Method for producing deionized water

摘要

A method for producing deionized water by an electro-regenerating deionization method, which comprises employing a deionized water producing apparatus comprising an electrodialyzer, and ion exchangers being accommodated in the demineralizing compartments, supplying water to be treated in the demineralizing compartments and supplying a concentrated water to the concentrating compartments, wherein the concentrated water at the outlet of the concentrating compartments has a S value of 7 or more as defined by the following formula (1) and a pH of 2.5 or more:wherein gamma is electro-conductivity(muS/cm), A is hydrogen ion concentration (mol/l), and B is magnesium ion concentration (ppb).