Steam-Based In-Situ Soil Remediation

Mercury occurs naturally in rocks, soils, water, and air; anthropogenic sources of mercury, as a contaminant of concern, are found at 290 Superfund National Priority Sites. Thermal treatment, whether practiced above ground on contaminated materials removed from a site, or in ground, is highly effective in removing more than 90 % of mercury in place, depending on site-specific factors and temperatures achieved usually heating to greater than 300 C is required to meet land disposal standards. Treating mercury in the ground avoids the added hazards of transporting contaminant soil to a treatment facility and reduces exposure risks. PCI proposes an innovative direct-fire catalytically stabilized steam generation technology that offers significant energy savings compared to steam boilers, and unlike boilers can operate at the high temperatures needed to be effective for in-situ mercury removal for a wide range of soil porosities, water content, and locations below or in the vadose zone. The technology promises a compact and low emission system that can provide extremely high rates of heat and mass injection in relatively short times (e.g. 10 million BTU/hr from a 4.5 diameter OD system). The process can achieve clean combustion at temperatures from discharge temperatures 300 C to in excess of 1000 C, depending on level of air and water injection, producing super-heated steam with water contents over 60 %. This technology has been developed to work in shallow to deep well bores and should be ideally suited for thermal steam remediation of contaminated soils, especially those containing mercury and its compounds. Commercial Applications and other Benefits: The proposed effort will lead to the ability to remediate contaminated sites in a more efficient and faster manner, leading to reduced costs for mercury removal as well as removal of non-aqueous liquids and other contaminants. Spin-off applications include enhanced and secondary recovery of crude oils and methane hydrates