Simultaneous removal of ammonium nitrogen, dissolved chemical oxygen demand and color from sanitary landfill leachate using natural zeolite

In this study, natural zeolite with maximum adsorption capacity of 3.59 mg g−1 was used for the simultaneous removal of ammonium nitrogen (NH4+-N), dissolved chemical oxygen demand (d-COD) and color from raw sanitary landfill leachate (SLL). Saturation, desorption and regeneration tests of zeolite were performed. Optimum adsorption conditions were found for particle size 0.930 µm, stirring rate of 1.18 m s−1, zeolite dosage of 133 g L−1 and pH 8. NH4+-N removal efficiency reached 51.63 ± 0.80% within 2.5 min of contact. NH4+-N adsorption follows mostly the linear pseudo-second order model, with intra-particle diffusion. NH4+-N desorption follows the linear pseudo-second order model. Adsorption data fitted to the Temkin Isotherm in linear and nonlinear forms. Saturation tests showed that zeolite can be efficiently used in three successive adsorption cycles. NH4+-N release from the saturated zeolite was not completely reversible, suggesting that the zeolite may be used as slow ΝΗ4+-Ν releasing fertilizer and an attractive low cost material for the treatment of SLL. NH4+-N removal with the regenerated zeolite exceeded 40% of the initial concentration in the fluid within 2.5 min. SEM analysis showed significant changes through saturation and regeneration. XPS revealed that adsorption of ΝΗ4+-Ν to the zeolite was accompanied by ion exchange.