Reverse Osmosis (RO)

A modern method of desalination that separates dissolved salts from water by pumping the water through a membrane at a high pressure. As the salt concentration of feedwater increases, so does the pumping pressure and electrical energy required to accomplish RO desalination. The pore size of reverse osmosis membranes is so small that mostly water passes through. These membranes are also used in desalination plants because they can take salt out of seawater. Small reverse osmosis plants are often used on ships. Portable plants can be used in emergency situations where public health becomes threatened by contaminated water supply. Reverse osmosis requires a lot of energy and is, therefore, an expensive process that is not always justified based on sustainability.