Physical and numerical modeling for assessing chromium migration and retention dynamics in clayey soil

The disposal of chromium-laden sludge from tannery industries poses significant challenges to geo-environmental professionals, particularly due to the potential for sub-surface migration of toxic leachate, which can severely degrade soil and groundwater quality. This research investigates the migration behavior of chromium(VI) through clayey soil using column tests to evaluate the contaminant buffering capacity, thereby providing insight into its use as a landfill liner material within waste containment structures. The breakthrough curve (BTC) resulting from the column tests indicated that a soil bed height of 10 cm became saturated with solute after 45 days, demonstrating a good retention capacity for chromium(VI), as the slope of the BTC was notably flat. Furthermore, numerical modeling was conducted using the HYDRUS 1D solute transport software, revealing that the modeled results were in considerable agreement with the experimental BTC data (R2 = 0.7212, RMSE = 0.4418). Consequently, the HYDRUS 1D model emerges as a valuable tool for optimizing the thickness of clayey soil liners in chromium-laden waste containment structures, effectively preventing toxic leachate migration through sub-surface soil and safeguarding groundwater from contamination.