Centrifuge Modeling and Numerical Simulation of Air Sparging Process

Abstract

Air sparging (AS) is one of the in-situ groundwater remediation techniques for remediating volatile organic compounds (VOCs) contaminated soil, and the knowledge of air flow features is essential in designing air sparging system for soil remediation. The centrifuge modeling technique was employed to simulate the in-situ conditions and to investigate air follow characteristics during air sparging by using glass beads as soils. Several centrifugal modeling tests were performed under various g-levels. According to the test results, the zone of influence (ZOI) during air sparging is in a truncated-cone shape under various g-levels, which can be expressed by the lateral expansion around the air injection point and the cone angle between the vertical axis and the boundary of ZOI. A 2D numerical model is used to model the air movement during air sparging process. The ZOI and the water saturation distribution were obtained. The results agree well with the centrifuge test data, which indicates the two phase flow model is reasonable to simulate the air sparging process. It was also shown that air compressibility and buoyant force have a significant influence on the extent of ZOI and should be adequately considered. Hence centrifuge modeling and numerical simulation can be used as a design tool for in-situ air sparging system