Sodium zeolite softening is an ion exchange method for removing hardness from water sources achieved by exchanging calcium and magnesium ions for sodium. This process is ideal when applied to domestic, commercial and industrial water softening due to useful purposes such as filtering, odor removal and ion exchange.
When a softener with fresh resin is in service, the sodium ions in the surface layer of the bed are immediately exchanged with calcium and magnesium. This will produce soft water with very little residual hardness in the waste matter. The resin bed will continue to exchange its sodium ions with calcium and magnesium ions until the hardness concentration in the waste material increases rapidly. Referred to as the “breakthrough point” it is the point at which regeneration is needed.
The following is a typical regeneration sequence:
- Counterflow backwash the resin. Specified rates based on temperature and manufacturer’s data. Backwashing removes surface deposits and fines, classifies resin and conditions the resin bed for proper regeneration.
- Regenerate. Brine regeneration consists of educting saturated brine from a brine tank or other source and diluting it to generally 8% to 10% by weight NaCl. The brine should elude through the resin bed, first increasing in concentration, then reaching a peak and decreasing until only dilution water is present.
- Rinse. The fast rinse cycle compacts the resin bed as well as rinsing the final residual brine from it.
Poor regeneration practices are often the cause of problems in zeolite softener systems. An elution study is used to identify and correct softener problems. The study plots the concentration (specific gravity) of brine from a zeolite softener during regeneration along with recording cycle times. The information is then used to troubleshoot and evaluate systems.