Reverse Osmosis is a technology that is used to remove a large majority of contaminants from water by pushing the water under pressure through a semi-permeable membrane.
How does Reverse Osmosis work?
Reverse Osmosis works by using a high pressure pump to increase the pressure on the salt side of the RO and force the water across the semi-permeable RO membrane, leaving almost all (around 95% to 99%) of dissolved salts behind in the reject stream. The amount of pressure required depends on the salt concentration of the feed water. The more concentrated the feed water, the more pressure is required to overcome the osmotic pressure.
The desalinated water that is demineralized or deionized, is called permeate (or product) water. The water stream that carries the concentrated contaminants that did not pass through the RO membrane is called the reject (or concentrate) stream.
Understanding the difference between passes and stages in a Reverse Osmosis (RO) system
The terms stage and pass are often mistaken for the same thing in an RO system and can be confusing terminology for an RO operator. It is important to understand the differnce between a 1 and 2 stage RO and a 1 and 2 pass RO.