Laboratory Study of the Effect of Electromagnetic Waves on Airflow during Air Sparging

Abstract

Air sparging is a technique that uses the injection of a gas (e.g., air, oxygen) into the subsurface to remediate saturated soils and groundwater contaminated with volatile organic compounds (VOCs). During air sparging, air or oxygen is injected into the subsurface below the lowest known depth of chemical contamination. The injected air will rise through the contaminated zones by buoyancy. Contaminant removal efficiency and air sparging performance are highly dependent on the pattern and type of airflow. Airflow, however, suffers from air channel formation (i.e., preferential paths for airflow), limiting remediation to smaller contaminated zones. This paper presents the results of experimental work investigating the possibility of controlling and improving airflow patterns through a saturated glass-bead medium using electromagnetic (EM) waves to enhance air sparging. The test setup consists of a resonant cavity made of an acrylic tank covered with transparent, electrically conductive films. Experimental measurement of the electric field component of EM waves is performed at different frequencies. Airflow pattern is also studied at different air-injection pressure levels with/without EM stimulation. The zone of influence (ZOI) during air sparging is monitored using digital imaging. A quantitative approach is then taken to correlate the characteristics of EM waves and airflow patterns.