Multi-field coupled migration characteristics of heat and mass in the process of in-situ thermal remediation of organic contaminated soil

This paper built a simulation test platform for soil in-situ thermal remediation, and studied the temporal and spatial distribution of temperature, moisture and electrical conductivity in the process of thermal remediation under the condition of multi heat source heating and extraction. The effects of different initial moisture content, dry density, heating temperature and heating time on heat and mass coupling migration characteristics and removal of organic pollutants and heavy metal ions are analyzed. The results show that the temperature shows a decreasing trend with the increase of soil initial moisture content, and shows different rules with the change of dry density under different moisture content. The moisture shows a change rule of first increasing and then decreasing, which is significant with low moisture content and high dry density, with a similar change in electrical conductivity. The gradual heating process can promote the further migration of moisture, but it is unfavorable for the temperature rise at the point far away from the heat source. Low moisture content, low dry density and long heating time are more conducive to the removal of organic pollutants, but the effect of in-situ thermal remediation on the remediation of heavy metal ions Cd 2+ is not obvious.