Volume 3, Issue 6 (June 2006)
Effect of Dispersivity of Filling Material on Performance of Contaminant Barrier
The performance of pollution barriers is discussed using solute soil dispersion parameters. Masa sandy loam and Toyoura sand, with dispersivities of 0.21 and 0.17 cm at saturation, respectively, were used as barrier material. 2.5 wt.% of the synthetic P-type zeolite was mixed with the soil to control the adsorption capacity of the barrier without changing soil structure. Soils were packed into an acrylic plastic column to form model barriers with different thicknesses. Adsorption capacity of the columns was between 6.1 and 7.5 mmolc per column. 42 mg·dm−3 Cd as nitrate solution was applied to the column under water saturated conditions, and effluent was collected at the bottom of the column. A relatively thin barrier, i.e., five times greater than the dispersivity, resulted in the detection of Cd with only 0.075 mmolc load of Cd, while a thicker barrier, 30 times greater than dispersivity, showed no leak of Cd with a 0.9 mmolc load of Cd added to the column.