Reverse osmosis membrane technology

Z. Amjad, ed.. Reverse Osmosis Membrane Technology, Water Chemistry and Industrial Applications, Van Nostrand Reiohold, New York, 1993. 

Williams, Michael E., "A Brief Review of Reverse Osmosis Membrane Technology," white paper, EET Corporation and Williams Engineering Services Company, Inc., www.eetcorp.com/heepm/RO ReviewE. pdf, 2003. 

In contrast to the caseins, whey proteins retain their solubility in the pH 4.5-5.0 range, provided they have not been denatured. It is therefore relatively difficult to recover and purify undenatured protein concentrates on a commercial scale. Processes that separate the whey proteins from the low molecular weight, nonprotein components of whey have been used with only moderate success to date (18). Such processes utilize ultrafil-tration/reverse osmosis membrane technology, gel filtration by the basket centrifuge technique, polyvalent ion precipitating agents... 

L. Y. Dudley, Membrane autopsies for reversing fouling in reverse osmosis. Membrane Technology 95, 9-12 (1998). 

Membranes. Photopolymer chemistry is being applied to the design and manufacture of a variety of membrane materials. In these applications, photopolymer technology is used to precisely define the microscopic openings in the membrane as it is being formed or to modify an existing membrane. Some of the applications of photopolymer chemistry to membranes include the modification of ultrafiltration membranes (78) and the manufacture of amphiphilic (79), gas permeable (80), untrafiltration (81), ion-selective electrode (82) and reverse osmosis membranes. 

Reverse osmosis membrane process, 27 637 Reverse osmosis membrane cleaning citric acid application, 6 647 Reverse-osmosis membranes, 75 811, 825 development of, 75 797 Reverse osmosis models, 27 638-639 Reverse osmosis permeators, 76 19 Reverse osmosis seawater desalination process, 26 85 Reverse osmosis systems blending in, 26 80-81 brackish and nanofiltration, 26 80-83 Reverse osmosis technology... 

Reverse osmosis is applicable for the separation, concentration, and/or fractionation of inorganic or organic substances in aqueous or nonaqueous solutions in the liquid or the gaseous phase, and hence it opens a new and versatile field of separation technology in chemical process engineering. Many reverse osmosis processes are also popularly called "ultrafiltration", and many reverse osmosis membranes are also practically useful as ultrafilters. 

The rapid expansion of reverse osmosis technology during the past two decades has resulted in the development of a variety of new membranes. Unique polymer systems and fabrication methods have led to the production of membranes with significantly improved performance and reliability. In spite of these developments little is known about chemical sensitivity or life expectancy of reverse osmosis membranes used in desalting applications. Manufacturers are consequently reluctant to guarantee their products for long runs especially in unique chemical environments. 

The successful development of asymmetric cellulose acetate membranes by Loeb and Sourirajan in the early sixties, at the University of California, Los Angeles, has been primarily responsible for the rapid development of Reverse Osmosis (RO) technology for brack sh/sea water desalination. Reverse Osmosis approaches a reversible process when the pressure barely exceeds the osmotic pressure and hence the energy costs are quite low. Theenergy requirement to purify one litre of water by RO is only O.OO3 KW as against 0,7 KV required just to supply the vaporisation energy to change the phase of one litre of water from liquid to vapour by evaporation. Thus RO has an inherent capability to convert brackish water to potable water at economic cost and thus contribute effectively to the health and prosperity of all humanity. 

S.S. Kremen, Technology and Engineering of ROGA Spiral-wound Reverse Osmosis Membrane Modules, in Reverse Osmosis and Synthetic Membranes, S. Sourirajan (ed.), National Research Council Canada, Ottawa, Canada, pp. 371-386 (1977). 

J.E. Cadotte, R.J. Petersen, R.E. Larson and E.E. Erickson, A New Thin Film Sea Water Reverse Osmosis Membrane, Presented at the 5th Seminar on Membrane Separation Technology, Clemson University, Clemson, SC (1980). 

R.J. Petersen and J.E. Cadotte, Thin Film Composite Reverse Osmosis Membranes, in Handbook of Industrial Membrane Technology, M.C. Porter (ed.), Noyes Publications, Park Ridge, NJ, pp. 307-348 (1990). 

Electrodialysis is now a mature technology, with Ionics remaining the worldwide industry leader except in Japan. Desalting of brackish water and the production of boiler feed water and industrial process water were the main applications until the 1990s, but electrodialysis has since lost market share due to stiff competition from improved reverse osmosis membranes. Beginning in the 1990s,... 

The reverse-osmosis membrane process is considered universally as the most promising technology for brackish and seawater desalination [18]. Potential directions for reducing desalination costs may be deduced by analyzing the cost of the components. 

Ridgeway, Harry F., "Microbial Adhesion and Biofouling of Reverse Osmosis Membranes," in Reverse Osmosis Technology, Parekh Bipin S., Marcel Dekker, Inc., New York, New York, 1988. 

Ridgway H.F., Kelly A., Justice C., and Olson B.H., Microbial fouling of reverse osmosis membranes used in advanced wastewater treatment technology Chemical bacteriological and ultrastiuctural analyses. Applied and Environmental Microbiology 46 1983 1066-1084. 

Ridgway, H.F., Microbial adhesion and biofouling of reverse osmosis membranes. In Reverse Osmosis Technology, Applications for High Purity Water Production, Pakekh, B.S. and Dekker, M., Eds., Marcel Dekker, New York, 1988, p. 429. 

A reverse osmosis membrane is commercially available, named NF-40 (FilmTec Corporation), which is closely based on the NS-300 membrane technology. Typical solute rejection data for this membrane are as follows sodium chloride, 45% calcium chloride, 70% magnesium sulfate, 93% sucrose, 98%. Water flux of the membrane averages about 23 gfd at 225 psi and 25°C. As already noted for NS-300, the sulfate anion is associated with high rejection the chloride anion, low rejection. Partial discrimination between monovalent and divalent cations (sodium versus calcium) has also been observed for NF-40. The membrane can be operated at temperatures to 45°C and in a pH range from 3 to 11. In this respect, it would find probable use in industrial separations where... 

A new variation related to the FT-30 membrane is being developed-the NF-50 composite membrane-which would appear to occupy a unique place in membrane technology. The NF-50 membrane has approximately the same characteristics as NTR-7250 and NF-40, but possesses an extremely high water flux. Reverse osmosis operation in large systems at a pressure of 35 to 50 psi is possible. The NF-50 membrane thus becomes the first example of a reverse osmosis membrane capable of operation at ultrafiltration membrane pressures. 

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