Enhancement of Ammonium Adsorption Capacity with Pretreated Natural Zeolites

The need for a simple and efficient method of ammonia removal from treated wastewater in Advanced Life Support systems is critical to future long-term space missions. Current wastewater technologies, microbiological digestion via wastewater or compost, produce a wastewater containing concentrated ammonium. This study evaluated the cation exchange properties of various zeolites from both the clinoptilolite and chabazite classes. When the initial NH₃-N concentrations, 100 - 300 mg/L NH₃-N, of synthetic wastewater was applied to batch reactors, ammonium uptake by clinoptilolite was comparable to that of chabazite. However, for very high loadings of concentrations, 500 – 1000 mg/L NH₃-N, chabazite with sodium as the exchangeable ion was found to provide the highest maximum capacity (32.73 mg NH₃-N/g_zeolite), in terms of the adsorption capacity. The adsorption capacity of chabazite was enhanced by pre-heating it for one hour.