Remineralization of desalinated water: Methods and environmental impact

Desalinated water is not suitable for direct use as it is prone to corrosion and has adverse effects on human health and the environment. Desalinated water is slightly acidic, lacks minerals and cannot be used un-buffered, thus making remineralization an important component downstream of desalination. We systematically review remineralization requirements and regulations with respect to corrosion control, human health and agriculture needs. This includes not only concentrations of specific ions, but also relative ratios. We compare and contrast existing remineralization methods with emerging, energy-efficient methods that require less chemicals. The impact of the lack of certain minerals such as magnesium, calcium and sulfate, on health and environment are evaluated in order to guide regulatory bodies towards maintaining safe standards. Emerging methods include harvesting minerals from seawater or brine through the combination of nanofiltration membranes with others (CIX, UF, Diananofiltration) and using them to re-mineralize the product stream. This reduces the need for chemicals from an external source and thus lowers the environmental impact. This review is to be used as a tool for guiding readers in proper remineralization choices depending on their application.