The high cation exchange capacity (C.E.C.) of GSA zeolites combined with their selective affinity for specific cations make them uniquely suited to various applications in water treatment. These natural zeolites have been shown to be effective in industrial and municipal waste water systems. The following is a listing of those cations which can be removed from various effluents by GSA zeolites under the proper conditions:

Rb⁺ Li⁺ K⁺ Cs⁺ NH⁺⁴

Na⁺ Ag⁺ Cd⁺² Pb⁺² Zn⁺²

Ba⁺² Sr⁺² Cu⁺² Ca⁺² Hg⁺²

Mg⁺² Fe⁺³ Co⁺³ Al⁺³ Cr⁺³

One of the first full scale projects to incorporate natural zeolites in a municipal tertiary water treatment system was built for the Tahoe Truckee Sanitation Agency. This system, designed by CH₂M Hill, utilizes zeolite as an ion exchange medium for the removal of ammonium (NH⁺₄). The municipal effluent containing ammonium is passed through the natural zeolite which adsorbs the ammonium ion. The efficiency of ammonium removal is dependent upon temperature, water quality, and rate of flow. Regeneration of the natural zeolite bed for reuse is achieved by passing a brine solution through it. The regenerant then is passed through a stripping unit and the ammonium is converted into  ammonium sulfate, and sold as a fertilizer.

A pilot project near Denver, Colorado, is now using natural zeolites for the removal of ammonium in a potable water system. Similar systems are now in production which remove various pollutants including heavy metals and radioactive ions from industrial effluents.

One alternative to a typical tertiary water treatment plant is to apply effluents over natural soils. The soil filters the pollutants from the water as it gradually percolates to the natural ground-water table which may be recovered from wells for reuse. The soil, as an ion exchange medium, is regenerated by way of crop production capable of removing many of the pollutants. A major limitation of such systems is the requirement for percolation which typically necessitates the use of a sandy soil type not ideal for ion exchange. The low cation exchange capacity of these sandy soil can then be enhanced through the addition of GSA zeolites which will not impede percolation. Tests of such a system were carried out by Dr. Ian Pepper of the University of Arizona. In these tests, a turf grass was used to regenerate the system and adequate efficiencies of pollutant removal were found to be attainable. Additions of natural zeolites in these systems may be found to favorably improve the sequestering of heavy metals. Further testing is required to fully demonstrate this possibility.

Systems for the specific removal of cations from industrial wastes utilizing natural zeolites as a component of the filter medium have been commercialized. These systems have successfully recovered precious metals from plating operations as well as basic industrial pollutants from effluents.

This unique mineral has other diversified uses for which the following Web Pages are available:

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Last modified:  June 22, 2000