The ability of surfactant foam to enhance mobility control and LNAPL recovery in a heterogeneous ... more The ability of surfactant foam to enhance mobility control and LNAPL recovery in a heterogeneous porous media was investigated through sandbox experiments with p-xylene used as LNAPL. A layered heterogeneous porous media was represented in a 2D sandbox filled with two layers of coarse and medium silica sand. Based on previous tests, the surfactant solution used was Ammonyx Lo at a concentration of 0.1% (w/w). The sandbox experimental program included tracer tests done under both uncontaminated and contaminated conditions, foam injection under uncontaminated conditions and surfactant solution and foam injection under contaminated conditions. Tracer tests indicated that the permeability contrast between sand layers was increased by LNAPL contamination. Foam injection under uncontaminated conditions presented a S-shaped front that indicated a better mobility control than the piston-shaped front obtained during tracer tests. During foam injection, complete sweep of the sandbox was achie...
The use of surfactant solutions for the in situ recovery of residual NAPL in aquifers is increasi... more The use of surfactant solutions for the in situ recovery of residual NAPL in aquifers is increasingly considered as a viable remediation technique. The injection of a few pore volumes of high-concentration surfactant solutions can mobilize or solubilize most of the residual NAPL contacted by the solutions. However, the washing solutions` physico-chemical properties (low density and high viscosity), combined with
This paper presents laboratory studies, numerical modelling, and a soil washing field test as a r... more This paper presents laboratory studies, numerical modelling, and a soil washing field test as a remedial technology for mass reduction in a source zone of soil contaminated with the polychlorinated biphenyl (PCB) Aroclor 1248 beneath an industrial building. Due to its high viscosity, the Aroclor 1248 is almost immobile in soils at this site. The objective was therefore to select products capable of dissolving the Aroclor in situ. In the laboratory phase, two surfactants and three alcohols were selected using 52 distinct phase diagrams. Alcohols and surfactants used either alone or in combination were tested in sand columns with contaminated soil from the site. The washing solution used in the field test was composed of an anionic surfactant (Nansa HS 85 S, a dodecylbenzene sulfonate) and an alcohol (n-butanol). In laboratory trials, this solution recovered 99% of initial PCBs by dissolution after the injection of 10 pore volumes of solution. During the field test, however, recovery ...
Foam is promising for the remediation of non-aqueous phase liquids (NAPL) source zones; however, ... more Foam is promising for the remediation of non-aqueous phase liquids (NAPL) source zones; however, the production of foam and its behavior in porous media are poorly understood. A methodology for the selection of surfactants suitable for foam production applied to NAPL remediation was developed. Two criteria were initially used for surfactant selection: foamability as evaluated by the Ross–Miles test and interfacial tension reduction measured with the pendant drop method. Three promising surfactants were identified and used in sand column tests: Genapol LRO because it produced the highest foam height in the Ross–Miles test, Ammonyx Lo which exhibited the lowest interfacial tension with p -xylene and had the second highest foam height, and Tomadol 900 because it showed intermediate results in both tests. Viscosity was found to be proportional to foamability. Genapol LRO produced a foam so viscous that it destabilized by the end of the experiment. Ammonyx Lo produced a less viscous foam but with a stable front. Tomadol 900 produced an unstable foam with poor viscosity. Results from column tests gave indications of optimal conditions needed to produce a stable and viscous foam front.
In the last decade, remote sensing of the temporal variation of ground level and gravity has impr... more In the last decade, remote sensing of the temporal variation of ground level and gravity has improved our understanding of groundwater dynamics and storage. Mass changes are measured by GRACE (Gravity Recovery and Climate Experiment) satellites, whereas ground deformation is measured by processing synthetic aperture radar satellites data using the InSAR (Interferometry of Synthetic Aperture Radar) techniques. Both methods are complementary and offer different sensitivities to aquifer system processes. GRACE is sensitive to mass changes over large spatial scales (more than 100,000 km(2) ). As such, it fails in providing groundwater storage change estimates at local or regional scales relevant to most aquifer systems, and at which most groundwater management schemes are applied. However, InSAR measures ground displacement due to aquifer response to fluid-pressure changes. InSAR applications to groundwater depletion assessments are limited to aquifer systems susceptible to measurable d...
The ability of surfactant foam to enhance mobility control and LNAPL recovery in a heterogeneous ... more The ability of surfactant foam to enhance mobility control and LNAPL recovery in a heterogeneous porous media was investigated through sandbox experiments with p-xylene used as LNAPL. A layered heterogeneous porous media was represented in a 2D sandbox filled with two layers of coarse and medium silica sand. Based on previous tests, the surfactant solution used was Ammonyx Lo at a concentration of 0.1% (w/w). The sandbox experimental program included tracer tests done under both uncontaminated and contaminated conditions, foam injection under uncontaminated conditions and surfactant solution and foam injection under contaminated conditions. Tracer tests indicated that the permeability contrast between sand layers was increased by LNAPL contamination. Foam injection under uncontaminated conditions presented a S-shaped front that indicated a better mobility control than the piston-shaped front obtained during tracer tests. During foam injection, complete sweep of the sandbox was achie...
The use of surfactant solutions for the in situ recovery of residual NAPL in aquifers is increasi... more The use of surfactant solutions for the in situ recovery of residual NAPL in aquifers is increasingly considered as a viable remediation technique. The injection of a few pore volumes of high-concentration surfactant solutions can mobilize or solubilize most of the residual NAPL contacted by the solutions. However, the washing solutions` physico-chemical properties (low density and high viscosity), combined with
This paper presents laboratory studies, numerical modelling, and a soil washing field test as a r... more This paper presents laboratory studies, numerical modelling, and a soil washing field test as a remedial technology for mass reduction in a source zone of soil contaminated with the polychlorinated biphenyl (PCB) Aroclor 1248 beneath an industrial building. Due to its high viscosity, the Aroclor 1248 is almost immobile in soils at this site. The objective was therefore to select products capable of dissolving the Aroclor in situ. In the laboratory phase, two surfactants and three alcohols were selected using 52 distinct phase diagrams. Alcohols and surfactants used either alone or in combination were tested in sand columns with contaminated soil from the site. The washing solution used in the field test was composed of an anionic surfactant (Nansa HS 85 S, a dodecylbenzene sulfonate) and an alcohol (n-butanol). In laboratory trials, this solution recovered 99% of initial PCBs by dissolution after the injection of 10 pore volumes of solution. During the field test, however, recovery ...
Foam is promising for the remediation of non-aqueous phase liquids (NAPL) source zones; however, ... more Foam is promising for the remediation of non-aqueous phase liquids (NAPL) source zones; however, the production of foam and its behavior in porous media are poorly understood. A methodology for the selection of surfactants suitable for foam production applied to NAPL remediation was developed. Two criteria were initially used for surfactant selection: foamability as evaluated by the Ross–Miles test and interfacial tension reduction measured with the pendant drop method. Three promising surfactants were identified and used in sand column tests: Genapol LRO because it produced the highest foam height in the Ross–Miles test, Ammonyx Lo which exhibited the lowest interfacial tension with p -xylene and had the second highest foam height, and Tomadol 900 because it showed intermediate results in both tests. Viscosity was found to be proportional to foamability. Genapol LRO produced a foam so viscous that it destabilized by the end of the experiment. Ammonyx Lo produced a less viscous foam but with a stable front. Tomadol 900 produced an unstable foam with poor viscosity. Results from column tests gave indications of optimal conditions needed to produce a stable and viscous foam front.
In the last decade, remote sensing of the temporal variation of ground level and gravity has impr... more In the last decade, remote sensing of the temporal variation of ground level and gravity has improved our understanding of groundwater dynamics and storage. Mass changes are measured by GRACE (Gravity Recovery and Climate Experiment) satellites, whereas ground deformation is measured by processing synthetic aperture radar satellites data using the InSAR (Interferometry of Synthetic Aperture Radar) techniques. Both methods are complementary and offer different sensitivities to aquifer system processes. GRACE is sensitive to mass changes over large spatial scales (more than 100,000 km(2) ). As such, it fails in providing groundwater storage change estimates at local or regional scales relevant to most aquifer systems, and at which most groundwater management schemes are applied. However, InSAR measures ground displacement due to aquifer response to fluid-pressure changes. InSAR applications to groundwater depletion assessments are limited to aquifer systems susceptible to measurable d...
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