水位波动对表面活性剂修复苯胺污染土壤的影响研究

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

  • 摘要: 为探究水位波动对表面活性剂修复苯胺污染土壤的效果影响,以西北某农药污染场地的砂土和粉土为研究对象,设计单岩性(砂土)与双岩性(砂土-粉土-砂土)土柱,通过室内试验对土柱各土层和淋洗液中苯胺的质量浓度进行测定分析,探讨了在不同土柱岩性下,水位波动对表面活性剂修复苯胺污染土壤的影响。结果表明:(1)水位波动显著提升苯胺去除效率,单岩性砂土柱和双岩性土柱的去除效率分别提高10%和13%,累计去除量最高达9.63 mg。(2)土层岩性差异主导污染物迁移分布和修复效率,单岩性砂土因高渗透性促进垂向迁移,而双岩性土柱中粉土层由于其低渗透性和强吸附性截留污染物形成局部富集区,水位波动通过增强砂土-粉土界面水力梯度,克服了粉土对修复效率的限制,使双岩性土柱的苯胺去除效率较无波动条件提升13%,累计去除量达9.04 mg。(3)提高水位波动频率可加速污染物洗脱,但需平衡淋洗液流速与表面活性剂接触时间,以优化传质效率。研究表明,动态水位管理模式通过周期性调节淋洗参数,可有效强化表面活性剂对成层土壤中苯胺的解吸与迁移作用。在针对成层土污染场地修复治理工程中(如贺兰山冲积扇LPZ-HPZ结构),建议结合土层渗透性和吸附特性设计差异化修复方案,以提高经济性与精准性。

     

    Abstract: To explore the impact of water table fluctuation on the effectiveness of surfactant remediation of aniline-contaminated soil in stratified soil, sandy soil and silt soil from a pesticide-contaminated site in Northwest China were selected as research objects. Single-rock-type (sandy soil) and dual-rock-type (sandy soil-silt soil-sandy soil) soil columns were designed. Through indoor experiments, the mass concentrations of aniline in each soil layer and the leachate of the soil columns were determined and analyzed. The influence of water table fluctuation on surfactant remediation of aniline-contaminated soil under different soil column rock types was discussed. The results show that: (1) Water table fluctuation significantly improves the removal efficiency of aniline. The removal efficiencies of single-rock-type sandy soil columns and dual-rock-type soil columns increase by 10% and 13% respectively, and the cumulative removal amount reaches up to 9.63 mg. (2) The difference in rock type of soil layers dominates the migration and distribution of pollutants and the remediation efficiency. The single-rock-type sandy soil promotes vertical migration due to its high permeability, while in the dual-rock-type soil column, the silt soil layer retains pollutants due to its low permeability and strong adsorption, forming a local enrichment zone. Water table fluctuation enhances the hydraulic gradient at the interface between sandy soil and silt soil, overcoming the limitation of silt soil on the remediation efficiency, and increases the aniline removal efficiency of the dual-rock-type soil column by 13% compared to the no-fluctuation condition, with a cumulative removal amount of 9.04 mg. (3) Increasing the frequency of water table fluctuation can accelerate the desorption of pollutants, but it is necessary to balance the flow rate of leachate and the contact time of surfactant to optimize the mass transfer efficiency. The study shows that the dynamic water table management mode can effectively enhance the desorption and migration of aniline in stratified soil by periodically adjusting the leaching parameters. In the remediation and treatment projects of stratified soil contaminated sites (such as the LPZ-HPZ structure of the Hengshan alluvial fan), it is recommended to design differentiated remediation schemes based on the permeability and adsorption characteristics of soil layers to improve economic efficiency and precision.

     

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