Quantitative analysis of Cu(II)-induced deterioration effects on barrier performance of soil-bentonite slurry

Abstract

Abstract The soil-bentonite (SB) slurry-based barrier technology was successfully used to isolate the heavy metal contaminants at sites. While the heavy metal-induced deterioration effects arouse the urgent need for assessment of the barrier performance. In this study, experimental investigation and theoretical work were performed for quantitative analysis of the deterioration effects. Test results showed that incorporating and increasing the bentonite content in SB slurry could decrease the hydraulic conductivity and increase the contaminant retention of the barrier system. However, after experiencing the Cu(II) contamination, this barrier performance would be rapidly deteriorated and failed to meet the requirement for isolating the contaminated site, especially for Cu(II) concentrations higher than 500mg/L. On this basis, two deterioration parameters were successfully proposed for quantitative analysis of this deterioration effect from the viewpoints of hydraulic conductivity and contaminant retention. In further step, an optimal design method of a barrier system was established and confirmed using the proposed deterioration parameters, for a given service life of barrier system and Cu(II) concentration at contaminated site.