Abstract:

In practical remediation projects, it is very difficult to leach heavy metal contaminated soil with high clay content. This is not only because high clay content soil has poor permeability, but also because the specific impact and mechanism of clay content on the leaching of contaminated soil are not yet clear. Therefore, this study investigated the consolidation and heavy metal adsorption and desorption characteristics of soils with different clay content through consolidation tests and oscillatory centrifugation tests. The research results show that there are significant differences in the physical and mechanical properties of soils with different clay content. High clay content soils have higher liquid plastic limits and greater compressibility, while soil permeability and porosity are lower. Moreover, the increase in clay content significantly enhances the soil's adsorption capacity for heavy metal ions, while reducing the removal efficiency of chemical leaching. The content of clay particles increases from 20% to 50%, and the maximum adsorption capacity of heavy metals can be increased by 50%, while the removal rate can be reduced by up to 20%. Among them, the change between the clay particle content of 20% and 30% is particularly significant, mainly due to the formation of a large number of aggregates. The differences in these physical and mechanical properties and adsorption desorption characteristics will have a significant impact on the selection of technology and parameters in soil leaching. Therefore, the conclusion of this experiment can provide a certain reference basis for the optimization of heavy metal contaminated soil leaching and remediation technology.

Key words: heavy metal pollution, clay content, sedimentation method, consolidation test, adsorption-desorption