Thermally Enhanced Vapor Extraction for Removing PAHs from Lampblack-Contaminated Soil

Abstract

This work summarizes the results of a feasibility study in support of a soil venting-thermal desorption (SVTD) process for remediating lampblack-impacted soil. Lampblack is the solid residue resulting from the gasification of crude oil. The SVTD process couples soil vapor extraction with in situ heating. The objective of this study is to determine the required temperature for desorbing polycyclic aromatic hydrocarbons (PAHs), the compounds of regulatory concern, from lampblack. Bench-scale results are reported for the treatment of a soil-lampblack matrix containing 11 PAHs totaling about 4100 ppm (mg/kg) total PAH (TPAH). Solids characterization analyses suggested that these PAHs constitute about 60% of the organic residue on a solid matrix dominated by fine-grained sand and carbon-based lampblack particles. Thin section imagery supports the conceptual model of hydrocarbons associated with the surface of sand grains. SVTD testing for the sand-lampblack solids indicates that temperatures in excess of about...