Optimization Of Remediation Of Trichloroethylene Contaminated Soil By In-situ Thermal Desorption

The problem of trichloroethylene pollution exceeds the standard exists in typical villages and towns.The research on in-situ thermal desorption technology has very important practical significance to improve the soil environment in villages and towns and promote the engineering application of trichloroethylene contaminated site remediation.In this study,the removal effect of trichloroethylene in soil under different heating temperatures was studied by independently setting up the in-situ thermal desorption soil target heating temperature test rig.he in-situ thermal desorption remediation test bench was set up to study the soil temperature field and heat source temperature variation in the soil heating process,and analyze the output of condensate wastewater and the removal effect of trichloroethylene in contaminated soil.COMSOL numerical simulation software was used for numerical simulation calculation,and the influence of different heat source layout parameters on soil heating effect was analyzed in the actual site.The heat source combination scheme was optimized with energy consumption as the index.The main contents are as follows:1)The in-situ thermal desorption soil target heating temperature test rig was constructed,physical experiments were carried out to study the target heating temperature,and the removal effect of trichloroethylene in contaminated soil under different heating temperatures was discussed.The results showed that the higher the heating temperature,the better the removal effect of trichloroethylene in soil,when the heating temperature is 70℃,trichloroethylene can be effectively removed.2)The in-situ thermal desorption repair effect test bench was constructed,and the variation rules of soil temperature and heating rod surface temperature during soil heating were obtained through physical test.The output of condensate wastewater and the in-situ thermal desorption repair effect were analyzed.The results show that the higher the temperature of the heat source is,the closer the distance is to the heat source,the faster the soil warms up,and the faster the soil responds to the temperature change of the heat source.The yield of condensate wastewater increases with the increase of soil temperature.The overall restoration rate of trichloroethylene in soil was up to the standard of 80.0%,and the restoration effect was good.In the process of soil cooling,trichloroethylene had migration characteristics between soil particles and pores.3)The numerical simulation is carried out by COMSOL numerical simulation software.The numerical simulation results are in good agreement with the physical experiment results,and the numerical simulation model is reliable.4)The influence of different heat source temperature,heat source arrangement and heat source spacing on the removal effect of trichloro ethylene contaminated site was studied by numerical simulation,and the energy consumption per unit area was analyzed under the spacing of 2m,2.5m,3.0m,3.5m,4.4m and 4.5m when heat sources at 700℃ were arranged in equilateral triangle.The results show that heat sources arranged in equilateral triangle have better heating effect on soil.The higher the heat source temperature is,the smaller the distance is,and the heating effect on soil is obvious.Compared with other combination schemes,when the heat sources at700 ℃ are arranged in equilateral triangle and the spacing is 3.5m,the energy consumption per unit area is the lowest,which is the optimal scheme.There are 38 figures,23 tables and 93 references in this thesis.