Uses of Reverse Osmosis
Reverse osmosis can be used to either purify water or to concentrate and recover dissolved solids in the feed water (known as “dewatering”). The most common application of Reverse Osmosis is to replace ion exchange, including sodium softening, to purify water for use as boiler makeup to low- to medium-pressure boilers, as the product quality from an RO can directly meet the boiler make-up requirements for these pressures. For higher-pressure boilers and steam generators, Reverse Osmosis is used in conjunction with ion exchange, usually as a pretreatment to a two-bed or mixed-bed ion exchange system. The uses of Reverse Osmosis prior to ion exchange can significantly reduce the frequency of resin regenerations, and hence, drastically reduce the amount of acid, caustic, and regeneration waste that must be handled and stored. In some cases, a secondary RO unit can be used in place of ion exchange to further purify product water from an RO unit.
Effluent from “Filtration Spectrum” comparing the rejection capabilities of reverse osmosis with other membrane technologies and with the separation afforded by conventional filtration.
The second RO may be used directly or is sometimes polished with mixed-bed ion exchange or continuous electrodeionization to achieve even higher product water purity.
Other common applications of Reverse Osmosis include:
- Desalination of seawater and brackish water for portable use. This is very common in coastal areas and the Middle East where supply of fresh water is scarce.
- Generation of ultrapure water for the microelectronics industry.
- Processing of dairy products.
- Generation of process water for beverages (fruit juices, bottled water, beer).
- Concentration of corn sweeteners.
- Waste treatment for the recovery of process materials such as metals for the metal finishing industries, and dyes used in the manufacture of textiles.
- Water reclamation of municipal and industrial wastewaters
- Generation of high-purity water for pharmaceuticals.