Removal of Concentrated-calcium Ions using Packed Columns of Zeolites

Tests of ion exchange column using fixed beds of zeolites were carried out to remove concentrated-calcium ions in industrial wastewater. Relative removal efficiency of calcium ions was accomplished through the comparison of breakthrough curves between synthetic wastewater composed of alone and real industrial wastewater from a stainless-steel factory; particularly when effluent concentration reached at the breakthrough point (), and calculated CEC (cation exchange capacity) for real wastewater was 49.6 meq/100g in spite of 67.9 meq/100g for synthetic wastewater. This lower removal efficiency of real wastewater was caused by the presence of competitive cations inside. In both experiments, measured MTZ (mass transfer zones) exceeded over 50% of the column length because of the high calcium concentration (>500ppm) in both influents. Finally, by modifying the flowrates of regenerating solution (3.8% NaCl), the optimal regeneration was observed at the flowrate of 23.0ml/min which was twice faster than the inflow flowrate (11.5 ml/min, HRT=2 hrs).