REDUCTION OF ANION LOAD IN ULTRAPURE WATER SYSTEM

摘要

PURPOSE:To reduce the load of an ion exchange apparatus, by preparing air from which carbon dioxide is preliminarily removed in the packed bed of a wet adsorbing tower using an alkali agent and removing carbon dioxide in water in a decarbonator using said air. CONSTITUTION:Raw water 1 to be treated is sent into the upper part of a raw water decarbonator 4 from a raw water tank 2 by a raw water pump 3. Hydrochloric acid or sulfuric acid is injected in a water feed line 5 from an acid storage tank 6 to lower the pH of raw water to 4-5 and an almost entire quantity of alkalinity is preliminarily converted to carbon dioxide. Air is sucked in a wet adsorbing tower 9 by a blower 8 and allowed to pass through a packed bed 14 to which alkali water 11 is sprayed to absorb and remove carbon dioxide from air through gas-liquid contact. Therefore, when carbon dioxide in raw water is expelled and removed in the decarbonator 4 using said air, decarbonation is performed efficiently and raw water low in carbon dioxide concn. is obtained.