Iron Removal

[Scoobz7]

Hello,

I am currently working on an Iron Removal project that uses Sodium Hypochlorite to precipitate it out of solution and then filtered using a sand filter unit.
We have been having some problems with large particles being formed in the sand bed instead of prior to it.
What I need to find out is the average time it takes for Sodium Hypochlorite to precipitate out the iron.
Any help is greatly appreciated.

Thanks,
Ron

 

[kenvlach]

Hi Ron,
It would help to know initial & final pH, ORP and residence time(s).

My guess is that you are trying to do 2 things at once – oxidize Fe⁺² to Fe⁺³ while maintaining a high pH for precipitation of Fe(OH)₃. The problem is that the oxidation reaction is slow at high pH, with the result being that the reaction only occurs when catalyzed by the sand (greensand?).

I suggest oxidizing at a lower pH, e.g., 4, and then raising the pH to 9. The oxidation will be rapid, and the precipitation will then occur as rapidly as the pH is raised.

Hope this helps,
Ken