The removal of salinity from water using membranes has many applications across several industries including drinking water production, wastewater treatment, purification and water injection. Membrane desalination works by the principle of osmosis, the flow of water from a dilute solution to a concentrated solution through a semi-permeable membrane (a membrane which allows water to pass but not salt). The reverse of this, called reverse osmosis, involves the flow of water from a concentrated to a dilute solution and occurs when the concentrated solution is placed under a sufficiently high pressure.
This principle is applied for the majority of membrane desalination processes including Seawater Reverse Osmosis (SWRO), Brackish Water Reverse Osmosis (BWRO) and Nanofiltration (NF). A key application is Sulphate Removal (SR) processes. This makes use of specialised NF membranes to remove sulphate ions from injection water and prevent the formation of barium sulphate and strontium sulphate scales in oil wells; which are difficult and costly to remove.