The effectiveness of silica sand in semi-aerobic stabilized landfill leachate treatment

Abstract

This study examines the suitability of natural silica sand as a low-cost adsorbent for the removal of ammoniacal nitrogen and heavy metals, particularly iron and zinc, from semi-aerobic stabilized landfill leachate. Leachate samples were collected from the Pulau Burung landfill site (PBLS) in Penang, Malaysia. The above-mentioned contaminants are highlighted in this study because of their unsafe concentrations at PBLS. The effects of shaking time, settling time, and silica sand dosage on the study parameter removal efficiencies were investigated to predict the performance of the process. The adsorptions of ammoniacal nitrogen, iron, and zinc were judiciously described by Langmuir and Freundlich isotherm models. The optimum removal efficiencies of ammoniacal nitrogen, iron, and zinc obtained were 51%, 44.4%, and 39.2%, respectively, with a shaking time of 90 min, a settling time of 60 min, and with a dosage of 60 g (0.5 kg/L) of silica sand. Based on the coefficient of determination (R2) values obtained from Langmuir and Freundlich isotherm models, ammoniacal nitrogen, iron, and zinc adsorption were better fitted to the Freundlich model.