NITRATE/SULFATE REMOVAL SYSTEMS
Various regulatory agencies deem nitrates in excess of 45 mg/l as NO3 (10 mg/l as N) to be harmful especially to infants, the elderly, and immune system compromised people. It is also harmful to some fowl and livestock. Sulfates in excess of 250 mg/l may have detrimental health effects. Since the late 70’s, special ion exchange resins have been available to remove nitrates and sulfates from water. These are anion resins typically provided in the chloride form. Their important feature is that they do not release accumulated nitrates or sulfates which are referred to as “dumping”. As a result, even if there is a failure the water out of the systems never has a con-tent of either nitrates or sulfates higher than the incoming water.
Such systems are exactly like a residential or commercial water softener in function and appearance except SOME of the softening resin is replaced with the special anion resin. By having both types of resin in the same tank (they do not mix but rather stay in separate layers) full use of the salt is obtained sodium or potassium (Na or K) for the softening resin and chloride (Cl) for the nitrate/sulfate resin—and maximum efficiency is obtained. By knowing the capacity of the anion resin (about 15,000 grains/cu. ft.) and the softening resin (about 30,000 grains per cu. ft.) and the nitrate plus sulfate content of the water converted to grains per gallon as calcium bicarbonate we can put the exact ration of each resin into a tank.