene, and polyester for more robust phy.sicai characteristics. 

The earlier method for removal of settled muck in the melter involved manual scooping of sludge. Provision of an on-line strainer was not very efficient. Hence it was replaced by filtration of liquid sulfur by pumping it through steam jacketed filters ... 

Standard blocking has been reported to be an appropriate filtration model for cartridge filtration of liquids and a form of the standard blocking equations shown in Table 2.3 has been used to correlate the filtration of viscose and cellulose acetate [Grace, 1956]. The model assumed in the derivation of the standard blocking equations is that... 

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