Reverse osmosis ultrapure water

Gupta, S.K.S. and Rimpelainen, S., Liquid Radwaste Processing with Spiral-Wound Reverse Osmosis, ULTRAPURE WATER,... 

Sen Gupta, S.K., Rimpelainen, S., Liquid radwaste processing with spiral-wound reverse osmosis, Ultrapure Water , Knowledgebase, UP140132, 1, 1997. 

L.P. Comb, Silica chemistry and reverse osmosis, Ultrapure Water 13 (1) (1996) 41—43. 

Although the principal appHcation of reverse osmosis membranes is still desalination of brackish water or seawater to provide drinking water, a significant market is production of ultrapure water. Such water is used in steam boilers or in the electronics industry, where huge amounts of extremely pure water with a total salt concentration significantly below 1 ppm are required to wash siUcon wafers. 

Amjad, Zahid Zibrida, John F. Zuhl, Robert W. Silica Control Technology for Reverse Osmosis Systems. Ultrapure Water, Tall Oaks Publishing, Inc., USA, February 1999. 

There are five basic water purification technologies—distillation, ion exchange, carbon adsorption, reverse osmosis, and membrane filtration. Most academic laboratories are equipped with in-house purified water, which typically is produced by a combination of the above purifying technologies. For most procedures carried out in a biochemistry teaching laboratory, water purified by deionization, reverse osmosis, or distillation usually is acceptable. For special procedures such as buffer standardization, liquid chromatography, and tissue culture, ultrapure water should be used. 

Reverse osmosis performs a separation without a phase change. Thus, the energy requirements are low. Typical energy consumption is 6 to 7 kWh/m2 of product water in seawater desalination. Reverse osmosis, of course, is not only used in desalination, but also for producing high-pressure boiler feedwater, bacteria-free water, and ultrapure water for rinsing electronic components—because of its properties for rejecting colloidal matter, particle and bacteria. 

Currently, approximately one billion gal/day of water are desalted by reverse osmosis. Half of this capacity is installed in the United States, Europe, and Japan, principally to produce ultrapure industrial water. The remainder is installed in the Middle East and other desert regions to produce municipal drinking water from brackish groundwater or seawater. In recent years, the interfacial composite membrane has displaced the anisotropic cellulose acetate membrane in most applications. Interfacial composite membranes are supplied in spiral-wound module form the market share of hollow fiber membranes is now less than... 

Approximately one-half of the reverse osmosis systems currently installed are desalinating brackish or seawater. Another 40 % are producing ultrapure water for the electronics, pharmaceutical, and power generation industries. The remainder are used in small niche applications such as pollution control and food processing. A review of reverse osmosis applications has been done by Williams et al. [52],... 

Production of ultrapure water for the electronics industry is an established and growing application of reverse osmosis [54,55], The usual feed is municipal... 

Electrodeionization systems were first suggested to remove small amounts of radioactive elements from contaminated waters [27], but the principal current application is the preparation of ultrapure water for the electronics and pharmaceutical industries [28], The process is sometimes used as a polishing step after the water has been pretreated with a reverse osmosis unit. 

Adapted from "Reverse Osmosis Performance Data Collection and Interpretation," originally presented at the 28th Annual Electric Utility Chemistry Workshop, Champaign, IL, May 2008, and published in "UltraPure Water Journal, www.ultrapurewater.com, April, 2009. 

Figure 2.6 schematically illustrates sections of a typical semiconductor ultrapure water (UPW) production process in a semiconductor plant. The water circuit consists of two main sections (1) makeup (or central) system and (2) polishing loop, which provides water at the point of use. There are multiple locations in such a water process where membrane degassing could be needed as shown in the figure. Reverse osmosis is mostly used in makeup line as the primary purification means in such processes. In the past, large and inflexible vacuum towers were frequently used after RO to remove dissolved gases, such as O2, N2, and CO2. Membrane contactors are the norm today for replacement or supplement to vacuum towers in makeup lines, as shown in Figure 2.6. 

A variety of reverse osmosis membrane systems based on cellulose acetate, aromatic polyamides, and other polymers have been tested for their potential applications. Reverse osmosis membrane equipment is available for large-scale operation since the process is widely used for the production of potable water from sea or brackish waters and upstream of ion exchange in the preparation of ultrapure water for steam-generating boilers. In these applications, the feed concentrations may vary from 500 to 40,000 mg/L of dissolved solids. The RO technique can be used at pH values between 3 and 12 and up to 45°C. 

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