Ultrafiltration technologies

J. Scott, ed.. Membrane and Ultrafiltration Technology 1980, Recent Advances, Chemical Technology Review No. 147, Noyes Data Corp., Park Ridge, N.J.,... 

Gomez M, Plaza E, Garralon G et al (2007) A comparative study of tertiary wastewater treatment by physico-chemical-UV process and macrofiltration-ultrafiltration technologies. Desalination 202 369-376... 

Scott, J. Membrane and Ultrafiltration Technology Noyes Data Corp. Park Ridge, NJ, 1980. 

B.R. Breslau, A.J. Testa, B.A. Milnes and G. Medjanis, Advances in Hollow Fiber Ultrafiltration Technology, in Ultrafiltration Membranes and Applications, A.R. Cooper (ed.), Plenum Press, New York, NY, pp. 109-128 (1980). 

B.R. Breslau, P.H. Larsen, B.A. Milnes and S.L. Waugh, The Application of Ultrafiltration Technology in the Food Processing Industry, The 1988 Sixth Annual Membrane Technology/Planning Conference, Cambridge, MA (November, 1988). 

However, the short lifetime of in-line cartridge filters makes them unsuitable for microfiltration of highly contaminated feed streams. Cross-flow filtration, which overlaps significantly with ultrafiltration technology, described in Chapter 6, is used in such applications. In cross-flow filtration, long filter life is achieved by sweeping the majority of the retained particles from the membrane surface before they enter the membrane. Screen filters are preferred for this application, and an ultrafiltration membrane can be used. The design of such membranes and modules is covered under ultrafiltration (Chapter 6) and will not be repeated here. 

Hollow Fiber Ultrafiltration Technology" in Ultrafiltration Membranes and Applications, ed. by A.R. Cooper, Plenum Press, NV (1980) pp. 109-127. 

C. Ultrafiltration Technology in Cheesemaking Biochemistry of Cheese Ripening... 

Little has been published on recovery of fully-synthetic, acrylic-based compounds besides the use of ultrafiltration technology. A process was developed by BASF on a possible procedure for recovery of acrylic size (Duerrbeck, 1985) and Leitner (1994) described an ultrafiltration recovery system for polyacrylate sizes that are reapplicable with a portion of PVA. A novel membrane technology, using spiraled instead of the usual tubular membranes, has been suggested (Stolch, 2002)... 

Wet spinning of this type of hoUow fiber is a weU-developed technology, especiaUy in the preparation of dialysis membranes for use in artificial kidneys. Systems that spin more than 100 fibers simultaneously on an around-the-clock basis are in operation. Wet-spun fibers are also used widely in ultrafiltration appUcations, in which the feed solution is forced down the bore of the fiber. Nitto, Asahi, Microgon, and Romicon aU produce this type of fiber, generaUy with diameters of 1—3 mm. 

Membrane Sep r tion. The separation of components ofhquid milk products can be accompHshed with semipermeable membranes by either ultrafiltration (qv) or hyperfiltration, also called reverse osmosis (qv) (30). With ultrafiltration (UF) the membrane selectively prevents the passage of large molecules such as protein. In reverse osmosis (RO) different small, low molecular weight molecules are separated. Both procedures require that pressure be maintained and that the energy needed is a cost item. The materials from which the membranes are made are similar for both processes and include cellulose acetate, poly(vinyl chloride), poly(vinyHdene diduoride), nylon, and polyamide (see AFembrane technology). Membranes are commonly used for the concentration of whey and milk for cheesemaking (31). For example, membranes with 100 and 200 p.m are used to obtain a 4 1 reduction of skimmed milk. 

One unique appHcation area for PSF is in membrane separation uses. Asymmetric PSF membranes are used in ultrafiltration, reverse osmosis, and ambulatory hemodialysis (artificial kidney) units. Gas-separation membrane technology was developed in the 1970s based on a polysulfone coating appHed to a hoUow-fiber support. The PRISM (Monsanto) gas-separation system based on this concept has been a significant breakthrough in gas-separation... 

Ultrafiltration is a pressure-driven filtration separation occurring on a molecular scale (see Dialysis Filtration Hollow-fibermembranes Membrane TECHNOLOGY REVERSE osMOSis). Typically, a liquid including small dissolved molecules is forced through a porous membrane. Large dissolved molecules, coUoids, and suspended soHds that caimot pass through the pores are retained. 

Most ultrafiltration membranes are porous, asymmetric, polymeric stmctures produced by phase inversion, ie, the gelation or precipitation of a species from a soluble phase (see Membrane technology). 

Membrane Filtration. Membrane filtration describes a number of weU-known processes including reverse osmosis, ultrafiltration, nanofiltration, microfiltration, and electro dialysis. The basic principle behind this technology is the use of a driving force (electricity or pressure) to filter... 

Whey has been used ia some substitute dairy products but aot as a source of proteia. Whey proteias have beea used ia dairy substitutes only siace the commercialisation of ultrafiltration (qv) technology. Membranes are used that retain proteia and permit water, lactose, and some minerals to pass through as permeate. Proteia coaceatrates are available from both acid and sweet whey and ia coaceatratioas of 35—80 wt % proteia. Whey proteia isolates are commercially available having proteia >90 wt%. The cost of these isolates is too high, however, to make them economical for substitute dairy foods. 

Fermentation Processes. The efficient production of penicillin, yeasts, and single-ceUed protein by fermentation requires defoamers to control gas evolution during the reaction. Animal fats such as lard [61789-99-9] were formerly used as a combined defoamer and nutrient, but now more effective proprietary products are usually employed. Defoamer appHcation technology has also improved. For example, in modem yeast production faciHties, the defoamers are introduced by means of automatic electrode-activated devices. One concern in the use of defoamers in fermentation processes is the potential fouHng of membranes during downstream ultrafiltration (qv). SiHcone antifoams (43,44) seem less troubled by this problem than other materials. 

Reverse Osmosis and Ultrafiltration. Reverse osmosis (qv) (or hyperfiltration) and ultrafilttation (qv) ate pressure driven membrane processes that have become well estabUshed ia pollution control (89—94). There is no sharp distinction between the two both processes remove solutes from solution. Whereas ultrafiltration usually implies the separation of macromolecules from relatively low molecular-weight solvent, reverse osmosis normally refers to the separation of the solute and solvent molecules within the same order of magnitude in molecular weight (95) (see also Membrane technology). 

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