Sulfite Oxidation Reaction (Oxygen Scavenging)

The form-change reaction inside the feedwater tank where sulfite reacts with dissolved oxygen to produce sulfate. Residual sulfite is consumed in proportion to the oxygen load, which is why a higher oxygen load erases the sulfite residual if feed rate is unchanged.

$$\mathrm{S}{\mathrm{O}}_3^{2-}+\frac{1}{2}{\mathrm{O}}_2\to \mathrm{S}{\mathrm{O}}_4^{2-}$$

Variables

Symbol	Meaning	Unit
$\mathrm{S}{\mathrm{O}}_3^{2-}$	Sulfite ion (oxygen scavenger reactant)	mg/L
${\mathrm{O}}_2$	Dissolved oxygen consumed	mg/L
$\mathrm{S}{\mathrm{O}}_4^{2-}$	Sulfate ion (product)	mg/L

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Part of The Blueprint of Water