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Nitrate Removal from Drinking Water
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Nitrate contamination is a drinking water issue for residential, industrial and municipal markets. The EPA has approved Ion Exchange and Reverse Osmosis as treatment methods for the removal of nitrates from drinking water.
What are nitrates?
Nitrates naturally occur in our environment and are necessary to support plant life. Nitrates (NO3) and nitrites (N02) are nitrogen-oxygen chemical groups/units that combine with various organic and inorganic compounds. Nitrates when taken into the human body convert to nitrite.
How does it get in water?
The most common source of nitrate is runoff from chemical fertilizers. The nitrogen in the fertilizer changes to nitrate when it comes into contact with the soil. Because nitrates are highly soluble and do not bind to the soil, the nitrates that are not consumed by the crops become the source of groundwater contamination. Furthermore, nitrates do not evaporate so they are likely to remain in the water until consumed by plant or other organisms.
In addition to fertilizer, all sources of combined nitrogen, particularly organic nitrogen and ammonia should be considered as potential nitrate sources, including human sewage and livestock manure. Please refer to the EPA Consumer Factsheet
What are the effects of nitrate?
The EPA has set an MCL (maximum contaminant level) for nitrate of 10 ppm and nitrite at 1 ppm.
Again, according to the EPA Consumer Factsheet:
"Short-term: Excessive levels of nitrate in drinking water have caused serious illness and sometimes death. The serious illness in infants is due to the conversion of nitrate to nitrite by the body, which can interfere with the oxygen-carrying capacity of the childs blood. This can be an acute condition in which health deteriorates rapidly over a period of days. Symptoms include shortness of breath and blueness of the skin.
Long-term: Nitrates and nitrites have the potential to cause the following effects from a lifetime exposure at levels above the MCL: diuresis, increased starchy deposits and hemorrhaging of the spleen."
The Ion Exchange Process
The ion exchange system used for nitrate removal is very similar to a water softener. Instead of using a softening resin, a cation ion exchange resin, an anion exchange resin is used. Both systems use sodium chloride salt (brine) to regenerate the ion exchange resin. Nitrate removal is not as straightforward as hardness removal. Based on your specific requirements, Res-Kem will suggest one of two different anion resins. The choices are a Type II Anion resin or a Nitrate Selective Anion resin.
A Type II Anion (strong base) is best applied to municipal supplies where there is regular testing and maintenance of the system. Because Type II Anion resin is not nitrate selective there will be other ions, primarily sulfate, that compete for the exchange site. To properly size up this system, a complete water analysis will be required to ensure complete compliance and avoid nitrate "dumping" as the system approaches exhaustion. The nitrate level during dumping can be many times higher than the untreated nitrate concentration.
Nitrate selective anion resin is an option used principally on smaller municipal systems and private well sources. Nitrate selective anion resin strongly prefers the nitrate ions to the competing sulfate ions. With this resin we avoid nitrate "dumping". In general this resin may be up to 50% more in cost.
 Download Res-Kem Zeo-Tech Nitrate Removal Brochure
Contact Res-Kem Corp. - Your Water Treatment Equipment Specialist Click Here to Contact Res-Kem for further assistance with all your municipal drinking water contaminant removal needs.
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