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Sodium Bisulfite Residual
Posted: Monday, July 26, 2010 1:06 PM
Joined: 7/26/2010
Posts: 8

Hello to all,


At our WWTP we are required to constinuously monitor our de-chlorination agent (Sodium Bisulfite). In the event of equipment malfunctions, we need to acquire grab samples and run them ourselves.


Does anyone knows what type of equipment we would need for such purpose? We would prefer handheld meters, but it seems that there are none...


Thank you very much!!

Posted: Monday, July 26, 2010 1:32 PM
Joined: 12/31/2009
Posts: 40

There is a titration method to check for sulfite.  Try SM 4500 SO3 B.  It requires sulfuric acid, potassium iodide-iodate titrant, sulfamic acid crystals, EDTA reagent and starch indicator.  I don't know what kind of levels you want in your process, but I think it is only good down to about 1 or 2 mg/L sulfite.  Sulfite is about 80% by mass of the sodium bisulfite compound, so you could only measure about 2-3 mg/L of sodium bisulfite.

Posted: Monday, July 26, 2010 4:26 PM


Thank you DSmith for your response!


Our limit for chlorine residual is 0.01mg/L, theoricatically any indication of bisulfite in our final effluent is an indication of the lack of chlorine residual.


Again, thank you.

James Royer
Posted: Tuesday, July 27, 2010 8:50 AM
Joined: 9/21/2009
Posts: 98

Hach has a drop count titration method which makes it a simple analysis. Each drop is 1 mg/L so we make a 1/10 dilution of titrant so we can see 0.1 mg/L detection. This is for process control so we just want to be sure the procedure works. The result is in sodium sulfite so just adjust your units for sulfite or bisulfite as you would like to see them.

Posted: Tuesday, July 27, 2010 12:24 PM

Are you required to check sulfite only when your TRC is <0.1?

Posted: Tuesday, July 27, 2010 12:25 PM

Sorry, I meant <0.01 ppm

Posted: Tuesday, August 17, 2010 11:12 PM
Joined: 7/26/2010
Posts: 8

It is optional for us to either report bisulfite or chlorine residual values in order to support compliance of the NPDES permit.

Posted: Sunday, June 26, 2011 3:20 PM
It's much esiaer to understand when you put it that way!
Posted: Sunday, June 26, 2011 6:40 PM
I bow down humbly in the presence of such graetenss.
Posted: Monday, June 27, 2011 6:43 AM
Wow! That's a rlelay neat answer!
Posted: Monday, June 27, 2011 1:07 PM
There’s a terrific aoumnt of knowledge in this article!
Posted: Monday, June 27, 2011 1:33 PM
This forum neeedd shaking up and you’ve just done that. Great post!