soluble iron in bore water

[matty77]

I wish to desalinate a bore water using RO. The water contains soluble iron at 3.7mg/l. After exposure to air for approximately 1 hour the water exhibits a slight cloud which is a very fine iron precipitant that is too fine to filter with media type filtration. I am considering designing the system to leave the iron in the soluble state and feed the RO with this whilst excluding air from the system.
Dosing metabisulfite reverses the iron oxidation and the water once again appears clear.
Ph of the water is 7.5, flowrate of permeate 1.25 m3/hr, recovery 65%.
Has anybody had experience with this type of system, ie high soluble iron feedwater or dosing a reducing agent to maintain iron in soluble form or know whether this approach is likely to work

 

[whoislee]

Beware of iron fouling on the RO membranes...it will cost much to clean and membrane life is shortened.

Best to remove iron prior to RO via greensand filter.

There are 2 sides of a coin
One is to give, one is to take
Give until it hurts with a smile

 

[sklone]

Does the fines settle after some time, say 2 hrs.?? If they settle, then presence of organics is very low or negligible and Birm, Pyrolox, MetalEase, Filox ( expensive ) filter can be used. Manganese Greensand filter can be used too.

Manganese greensand requires regeneration with Potassium Permanganate.

You can find out operating condition of the other types of filters by checking Clack Corporation website. Catalogues can be downloaded from there.

If the fines do not settle, treatment shall be a little tedious. Chemical - Physicl treatment is called for. Filtration with Granular Activated Carbon (GAC) Filter can also work. Need a pilot study.

I have successfully commissioned filters using, Birm, Pyrolox, MetalEase and GAC for differetn type of tube well water.

Need to identify the type of iron presence, sulfide, etc. Organic based or not.

Hope this help.