Influence of Porous Media, Airflow Rate, and Air Channel Spacing on Benzene NAPL Removal during Air Sparging

To study the effects of porous media type, airflow rate, and air channel spacing on NAPL removal, air sparging of a benzene NAPL was performed in a lab-scale reactor with two isolated vertical air channels on either side of the NAPL. Experimental conditions included three discrete air channel distances, three types of saturated porous media, and five airflow rates. Benzene NAPL removal efficiency was shown to increase from 7.5% to 16.2% with increasing porous media mean particle size (from 0.168 to 0.305 mm, respectively) over the 168 h of operation. Initial change in the airflow rate had an effect on contaminant removal rate, but further change in the airflow rate had little effect. Benzene NAPL removal efficiency was shown to decrease with increasing channel spacing, but the mere presence of air channels was shown to suppress lateral contaminant migration. Benzene removal efficiency was shown to be highly correlated ( r 2 = 0.96) with the mean particle diameter, the square root of the uniformity coefficient, and the inverse of the square of the distance between the NAPL and the air channel.