The Principle and Uses of Reverse Osmosis Water Filters
As its name implies, this process is the reverse of normal osmosis in which water normally filters across a semi-permeable membrane from a solution that has a low concentration of dissolved solids to one in which the concentration is higher. The explanation for this phenomenon lies in the fact that the difference in solute concentrations creates a pressure gradient that will only cease to exert its effect once the concentrations on both sides of the membrane are identical and a state of equilibrium is attained. The process closely parallels that employed by living cells in order to meet their nutritional needs and to maintain their shape.
The Process Explained
The key to the reversal of the natural process is pressure. When applying sufficient pressure by means of a pump, it is possible to halt the natural flow due to osmotic pressure and for the mechanical pressure to drive the movement of solvent in the opposite direction. Depending upon the levels of dissolved solids in the solvent that is to be treated, the pressure that will be required to counteract the normal direction of flow can vary quite considerably.
For instance, when one is simply attempting to improve on the brackish output from the average borehole, it is likely that something between about 30 to 250 pounds per square inch (2-17 bar) will be quite enough to do the trick. Where contamination levels are considerably higher as in a desalination plant, for example, then the applied pressure required will more likely be in the region of 600 to 1200 psi (40-82 bar).
In fact, applications involving the use of reverse osmosis are not limited to water purification when conventional filters alone will most often prove inadequate.
Meeting the Local Requirements
In South Africa, one company has been involved in the supply and installation of high performance equipment employing this and other forms of advanced technology applicable to the treatment of water in a wide range of circumstances since its launch in 1998. WaterIcon is the brand name that has been adopted for the local market by the parent company in Beijing.
Over the course of 15 years, it has been a name that has earned a reputation for quality products and service and one that is widely respected within many of the nation’s key industries to which its services continue to become increasingly important.
A Surprisingly Versatile Technology
One particularly interesting modification of this technology is to be seen in a commercial process used to treat selected wines and champagne that results in the total removal of its alcohol content. Curiously, the product is in great demand worldwide, especially by those whose religious convictions forbid the intake of alcoholic beverages. Though free of ethanol, these preparations still allows consumers to savour the many other enjoyable flavours that result from fermentation that are so characteristic of the fruit of the vine but that are simply not present in unfermented grape juice.
Other applications are seen in the food industry where RO, as it is commonly termed, is often used as a more economical alternative to the use of heat treatment when concentrating liquids such as fruit juices. Apart from the lower cost of operation, the use of reverse osmosis water filters is a lot less likely to result in degradation of the nutrient proteins in foodstuffs.
Other products such as maple syrup and the powdered whey protein that is commonly included in those expensive nutritional supplements that are specially formulated for bodybuilders also undergo a concentration process that relies upon the use of RO technology. However, in each of the cases described, it is actually the concentrate that will be harvested and not the solvent as is the case when RO procedures are employed as a means by which to purify the solvent.
In the home, more and more consumers are becoming concerned about the quality of their municipal supply and are employing this same technology to improve the quality of the tap-water upon which they must rely every day of their lives for drinking and cooking purposes. Equipment such as that available from WaterIcon employs several stages in order to achieve the desired purity. One or two preliminary filtration steps trap sediment while an active carbon layer retains chlorine and organic molecules. Next is the reverse osmosis membrane which, in more sophisticated systems, may be followed by additional water filters and a UV lamp for sterilization purposes.