Given the ever increasing need for more complete recovery of pure water, elements and salts from raw water, new technologies such as ultra high recovery NF or RO, cheap salt crystallisation and more effective element recovery technologies need to be developed. This water may originate from widely varying sources, e.g. river or sea, or mining, oil or gas winning activities. Inevitably, such future (combined) systems will be prone to excessive scaling as all solutes and particulate matter will inevitably precipitate out somewhere. A strategy to direct this precipitation to controllable parts of the system may involve removal of scaling compounds as CaCO3, BaSO4, CaSO4, SiO2 from input and recycle streams by for instance ion exchange, solvent extraction, seeded crystallisation, etc., and where applicable application of antiscalants. Antiscalants can serve to delay the precipitation long enough to allow the supersaturated concentrate stream to be fed to a small treatment unit where they be regenerated, and where the scaling compound can be crystallised in a controlled way.
