Method to Improve Water Recovery from Desalination Systems Using Ion Exchange Technology

Background: Water desalination technologies are important in a future “water-scarce world”. Many water desalination technologies have been developed but many of the current techniques experience scale formation due to mineral and salt precipitation which restricts the flow of water damages membranes reduces heat transfer efficiency and clogs system components. These effects can significantly reduce overall system performance and can be costly for the desalination unit. To reduce the clogging current techniques use a very conservative design so that only 70-85% of brackish feed water can be recovered. This low recovery has disadvantages such as poor utilization of a scarce water resource and production of a large-volume waste stream which increases the cost of waste management. The need for a clean technology to prevent scale formation in desalination units with increased water recovery and less waste production is evident. Technology Description: This invention is a method to use ion exchange as an intermediate step in a desalination process train. The initial unit process can be any desalination process (membrane or thermal). Ion exchange columns can remove ions from the concentrate of the first stage desalination process. A second stage desalination process can be membrane based or thermally driven or a combination technology. The product water from second stage process can be combined with the product water from the first to increase the overall product water recovery. The concentrate from the second desalination process can be used to regenerate the ion exchange columns. Further exemplary and detailed system configurations and efficient designs are depicted for this novel technology. Applications: Water desalination