Seawater desalination RO is a pressure driven separation process, producing purified water by forcing the water through a semi-permeable membrane while the impurities cannot pass through the membrane. While there have been different configurations for the membrane, today most industrial SWRO systems utilize spiral wound membranes.
Spiral wound RO membrane elements operate installed in pressure vessels. A pressure vessel usually contains from one to six elements connected in series. An RO system can be configured to have a single pressure vessel (small systems) or a number of pressure vessels connected in parallel (array) or in series (stage).