Sorption and desorption of ammonium by zeolite: Batch and column studies

Abstract

The major objective of this research was to investigate the efficiency of zeolite in the removal of NH₄-N from swine wastewater and desorption of the sorbed NH₄-N from the zeolite saturated with N. Sorption experiments were conducted on the sorbents, zeolites I, II and III. Zeolites II and III which are natural and unmodified, showed better sorption (4400–4500 mg kg⁻¹ with 500 mg L⁻¹ feed concentration) compared to Zeolite I (3053 ± 127 mg kg⁻¹ with 500 mg L⁻¹ feed concentration), which is a surfactant modified zeolite. Freundlich and Langmuir isotherms were plotted from the sorption experimental data. Column studies indicated that, columns with flow rates of 2 and 3 mL min⁻¹, reached the breakthrough point within about 100 h. The possibility of regeneration of the column material was investigated by flushing the column with 0.1 N HCl. The results from this experiment showed that even after desorption with DI water for more than 250 h, considerable amount of N was still available in the column that was available for desorption by 0.1 N HCl. This confirms that zeolite could be a good substrate for slow N release in soil. The application of Zeolite II for the NH₄-N removal from swine wastewater supports this observation.

Keywords:

• Desorption
• nitrogen
• sorption
• zeolite

Acknowledgments

This study was supported by the grant from Texas A&M University – Southern Water Quality Program, Prime Award No. 2008-51130-19537.