Reverse osmosis is widely used in industry and potable water production for removing dissolved salts from water. Typical industrial use cases include the treatment of water needed for power and heat production as well as in surface treatment, production processes, air moisturising, washing and rinsing. In addition, reverse osmosis water is used in brewing, hydroponics and many other applications where it necessary to have mineral-free water before exactly the right amounts of substances are added. In reverse osmosis, water is separated into permeate (filtrated water) and concentrate (residue water stream that includes all filtrated substances). The share of permeate and concentrate varies. The yield is typically between 70–80% with fresh water and 30–60% with brackish and sea water.
Reverse osmosis feed water requires pre-treatment as a rule. This is the only way to ensure that system efficiency remains at a good level and prevent membrane scaling. Typical pre-treatment stages consist of multimedia filtration (when there are insoluble solids in the water) and softening (typically applied if the hardness is over 5° dH). Instead of water softeners, it is possible to use antiscalant dosing before RO (chemical that prevents scaling). With a single-stage reverse osmosis system, it is possible to reduce dissolved solids (TDS) by 99.5%.
Required information for system design
To complete a reverse osmosis system design, a raw water analysis is needed together with information about the required water flow/capacity of system and the required water quality after treatment or information about the use of the water produced. If the equipment is being installed in an existing space, information about available drainage and room dimensions is also good to know.