Concentration of ammonium from municipal wastewater using ion exchange process

• Strong acid cation exchange resin has the highest capacity among studied materials.
• Natural zeolite is the most selective for ammonium ions among studied materials.
• Electric conductivity measurements can be used for ammonium breakthrough detection.
• Ammonium can be concentrated from 26 to 581 mg NH4-N/L from municipal wastewater.

The scope of this study is concentration of ammonium from municipal wastewater using ion exchange process. Four types of ion exchange materials were tested in packed bed columns, namely strong and weak acid cation exchange resins and natural and synthetic zeolites. In total 23 runs of saturation and regeneration were done using synthetic wastewaters of different kinds and pretreated municipal wastewater. Due to its high exchange capacity and fast regeneration strong acid cation exchange resin was found to be the most suitable for ammonium concentration under condition that selectivity of ammonium removal is not of a main concern and it allows concentrating ammonium from 27 to 580 mg NH4-N/L. If selective ammonium removal is required, natural zeolite should be used instead. Regeneration with 0.17 M HCl and 0.17–0.51 M NaCl was tested and suitability of different regenerants for different technologies of spent regenerant treatment was discussed. It was shown that electric conductivity measurements can be used for detection of breakthrough and estimation of ammonium concentration in outflow from an ion exchange column. Breakthrough curve fitting with Thomas and Adams–Bohart models was performed which gave information about the maximum exchange capacity of materials and kinetics of ion exchange.