MIXED BED WATER PURIFYING APPARATUS

PROBLEM TO BE SOLVED: To prevent an anion exchange resin once regenerated from returning to the previous state in one series of a regeneration process by housing the anion exchange resin, a cation exchange resin and an inactive resin having larger specific gravity than that of the anion exchange resin after the regeneration and smaller specific gravity than that of the cation exchange resin before the regeneration in a water purification column. SOLUTION: The anion exchange resin 2, the cation exchange resin 3 and additionally the inactive resin 10 having larger specific gravity than that of the anion exchange resin 2 after the regeneration and smaller specific gravity than that of the cation exchange 3 resin before the regeneration the housed in the purification column 1. The regeneration of the ion exchange resins 2, 3 is carried out by passing a sodium hydroxide through the resin in the uniformly mixed state at first and separating by water stream into a laminar state so as to position the anion exchange resin 2 after regeneration at the uppermost layer, the cation exchange resin 3 before the regeneration at the lowermost layer and the inactive resin 10 at the intermediate layer. After that, the cation exchange resin is regenerated by hydrochloric acid to prevent the anion exchange resin from returning to the state before the regeneration.