In situ thermal remediation uses heat to treat contaminated soil, either through volatilisation, combustion, or chemical processes. The method elevates subsurface temperatures to mobilise contaminants, enhance chemical and biological reactions, or directly destroy pollutants. Various techniques, including hot air or steam injection, electrical heating, and smouldering, are used depending on the type of contamination and soil conditions.
Heat deployment methods can vary widely, ranging from surface heating using blankets and steam injection to more complex methods like electrical conductive heating and in situ flushing. One approach involves heating the subsurface with hot gases or water, while others use electromagnetic radiation such as microwave heating. Each method has its specific advantages depending on the contaminant and the depth at which treatment is required.
While effective for various contaminants like VOCs, PAHs, and pesticides, in situ thermal remediation faces challenges such as potential emissions to the atmosphere and aquifers. Health and safety concerns arise from the use of high temperatures, electricity, and radiation, which require careful management. Moreover, subsurface heterogeneities, like clay layers or underground infrastructure, can hinder the process’s effectiveness.
Despite these challenges, in situ thermal methods offer significant advantages, including the ability to treat contaminated areas without excavation and reduce risks to human health. However, concerns about energy consumption and possible damage to soil structure need to be addressed. Innovations in the field continue to improve efficiency, such as using thermal treatments for managing invasive weeds on brownfield sites, showing potential for broader applications.