| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrapure water production system and method that can produce ultrapure water having extremely reduced TOC concentration, in particular urea concentration, using a small amount of chemicals at high water recovery rate.SOLUTION: In an ultrapure water production system, a primary pure water system comprises: a color removal device that removes color components in raw water; a cation exchange device that removes alkaline earth metals in the color removed water from which color has been removed; a decarbonation device that removes dissolved carbonic acid in the cation-exchanged water subjected to the cation exchange treatment; a urea decomposition device that oxidatively decomposes urea in water to be treated subjected to the decarbonation treatment; and a reverse osmosis membrane device that performs reverse osmosis membrane treatment of the urea-decomposed water subjected to the oxidative decomposition of urea. The urea decomposition device comprises: an alkali agent feeder that feeds an alkali agent to the urea decomposition device to adjust the pH of the water to be treated to 9 or more; and a hypobromous acid feeder that adds hypobromous acid to the urea decomposition device. |
