Desalination (also known as de-salting) is a process where dissolved ions are removed from high-salinity input water. Using this technique, fresh water can be produced from seawater or brackish water. There are many applications of desalination technologies used in industrial and commercial water filters. One of the most common uses is to produce drinkable water, for domestic or municipal purposes, from saltwater. However, the use of industrial desalination, meaning the use of desalination water treatment technologies for industrial purposes is growing steadily. 97.5% of the world’s water exists in the oceans in the high-salinity form. Only 2.5% of water on the planet is fresh water. Approximately 69% of that water is frozen in glaciers, thus the need for effective desalination techniques becomes abundantly clear.
Reverse Osmosis Plants
Major desalination processes employ specialised membrane technologies. Reverse Osmosis (RO) is currently the dominating technique for desalination capacity across the world.RO plants usually need an extensive pre-treatment process to avoid membrane being fouled by sediment or minerals. As a result of dissolved CO2, the water product from RO processes is often slightly more acidic than the feed water. It is therefore common to employ post-treatments that ensure pH neutralisation, along with remineralisation of the water.
High quality RO systems comprise technology to remove sediment, chemicals and ions, using carbon, and membrane technology to give an output of highly-purified, potable water. The water is forced at high pressure through a semi-permeable membrane, which results in the separation at the molecular level of clean water from the majority of contaminants.
Seawater RO Plants
Industrial filtration of seawater is almost exclusively accomplished using RO systems as part of the many-step process. Recent developments in the RO technology used for desalination of sweater include improvements to the rejection rate of the RO membrane. This goes alongside the introduction of membrane elements that surpass an operating capacity of 70 bar (equal to 1000 psi). Improved availability of inter-stage booster pumps that are directly driven also help to improve flexibility in optimising the operating parameters.
Brackish RO Systems
Brackish water is classed with having a lower salinity compared to seawater but still contains high enough levels of dissolved minerals and salts to makes it less desirable for many applications. A brackish RO system may be used to eliminated these impurities and provide potable water for a variety of applications.