School of Resource and Environmental Engineering, Hefei University of Technology, Hefei 230009, China.
School of Resource and Environmental Engineering, Hefei University of Technology, Hefei 230009, China.
J Contam Hydrol. 2022 Oct;250:104049. doi: 10.1016/j.jconhyd.2022.104049. Epub 2022 Jul 7.
Surfactant-enhanced air sparging (SEAS) is an effective technology for the remediation of volatile organic compounds contamination of medium and high-permeability soil, though applying SEAS to low-permeability soil contamination has rarely been explored. In this study, a series of two-dimensional physical model tests were designed to explore the feasibility and remediation characteristics of SEAS on low-permeability soil. In the test results, the incorporation and increase in surfactant concentration promoted air channel formation in the low-permeability soil, finally reduced the capillary breakthrough pressure and improved the airflow rate. The majority of the exhausted gaseous contaminants were distributed along the horizontal direction, differing from the results observed in medium and high-permeability soils. The exhausted gaseous contaminant concentration changed slightly when the sparging pressure and surfactant concentration increased at relatively low levels and increased as the sparging pressure and surfactant concentration increased further. Increasing the air sparging pressure without surfactant incorporation or with a low surfactant concentration cannot effectively remove the contaminant, while the removal efficiency can be enhanced with further increases in surfactant concentration. The discrete remediation characteristics had been confirmed during SEAS application on low-permeability soil, then the relationships between the ratios of remediation area and remediation extent under different surfactant concentrations and sparging pressures were established for remediation efficiency evaluation. Using this method, the discrete remediation characteristics can be recreated once the surfactant concentration and the sparging pressure were chosen. On the other side, targeted improvements in the remediation area or extent can be achieved by controlling the surfactant concentration and sparging pressure. Through this study, SEAS technology and the proposed evaluation method were successfully implemented in soil with hydraulic conductivity around 9E-7 m/s, which expanded the application scope of SEAS technology for contaminant removal.
表面活性剂强化空气吹脱（SEAS）是一种修复中高渗透性土壤中挥发性有机化合物污染的有效技术，但很少有人探索将 SEAS 应用于低渗透性土壤污染。本研究设计了一系列二维物理模型试验，以探讨 SEAS 对低渗透性土壤的可行性和修复特性。在试验结果中，表面活性剂浓度的增加促进了低渗透性土壤中空气通道的形成，最终降低了毛细突破压力，提高了气流速率。大部分耗尽的气态污染物沿水平方向分布，与中高渗透性土壤中的结果不同。在相对较低的注气压力和表面活性剂浓度下，当注气压力和表面活性剂浓度增加时，耗尽的气态污染物浓度变化不大，进一步增加时会增加。不添加表面活性剂或表面活性剂浓度较低时增加空气注入压力并不能有效地去除污染物，而进一步增加表面活性剂浓度可以提高去除效率。在低渗透性土壤上应用 SEAS 时已经确认了离散修复特性，然后建立了不同表面活性剂浓度和注气压力下修复面积与修复程度之比与修复效率评价之间的关系。使用这种方法，一旦选择了表面活性剂浓度和注气压力，就可以再现离散修复特性。另一方面，可以通过控制表面活性剂浓度和注气压力来实现对修复面积或程度的有针对性的改善。通过这项研究，成功地将 SEAS 技术和提出的评价方法应用于水力传导率约为 9E-7 m/s 的土壤中，扩大了 SEAS 技术用于去除污染物的应用范围。
