flushing, the last technique being the most efficient. At larger scales, i.e., in 3D tanks,
which can be closer to field conditions, we did not find any comparison of several
techniques.
The aim of the present study is thus to provide a detailed comparison of several
widely used techniques for residual NAPL removal. The objective is to assess their
sensitivity to heterogeneity and thus their scalability, here from columns to 3D tanks.
The chosen treatment techniques are oxidation, surfactant flushing, sparging, and
thermal treatment.
The specific objectives of this chapter are as follows:
• To compare four techniques using the same experimental conditions.
• To determine, in a homogeneous porous medium (columns), the physical and
chemical factors that may limit the efficiency of the investigated treatment
techniques.
• To compare the four treatment techniques in tanks including defined
heterogeneity.
• To analyze the spatial distribution of the remaining NAPL after the treatment.
• To assess the potential scaling of the results from batches to pilot and finally their
potential use for field application.
As most of the literature is devoted to chlorinated solvents, it was decided to work
on L-NAPL to fill some of the existing knowledge gaps. Our results are then
compared to literature ones to appreciate the relative role of the physical properties
of the molecule and its composition.
4.2 Materials and Methods
Lower-scale experiments were used to focus on larger-scale ones, leading to different treatments used for different scales. At the batch scale, only the oxidants were
tested to choose the right conditions for the column scale. Then, based on column
results, only one oxidant type was used at the tank scale. For sparging and surfactant,
a trial at batch scale is meaningless. Thermal treatment results at batch scale are
already known. These three treatments were realized at the column scale, based on
literature results, to find the best conditions.
4.2.1 Scale 1: Batch Experiments
In order to test the efficiency of different oxidants (permanganate, persulfate,
Fenton’s reagent, and ozone) and to define the best concentrations and reaction
times, several experiments were conducted in batches with different contaminants:
diesel fuel, Benzene/Toluene/Xylene (BTX) mixture, and a n-decane/menthol mixture. Menthol is a cyclic compound with an OH group. The objective of this mixture
4 Comparing the Efficiency of Oxidation, Sparging, Surfactant Flushing, and. . .
215
which can be closer to field conditions, we did not find any comparison of several
techniques.
The aim of the present study is thus to provide a detailed comparison of several
widely used techniques for residual NAPL removal. The objective is to assess their
sensitivity to heterogeneity and thus their scalability, here from columns to 3D tanks.
The chosen treatment techniques are oxidation, surfactant flushing, sparging, and
thermal treatment.
The specific objectives of this chapter are as follows:
• To compare four techniques using the same experimental conditions.
• To determine, in a homogeneous porous medium (columns), the physical and
chemical factors that may limit the efficiency of the investigated treatment
techniques.
• To compare the four treatment techniques in tanks including defined
heterogeneity.
• To analyze the spatial distribution of the remaining NAPL after the treatment.
• To assess the potential scaling of the results from batches to pilot and finally their
potential use for field application.
As most of the literature is devoted to chlorinated solvents, it was decided to work
on L-NAPL to fill some of the existing knowledge gaps. Our results are then
compared to literature ones to appreciate the relative role of the physical properties
of the molecule and its composition.
4.2 Materials and Methods
Lower-scale experiments were used to focus on larger-scale ones, leading to different treatments used for different scales. At the batch scale, only the oxidants were
tested to choose the right conditions for the column scale. Then, based on column
results, only one oxidant type was used at the tank scale. For sparging and surfactant,
a trial at batch scale is meaningless. Thermal treatment results at batch scale are
already known. These three treatments were realized at the column scale, based on
literature results, to find the best conditions.
4.2.1 Scale 1: Batch Experiments
In order to test the efficiency of different oxidants (permanganate, persulfate,
Fenton’s reagent, and ozone) and to define the best concentrations and reaction
times, several experiments were conducted in batches with different contaminants:
diesel fuel, Benzene/Toluene/Xylene (BTX) mixture, and a n-decane/menthol mixture. Menthol is a cyclic compound with an OH group. The objective of this mixture
4 Comparing the Efficiency of Oxidation, Sparging, Surfactant Flushing, and. . .
215