Hu Liming, Meegoda Jay N, Du Jianting, Gao Shengyan, Wu Xiaofeng
State Key Laboratory of Hydro-Science and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, 100084, China.
J Environ Monit. 2011 Sep;13(9):2443-9. doi: 10.1039/c0em00594k. Epub 2011 Jul 13.
Air sparging (AS) is one of the groundwater remediation techniques for remediating volatile organic compounds (VOCs) in saturated soil. However, in spite of the success of air sparging as a remediation technique for the cleanup of contaminated soils, to date, the fundamental mechanisms or the physics of air flow through porous media is not well understood. In this study, centrifugal modeling tests were performed to investigate air flow rates and the evolution of the zone of influence during the air sparging under various g-levels. The test results show that with the increase in sparging pressure the mass flow rate of the air sparging volume increases. The air mass flow rate increases linearly with the effective sparging pressure ratio, which is the difference between sparging pressure and hydrostatic pressure normalized with respect to the effective overburden pressure at the sparging point. Also the slope of mass flow rate with effective sparging pressure ratio increases with higher g-levels. This variation of the slope of mass flow rate of air sparging volume versus effective sparging pressure ratio, M, is linear with g-level confirming that the air flow through soil for a given effective sparging pressure ratio only depends on the g-level. The test results also show that with increasing sparging pressure, the zone of influence (ZOI), which consists of the width at the tip of the cone or lateral intrusion and the cone angle, will lead to an increase in both lateral intrusion and the cone angle. With a further increase in air injection pressure, the cone angle reaches a constant value while the lateral intrusion becomes the main contributor to the enlargement of the ZOI. However, beyond a certain value of effective sparging pressure ratio, there is no further enlargement of the ZOI.
空气注射法（AS）是用于修复饱和土壤中挥发性有机化合物（VOCs）的地下水修复技术之一。然而，尽管空气注射法作为一种修复受污染土壤的技术取得了成功，但迄今为止，空气在多孔介质中流动的基本机制或物理原理仍未得到很好的理解。在本研究中，进行了离心模拟试验，以研究在不同重力水平下空气注射过程中的空气流速和影响区域的演变。试验结果表明，随着注射压力的增加，空气注射体积的质量流量增加。空气质量流量与有效注射压力比呈线性增加，有效注射压力比是注射压力与静水压力之差，相对于注射点处的有效上覆压力进行归一化。此外，质量流量与有效注射压力比的斜率随着重力水平的提高而增加。空气注射体积的质量流量与有效注射压力比M的斜率变化与重力水平呈线性关系，这证实了对于给定的有效注射压力比，空气在土壤中的流动仅取决于重力水平。试验结果还表明，随着注射压力的增加，由锥体尖端宽度或侧向侵入以及锥角组成的影响区域（ZOI）将导致侧向侵入和锥角均增加。随着空气注入压力的进一步增加，锥角达到恒定值，而侧向侵入成为影响区域扩大的主要因素。然而，超过有效注射压力比的某个值后，影响区域不再进一步扩大。
