Cheng Kuang, Zhang Te, Peng Kairan, Feng Yahang, Liu Hongshuai, Medawela Subhani
College of Civil Engineering & Architecture, Hebei University, Baoding 071002, China; Institute of Geotechnical Engineering, Hebei University, Baoding 071002, China.
College of Civil Engineering & Architecture, Hebei University, Baoding 071002, China; Institute of Geotechnical Engineering, Hebei University, Baoding 071002, China.
J Contam Hydrol. 2023 Apr;255:104165. doi: 10.1016/j.jconhyd.2023.104165. Epub 2023 Feb 16.
Air sparging (AS) is a popular technology for the in-situ remediation of groundwater contaminated by volatile organic compounds. The scope of the zone within which injected air exists, i.e., zone of influence (ZOI) and the airflow characteristics within ZOI are of great interest. However, few studies have shed light on the scope of the zone within which air flows, namely, the zone of flow (ZOF) and its relation with the scope of ZOI. This study focuses on the ZOF characteristics and its relation with ZOI based on quantitative observations of ZOF and ZOI using a quasi-2D transparent flow chamber. The relative transmission intensity obtained by the light transmission method presents a rapid and continuous increasing near the ZOI boundary, providing a criterion for the quantitative determination of ZOI. An integral airflow flux approach is proposed to determine the scope of ZOF based on the airflow flux distributions through aquifers. The ZOF radius decreases with the growth of particle sizes of aquifers; while it increases first and then keeps constant with the increase of sparging pressure. The ZOF radius is around 0.55- 0.82 times of the ZOI radius, which depends on air flow patterns related to particle diameters d, that is, 0.55- 0.62 for channel flow (d < 1- 2 mm), while 0.75- 0.82 for bubble flow (d > 2- 3 mm). The experimental results show that the sparged air is entrapped with little flowing inside ZOI regions that are outside the ZOF, which should be considered carefully in the design of AS.
空气注入法（AS）是一种用于原位修复受挥发性有机化合物污染的地下水的常用技术。注入空气存在的区域范围，即影响区（ZOI）以及影响区内的气流特征备受关注。然而，很少有研究阐明空气流动的区域范围，即流动区（ZOF）及其与影响区范围的关系。本研究基于使用准二维透明流动室对流动区和影响区进行定量观测，重点研究流动区特征及其与影响区的关系。通过光透射法获得的相对透射强度在影响区边界附近呈现快速且持续增加，为影响区的定量确定提供了一个标准。提出了一种基于通过含水层的气流通量分布来确定流动区范围的整体气流通量方法。流动区半径随含水层颗粒尺寸的增大而减小；而随着注入压力的增加，它先增大然后保持恒定。流动区半径约为影响区半径的0.55 - 0.82倍，这取决于与颗粒直径d相关的气流模式，即对于通道流（d < 1 - 2毫米）为0.55 - 0.62，而对于泡状流（d > 2 - 3毫米）为0.75 - 0.82。实验结果表明，注入的空气在流动区之外的影响区区域内被困住且很少流动，这在空气注入法设计中应予以仔细考虑。
