Dechlorination
Dechlorination
(OP)
I am working on a treatment plant that will be using sodium bisulphite to dechlorinate waste water that will be discharged to a lagoon. Does anyone have any information on the dosing rates of sodium bisulphite vs chlorine in order to effectively "dechlorinate" the water?





RE: Dechlorination
I have no values for sodium bisulphite, but I can give you values for the five compounds used for dechlorination. Once you know the chlorine required to be removed (in mg/l), you multiply it with the following factors to get the dosages:
1. Hydrogen Peroxide 0.479
2. Sulphur Dioxide 0.901
3. Sodium Thiosulphate 2.225
4. Sodium Sulphite 1.775
5. Sodium Pyrosulphite 1.338 (Sodium Metabisulphite)
You can then convert it using the % commercial grade and specific gravity of the above chemicals
Khalid
kmehmood@amwater.com
RE: Dechlorination
Suitable contact materials for s.bisulf. are stainless (304, 316), PVC, FRP and similar. Diaphragm pumps are prefered for metering applications.
In comparison, sodium metabisulfite is 1.34 mg/mg, and again 1.38 parts alkalinity are required.
Both materials react very rapidly with residual chlorine, both free and combined forms and contact times are very short.
Hope this helps,
John