Extraction of commercially valuable mineral salt from reverse osmosis brine using a spray dry process

Abstract

As the need for drinkable water increases, thermal and membrane desalination of seawater have emerged as the two most effective solutions. Both thermal and membrane desalination systems, however, release large quantities of concentrated brine back into the sea. The continuous discharge of enormous amount of brine into the sea will disrupt the aquatic ecosystem and increase the seawater salinity level. In this study, spray dry technology is utilized for isolation of minerals from reverse osmosis brine and there by achieving zero liquid discharge concept. The procedure involves spraying feed into a chamber, followed by the introduction of heated air. The flow rates of the spray dryer and hot air can be adjusted. Consequently, the amount and concentration of feed residue in the chamber can be altered. The residue from the first vaporization chamber was cooled to a specified temperature and centrifuged to separate the minerals in crystal form. The centrifuge reject was fed to a second vaporization chamber for further concentration and separation of pure mineral salts. This cycle was repeated between two and six times to isolate all significant minerals from the brine. The vaporized water from all chambers was condensed to generate pure water as a by-product.