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Sulfide Removal from Water
Sulfide when found in wastewater is normally regulated to less than 1 mg/l. It can be removed from the water by oxidation or precipitation. Oxidants like hydrogen peroxide, chlorine, sodium hypochlorite and potassium permanganate can be used to convert sulfide to sulfur, sulfite or sulfate.
If the reaction is done with excess oxidants than the final product is sulfate. If sulfate is regulated, then the reaction may be limited to the sulfite production by the addition calcium. In this reaction, the sulfite is precipitated as calcium sulfite limiting the production of sulfate ion.
Sulfide can also be removed from water by the addition of ferrous ion which precipitates ferrous sulfide.
H2O2 + 2 e- è
2 OH-
S-- è
S + 2 e-
S + 3 H2O è
SO3-- +
6 H+ + 4 e-
SO3 -- +
H2O è
SO4-- + 2 H+
+ 2 e-
Ca++ +
SO3-- è
CaSO3
Fe++ + S-- è FeS
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