Well Water : Manganese Removal 1

[Best1]

Dear All,

I have read some of the post on here with interest, but am still a little confused. Trying to design an Fe Mn removal plant. Design Criteria
inlet outlet
Fe 3.5mg/l 0.1 mg/l
Mn 0.15 mg/l 0.02 mg/l

Removing of iron is simple, but confused on removal of Mn. was thinking of having pH correction (>7.5) and oxidation step (Cl2) followed by contact tank provideing 30 mins detention time to alloww complete oxidation of iron. Then passing this through a pressure filter. My fear is that at these conditions the Mn wont be oxidised (requires much higher pH and contact time). Do i need to use MnO2 or greensand filter to ensure Mn oxidation. If so do i need to increase pH furhter?
What would be the optimum treatment? This is for a remote site in Lybia, so the use of biological filters, or membrane technology may not be appropriate, hence a basic, easy to work system would be ideal.
Many thanks team!!

 

[Bjegovic]

increasing ph up to cca 9 will give immediate good results.

if this is potable water, high ph is not acceptable. chlorination + filtration (greensand) will work ok, but you need 3-4 times stechiometric chlorine dose for manganese.

0.02 mg/l mangane is quite low, we had this tested with Mn less than 0.04 mg/l consistently...

 

[thundair]

check out

http://herkules.oulu.fi/isbn9514270487/index.html?lang=en

Cheers

 

[bimr]

Would have to disagree with Bjegovic. Although chlorine is somewhat more active than dissolved oxygen, the pH values required for complete oxidation are nearly as high as with air oxidation. You would need a pH of 10 to oxidize the manganese in 30 minutes.

Would recommend that you use a manganese greensand process. Note that if the free carbon dioxide of the raw water is high, it is advisable to remove it to prevent the manganese pickup from an exhausted bed.