A Conceptual Model of Field Behavior of Air Sparging and Its Implications for Application

Ahlfeld, David P.; Dahmani, Amine; Ji, Wei

doi:10.1111/j.1745-6592.1994.tb00491.x

Cited by 69 publications

(21 citation statements)

References 13 publications

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“…40, W09203, doi:10.1029/2003WR002960, 2004 aerobic biodegradation [e.g., Reddy and Adams, 2001;Brooks et al, 1999;Ahlfeld et al, 1994;Ji et al, 1993;Marley et al, 1992;Bruell et al, 1997].…”

Section: W09203mentioning

confidence: 99%

Effects of air injection on flow through porous media: Observations and analyses of laboratory‐scale processes

Dror

Berkowitz

Gorelick

2004

Water Resources Research

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[1] The effects of air injection on flow through porous media were explored in a series of 1-m and 2-m laboratory flow cells. Our motivation was to examine air barriers as an alternative to hydraulic barriers to inhibit saline intrusion in coastal areas. Steady flow conditions were created in homogeneous and heterogeneous unconsolidated sand systems. Dry air was injected at progressively higher flow rates through a well in the center of each flow cell. Discharge and NaClÀtracer breakthrough data were measured at the outflow reservoir of each cell. In addition, a dye tracer was used to visualize the flow patterns. In all cases, air injection was found to produce stable, low-conductivity barriers that reduced discharge by an order of magnitude or more. Effective hydraulic conductivity values determined from discharge and hydraulic head data showed exponential declines with increased air-injection rates in all cases. Numerical simulation was used to quantify hydraulic conductivity and effective porosity values in the saturated and aerated regions created by air injection, and to study advective flow behavior. Pore-filling cement formed in the air-injection region and was analyzed to determine its composition, mass, and volume. Approximately 60% of the cement consisted of soluble minerals, and 40% was less soluble carbonates. Evaporation and increase in solution pH due to stripping of CO 2 by the injected air were responsible for creating the cement. The cement occupied <10% of the pore space in the sand-cement aggregate. Both the air and mineral pore-fillings dissolved when air injection ceased, indicating that both barriers are temporary. These results serve as a preliminary proof of concept that air-injection barriers might effectively inhibit undesired subsurface flow, such as saline intrusion or contaminated groundwater.

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Section: W09203mentioning

confidence: 99%

Effects of air injection on flow through porous media: Observations and analyses of laboratory‐scale processes

Dror

Berkowitz

Gorelick

2004

Water Resources Research

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“…it cannot be moved by natural hydromechanic forces ("immobile groundwater"). Thus, these zones are barely directly affected by the remediation measure (Ahlfeld et al, 1994;Leeson et al, 2002;Geistlinger et al, 2006;Pohlert et al, 2008). Whereas contaminant transfer from mobile groundwater to the injected air is governed mainly by advection and dispersion with diffusion only needed for short mass transfer lengths, mass transfer from immobile groundwater into the injected air is mainly governed by diffusion over longer distances (Suthersan, 1999).…”

Section: In Situ Air Sparging E General Remarksmentioning

confidence: 95%

“…along channel-like flow paths. In the case of a multi-phase system (gas e liquid) these zones are characterized by low capillary forces (Ahlfeld et al, 1994;Geistlinger et al, 2006), i.e. they are occupied by groundwater that can easily be moved by hydromechanic forces ("mobile groundwater").…”

Section: In Situ Air Sparging E General Remarksmentioning

confidence: 99%

Using radon-222 as indicator for the evaluation of the efficiency of groundwater remediation by in situ air sparging

Schubert¹,

Schmidt²,

Muller³

et al. 2011

Journal of Environmental Radioactivity

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“…Air sparging also enhances aerobic biodegradation by increasing dissolved oxygen within the groundwater (Brubaker 1993;Johnson 1994;Adams and Reddy 2003). In general, the rate of mass removal is greater when the air plume is large, the flow rate is high, and a dense network of closely spaced air channels exists (Ahlfeld et al 1994a;Rabideau and Blayden 1998;Elder et al 1999, Adams andReddy 2000). The air channel density commonly is described by the air saturation (volume of air per volume of voids).…”

Section: Introductionmentioning

confidence: 97%

Effect of system variables and particle size on physical characteristics of air sparging plumes

Baker¹,

Benson

2007

Geotech Geol Eng

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Air was injected through a well in a thin transparent tank filled with saturated glass beads to study how the size and air saturation of air sparging plumes are affected by particle size and gradation; operational parameters such as injection pressure, well depth, injection pressure pulsing; and well outlet configuration. V-shaped air plumes with an apex between 408 and 608 were obtained for all tests. The air pressure required to initiate sparging agreed closely with the sum of the air entry pressure and the hydrostatic pressure, with higher initiation pressures required in the fine and wellgraded beads. Higher air flow rates and air saturations were obtained in coarser beads at a given pressure, and the variation in flow rate was consistent with estimated air permeabilities. Peak average air saturations were 28-56% for the coarsemedium beads, 10% for the well-graded beads, and 8% for the fine beads. Air saturation and the radius of influence increased modestly (<40%) as the normalized injection pressure exceeded 0.1. Radius of influence increased by approximately a factor of two as the well depth increased, but leveled off once the ratio of radius of influence to well depth reached 0.60-1.05. Pulsing of injection pressure had no effect on the initiation pressure, air flow rate, or air saturation, but increased the size of the air plume and the radius of influence slightly (<15%). Well outlet configuration had only a slight affect the radius of influence (<10%), air saturation (<10%), or air flow rate (<12%). Dye testing showed that water surrounding the air plume circulated during continuous and pulsed sparging. However, pulsed sparging resulted in greater and more defined circulation of water within and adjacent to the air plume, which should reduce mass transfer limitations during sparging.

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A Conceptual Model of Field Behavior of Air Sparging and Its Implications for Application

Cited by 69 publications

References 13 publications

Effects of air injection on flow through porous media: Observations and analyses of laboratory‐scale processes

Effects of air injection on flow through porous media: Observations and analyses of laboratory‐scale processes

Using radon-222 as indicator for the evaluation of the efficiency of groundwater remediation by in situ air sparging

Effect of system variables and particle size on physical characteristics of air sparging plumes

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