TY - JOUR
T1 - Effect of flow rate changes and pulsing on the treatment of source zones by in situ air sparging
AU - Johnson, Paul C.
AU - Das, Amarjyoti
AU - Bruce, Cristin
PY - 1999/5/15
Y1 - 1999/5/15
N2 - Laboratory-scale two-dimensional aquifer physical model studies were conducted to qualitatively assess how changes in air injection rate, air injection pulsing, and chemical type affect the rate and extent of removal by in situ air sparging. In this work, the treatment of immiscible-phase source zones in coarse media has been simulated. To provide a basis for comparison, equivalent unsaturated-soil soil vapor extraction-like simulation experiments were also conducted. Results suggest that, (i) initially, removal occurs from within saturated zone air flow channels at rates similar to those observed for soil vapor extraction, (ii) during this initial period, removal rates are proportional to air flow rate and equilibrium chemical vapor concentrations, (iii) while increased air injection rates improve volatilization rates in the short-term, the long-term cumulative removal efficiency may not be affected unless the saturated zone air flow distribution changes significantly with flow rate, (iv) pulsing the air injection can improve the long-term cumulative removal efficiency, and (v) while short-term removal efficiency improves with increasing flow rate and vapor pressure, the long-term removal efficiency appears to improve with increasing solubility.
AB - Laboratory-scale two-dimensional aquifer physical model studies were conducted to qualitatively assess how changes in air injection rate, air injection pulsing, and chemical type affect the rate and extent of removal by in situ air sparging. In this work, the treatment of immiscible-phase source zones in coarse media has been simulated. To provide a basis for comparison, equivalent unsaturated-soil soil vapor extraction-like simulation experiments were also conducted. Results suggest that, (i) initially, removal occurs from within saturated zone air flow channels at rates similar to those observed for soil vapor extraction, (ii) during this initial period, removal rates are proportional to air flow rate and equilibrium chemical vapor concentrations, (iii) while increased air injection rates improve volatilization rates in the short-term, the long-term cumulative removal efficiency may not be affected unless the saturated zone air flow distribution changes significantly with flow rate, (iv) pulsing the air injection can improve the long-term cumulative removal efficiency, and (v) while short-term removal efficiency improves with increasing flow rate and vapor pressure, the long-term removal efficiency appears to improve with increasing solubility.
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U2 - 10.1021/es9807688
DO - 10.1021/es9807688
M3 - Article
AN - SCOPUS:0033562407
SN - 0013-936X
VL - 33
SP - 1726
EP - 1731
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 10
ER -