Multifunctional application of zeolite for ammonium removal and ammonia emission mitigation in wastewater, carcass leachate, and paddy

Excess ammonium in water and ammonia volatilization from soils pose serious environmental challenges, including eutrophication, air pollution, and nitrogen loss. This study evaluated the use of natural zeolite (clinoptilolite) for ammonium removal from wastewater and carcass leachate, as well as for mitigating ammonia emissions from paddy soils. Thermal activation of zeolite from 0 to 900 °C showed that NH4–N removal efficiency decreased from 78.5% to 1.4% because of the collapse of the crystalline framework at high temperatures. Batch adsorption experiments indicated that equilibrium was reached within 30 min, with a maximum adsorption capacity of 10.05 mg/g. The adsorption kinetics and equilibrium were best described by the pseudo-second-order and Freundlich models, respectively, suggesting multilayer chemisorption on heterogeneous surfaces. In leachate from thermochemically treated carcasses (49.6 mg/L NH4–N), 84.1% removal was achieved at a zeolite dose of 20 w/w%, increasing slightly to 89.3% at 40 w/w%. Under simulated paddy conditions, 30 g of zeolite reduced cumulative NH3 volatilization from urea by 28.8% compared with the control. These findings demonstrate that zeolite effectively removes ammonium from liquid wastes and mitigates gaseous nitrogen losses, providing a sustainable approach for nutrient management and pollution control in agricultural and waste treatment systems.