Effect of water-level fluctuation on the removal of benzene from soil by SVE.

In areas that experience frequent fluctuations in groundwater levels, changes in soil void space caused by fluctuations in groundwater levels directly affect the efficacy of soil vapor extraction (SVE). Most studies of SVE technology of oil-contaminated soil remediation do not consider fluctuations in groundwater levels. Here, we constructed an experimental device to study the removal of benzene by SVE under fluctuating groundwater levels. Key parameters affecting the remediation effect of SVE, such as the extraction flow, extraction time, extraction method, initial soil moisture content and initial pollutant content, were studied to characterize their effects on the efficacy of benzene removal by SVE under stable and fluctuating groundwater levels. The removal rate of benzene by SVE was approximately 10% higher under fluctuating water levels than under stable water levels. Extraction flow can directly change the removal rate under fluctuating groundwater levels. Under fluctuating groundwater levels, the removal effect of SVE on benzene in different soils of the "stabilization zone - fluctuation zone - saturation zone" also significantly differed; specifically, the removal effect of SVE in the fluctuation zone and stabilization zone was superior to that in the saturation zone. Given the fluctuation in groundwater levels at the study site, the remediation. • The difference of benzene removal with water level fluctuation and stabilization under different parameters was explored. • The remediation efficiency of SVE can be increased by about 10% compared with that under stable groundwater levels. • The difference of benzene removal in site with water level fluctuation and stabilization was explored by mathematical model. • When the fluctuation frequency is low, benzene is more difficult to remove by SVE relative to higher fluctuation frequency. [ABSTRACT FROM AUTHOR]