| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that when water is not passed through a domestic water softening device using ion-exchange resin over a long period of time, harmless organic matter flows out from the ion-exchange resin and the softening device treated water is contaminated by the organic matter in the form of some odor substances or colored water. SOLUTION: The water-softening/softening-device-regeneration process comprises a conventional water passing stage (water softening stage); a conventional regeneration stage; a conventional flow displacement stage for passing raw water through a flow displacement passage successively comprising a treatment vessel and a drain line; and a new washing stage for passing raw water through a washing passage successively comprising the treatment vessel and the drain line; wherein the flow rate of raw water used in the washing stage is higher than that used in the flow displacement stage and when it is detected that in the water passing stage, no flow of raw water or no flow of treated water by the treatment vessel exists in a passing water passage for a prescribed period of time or longer, the washing water stage is performed and thereafter, the softening operating is shifted from the washing stage to the water passing stage.
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