EVALUATION OF OPERATIONAL AND TRANSPORT PARAMETERS OF CHROMIUM ION THROUGH RED EARTH BENTONITE MIXTURESS. N. Maya Naik, Shankara and G.D. Kumara
The assessment of any landfill liner system requires the contaminant transport parameters through selected liner materials. Normally clay soils alone or bentonite amended with soils are widely used as bottom liner. Bentonite is used due to its high adsorption capacity and soil is used to impart the required volume stability and strength. The performance of the liner has to be evaluated for the breakthrough times under diverse hydrological systems by knowing the hydraulic conductivity of the compacted liner and sorption capacity. In this work transport parameters of Chromium ion in red earth bentonite mixtures (kaolinitic soil) are determined by batch test and experimental breakthrough curves (BTC) through column tests. Then experimental BTC is compared with theoretical breakthrough curves generated using POLLUTE v 7 software. The Theoretical BTC is modeled with measured hydraulic conductivity, density and porosity. The tested red earth bentonite mixtures ratios were (70-30), (80-20), and (90-10) with chromium in the aqueous mixture. The batch test reveals that the ratio (70-30) of red soil and bentonite mix gave the highest efficiency. This mixture was optimized with parameters, pH 1.5, and equilibrium time 180 minutes duration and removal efficiency of the ion 49.5%. The same optimized mixture is used to conduct column experiments, by matching the experimental BTCs of the column experiments with the theoretical BTCs modeled by POLLUTE v 7 software, the diffusion coefficient and retardation were determined as 1.22x10-7 cm2/s and 26 respectively.
Enter your contact information below to receive full paper.