Abstract:

Air sparging (AS) has been proven to be one of the most effective means of removing volatile organic compounds in saturated soils and groundwater. Firstly, the effect of air flow rates on air saturation and radius of influence (ROI) was investigated using a two-dimensional laboratory sand tank. The results show that improving air flow rate can increase higher air saturation and wider ROI. However, the increases of air flow rate and air saturation, ROI are disproportionate. With the increase of air flow rate, the increase amplitude of air saturation, ROI becomes slow. Then the effect of different air flow rates on chlorobenzene migration and removal in sand tank with a certain hydraulic gradient was also studied. The air injection into groundwater can reduce the hydraulic conductivity within the zone of influence, can slow down groundwater flow and contaminant migration. When no air flow injected, the proportion of chlorobenzene migrated out of the sand profile with the effluent groundwater is 19.7% after 130 hours. While the proportions were only 3.6% and 0.9% at air injection rates of 0.1, 0.2 m³/h respectively. Meanwhile, 68.2% and 78.6% of the initial chlorobenzene mass has been removed at the two air injection rates respectively. This result reveals that AS can effectively control and remove contaminant migration in groundwater. This effect will be more obvious when higher air flow rate is used.

Key words: air sparging;, chlorobenzene, radius of influence, contaminant migration