Boron removal in brackish water desalination systems

Boron removal in seawater RO desalination systems is usually done by a second desalination pass, operating at high pH (pH≥10). This method is not economical for reduction of boron content in permeate of brackish water desalination. The most suitable method for this purpose would be through boron selective ion exchange (IX) resins. However, in some cases the use of high boron rejection membranes, especially developed for seawater desalination, is preferred. Alternatively, especially for brackish sources with boron content too high for reduction to the required low concentration (ᐸ0.5 mg/l) by seawater RO membranes alone, a combination of high boron rejection seawater membranes and an IX system can be applied. A case study for reducing of boron in brackish source from 0.62 mg/l to 0.3 mg/l is presented. Optimization tools for a comprehensive economic analysis are presented.