Influence of Zeolite Dose on Eliminating Nitrogen Load of Europhia Sediment Capping with Active Barrier System (ABS)

Abstract

Abstract: This study investigated to eliminate the nitrogen load of sediment from Yangzhou ancient canal capping with an active barrier system (ABS) using two kinds of zeolite with five different coverage densities. For ABS capping with zeolite F1 when the zeolite dose is low (0.21 kg/m2 and 0.62 kg/m2), it is found that ABS failed to achieve good control in preventing N release in the entrophic sediments as total nitrogen (TN) concentrations of overlying water were increased to 3.76 mg/L and 3.13 mg/L, respectively after 16 days. However, when zeolite density was increased to 1.04 kg/m2, TN concentration of overlying water decreased to 1.94 mg/L and TN removal efficiency is up to 50% after 16 days. For ABS capping with zeolite F2 TN concentration of overlying water is reported to descend in both low dose and high dose series. It is found that zeolite F2 is unfit for remediation of sediments from ancient Canal in Yangzhou because the ability in preventing release of ammonia nitrogen from sediments is weak. A possible explanation is that microorganism attaching on surface of two zeoltes differs to cause large difference of removal capacity between zeolite F1 and zeolite F2. It is found that nitrification and denitrification is the principal pathway for the former one while nitrite accumulation appears in the latter. To sum up, the capacity of eliminating TN load by zeolite F1 is stronger than that by zeolite F2, the optimum capping density of zeolite F1 is 1.04 kg/m2.