A study of layered-unlayered extraction of benzene in soil by SVE

With the aim to improve the pollution removal efficiency, a layered extraction simulation device for the removal of benzene-contaminated soil via soil vapor extraction was constructed. The removal of benzene from soils by both layered extraction and unlayered extraction was explored based on the factors of extraction flow, extraction time, initial contaminant content, initial soil moisture content, and extraction method. Under the same conditions, layered extraction improved the repair efficiency, shortened the repair time, and decreased the cost of repair. Different factors exerted different influences on the extraction effect, but overall, compared with unlayered extraction, the removal rate of layered extraction can be increased by 2-20%. In particular, when the content of benzene was high, layered and intermittent extraction could remove more than 90% of benzene from the soil. When layered extraction was adopted, the pressure loss in the lower part of the soil layer was small and the air flow into the soil was large, which can promote the volatilization of benzene and thus improve its removal rate. (C) 2020 Elsevier Ltd. All rights reserved.