WATER PURIFICATION SYSTEM AND ULTRAPURE WATER PRODUCT

摘要

Ultrapure water containing less than 10 ppt total ions, other than hydrogen ion and hydroxide ion is produced by passing deionized water through a system comprising an ultrafiltration step, an oxidizing step where water is exposed to ultraviolet light and ion exchange step. The treated water is recirculated through the oxidizing step and the ion exchange step. Product water from the system can be recovered on a continuous basis so long as the ratio of volume of water circulated within the system to volume of water drawn from the system is at least 10 and preferably at least 20.