Surface run-off, and drainage are unavoidable factors and hence, man has incessantly come up with a number of ways to separate water solubles from the pure form. The process of water filtration is one taught to us by nature, especially that of reverse osmosis.
Osmosis is defined as 'the flow of water from a region of low solute concentration to that of high solute concentration via a semi-permeable membrane'. This process occurs naturally in nature and is part of the animate and inanimate.
It is the ability of a body or cell membrane to soak in water, devoid of solvents. In the science of water purification, the process is reversed. It involves the flow of pressurized water from a region of high solute concentration to that of low solute concentration.
How Does Reverse Osmosis Work?
Reverse osmosis water filtration systems use pressure to force water through a specially designed membrane. The membrane plays a vital role in ensuring that the solvent permeates to the opposite side, by retaining the solutes or particles dissolved in water.
The result is the natural movement of the solvent (water) from an area of high solute (pollutant) concentration, through the membrane, to an area of low solute concentration. The exerted pressure is referred to as osmotic pressure.
In the water filter, the membrane used for reverse osmosis comprises a dense barrier layer. It is fitted within a polymer matrix that facilitates the filtration of pollutants and debris from the water source. The polymer matrix design, only allows water to pass through the layer, retaining any type of salt ion.
The applied pressure in the water system is usually anything between:
- 2 and 17 bar or 30 to 250 psi, to treat fresh, brackish water.
- 40 and 80 bar or 600 to 1000 psi, to treat seawater.
Working of an RO Water Purifier
A reverse osmosis water purifier differs in size and capacity, according to the community or region being catered to. Ideally the 24 bar or 350 psi reading is the natural osmotic pressure that is targeted for optimum filtration results.
These water purifiers are known for excellent desalination or the removal of salt from sea water. They are popularly used to make pure, freshwater accessible for a number of domestic, medical and industrial applications.
The design takes no more than two compartments and the special semipermeable membrane. The impure water is routed into one compartment of the design and released, under pressure, through the membrane into the adjacent compartment.
The water from the second compartment is then directed via pipes and hoses to various faucets and subsequent storage systems. The water is treated via the application of osmotic pressure to generate an analogous flow that is triggered caused by a pressure differential.
Around the world, a number of households and medical units use water from drinking water purification systems. The water is used for direct consumption as well as cooking. These water purifiers are alternately customized to suit individual requirements.
Some customizations include sediment filters to trap rust and calcium carbonate solubles, activated carbon filters to trap chlorine and organic chemicals and ultra-violet lamps to kill microbes. Portable RO water filters are used by people in remote areas and travelers and also to treat waste water, to conserve this very precious natural resource.