Reverse osmosis is one of the modern methods used by the shipping industry to produce freshwater from seawater. This method of water production does not use a waste heat source, unlike a freshwater generator, to desalinate the seawater to convert it into freshwater with low salt ppm.
Principle of Reverse Osmosis
As the name suggests, this method works on reversing the osmosis principle. The principle of reverse osmosis is based on the movement of water molecules through a semi-permeable membrane from a region of high concentration to a region of low concentration
When a chemical solution is separated from pure water by a semi-permeable membrane (allowing passage of water, not salt) then the pure water flows through the membrane until all the pure water has passed through or until the hydrostatic pressure head of the salt solution is sufficiently big enough to arrest or stop the process.
Reverse osmosis is the use of this phenomenon in the reverse direction. This results in water being forced through the membrane from the concentrated solution toward the more dilute one. This is achieved by applying pressure of the osmotic pressure of the concentrated solution.
Reverse osmosis is a highly efficient process for producing freshwater, with up to 99% of impurities removed from the seawater. It is widely used in the maritime industry for producing freshwater on ships, as well as in the production of bottled water and other industrial applications.