Performance evaluation of lateritic soil and fungi ( <i>Agaricus impudicus</i> ) in the adsorption and desorption of ammonium nitrogen from human urine

The recovery of ammonium nitrogen (NH₄⁺-N) from human urine offers a sustainable strategy to mitigate eutrophication and enhance nutrient recovery for agricultural use. Despite numerous adsorbents being explored, low-cost and eco-friendly options remain limited, prompting investigation into locally available lateritic soils (LS) and the fungus <i>Agaricus impudicus</i> as alternative materials. This study evaluated the potential of LS and fungal biomass as adsorbents for NH₄⁺-N recovering from human urine. The materials were characterized using FTIR, SEM, and elemental analysis to determine surface functional groups and morphological features relevant to adsorption. Batch experiments were conducted to assess the adsorption capacity and desorption properties of the adsorbents. The equilibrium data were analyzed using Dubinin-Radushkevich (D-R), Freundlich, and Langmuir isotherm models to determine the adsorption mechanisms and capacities. The D-R model best described NH₄⁺-N adsorption on LS (<i>R</i>² = 0.968), indicating a predominantly physical adsorption process, while the Freundlich model best fitted the fungal biomass data (<i>R</i>² = 0.813), suggesting multilayer adsorption on heterogeneous surfaces. LS exhibited a higher adsorption capacity (16.314 mg/g) than fungal biomass, which could be attributed to its mineralogical composition. Overall, both adsorbents demonstrated effective NH₄⁺-N removal and moderate nutrient release, highlighting their potential for sustainable nutrient recovery and reuse in agriculture.