Reverse osmosis occurs when concentrated water is pushed through a membrane to produce fresh water on the other side, according to About.com chemistry section. Reverse osmosis allows water molecules to pass from concentrated solutions to make fresh water, and it keeps foreign particles at bay.
Reverse osmosis produces energy, treats waste-water and recycles liquids. This system is used in residential and commercial filtration. The process desalinates water and turns seawater into drinking water. For instance, the pressure pushes water molecules through the membrane, but the salt particles are too large to fit through the filtration, and this results in drinkable water on the other side.
Reverse osmosis filters out other impurities in water, such as excessive fluoridation and chemical deposits. The membrane allows the filtration of water molecules, but not larger molecules and ions. Other liquids, such as ethanol, can go through the same reverse osmosis process as water. The wine, dairy and maple syrup industries take advantage of reverse osmosis as well.
Reverse osmosis is also being looked upon as a solution to address overpopulation and global warming. The main disadvantages of reverse osmosis are that larger systems from water plants can trap fish, and the filtration systems tend to harbor bacteria. Reverse osmosis systems are expensive projects to commence, especially for developing nations.