Studies on removal of ammonium ions from synthetic aqueous solutions and field leachate samples using clinoptilolite

Abstract

The aim of this study is to investigate the capacity of the clinoptilolite for ammonium nitrogen removal from both synthetic solutions and solid waste leachate. Initially, studies were performed in batch reactors using synthetic ammonia nitrogen solutions, in order to establish the applicability of both kinetic sorption rate models as well as the adsorption isotherm models. Subsequently, column studies were carried out with leachate collections from the field to establish the breakthrough time intervals and concentrations, specifically for ammonia nitrogen. The effect of clinoptilolite sample pre-treatments on removal efficiency was also investigated in a series of batch-wise experiments. The Langmuir, Freundlich and Tempkin equations, which are in common use for describing sorption equilibrium of wastewater-treatment applications, were applied to the experimental data. The sorption kinetics were tested for pseudo-first order, pseudo-second order, Elovich and intra-particle diffusion models, and the rate constants of all kinetic models were calculated and compared. The best correlation coefficient was obtained using the pseudo second-order kinetic model, which shows that ammonium uptake process followed the pseudo-second order rate expression. The results obtained clearly showed that the zeolitic tuffs of the Cankiri-Corum Basin in Turkey can be used for removal of ammonium ions both from synthetic aqueous solutions and leachate.