Reverse Osmosis Principles

A process unit for purifying salt water is based on the reverse osmosis principle. In such a device, hollow fibers are used that retain the salt but permit water to diffuse out. For a unit using 900,000 hollow fibers (diameters of 85 and 42 x 10 m, respectively) that are 0.9 m long, the volumetric output (feed pressure of 2.86 x 10 pascals) is 8.76 x 10 m /sec. What is the pressure drop in an individual fiber from inlet to outlet ... 

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... 

What is Reverse Osmosis and the general principle of operation ... 

Over the past three decades, there has been a growing industrial interest in using reverse osmosis for several objectives such as water purification and demineralization as well as environmental plications (e.g.. Comb, 1994 Rorech and Bond, 1993, El-Halwagi, 1992). The first step in designing the system is to understand the operating principles and modeling of RO modules. 

Sourirajan, S., and Matsuura, T. (1985). Reverse Osmosis/Uitrafiltration Process Principles, National Research Council, Ottawa, Canada. 

An alternative method of purifying water is by reverse osmosis. Under normal conditions, if an aqueous solution is separated by a semi-permeable membrane from pure water, osmosis will lead to water entering the solution to dilute it. If, however, sufficient pressure is applied to the solution, i.e. a pressure in excess of its osmotic pressure, then water will flow through the membrane from the solution the process of reverse osmosis is taking place. This principle has been... 

The relevance of LSC data to reverse osmosis stems from the physicochemical basis (adsorption equilibrium considerations) of liquid-solid chromatography (52), and the principle that the solute-solvent-membrane material (column material) Interactions governing the relative retention times of solutes in LSC are analogous to the interactions prevailing at the membrane-solution Interface under reverse osmosis conditions. The work already reported in several papers on the subject (53-58) indicate that the foregoing principle is valid, and hence LSC data offer an appropriate means of characterizing interfacial properties of membrane materials, and understanding solute separations in reverse osmosis. 

In all the foregoing discussion on reverse osmosis transport, system analysis and process design, no new chemical engineering principle Is Involved. But the manner In which the known principles are combined and expressed Is new the kind of results arising from such expressions Is new and the direction such approach sets for future work on the subject Is also new, all of which open a new area of chemical engineering. 

S. Souriiajan and T. Matsuura, Reverse Osmosis/ Ultrafiltration Principles, National Research Council of Canada, Ottawa, Canada, 1985. 

In bioprocesses, a variety of apparatus that incorporate artificial (usually polymeric) membranes are often used for both separations and bioreactions. In this chapter, we shall briefly review the general principles of several membrane processes, namely, dialysis, ultrafiltration (UF), microfiltration (MF), and reverse osmosis (RO). 

We can use the same filtration principle for the separation of small particles down to small size of the molecular level by using polymeric membranes. Depending upon the size range of the particles separated, membrane separation processes can be classified into three categories microfiltration, ultrafiltration, and reverse osmosis, the major differences of which are summarized in Table 10.2. 

In principle, pollution control should be a major application for reverse osmosis. In practice, membrane fouling, causing low plant reliability, has inhibited its widespread use in this area. The most common applications are special situations... 

A method of producing drinkable water from salt water is reverse osmosis, in which a pressure just in excess of the osmotic pressure is applied to the solution in order to reverse the flow of the solvent (H2O). In principle, what pressure would be required to produce pure water from sea water at 25°C Assume that sea water has a density of 1.021 g/mLand can be considered equivalent to 3.00% by weight NaCl, which is 100% ionized. Express your answer in atm, kPa, and psi. 

Wild, P. M., G. W. Vickers, and N. Djilali (1997). Fundamental principles and design considerations for the implementation of centrifugal reverse osmosis. Proc. Inst. Mechanical Engineers, Part E J. Process Mechanical Eng. 211, E2, 67-81. MEP, London. 

Bourns, W.T. and Le, V.T., The Reverse Osmosis Plant in CRNL Waste Treatment Centre-Description Design and Operation Principles, Report CRNL-2352, Atomic Energy of Canada Ltd., Chalk River, 1984. 

---