Use Of Sulfites To Remove Chlorine Or Chloramine In High Purity Water

Question
A USP system was designed with a sulfite injection system. The question is, can bisulfite or metabisulfite be used to replace the sulfite?

Answer
Injection of sulfites is one way of removing chlorine or chloramines from high purity water systems. The other methods include activated carbon and ultraviolet lights. Chlorine or other oxidizing agents must be completely removed prior to reverse osmosis units using TFC membranes or continuous deionization (CDI) units to avoid oxidation of the membrane. This discussion focuses on injection of sulfites. Municipal water treatment facilities usually add a disinfecting agent to the water before it is distributed to the users. Common agents are chlorine, chloramines, and ozone. When chlorine gas dissolves in water, it hydrolyzes to form the antibacterial agents hypochlorous acid and hypochlorite.