Laboratory Characterization of Surfactant-Enhanced Air Sparging Effectiveness on VOC-Contaminated Soil with Low Permeability
2022
Zha, Fusheng | Li, Haonan | Xu, Long | Kang, Bo | Sun, Xianguo
Surfactant-enhanced air sparging (SEAS) technology has been widely accepted to remediate VOC-contaminated soil with medium or high permeability, while the remediation efficiency and mechanism in low permeability soil have been rarely explored, which is of great importance to the field implementation due to the heterogeneous stratigraphic distribution at site. For this purpose, the surfactant-enhanced single air channel sparging tests and solubilization/desorption tests are comprehensively designed and performed in this study. Results showed that the exhaust gaseous MTBE concentration is significantly lower, and the time to reach concentration equilibrium is longer for air sparging in low permeability soil, which could be modified with surfactant incorporation. The reduced MTBE concentration, enlarged remediation zone, and the total MTBE removal rate in the low permeability soil could be observed after implementing the SEAS technology and will be further enhanced with sparging pressure increasing. The mass transfer zone (MTZ) in low permeability soil is enlarged with the increased surfactant concentration, based on which an exponential growth relation is established for MTZ quantitative prediction. The improved remediation efficiency of SEAS technology on low permeability soil is confirmed to be controlled by the contaminant solubilization/desorption mechanism, rather than the surface tension reduction mechanism that was conventionally confirmed in medium or high permeability soil.
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