| 摘要 |
PROBLEM TO BE SOLVED: To efficiently separate a cation exchange resin and an anion exchange resin from each other by effectively utilizing water in a system as back washing water at the time of regenerating a mixed resin layer of a mixed bed type ion exchange demineralizer in a pure water producing method having a RO membrane separation process by a RO membrane separation device and an ion exchange process by the mix bed type ion exchange demineralizer. SOLUTION: This cation exchange resin and the anion exchange resin are separated from each other by passing the permeated water and/or the concentrated water of the RO membrane separation device through the mixed resin layer in upward water stream to back wash at the time of regenerating the mixed resin layer in the pure water producing method having the RO membrane separation process for demineralizing by passing water through the RO membrane separation device after an alkali agent is added and the ion exchange process for demineralizing by passing water through the mixed resin layer of a cation exchange resin with an anion exchange resin. |
