Enhanced in situ thermal treatment of soil and groundwater: high temperature treatment and combined remedies

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The clean-up of contaminated sites is a multi-billion-dollar problem. Failure to clean up contaminated soil and groundwater in urban areas limits the redevelopment of brownfield properties required for sustainable urban development, and threatens human and ecological health. Many of the most difficult-to-treat sites have complex geology and are contaminated with non-aqueous phase liquids (NAPLs), a class of hazardous industrial liquids that includes petroleum fuels, creosote, coal tar and chlorinated solvents. In situ thermal treatment (ISTT) technologies are used to treat these chemicals at complex sites by heating the soil and groundwater to vapourize and remove contaminants. ISTT technologies are often used when clean-up is required over short timeframes, and under conditions where injection-based clean-up technologies fail. However, ISTT applications can be costly and energy-intensive, and new research is needed to develop approaches to shorten operation times and ensure performance over a range of contaminants. This research will use a combination of laboratory experiments and numerical modelling to close identified knowledge gaps related to ISTT, leading to the development of improved conceptual models, operation strategies, and simulation tools. Two-dimensional flow cell experiments will be used to investigate the removal of contaminants that boil at temperatures higher than the boiling point of water, as well as to develop optimized extraction schemes to reduce heating times and energy use. One-dimensional and two-dimensional experiments will be used to investigate complementary, lower-energy, post-heating technologies, including thermally-enhanced bioremediation and reactant mixing by thermal convection. Simulations using two different numerical approaches will be compared to the experimental results and to each other, to assess model capabilities and develop techniques for accurate simulation of key ISTT processes. This research will be conducted by a team of University researchers and an industry partner, and will train seven HQP over four years on technical and professional skills relevant to the clean-up of complex contaminated sites.