columns using an ozone generator (BMT 802, BMT Messertechnik, GmbH) with a
fixed ozone rate production which resulted in 10.5 g of ozone during the 7 days of
the experiment. For surfactant flushing, 40 PV of a Tween80
® solution at
150 mg L
À1 (%10 CMC) was injected at a rate of 2 PV per day for each set of
experiments. Air injection was realized at a continuous low flow rate of 1 mL min
À1
for a total of 2 PV (98 mL) per day. For thermal treatment, the columns were kept in
an oven with a Tedlar bag at the outlet (at room temperature).
4.2.3 Scale 3: Tank Experiments
Most of the tank experiments, materials and methods are described in detail in Atteia
et al. (2017). Each tank consisted mainly of a 1 m
3 box filled with sand including
three contaminated lenses (26 Â 26 Â 5 cm): the middle lens being built with the
same sand as the overall tank and the top and bottom one consisted of lower
permeability sands. The pore volumes of the tanks, measured during water addition,
were close to 247 L. All tanks contained three injection and three pumping wells and
were sealed with clays to allow gas sampling (Fig. 4.1).
The contamination was done by a 10% saturation content of a 1:1 mixture of
decane and toluene. All operations were done to avoid losses and a blank was done at
the end of the lenses processing.
The tanks were washed during 80 days with a pore velocity of 17 cm day
À1
(or 0.18 PV day
À1 ). After the conditioning period, the four tanks were used as
follows: (1) persulfate activated with Fe(II), (2) surfactant (Tween 80
® ), (3) sparging
with air followed by ozone, and (4) low temperature (80
C) thermal treatment.
These treatments are described in detail in Atteia et al. (2017). Briefly, persulfate was
added first at 50 g L
À1 , followed by water, then 5 g L
À1 of persulfate and then again a
50 g L
À1 solution, each addition being around 1 PV. Eight PVs of Tween 80 were
added at 10 CMC for the surfactant tank. For sparging, air was injected at a flow rate
of 600 L day
À1 over 2 weeks. The thermal treatment was conducted by letting water
at 80–90
C recirculate at the tank bottom.
At the end of the experiments, the porous media was extracted from tanks for
contaminants analysis. In each layer, nine samples were taken on a regular grid. Each
sample was composed of a mixture of three subsamples (3 mL of sand). In addition,
in the low hydraulic conductivity lenses, nine samples were taken in a regular grid,
again made of three subsamples. In the lens of layer two, one sample (with three
subsamples) was collected.
4 Comparing the Efficiency of Oxidation, Sparging, Surfactant Flushing, and. . .
219
fixed ozone rate production which resulted in 10.5 g of ozone during the 7 days of
the experiment. For surfactant flushing, 40 PV of a Tween80
® solution at
150 mg L
À1 (%10 CMC) was injected at a rate of 2 PV per day for each set of
experiments. Air injection was realized at a continuous low flow rate of 1 mL min
À1
for a total of 2 PV (98 mL) per day. For thermal treatment, the columns were kept in
an oven with a Tedlar bag at the outlet (at room temperature).
4.2.3 Scale 3: Tank Experiments
Most of the tank experiments, materials and methods are described in detail in Atteia
et al. (2017). Each tank consisted mainly of a 1 m
3 box filled with sand including
three contaminated lenses (26 Â 26 Â 5 cm): the middle lens being built with the
same sand as the overall tank and the top and bottom one consisted of lower
permeability sands. The pore volumes of the tanks, measured during water addition,
were close to 247 L. All tanks contained three injection and three pumping wells and
were sealed with clays to allow gas sampling (Fig. 4.1).
The contamination was done by a 10% saturation content of a 1:1 mixture of
decane and toluene. All operations were done to avoid losses and a blank was done at
the end of the lenses processing.
The tanks were washed during 80 days with a pore velocity of 17 cm day
À1
(or 0.18 PV day
À1 ). After the conditioning period, the four tanks were used as
follows: (1) persulfate activated with Fe(II), (2) surfactant (Tween 80
® ), (3) sparging
with air followed by ozone, and (4) low temperature (80
C) thermal treatment.
These treatments are described in detail in Atteia et al. (2017). Briefly, persulfate was
added first at 50 g L
À1 , followed by water, then 5 g L
À1 of persulfate and then again a
50 g L
À1 solution, each addition being around 1 PV. Eight PVs of Tween 80 were
added at 10 CMC for the surfactant tank. For sparging, air was injected at a flow rate
of 600 L day
À1 over 2 weeks. The thermal treatment was conducted by letting water
at 80–90
C recirculate at the tank bottom.
At the end of the experiments, the porous media was extracted from tanks for
contaminants analysis. In each layer, nine samples were taken on a regular grid. Each
sample was composed of a mixture of three subsamples (3 mL of sand). In addition,
in the low hydraulic conductivity lenses, nine samples were taken in a regular grid,
again made of three subsamples. In the lens of layer two, one sample (with three
subsamples) was collected.
4 Comparing the Efficiency of Oxidation, Sparging, Surfactant Flushing, and. . .
219