PHYSICAL MODELING OF AIR SPARGING FOR GROUNDWATER REMEDIATION

Air sparging (AS) is one of the most efficient techniques to remediate saturated soils and groundwater contaminated with voltaic organic compounds. Air flow plays a dominant role in air sparging efficiency. In this paper, the physical modeling technique of 1 g and centrifuge tests was employed to study the characteristics of air flow through saturated porous media under a wide range of air injection pressure during air sparging. The test results show the air flow velocity increases with the increase of the sparging pressure. Pore size distribution of the porous media has dominant influence in air flow patterns, i.e., micro-channel flow or individual bubble flow. The preferential flow through least resistance route occurs during the air breakthrough process, and the minimum sparging pressure is determined by the micro-structure of the porous media, i.e., the larger pore size. There exists a critical sparging pressure, while the zone of influence (ZOI) expands with the sparging pressure increase until it reaches the critical value. The ZOI decreases with the increase of soil particle size and g level. The ZOI is cone-shaped, and can be adequately described by use of the lateral intrusion length and cone angle. These conclusions provide valuable references for design and application of air sparging for groundwater remediation.