Experimental Research on the Effectiveness of Contaminant Thermal Desorption Through Electrothermal Technologies

The Sustainable Development Goals identify the need to restore degraded soils in order to improve their productivity. There is broad consensus on the need to enhance the soil resource. The aim is to support food production as well as to store and supply clean water, conserve biodiversity, sequester carbon and increase resilience in the context of profound climate change. These goals require the implementation of sustainable soil management practices worldwide. The choice of the best remediation technologies applicable to a contaminated site need to account for two fundamental elements: an in-depth evaluation/comparison of the different applicable intervention technologies and a rigorous and complete analysis of the environmental context in which the contaminant was found. The evaluation of the environmental context, combined with the definition of the chemical-physical and toxicological characteristics of the contaminants, together with the analysis of the potential active migration paths and any receptors present at the site, constitutes a fundamental part of the remediation plan. When selecting a remediation strategy high priority need to be posed to the application of in situ technologies because they allow the remediation of soil and aquifers in their natural location, without resorting to excavation and disposal operations, minimizing the impacts of remediation interventions. In recent years, environmental problems related to increasing pollution have posed a significant challenge for soil remediation techniques. Among the various methods addressed, Thermal Desorption (TD) is widely used due to its advantages, such as suitability for different types of contaminants, relatively short treatment periods, high efficiency, and high safety. Typically, the heating source for this process involves the burning flame of a flammable gas, which introduces additional issues related to the treatment of the resulting off-gas. Electroheating technologies based on high-frequency electromagnetic radiation, specifically microwaves and radio frequency heating, have been recently investigated for this kind of application because they offer benefits such as faster heating rates, compared to traditional systems, and selective heating of specific compounds. Moreover, since the necessary technological apparatus is powered exclusively by electricity, this technology opens the possibility of using renewable energy sources or utilizing electricity certified as produced from renewable sources. The aim of this work is to compare the effectiveness of thermal desorption for soils contaminated with Anthracene and Perfluorooctanoic acid (PFOA) using three different technologies, where the heating is generated through electromagnetic sources, in a laboratory-scale scenario. The three different technologies which are compared in this work are: microwave (MW) heating, radio frequency (RF) heating and resistor heating. Although there are different works in literature which investigates the potential of electrothermal technologies in this field of application, to the author’s knowledge an experimental comparison of the different methods has never been proposed before.