Reverse osmosis is a process most commonly used to treat brackish water (water that is more salty than fresh water with <14000ppm of salt) and seawater (water that has more than 14,000ppm of salt). The untreated water is forced through a semi-permeable membrane to overcome the osmotic pressure of the high salt concentration in the untreated water. The semi-permeable membrane allows fresh water to flow through but sifts out larger molecules such as salt, dissolved metals, bacteria and viruses. This process allows us to separate the dissolved salts from the fresh water. The salt is collected in a concentrate (also called brine or reject) and the fresh water is now called permeate (or product).
Reverse Osmosis and Desalination
Reverse Osmosis can be used in a variety of ways. The most common use of reverse osmosis is in a desalination plant. The larger the semi-permeable membrane surface area the more water that can be treated. A typical desalination plant has multiple semi-permeable membranes arranged in a variety of configurations known as array and passes allowing for larger quantities of water to be treated. There are also smaller desalination plants with simpler membrane configurations that can be used within the home.
The required freshwater production of a desalination plant and the salinity of the water as well as the various ions that it contains will determine the size of the desalination plant and the appropriate type of semi-permeable membrane. As we mentioned earlier saltwater has a higher salt concentrate compared to brackish water. Because of the difference in salinity there will be a difference as to how much permeate (freshwater) a desalination plant can produce. The more salt and ions contained in the water the Higher the feed pressure requirement will be and lower If an organisation were wanting to produce a set amount of water each month, it is important to take into account the salinity and the various ions in the water requiring treatment.
Reverse Osmosis desalination is not only for brackish or saltwater it can be used to treat water from rivers, artesian and boreholes. Our range of reverse osmosis products take into account all the little things like salinity and ions so that you don’t have to worry about them.