Research on the impact of water-level fluctuations on the remediation of aniline-contaminated soils using surfactants

In actual contaminated soil remediation projects, the phenomenon of groundwater level fluctuations is often observed, and it has a significant impact on the migration and removal of pollutants. This study focused on the sandy soil and silt soil from a pesticide-contaminated site in the northwest. Single medium soil columns (homogeneous sandy soil) and layered heterogeneous medium soil columns (sand-silt-sand layer sequence structure) were constructed. Through indoor simulation experiments, the influence mechanism of water level fluctuations on the remediation process of aniline-contaminated soil mediated by surfactants was investigated. The results indicated that, compared with the stable water level condition, the removal efficiency of aniline by surfactants was significantly improved under the fluctuating water level condition. Under different water level fluctuation frequencies (5 and 10 mL/min), the removal rates in the single medium soil column increased by 9.76% and 10.39%, respectively, and in the layered heterogeneous medium soil column, the rates increased by 13.02% and 13.56%, respectively. The water level fluctuations had a more remarkable enhancement effect on the remediation of the layered heterogeneous medium soil column, and the increase in fluctuation frequency facilitated the migration and desorption processes of aniline in the soil. The research demonstrated that a dynamic water level management mode could be adopted in the actual contaminated site remediation process. By periodically adjusting the leaching parameters, the remediation efficiency of surfactants for aniline in layered soil could be synergistically enhanced. This achievement can provide a theoretical basis and engineering solution for the precise remediation of organic contaminated sites under complex geological conditions.