What Is Reverse Osmosis?

Answer 1

Reverse osmosis occurs when the water is moved across the membrane against the concentration gradient, from lower concentration to higher concentration. To illustrate, imagine a semipermeable membrane with fresh water on one side and a concentrated aqueous solution on the other side. If normal osmosis takes place, the fresh water will cross the membrane to dilute the concentrated solution. In reverse osmosis, pressure is exerted on the side with the concentrated solution to force the water molecules across the membrane to the fresh water side.

Reverse osmosis is often used in commercial and residential water filtration. It is also one of the methods used to desalinate seawater. Sometimes reverse osmosis is used to purify liquids in which water is an undesirable impurity (e.g., ethanol).

Answer 2

Osmosis refers to the movement of a solute or solvent from an area of greater concentration to an area of lower concentration though a membrane.
In the reverse osmosis, pressure is applied to "force" the flow of solvent through a semi-permeable membrane, actually, concentrating the solute (impurities/electrolytes/minerals too large to pass through the membrane) on the high pressure side and concentrating the solvent (purifying) on the lower pressure side of the membrane.

Answer 3

Reverse osmosis is the process of pushing a solution through a filter that traps the solute on one side and allows the pure solvent to be obtained from the other side.

Answer 4

osmosis is the diffusion of water from high to low concentration...reverse osmosis is reverse...its the diffusion of water from low to high concentration

Answer 5

Hi! According to Wikipedia:

Reverse osmosis is the process of pushing a solution through a filter that traps the solute on one side and allows the pure solvent to be obtained from the other side. More formally, it is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. This is the reverse of the normal osmosis process, which is the natural movement of solvent from an area of low solute concentration, through a membrane, to an area of high solute concentration when no external pressure is applied. The membrane here is semipermeable, meaning it allows the passage of solvent but not of solute.

The membranes used for reverse osmosis have a dense polymer barrier layer in which separation takes place. In most cases the membrane is designed to allow only water to pass through this dense layer while preventing the passage of the solute (such as salt). This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 2–14 bar (30–200 pounds per square inch) for fresh and brackish water, and 40–70 bar [(600–1000 psig)] for seawater, which has around 24 bar (350 psi) natural osmotic pressure which must be overcome.

This process is best known for its use in desalination (removing the salt from sea water to get fresh water) and has been used in this way since the early 1970s.

Method
When two solutions with different concentrations of a solute are mixed, the total amount of solutes in the two solutions will be equally distributed in the total amount of solvent from the two solutions. This is achieved by diffusion, in which solutes will move from areas of higher concentration to areas of lower concentrations until the concentration in all the different areas of the resulting mixture are the same, a state called equilibrium.

Instead of mixing the two solutions together, they can be put in two compartments where they are separated from each other by a semipermeable membrane. The semipermeable membrane does not allow the solutes to move from one compartment to the other, but allows the solvent to move. Since equilibrium cannot be achieved by the movement of solutes from the compartment with high solute concentration to the one with low solute concentration, it is instead achieved by the movement of the solvent from areas of low solute concentration to areas of high solute concentration. When the solvent moves away from low concentration areas, it causes these areas to become more concentrated. On the other side, when the solvent moves into areas of high concentration, solute concentration will decrease. This process is termed osmosis. The tendency for solvent to flow through the membrane can be expressed as "osmotic pressure", since it is analogous to flow caused by a pressure differential.

In reverse osmosis, in a similar setup as that in osmosis, pressure is applied to the compartment with high concentration. In this case, there are two forces influencing the movement of water: the pressure caused by the difference in solute concentration between the two compartments (the osmotic pressure) and the externally applied pressure. In the same way as in conventional osmosis, the solute cannot move from areas of high pressure to areas of low pressure because the membrane is not permeable to it. Only the solvent can pass through the membrane. When the effect of the externally applied pressure is greater than that of the concentration difference, net solvent movement will be from areas of high solute concentration to low solute concentration, and reverse osmosis occurs.

Answer 6

Its like regular osmosis, only backwards.

;o)

Answer 7

Definitions of Reverse Osmosis on the Web:

A water treatment process whereby dissolved salts, such as sodium, chloride, calcium carbonate, and calcium sulfate may be separated from water by forcing the water through a semi-permeable membrane under high pressure. The water diffuses through the membrane and the dissolved salts remain behind on the surface of the membrane. ...
www.jvwcd.org/swjvgwp/glossary.html

This is a purification method for tap-water. Prefiltered tap water is pushed through a reverse osmosis membrane. Water that makes it through is considered pure, while water that does not, is sent through a special tube and is rendered impure. As it relies on water which is able to pass through the membrane, it also generates a large quantity of "waste" water which cannot be used. This is one of the best, but slowest methods of tap water purification. ...
www.aqualink.com/basic/zglossa.html

a process where water is cleaned by forcing water through an ultra-fine semi-permeable membrane which allows only the water to pass though and retains the contaminants; these filters are sometimes used in tertiary treatment and to pretreat water in chemical laboratories.
www.wef.org/publicinfo/newsroom/wastewater_glossary.jhtml

An expensive and inconvenient commercial process through which alcohol and acetic acid can be removed from the wine so that it meets aesthetic or, more commonly, regulatory levels.
winemakermag.com/referenceguide/winemakingdefinitions/

A process used to purify concentrated solutions (often water with high levels of dissolved salts) in which pressure is applied to the more concentrated (or contaminated) solution on one side of a semipermeable membrane. The result is the movement of solvent, but not solutes, from the more concentrated side to the more dilute side, thus separating clean solvent from the concentrated solution. ...
www.st.com/stonline/press/news/glossary/r.htm

A method of producing pure water by forcing saline or impure water through a semi-permeable membrane across which salts or impurities cannot pass.
www.florite.com/support/terminology.htm

A water treatment method used to remove dissolved inorganic chemicals and suspended particulate matter from a water supply. Water, under pressure, is forced through a semi-permeable membrane that removes molecules larger than the pores of the membrane.
www.ext.colostate.edu/pubs/crops/04717.html

A treatment process used in water systems by adding pressure to force water through a semi-permeable membrane. Reverse osmosis removes most drinking water contaminants. Also used in wa- stewater treatment. Large-scale reverse osmosis plants are being developed.
www.waterquality.de/hydrobio.hw/RTERMS.HTM

A water treatment method whereby water is forced through a semi permeable membrane which filters out impurities.
www.alpha-plumbing.com/plumbing-terminology-r.htm

Reverse Osmosis units remove most inorganic chemicals such as salts, metals and minerals as well as microorganisms and many (but not all) organic compounds. Reverse Osmosis units are often used in conjunction with mechanical and activated carbon filters. Reverse Osmosis units use large amounts of water, usually 75% is discarded with the contaminants.
www.uldrinkwell.com/drinkwell/glossary.html

Reverse osmosis is a process that separates impurities from water by forcing it through filters under great pressure into a spirally wound tube called a reverse osmosis element. The membrane allows water to pass through the filter while rejecting suspended and dissolved impurities and most color and odor-causing compounds. If the filters do not absorb the contaminants, then they have to pass through three post-treatment cylinders
www.gulflink.osd.mil/water_use/water_use_taba.htm

A method of water treatment by forcing pure water to pass through membranes that will not pass sodium or chloride ions.
www.myronl.com/main/faqs.htm

A filtration process that removes dissolved salts and metallic ions from water by forcing it through a semipermeable membrane. This process is also highly effective in removing microbes from water.
www.cdc.gov/mmwr/preview/mmwrhtml/ss5108a4.htm

Mechanical pressure is applied to an impure solution to force pure water through a semi-permeable membrane. The term is reverse osmosis, because normal osmosis would result in pure water moving in the other direction to dilute the impurities. Reverse osmosis is theoretically the most thorough method of large-scale water purification available, although perfect semi-permable membranes are difficult to create.
www.thetexts.com/wikipedia/w/wa/water.html

the process of removing minerals from water, which is forced by pressure through a differentially permeable membrane, filtering out the minerals; can happen when growers accidentally apply too strong of a nutrient to a plant's roots, leeching life out of the plant.
www.growingedge.com/basics/glossary.html

Reverse osmosis requires external pressure to reverse natural osmotic flow. As pressure is applied to the saline solution, water flows through the semipermeable membrane (see figure 3). Reverse Osmosis Membrane A reverse osmosis membrane has a thin microporous surface that rejects impurities, but allows water to pass through. The membrane rejects bacteria, pyrogens, and 85%-95% of inorganic solids. Polyvalent ions are rejected easier than monovalent ions. ...
www.thorntoninc.com/terminology.htm

The act of reversing a diffusion through a semipermeable membrane, typically separating a solvent and a solution, that tends to equalize their concentrations.
www.sea-us.org.au/isl/islspeak.html

The process of forcing water through a semi-permeable membrane for the removal of particulates and other matter. It is one of the significant steps taken to purify water for use.
www.jnevins.com/inkjetglossary.htm

A mechanical means of removing some of the water from the sap before boiling.
www.hallfarms.com/sweettalk.html

The process of removing dissolved minerals from water as it is forced under pressure through a tightly bound membrane. Particles too large to pass through the membrane are flushed away to the drain.
www.pendred.com/huglos.htm

Forcing a liquid through a nonporous membrane, removing particles, along with dissolved molecules and ions. The finest form of membrane separation and is used to desalinate water for drinking, and in the preparation of ultrapure water for various industries.
www.pollutionengineering.com/CDA/ArticleInformation/features/BNP__Features__Item/0,6649,106432,00.html

RO, A treatment technology used to remove inorganic contaminants, where water with a low level of total dissolved solids passes through a semipermeable membrane into a solution containing a higher level of total dissolved solids; pump pressure is applied to the concentrated solution causing it to flow back across the membrane.
www.dnr.state.wi.us/org/water/dwg/OpCert/HTML/glossary.htm

under pressure water can be forced through a semipermeable membrane, removing salts which cannot pass the membrane
eies.njit.edu/~kebbekus/definitions_for_water_treatment.htm

A membrane procedure which separates ionic species from aqueous solutions to produce water of extremely high purity. Applied pressure forces H+ and OH ions across a membrane that does not allow for passage of other ions. The purity of the water can be measured with a conductance meter. --------------------------------------------------------------------------------
www.astropak.com/c_glossary.php

forces water through membranes that contain holes so small that even salts cannot pass through. Reverse osmosis removes microorganisms, organic chemicals, and inorganic chemicals, producing very pure water. Reverse osmosis units require regular maintenance or they can become a health hazard.
ci.monterey-park.ca.us/home/index.asp

Reverse Osmosis is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. In simpler terms, reverse osmosis is pushing a solution through a filter that traps the solute from one side and allows the obtainment of the pure solvent from the other side.
en.wikipedia.org/wiki/Reverse_osmosis