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Water Treatment

Water Treatment > Quality Water Solutions > Dechlorination

Introduction

While some residual chlorine may be an indication of safety, in many cases it is necessary to remove residual chlorine from treated water before consumption. It is also necessary to remove the residual chlorine from treated water before discharge into a sensitive aquatic environment. Sulfur dioxide containing compounds, such as sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate, ammonium bisulfite solution and ammonium thiosulfate solution are all effective dechlorinating agents.

Chemicals Used

Sodium Metabisulfite
Sodium Bisulfite Solution
Sodium Sulfite
Sodium Thiosulfate
Ammonium Bisulfite Solution
Ammonium Thiosulfate Solution

Quantity of Chemicals Required

		Parts required per part chlorine removed
Dechlorinating Agent	Formula	pH 4.0	pH 6.5	pH 9.0	pH 11.0
Sodium Metabisulfite	Na₂S₂O₅	1.47	1.47	1.47	1.47
Sodium Bisulfite *	NaHSO₃	1.61	1.61	1.61	1.61
Sodium Sulfite	Na₂SO₃	1.96	1.96	1.96	1.96
Sodium Thiosulfate	Na₂S₂O₃	2.67	2.23	1.60	1.00
Ammonium Bisulfite	NH₄HSO₃	1.54	1.54	1.54	1.54
Ammonium Thiosulfate	(NH₄)₂S₂O₃	2.40	2.13	2.70	1.09

* Calculated from results using Na₂S₂O₅ (when Na₂S₂O₅ dissolves in water, NaHSO₃ is formed according to the following equation: Na₂S₂O₅ + H₂O --> 2NaHSO₃).

Typical Applications

Potable Water Treatment Facilities - following superchlorination
Public Swimming Pools - following superchlorination
Municipal and Industrial Waste Water - prior to discharge
Dechlorination of Water - used in ion exchange and reverse osmosis
Dechlorination for Food and Beverage Applications



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