Reverse osmosis

=== Waste-stream considerations ===
Depending upon the desired product, either the solvent or solute stream of RO will be waste. For food concentration applications, the concentrated solute stream is the product and the solvent stream is waste. For water treatment applications, the solvent stream is purified water and the solute stream is concentrated waste.<ref>{{cite book|last=Weber|first=Walter J.|title =Physicochemical Processes for Water Quality Control|publisher =John Wiley & Sons|year =1972|oclc=1086963937|url=https://books.google.com/books?id=2rS0AAAAIAAJ|location =New York|isbn =9780471924357|page=320}}</ref> The solvent waste stream from food processing may be used as [[reclaimed water]], but there may be fewer options for disposal of a concentrated waste solute stream. Ships may use [[marine dumping]] and coastal desalination plants typically use [[marine outfall]]s. Landlocked RO plants may require [[evaporation pond]]s or [[injection well]]s to avoid polluting [[groundwater]] or [[surface runoff]].<ref>{{cite book |last=Hammer |first=Mark J.|url=https://books.google.com/books?id=qgVSAAAAMAAJ|title =Water and Waste-Water Technology |publisher =John Wiley & Sons |date =1975 |location=New York|isbn =9780471347262|page=266}}</ref>