Cascade Aeration

[kchayfie]

I'm in the process of sizing a cascade aerator to assist in the removal of iron from borehole water. I've based my calculation on a calculation for a similar aerator on a previous project and adapted it to suit my project. There is a point in the calculation that states the minimum residence time in the outlet sump is 7 minutes but the author of the calculation has failed to give a reference for this time or an explanation of how it has been derived. As the author is no longer with the company and none of my collegues can tell me where this residence time comes from, can anybody else help...

Thanks

 

[hydrae]

kchayfie

Iron removal by aeration has a recomened retention time of 20 minutes according to "Water Treatment Plant Operation Vol II" but the reaction is temperature dependent and highly pH dependent.
ph 6.25 = 300 min, pH 7.75 = 0 min.

Hydrae

 

[bimr]

Section 4.6.1.2 Detention of Ten States Standards is calling for a 30 minutes detention time.

Try searching previous posts before you put up a question. This was already discussed:

Time required for Iron oxidation
thread164-106305

 

[kchayfie]

Thanks bimr.

I guess I used the wrong keywords when searching for previous posts - the thread you linked was exactly what I've been looking for.

Looks like my 7 minutes is a no-go though!