Background and purpose: Ammonia in form of ammonium ions pollutes the acceptor water through industrial, domestic and agricultural wastewater. Ammonium ions are toxic and could decrease the dissolved oxygen in water and endanger the aquatic life. One of the conventional methods for removing ammonia from water and wastewater is exchanging the ions using zeolites. The aim of this study was to assess the efficacy of zeolite Clinoptilolite in removing ammonia from water, in both batch and continuous systems. Materials and methods: In this study batch experiments were exposed to different concentrations of natural Clinoptilolite (5, 10, and 50 g/l) with aqueous solution containing ammonium ions (1, 5and, 10 mg/l) in different exposure times (10 to 240 minutes). The continuous experiments were also conducted at ammonium concentrations of 5 and10 mg/l. Results: The maximum ammonium absorption occurred at pH=7 and in 60 minutes exposure time. Increase in initial concentration of ammonium increased the sorption capacity. Also, sorption capacity decreased when the absorbent material increased. Considering higher correlation coefficient (R2) the isotherm obtained in this study matches the Freundlich isotherm model. The results of column tests showed longer time to reach the breakpoint when initial concentration of ammonium decreased. Breakpoints for ammonium concentrations of 5 and 10 mg/l were 6.45 and 6.32 mg/g, respectively. Conclusion: This study proved that ion exchange using zeolite Clinoptilolite is a low cost method that could result in complete removal of ammonium from water.

Keywords: Clinoptilolite, ammonium, removal, sorption

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