COMSOL multiphysics 3.5a package for simulating the cadmium transport in the sand bed-bentonite low permeable barrier.

Here, batch study for Iraqi bentonite-cadmium aqueous solution interaction was conducted with conditions of contact time ≤ 120 min, sorbent dosage from 0.05 to 1 g per 100 mL and shaking speed from 50 to 300 rpm for initial concentration of 50 mg/L with initial pH of 3 to simulate the acetogenic phase in the sanitary landfill. The best conditions were 1 h, 0.7 g/100 mL and 250 rpm, respectively to obtain the highest removal (90%). The sorption data were well formulated by Freundlich and Langmuir models with determination coefficient (R²) ≥ 0.98 and sorption capacity of 145.3 mg/g; so, the removal process governed by the physico-chemical forces. The average coefficient of the hydraulic conductivity was found equal to 1.98 × 10⁻¹⁰ m/s and this is suitable for low permeable barrier (LPB). Finally, the predictions of COMSOL package were presented satisfactory simulation for the cadmium concentrations within two-dimensional physical model packed with sand aquifer and Iraqi bentonite. Two configurations of LPB were evaluated for restriction of contaminant front migration and the results proved that the surrounding of the location required to protect it from three sides against to the flow direction can be more dependable from continuous configuration. [ABSTRACT FROM AUTHOR]