Keeping Iron in Solution 1

[RBAC]

Hoping someone can help.

I need to find a quick fix to a problem (we're putting in a proper solution later)

I need some way of ensuring that Iron stays in solution for a period of time to allow it to be removed at a wtw rather than depositing in the pipework. Is this easily done?

 

[hotdipper]

You need to provide more specifics. What kind of pipe? What is the source of the Fe. What is the iron in? Is this a steam line, condensate line, cooling water line or other process line. What pH values can you stand in the line. How do you know the deposit is iron?

 

[RBAC]

Sorry, Know it's iron as samples have been taken. Not sure of pipe type. Solution is water and aim is to get it to a water treatment works for removal rather than it precipitating in the pipe and causing large slugs of high iron water to hit the works when the borehole is started up.

Iron is believed to be in the water source, not coming from the pipe. Levels are too high to retain it in solution to put into supply.

pH will need to be adjusted back to around neutral to allow further treatment to occur.

 

[hotdipper]

The iron could easily be put into solution with HCl. But if the treatment plant is a POTW they probably won't allow it. Filtering out the iron at the source would be the ideal approach, but doesn;t help your current situation. Depending on the form of the iron you may be able to chelate with EDTA. I suggest you call a local industrial water treatment company. They will likely have a number of products available. Unfortunately, with 4 miles of pipeline you not going to like the cost.

 

[bimr]

First off, you should be over in the Water treatment & distribution Forum (7281 members) forum 164.

Iron sequestering is accomplished with a food grade polyphosphate. Polyphosphates "coat" and "tie up" the dissolved iron (Fe) ions by preventing a reaction with oxygen and subsequent precipitation. The sequestering agent prevents the staining effect but does not remove iron.

Sequestering only works when the iron is initially in the dissolved "clearwater" form. Sequestering chemicals may be reasonably effective for iron in concentration as high as 0.6 mg/l. As the iron concentration continues to increase, the level of expected success using a sequestering chemical decreases.

A chemical feed pump that starts and stops in tandem with a water well pump adds the sequestering agent. Maintenance is minimal.

Advantages of Sequestering
- Low cost equipment and chemicals.

Disadvantages of Sequestering
- The effectiveness of the treatment is reduced at higher water temperatures or when the water is aerated or when chlorine is added.
- Sequestering chemicals lose effectiveness with time. They revert from the "poly" to the "ortho" form of phosphate.
- Not effective for that portion of iron that has already oxidized and turned rusty.

You should also be aware that the use of polyphosphates may reduce the effectiveness of downstream iron removal processes. A local chemical supplier should be able to supply the polyphosphate.