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Current IssueSeptember 01, 2014
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Ask The Expert: High iron content in exit stream
06/01/2007 
 
Question:

Our well water is low in pH and free of iron. However, the water flows through a galvanized steel pipeline distribution network. At exit, the water now contains a high level of iron, which has become a nuisance! We suspect the iron source is the pipe. Kindly provide me with useful information to correct this condition without changing the galvanized pipe, because it is conduit installation?

Yemi Fagoyinbo, Hydrochem Engineering Services, Lagos Island, Lagos State, Nigeria

 

Answer: 

Most definitely the iron is the result of pipe corrosion.Use a neutralizing filter of calcium (calcite) and magnesium oxide (Corosex®) in a three-to-one ratio.Use a 10 x 40 tank and run it upflow. Start with half a cubic foot and check the pH downstream after a week or so (do this at several different flows to make sure the filter is not over-correcting).

C. F. 'Chubb' Michaud, C.E., CWS-VI, Systematix, Inc.

Iron pipe corrosion is an electro-chemical process that is largely governed by the oxidation-reduction potential (ORP) of the water, in addition to water temperature, pH, alkalinity and hardness. One solution is to change the water chemistry to limit the solubility of iron and encourage passivation (the formation of a solid protective coating on the inside of the pipe). Raising the pH of the water and adding oxidant to increase the ORP of the water may be the simplest solution.

Sue Rivera, Ph.D., MIOX Corporation

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