Advances in Low-Temperature Thermal Remediation

Remediation through traditional high-temperature thermal techniques (over 100 °C) are designed to remove contaminants like petroleum hydrocarbons via enhanced mobilization and volatilization. However, remedies of this nature can require significant infrastructure, capital, operational and maintenance costs, along with high energy demands and carbon footprints. Conversely, low-temperature thermal approaches (in the mesophilic range of ~15–40 °C) are an inexpensive and more sustainable method that can enhance the physical, biological, and chemical processes to remove contaminants. Heat transfer properties of subsurface sediments and other geological materials do not vary considerably and are relatively independent of grain size, unlike hydraulic properties that can vary several orders of magnitude within a site and often limit the pace of remediation of many in-situ technologies. Therefore, low-temperature thermal remediation is a promising alternative that can remediate contaminant mass present in both high- and low-permeability settings, including fractured rock. Emergence of risk-based non-aqueous phase liquid management approaches and sustainable best management practices further offer a platform for low-temperature thermal remedies to advance petroleum hydrocarbon remediation with lower capital and operational costs. Case studies demonstrating this approach along with preliminary sustainability comparisons of the associated reduced energy use and carbon footprint are described in this chapter.