The transformation and migration of contaminants during the remediation process of heterogeneous strata by the in-situ thermal conductive heating (TCH) technology: A literature review

There are currently large quantities of heterogeneous contaminated sites and the in-situ thermal conductive heating (TCH) technology have been widely used in soil remediation. Some engineering cases have shown that when soil remediation of heterogeneous sites use TCH technology, the gases carrying contaminants migrate laterally and contaminate clean areas. However, there are relatively few domestic studies on this phenomenon. Some international scholars have confirmed the occurrence of this phenomenon on the laboratory scale, but have not proposed an effective solution to the above scientific question. This study first introduced the heating mechanism and heating process of TCH. Meanwhile, the forms and transformation mechanism of organic contaminants were fully expounded during soil remediation by TCH. In addition, the formation, migration, accumulation, and lateral diffusion of gaseous contaminants were comprehensively reviewed during the in-situ thermal desorption of heterogeneous strata. Finally, arrangement methods of extraction pipes to effectively capture gas are provided for the heterogeneous contaminated soils remediated by TCH. The results of this study will provide theoretical and technical support for in-depth understanding of steam movement in heterogeneous formations and the remediation of heterogeneous contaminated sites by TCH technology.