NITRATE REMOVAL - As discussed in PURONEWS - Volume 1 Issue 9 - September 2002 Nitrates are removed by a variety of Strong Base Anion (SBA) or Weak Base Anion (WBA) resins. Standard anion resins are subject to Nitrate dumping since they prefer Sulfates over Nitrates. As they near exhaustion the Nitrate level can exceed the level of the influent Nitrates. These resins are best applied where there is a qualified operator to maintain the system. PUROLITE offers standard anion resins such as:
Standard WBA resin A100
Standard SBA resins A300
Also available is the Nitrate removing resin of my choice PUROLITE A520E our Nitrate Selective anion resin. These will not dump Nitrates. The effluent of the resin bed will not exceed the incoming Nitrate level. These I recommend especially for residential systems where the Home Owner is the operator and maintainer. All they need is a Nitrate test kit to occasionally test the water and call for service when there is a problem. I also recommend A520E even for those systems where a qualified operator is present such as Municipal Water Treatment Plants. REMEMBER: A520E will not dump Nitrates.
An advantage of using ion exchange for Nitrate removal is that it can be done inexpensively in a residential application on a whole house basis.
Water Hardness should be reduced if it exceeds 10 gpg. Iron content should be less than 1 ppm. The resin can be loaded into and used with a standard water softener unit with the following modifications:
1. Reduce backwash flow rate by 30-50%.
2. Double the backwash time.
3. Use an inlet basket strainer or a fine slotted inlet manifold.
If the water Hardness is 10 gpg or less you can top dress a water softener with these resins. A minimum 6 bed depth of the resin should be used. Remove the equal amount of softening resin from the unit. Follow the modifications listed above.