Comparison study of ammonia and COD adsorption on zeolite, activated carbon and composite materials in landfill leachate treatment

Chemical oxygen demand (COD) and ammoniacal nitrogen have always been the crucially problematic parameters in landfill leachate treatment. This study was conducted to investigate the adsorption properties of ammoniacal nitrogen and COD in semi-aerobic leachate from the Pulau Burung landfill site on zeolite, activated carbon and a new composite media in terms of adsorption isotherm and kinetic. The results show that all adsorbents fitted well with both Langmuir and Freundlich isotherms (R-2>0.9) for ammonia adsorption. A comparison study indicated that the adsorption capacity of composite adsorbent towards ammoniacal nitrogen was higher than zeolite and activated carbon and comparable to activated carbon for COD. Findings from a kinetic study indicated that the adsorption of ammonia on new composite adsorbent and zeolite follow almost all kinetic models such as pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion model, although pseudo-second-order was the most dominant. COD adsorption fitted well with the pseudo-second-order kinetic model, while activated carbon obeys the pseudo-first-order and intra-particle models. (C) 2010 Elsevier B.V. All rights reserved.