Question

Why is sulphur dioxide added to water after chlorination?

Answer 1

Answer:

Sulphur dioxide react with chlorine and water to produce sulphuric acid and hydrogen fluoride.

Answer 2

Dechlorination minimizes the effect of potentially toxic disinfection byproducts by removing the free or total combined chlorine residual remaining after chlorination. Typically, dechlorination is accomplished by adding sulfur dioxide or sulfite salts (i.e., sodium sulfite, sodium bisulfite, or sodium metabisulfite).