Reverse Osmosis (RO) is a membrane separation process designed to treat wastewater containing a variety of contaminants including organic compounds.
In regular osmosis, water flows across a membrane so that the concentration of impurity on each side of the membrane is equal; balance is achieved. In reverse osmosis, the opposite is forced to occur. Pressure is applied to one side of the membrane so that the ending concentration on either side of the membrane is uneven. By employing reverse osmosis, one can take water containing some impurities (such as saltwater) and pass it through a series of filters that capture the contaminants to achieve drinkable water. Many common water filters today involve the use of reverse osmosis.