Method for generating acid and base regenerants and use thereof to regenerate ion-exchange resins

摘要

A method and apparatus for generating acid and base regenerant solutions by utilization of a bipolar membrane electrodialysis stack (10). A mineral-containing salt solution (14) is continuously circulated (27) through the stack to produce a partially demineralized salt solution (28), an acid solution (30) and a base solution (32). The acid solution (16) and base solution (18) are continuously circulated through the stack (10) to increase the concentration thereof. The circulating salt solution is controlled to maintain the salt concentration (36, 38) in the range of 2% to 25% and the pH (109, 112) in the range of 8-11. The concentrations of the circulating acid solution (60) and base solution (64) are controlled to maintain the concentrations thereof in the range of .2N to 3.0N. The concentrated acid solution (20) and base solution (22) are utilized to regenerate exhausted ion-exchange resins (106, 108).