AWWA ACE65185

In an effort to reduce brine (i.e., chloride) use and discharge for softening and barium removal, the city of Crystal Lake, Illinois evaluated the use of calcium-form strong acid cation exchange for the removal of barium. Bench-scale pilot testing was conducted to evaluate the use of calcium chloride in lieu of sodium chloride for regenerating strong acid cation resin. The calcium-form resin was used to selectively remove the barium without affecting total hardness of the water. The selective removal of barium provides longer run cycles between regenerations and thus a considerable decrease in chloride use and discharge. The bench-scale testing was performed using 1-inch diameter glass 40- inches long with 20-inches of bed depth. The downflow service mode was operated at a flowrate of 11 bed-volumes (BV) per hour. The ion exchange column was operated until barium breakthrough was reached at 1.0 mg/L. The ion exchange system was operated at different cycles using different calcium chloride regeneration concentrations and empty bed contact times (EBCT). The use of hydrochloric acid (HCl) to restore the capacity of the resin was also evaluated in this study. The results show that the use of calcium cation exchange can successfully remove barium while significantly reducing chloride use and discharge. The same technology can be used to remove radium or strontium from the water. Includes reference, table, figures.