National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Technology, Jilin University, Changchun 130021, China; Key Laboratory of Groundwater Resources and Environment of Ministry of Education, College of New Energy and Environment, Jilin University, Changchun 130021, China.
Key Laboratory of Groundwater Resources and Environment of Ministry of Education, College of New Energy and Environment, Jilin University, Changchun 130021, China.
Sci Total Environ. 2020 Jun 20;722:137844. doi: 10.1016/j.scitotenv.2020.137844. Epub 2020 Mar 12.
The poor performance of air sparging (AS) remediation in heterogeneous porous media is receiving increasing attention. However, understanding of the air migration and flowrate distribution mechanisms in heterogeneous aquifers is still lacking. In this study, for experimental purposes, a heterogeneous aquifer with lenses of different permeabilities was designed in the laboratory. The effects of the double interface between a lens and the background media on the air migration were visually observed for the first time, and four types of double interfaces and their related air flowrate distributions were identified. These were bimodal distribution (∆P ≤ -1.1 kPa, i.e., the air entry suction difference between the background media and the lens), fingered distribution for a low-permeability lens (-1.1 <∆P ≤ -0.3 kPa), Gaussian distribution (-0.3 <∆P < 0.4 kPa), and fingered distribution for a high-permeability lens (∆P ≥ 0.4 kPa). The experimental results indicated that double interface characteristics and air injection rates affected air accumulation behavior. A mathematical model was established to simulate the experimental data of the air flowrate distribution, and it could well describe the air flowrate distribution patterns in heterogeneous aquifers. These findings are significant for improving our understanding of the mechanisms of air migration and flowrate distribution in heterogeneous aquifers, leading to a better design and prediction of the AS remediation required for heterogeneous aquifer pollution.
空气注入（AS）修复在非均质地层中的表现不佳正受到越来越多的关注。然而，人们对非均质地层中气窜和流量分布机制的理解仍然不足。在这项研究中，出于实验目的，实验室中设计了一个具有不同渗透率透镜的非均质含水层。首次直观地观察到透镜与背景介质之间的双界面对空气迁移的影响，并确定了四种双界面及其相关的气流分布类型。这些类型包括双峰分布（∆P ≤ -1.1 kPa，即背景介质和透镜之间的空气进气吸力差）、低渗透率透镜的指状分布（-1.1 <∆P ≤ -0.3 kPa）、高斯分布（-0.3 <∆P < 0.4 kPa）和高渗透率透镜的指状分布（∆P ≥ 0.4 kPa）。实验结果表明，双界面特征和注气率会影响空气的聚集行为。建立了一个数学模型来模拟气流分布的实验数据，该模型能够很好地描述非均质含水层中的气流分布模式。这些发现对于提高我们对非均质地层中气窜和流量分布机制的理解具有重要意义，有助于更好地设计和预测非均质地层污染所需的 AS 修复。
