Calcium sulfite is a key intermediate in wet flue gas desulfurization (FGD) processes, formed by the reaction of sulfur dioxide with calcium-based sorbents like limestone or lime in power plants burning coal or oil. It can be further oxidized to gypsum, a marketable byproduct used in construction materials. Additionally, it is employed in water treatment to scavenge excess chlorine, as a food preservative (E226) in beverages, dried fruits, and other applications due to its antioxidant properties, and in the paper industry for sulfite pulping to dissolve lignin from wood chips, facilitating cellulose pulp production.