Partial Demineralization of Brackish Waters by Ion Exchange

Interest in extending the usable water sources of the United States to include the extensive brackish water resources has prompted the investigation of a number of processes for demineralizing saline waters. To determine the economic feasibility of ion exchange, an investigation was made to optimize the operating variables of exchange systems consisting of strong-acid cation and weak-base anion resins. Salinities up to 200 mg/1 were investigated in pilot plant studies which simulated in all respects the proposed prototype operations. Net or operating exchange efficiencies varying from 67% to 93% were achieved by countercurrent operation, the re-use of regenerants, the use of low regeneration levels, and minimizing rinse water. Economic analyses indicate that ion exchange can be competitive with other methods.