Removing Ammonia From Wastewater Using Natural and Synthetic Zeolites: A Batch Experiment

Ion exchange based processes for the removal of ammonium from wastewater using zeolites could be an attractive additional or potentially complementary treatment option for conditions that pose a challenge for biological processes, such as variable load or low temperatures. A range of natural and synthetic zeolites have been studied for removing ammonium from wastewater. However, the relatively low capacity of zeolites and challenges regarding regeneration have so far complicated efforts in this research direction. Here, we compare the most commonly used natural zeolites US-Clinoptilolite, UK-Clinoptilolite, Mordenite and Chabazite (using Na- and Ca- as main cation exchanger) as well as a thermally modified US-Clinoptilolite and a synthetic zeolite MesoLite in terms of their capacity and regeneration efficiency to determine whether a synthetic zeolite like MesoLite can address the aforementioned problems related to capacity and regeneration efficiency. This investigation was performed as a series of batch experiments on synthetic and real wastewater solutions. When zeolites were pre-saturated with sodium ions, we found the overall highest capacity of 4.6 meq/g for the synthetic zeolite MesoLite, relative to a range between 1.1 and 2.1 meq/g for the natural zeolites. Ammonium adsorption capacity of MesoLite with real wastewater ranged between 74 and 97% of what was observed for a synthetically generated mono component solution set at approximately the same ionic load. Our results indicate that MesoLite could be an appropriate media for ion-exchange based tertiary treatment of wastewater.