Removal of ammoniacal nitrogen from contaminated groundwater using waste foundry sand in the permeable reactive barrier

The focal point of this study was to use the waste foundry sand (WFS) in the remediation of simulated aqueous solution contaminated with ammonia nitrogen through batch and column tests. Recycling this waste is a real application for sustainable principles because it will reduce disposal costs and the required area in the sanitary landfill. Based on the kinetic sorption measurements for ammonia nitrogen onto WFS, the predominant mechanism was the chemisorption because the measurements were well fitted with the pseudo-second-order model. In comparison with the Freundlich model, the sorption isotherm data were well formulated by models of Langmuir and Sips with a maximum adsorption capacity of 1.152 mg/g. The breakthrough curves for a duration of 80 h certified that the two weight ratios (10:90 and 20:80) of WFS:sand were suitable for maintaining the reactivity and conductivity of permeable reactive barrier (PRB) for pollutant under consideration. The results proved that the increasing of WFS and bed depth increased the breakthrough and saturation times with the sorption capacity of the barrier. Also, the appearance of these curves was directly proportional to the inlet concentration of pollutants and the flow rate of contaminated water. Statistical measures specifically Nash-Sutcliffe efficiency and coefficient of determination were proved that the breakthrough curves were well described by Thomas, Belter, and Yan models.