A large-scale experiment on mass transfer of trichloroethylene from the unsaturated zone of a sandy aquifer to its interfaces

Jellali, Salah; Benremita, Hocine; Muntzer, P.; Razakarisoa, Olivier; Schäfer, Gerhard

doi:10.1016/s0169-7722(02)00062-1

Cited by 59 publications

(53 citation statements)

References 28 publications

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“…Atmospheric release of vaporized TCE due to the outgoing gas flow accelerates mass transfer of dissolved TCE in the saturated zone into gas phase, and helps reduce the development of dissolved TCE plume in the saturated zone. Loss of contaminant mass to the atmosphere plays an import role in reducing the spreading of contaminant plumes in the subsurface (Mendoza and Frind 1990b;Jellali et al 2003). The results shown in Fig.…”

Section: Application Of Density-driven Transport Of a Contaminant In mentioning

confidence: 92%

“…8a, soil permeability has influence on determining daily TCE transfer rates, but the three flux curves show similar patterns regardless its magnitude. The location of a contaminant source is an important factor to determine its fate and distribution (Jellali et al 2003). In this study, a dominant portion of mobilized TCE is released into the atmosphere.…”

Section: Effect Of Permeability On Trichloroethylene Transportmentioning

confidence: 99%

“…The advection plays an important role in spreading dense VOCs such as trichloroethylene (TCE) and tetrachloroethylene in the subsurface (Mendoza and Frind 1990a;Falta et al 1989), and this in turn may become one of the key parameters in evaluating the effectiveness of MNA. Several experimental studies were carried out to investigate density-driven transport of VOCs in porous soil media and its effects on groundwater contamination (Conant et al 1996;Altevogt et al 2003;Jellali et al 2003). Through TCE-transport experiments, Lenhard et al (1995) demonstrated that density-driven advective flow of gas phase was significant in the downward movement of TCE gas-plume.…”

Section: Introductionmentioning

confidence: 99%

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Density-driven Transport of Volatile Organic Compounds and its Impact on Contaminated Groundwater Plume Evolution

Jang

Aral

2006

Transp Porous Med

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Density-driven advection of gas phase due to vaporization of chlorinated volatile organic compounds (VOCs) has a significant effect on fate and transport of contaminants. In this study, we investigated the effects of density-driven advection, infiltration, and permeability on contaminant plume evolution and natural attenuation of VOCs in the subsurface system. To analyze these effects, multiphase flow and contaminant transport processes were simulated using a three-dimensional Galerkinfinite-element-based model. Trichloroethylene (TCE) is selected as a target contaminant. Density-driven advection of gas phase elevated the potential of groundwater pollution in the saturated zone by accelerating downward migration of vaporized contaminant in the unsaturated zone. The advection contributed to increased removal rates of non-aqueous phase liquid (NAPL) TCE source and reduced dissolved TCE plume development in the downstream area. Infiltration reduced the velocity of the density-driven advection and its influence zone, but raised TCE transfer from the unsaturated to the saturated zone. The variation in soil permeability showed greater impact on contaminant migration within water phase in the saturated zone than within gas phase in the unsaturated zone. Temporal variations of TCE mass within two-dimensional (2D) and three-dimensional (3D) domains under several modeling conditions were compared. These results are important in evaluation of natural attenuation processes, and should be considered to effectively design monitored natural attenuation as a remedial option.

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Section: Application Of Density-driven Transport Of a Contaminant In mentioning

confidence: 92%

Section: Effect Of Permeability On Trichloroethylene Transportmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Density-driven Transport of Volatile Organic Compounds and its Impact on Contaminated Groundwater Plume Evolution

Jang

Aral

2006

Transp Porous Med

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“…The sand sample has a low fraction of organic matter (foc = 0.09 %, based on the French standard NF X 31-109) and a hydraulic conductivity of approximately 8 9 10 -4 m s -1 . The sand has already been the subject of several former research studies, and its characteristics were described by Jellali et al (2003), Benremita (2002), Bohy (2003), Bohy et al (2006), and Cotel et al (2011). The measured equivalent hydraulic conductivity of the clay/sand mixture was approximately 2 9 10 -4 , 5 9 10 -6 and 7 9 10 -7 m s -1 for a mass fraction of clay of 10, 20, and 30 %, respectively.…”

Section: Soil and Dyes Usedmentioning

confidence: 93%

Adsorptive removal of azo dyes from aqueous solutions by natural bentonite under static and dynamic flow conditions

Berez

Schäfer

Ayari

et al. 2016

Int. J. Environ. Sci. Technol.

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This work reports new findings on the physisorption of Foron Blue 291 on natural bentonite under both static and dynamic flow conditions of the aqueous solution that may prove important when using the adsorption technique for wastewater treatment. The quantity of dye retained by the solid matrix under both ideal exchange conditions between dyes and adsorbents given in a batch reactor and a pulse injection of dissolved azo dye in a soil column composed of a mixture of mean grain-sized sand and bentonite at different flow rates and at various mass fractions of bentonite was studied. Column experiments involving the use of a non-reactive tracer (Fluorescein) were performed to examine hydrodynamic behaviours of the clay/sand mixture studied. It is shown that advective-dispersive transport across a clay/sand mixture may be characterized by a double porosity medium. The results obtained on the reactive transport of Foron Blue 291 underscore that Foron Blue 291 adsorption depends heavily on the mass fraction of clay in a clay/sand mixture. With a clay mass fraction of 30 %, 77 % of the dissolved Foron Blue 291 mass was irreversibly removed by the adsorbent. At low flow rates, removal ratios obtained from the dynamic reactive system were similar to those obtained through previous static reactor experiments.

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“…Vapour plumes often affect the quality of outdoor air by VOC fluxes from the vadose zone to the atmosphere and the quality of air inside buildings by migration of VOCs from the vadose zone through concrete floor slabs. Transport of VOCs in the vadose zone is primarily due to diffusion (Pankow and Cherry 1996;Choi et al 2002;Jellali et al 2003;Bohy et al 2006). However, advection can also contribute to mass transport of VOCs.…”

mentioning

confidence: 99%

Evaluation of VOC fluxes at the soil-air interface using different flux chambers and a quasi-analytical approach

Cotel

Schäfer

Traverse³

et al. 2015

Water Air Soil Pollut

Self Cite

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Dense nonaqueous-phase liquids (DNAPLs) spilled on the soil migrate vertically depending upon gravity and capillary forces through the unsaturated zone of the porous aquifer, forming a vapour plume. These volatile organic compounds (VOCs) can be transferred by advection-diffusion to the groundwater or to the atmosphere. Evaluating DNAPL vapour fluxes at the soil-air interface is one of the key challenges in the remediation of contaminated sites. This work discusses the results of a large-scale vapour plume experiment with a well-defined trichloroethylene (TCE) spill, including a sequential raising and lowering of the water table, where the TCE vapour fluxes at the soil surface were experimentally quantified in two ways: (i) directly, with measurements at the soil-air interface using different flux chambers at various operational modes under both transient and steady-state conditions of the vapour plume, and (ii) indirectly, using a quasi-analytical approach based on soil gas measurements. It was shown that upward displacement of the water-air front during the controlled raising of the water table (approximately 10 cm h −1 ) increased the TCE vapour flux measured at the soil surface by factors of 4 to 10. Under steady-state transport conditions, TCE vapour fluxes measured using five types of flux chambers and three operational modes were similar. The effects of the flux chamber geometry, the accumulation of TCE vapours in the chamber headspace or the air recirculation at a low flow rate on the measured TCE vapour fluxes were low. At steady-state transport conditions, TCE vapour fluxes measured with the flux chambers and estimated using the quasianalytical approach were of the same order of magnitude. However, under transient conditions of the vapour plume, the TCE vapour flux predicted by the quasi-analytical approach greatly underestimated or overestimated the real TCE vapour flux at the soil-air interface.

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A large-scale experiment on mass transfer of trichloroethylene from the unsaturated zone of a sandy aquifer to its interfaces

Cited by 59 publications

References 28 publications

Density-driven Transport of Volatile Organic Compounds and its Impact on Contaminated Groundwater Plume Evolution

Density-driven Transport of Volatile Organic Compounds and its Impact on Contaminated Groundwater Plume Evolution

Adsorptive removal of azo dyes from aqueous solutions by natural bentonite under static and dynamic flow conditions

Evaluation of VOC fluxes at the soil-air interface using different flux chambers and a quasi-analytical approach

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