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What is Reverse Osmosis?

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Question added by Alex Al Yazouri , General Manager , Al Mushref Cooperative Society
Date Posted: 2015/06/11
Vinod Jetley
by Vinod Jetley , Assistant General Manager , State Bank of India

Although Reverse Osmosis seems like a complex system it is really a simple and straightforward water filtration process. And it's not a new process. High-pressure (pump driven) reverse osmosis systems have been used for years to desalinate* water – to convert brackish or seawater to drinking water. Having a better understanding of how a reverse osmosis system works will eliminate the mystery and confusion you may feel when you look at a reverse osmosis system -- with its many colored tubes and multitude of filters.

Reverse Osmosis is a process in which dissolved inorganic solids (such as salts) are removed from a solution (such as water). This is accomplished by household water pressure pushing the tap water through a semi permeable membrane. The membrane (which is about as thick as cellophane) allows only the water to pass through, not the impurities or contaminates. These impurities and contaminates are flushed down the drain.

khaled elkholy
by khaled elkholy , HR MANAGER , misk for import & export

Reverse Osmosis Filter System do? Producing Drinking Water Using Reverse Osmosis Although Reverse Osmosis seems like a complex system it is really a simple and straightforward water filtration process. And it's not a new process. High-pressure (pump driven) reverse osmosis systems have been used for years to desalinate* water – to convert brackish or seawater to drinking water. Having a better understanding of how a reverse osmosis system works will eliminate the mystery and confusion you may feel when you look at a reverse osmosis system -- with its many colored tubes and multitude of filters. Read on to enhance your knowledge of residential reverse osmosis systems. The most important points to remember: All RO Systems work the same way. Most RO (Reverse Osmosis) systems look alike. All RO Systems have the same basic components. The real difference is the quality of the filters and membranes inside the RO. SHOP RO SYSTEMS SHOP REPLACEMENT RO MEMBRANES & FILTERS2How does a Reverse Osmosis Membrane work? Reverse Osmosis is a process in which dissolved inorganic solids (such as salts) are removed from a solution (such as water). This is accomplished by household water pressure pushing the tap water through a semi permeable membrane. The membrane (which is about as thick as cellophane) allows only the water to pass through, not the impurities or contaminates. These impurities and contaminates are flushed down the drain. For a definition of **Reverse Osmosis. Ultimately, the factors that affect the performance of a Reverse Osmosis System are: Incoming water pressure Water Temperature Type and number of total dissolved solids (TDS) in the tap water The quality of the filters and membranes used in the RO System (see operating specs) SHOP RO SYSTEMS SHOP REPLACEMENT RO MEMBRANES & FILTERS Advantages of Reverse Osmosis Improves taste, odor and appearance. Highly effective purification process. Will remove the pollutants listed below and more! Consumes no energy Very convenient Flushes away pollutants, does not collect them Easy to keep clean Low production cost - gives you water of a guaranteed quality for pennies per gallon3What does a Reverse Osmosis System remove? A reverse osmosis membrane will remove impurities and particles larger than .001 microns. Chart of Osmosis System Removal Chart SHOP RO SYSTEMSSHOP REPLACEMENT RO MEMBRANES & FILTERS4What are the components of a Reverse Osmosis System? Basic components common to all Reverse Osmosis Systems: Cold Water Line Valve: Valve that fits onto the cold water supply line. The valve has a tube that attaches to the inlet side of the RO pre filter. This is the water source for the RO system. Pre-Filter (s): Water from the cold water supply line enters the Reverse Osmosis Pre Filter first. There may be more than one pre-filter used in a Reverse Osmosis system. The most commonly used pre-filters are sediment filters. These are used to remove sand silt, dirt and other sediment. Additionally, carbon filters may be used to remove chlorine, which can have a negative effect on TFC (thin film composite) & TFM (thin film material) membranes. Carbon pre filters are not used if the RO system contains a CTA (cellulose tri-acetate) membrane. Reverse Osmosis Membrane: The Reverse Osmosis Membrane is the heart of the system. The most commonly used is a spiral wound of which there are two options: the CTA (cellulose tri-acetate), which is chlorine tolerant, and the TFC/TFM (thin film composite/material), which is not chlorine tolerant. Post filter (s): After the water leaves the RO storage tank, but before going to the RO faucet, the product water goes through the post filter (s). The post filter (s) is generally carbon (either in granular or carbon block form). Any remaining tastes and odors are removed from the product water by post filtration. Automatic Shut Off Valve (SOV): To conserve water, the RO system has an automatic shutoff valve. When the storage tank is full (this may vary based upon the incoming water pressure) this valve stops any further water from entering the membrane, thereby stopping water production. By shutting off the flow this valve also stops water from flowing to the drain. Once water is drawn from the RO drinking water faucet, the pressure in the tank drops and the shut off valves opens, allowing water to flow to the membrane and waste-water (water containing contaminants) to flow down the drain. Check Valve: A check valve is located in the outlet end of the RO membrane housing. The check valve prevents the backward flow or product water from the RO storage tank. A backward flow could rupture the RO membrane. Flow Restrictor: Water flow through the RO membrane is regulated by a flow control. There are many different styles of flow controls. This device maintains the flow rate required to obtain the highest quality drinking water (based on the gallon capacity of the membrane). It also helps maintain pressure on the inlet side of the membrane. Without the flow control very little drinking water would be produced because all the incoming tap water would take the path of least resistance and simply flow down the drain line. The flow control is located in the RO drain line tubing. Storage Tank: The standard RO storage tank holds up to2.5 gallons of water. A bladder inside the tank keeps water pressurized in the tank when it is full. Faucet: The RO unit uses its own faucet, which is usually installed on the kitchen sink. In areas where required by plumbing codes an air-gap faucet is generally used. Drain line: This line runs from the outlet end of the Reverse Osmosis membrane housing to the drain. This line is used to dispose of the impurities and contaminants found in the incoming water source (tap water). The flow control is also installed in this line. Diagram of a Reverse Osmosis System with Basic Components:5Are all Reverse osmosis systems and filters the same? While one RO System may look just like the next in terms of design and components, the quality of those components can be very different. These differences can have a significant impact on the quality of the water the system produces. Here are some examples of questions you might ask and consequences associated with "less than desirable" quality. Has the manufacturer used sound methods? What types of welds have been used in these plastic products? Will they allow contaminated water to bypass the filtration system? Will they allow the system to leak? How has this filter or membrane been created? Will it allow the water to 'channel' and, in effect, bypass the removal component of this device? What about the quality of the 'fill'? Are its contents of a high enough quality to produce the expected percentage of contaminant reduction? Carbon quality, for instance, can have huge variances in reduction capability, reduction capacity, and the sloughing of 'fines', which can prematurely clog or foul the RO Membrane. What are the manufacturer's controls on tolerances or variations in specifications? If this component is rated as a1-micron filter will it truly filter out everything larger than1 micron or will it only do the job80% of the time? And, what if it actually filters at a .5-micron rate? That will stop the system from flowing -- clogging it and forcing filter replacement? If this is a sediment filter and it fails the excess sediment will clog or foul the RO Membrane. And in general - Are the materials used in this product FDA or NSF (National Safety Foundation) approved? If not, you might question their quality or performance ability. So, it becomes clear that the quality of the components is the key to an optimal functioning RO System. So, it becomes clear that the quality of the components is the key to an optimal functioning RO System. SHOP RO SYSTEMS SHOP REPLACEMENT RO MEMBRANES & FILTERS6How do you increase the gallon per day (gpd) capacity of the reverse osmosis membrane on a reverse osmosis system? The main reason to change to a higher flow reverse osmosis membrane is to improve the recovery rate which is to reduce the amount of time it takes to refill the storage tank. This insures that there is adequate water available during times of heavy usage or when the reverses osmosis system may feed more than one location such as an ice maker and a dispensing faucet. Changing to a higher flow membrane has no effect on the quality of the water your reverse osmosis system makes or the length of time the reverse osmosis membrane will last. The change to a higher capacity membrane is easy. You simply replace your old membrane with a new, higher capacity membrane, along with the correctly sized drain line flow restrictor. (Matching the membrane with the correctly sized drain line flow restrictor is important to ensure the proper product to waste ratio is meet. A mis-matched combination will allow either excess water to flow to the drain or cause premature fouling of the membrane.) Most standard reverse osmosis membrane housings will accommodate membranes ranging in capacities from10 –150 gallons per day. Flow Control Installation Instructions A complete listing of standard residential reverses osmosis membranes and corresponding drain line flow controls is on our membrane page or review the flow control guideline chart for residential reverse osmosis membranes on our parts page. SHOP RO SYSTEMS SHOP REPLACEMENT RO MEMBRANES & FILTERS7Where can I buy a quality reverse osmosis system or replacement filters and membranes? We carry replacement filters and membranes for most major brands of Reverse Osmosis systems. View our list of Reverse Osmosis Filters by brands that we carry. SHOP RO SYSTEMS We also have new Reverse Osmosis Systems available to purchase. See the features and benefits of each type of Reverse Osmosis System.

Elke Woofter
by Elke Woofter , Project Assistant , American Technical Associates

is a type of water purification  uses a semipermeable membrane to remove larger particles from drinking water

 

 

Deleted user
by Deleted user

 

Reverse osmosis takes place when pressure applied to a concentrated solute solution causes the solvent to pass through a semipermeable membrane to the lower concentrated solution, leaving a higher concentration of solute on one side, and only solvent on the other. Salt water is desalinated to make fresh water using reverse osmosis. There the solvent it water and the solute is salt. A more complete description. http://en.wikipedia.org/wiki/Reverse_osm...

Alex Al Yazouri
by Alex Al Yazouri , General Manager , Al Mushref Cooperative Society

Reverse osmosis is one of the processes that makes desalination (or removing salt from seawater) possible. Beyond that, reverse osmosis is used for recycling, wastewater treatment, and can even produce energy.

Water issues have become an extremely pressing global threat. With climate change come unprecedented environmental impacts: torrential flooding in some areas, droughts in others, rising and falling sea levels. Add to that the threat of overpopulation -- and the demand and pollution a swelling population brings -- and water becomes one of the paramount environmental issues to watch for in the next generation.

Water treatment plants and systems are now adapting reverse osmosis to address some of these concerns. In Perth, Australia (notably dry and arid, yet surrounded by sea), nearly17 percent of the area's drinking water is desalinated sea water that comes from a reverse osmosis plant [source: The Economist]. Worldwide, there are now over13,000 desalination plants in the world, according to the International Desalination Association.

But while knowing that reverse osmosis can convert seawater to drinking water is useful, what we really need to understand is how the heck the process occurs. Assuming that you have a fairly good grasp on the definition of "reverse," we better start by taking a look at how osmosis works before we put the two together.

Hasan Riaz
by Hasan Riaz , Mechanical Engineer , Saudi Bin Ladin Group (Hamad International Airport)

All the answers are very descriptive and detailed which clarify the basic concepts of Reverse Osmosis. Thank you gentlemen for your time.

Khaled Anwar
by Khaled Anwar , Senior Sales Engineer , "Automotive company''

I agree with the experts answers. Thank you 

mourad bouabne
by mourad bouabne , technical manager , Exeed/Tarsheed

it is a technology used to desalinate and or filter water or other liquid by passing under pressure the liquid through semi permable membrane.

thiagarajan reddy
by thiagarajan reddy , shift electrical engineer , chemplast sanmar ltd

The water is very much utilised for the basic need of humen being,today it is very very scarcity,the recycleling the waste is a must,to bank the water.reverse osmasis a way to clean  the waste water for reuse purpose.

Amit Hela
by Amit Hela , Assistant General Manager Project Planning & Scheduling , Primetals Technologies India Private Limited joint venture of Mitsubishi Heavy Industries and partne

 

  1. a process by which a solvent passes through a porous membrane in the direction opposite to that for natural osmosis when subjected to a hydrostatic pressure greater than the osmotic pressure.

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