In Situ Chemical and Physical Treatment of Groundwater

Various in situ physical or chemical methods have been proposed or tested to manage or remediate hydrocarbon-contaminated groundwater in cold regions, such as:

• The construction of vertical barriers to restrict the flow of contaminated groundwater,

• The use of multiphase extraction and vacuum-enhanced recovery to remove both contaminated groundwater and free product, and

• The installation of permeable reactive barriers to sorb hydrocarbons dissolved in groundwater.

It appears that there is very limited published information that documents the success of such in situ physical/chemical applications in cold regions. Therefore, some of these methods should be viewed as emerging technologies, or as being in a research and development phase. For example, Hornig et al. (2008) reported the laboratory testing of three sorbent materials [MYCELX coated sand, granular activated carbon (GAC) and surfactant-modified zeolite (SMZ)], for capture of sparingly soluble hydrocarbons in water. The purpose was to assess these materials for their potential use in permeable reactive barriers in cold regions. Methods included batch sorption tests and various surface characterization techniques. On a mass basis, GAC was found to be the best sorbent at both 20°C and 4°C; on a surface area basis, SMZ was a better sorbent than GAC. Both sorbents had reduced adsorption efficiency at 4°C compared to 20°C.

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