Among the available technologies for ammonium removal from wastewater, ion exchange represents one of the most promising ones in the perspective to recover ammonium and produce a fertilizing product. However, the vast majority of previous studies on ammonium ion exchange did not evaluate the process robustness under real operational conditions nor optimized the desorption step. In this paper, tests of ammonium removal and recovery were conducted on a metakaolin K-based geopolymer, compared with a high-performing Italian natural zeolite in K-form. Real municipal and saline wastewater was treated in a continuous flow pilot plant equipped with a 60-cm adsorption bed (bed volume 203 mL, sorbent mass 145–173 g, empty bed contact time 10 min). Geopolymer granules showed higher performances in terms of selectivity towards ammonium, operating capacity (8.5 mg_N g⁻¹ dry adsorbent at an inlet concentration of 40 mg_N L⁻¹), bed volumes of wastewater treated at the selected breakpoint (149). Geopolymer resulted to be a cost-effective adsorbent for wastewater treatment capable to adsorb cations by ion exchange, allowing a fractionated desorption procedure that led to recover ammonium in a solution composed mainly by NH₄NO₃ (37%_wt) and KNO₃ (56%_wt), potentially usable as fertilizer. The geopolymer robustness was assessed after repeated adsorption/regeneration cycles showing that the geopolymer mechanical and morphological properties did not deteriorate. The results make the tested geopolymer a very promising material for the optimization and scale-up of the ammonium recovery process in a circular economy perspective.

在从废水中去除铵的可用技术中，从回收铵和生产肥料产品的角度来看，离子交换是最有前途的技术之一。然而，以往关于铵离子交换的绝大多数研究都没有评估实际操作条件下的工艺稳定性，也没有优化解吸步骤。在本文中，对偏高岭土 K 基地质聚合物与高性能的 K 型意大利天然沸石进行了铵去除和回收测试。在配备 60 厘米吸附床（床体积 203 毫升，吸附剂质量 145-173 克，空床接触时间 10 分钟）的连续流动试验工厂中处理真正的市政和含盐废水。地质聚合物颗粒在对铵的选择性、操作能力（8._N g ^-1入口浓度为 40 mg _N L ^{- 1}的干吸附剂），在选定的断点处处理的废水床体积（149）。地质聚合物最终成为一种成本效益高的废水处理吸附剂，能够通过离子交换吸附阳离子，允许分馏解吸程序回收主要由 NH ₄ NO ₃ (37% _wt ) 和 KNO ₃ (56_重量百分比)，可能用作肥料。在重复吸附/再生循环后评估地质聚合物的稳健性，表明地质聚合物的机械和形态性能没有恶化。结果使测试的地质聚合物成为从循环经济角度优化和扩大铵回收过程的非常有前景的材料。