Impact of Presence and Concentration of Ionic Species on Regeneration Efficacy of Zeolites for Ammonium Removal

One of the biggest challenges to implementing ion exchange processes in full scale at wastewater treatment works is regeneration of the media. In this paper, regeneration efficiency as a function of brine type, brine reuse, molarity and pH was investigated for the zeolite MesoLite treating synthetic solutions of ammonium. When pretreating the zeolite with KCl rather than NaCl, a 30% improvement in regeneration efficiency was found in the first cycle, which dropped to a 10% improvement in the fifth cycle. For both systems, the observed uptake capacity during the load cycle remained constant, indicating that both were effective and that the brine could be reused five times without deterioration in the performance of the zeolite. The use of KCl was more effective at lower molarities than NaCl such that equivalent regeneration efficiencies were observed at 1.0M and 0.1M for NaCl and KCl respectively. Alteration of the pH between 9 and 12 had no impact on the regeneration efficiency. However, operation at pH 12 was possible without brine. Taken together, these findings indicate that the choice of regenerant can have significant implications on regeneration efficiency and that potassium chloride might be a potentially viable alternative choice.