1.5 Example of Field Assessment of Soil Flushing
with Reused Solutions (SFWRS)
SF tests with reused fluids were performed in Solec Kujawski (Poland) at the
EU-project Timbre test site with the aim of assessing technological efficiencies
and
costs
(http://www.timbre-project.eu/news-volltext/items/timbre-in-soleckujawski.html). The site was a former wood impregnation industrial plant operated
from 1876 to 2001. It had a surface of about 13 ha, while about 4 ha were heavily
polluted. The GW level was lower than 3.5 m below the soil surface. The soil was
sandy and the plot of land used for experiments was contaminated because of
dripping from impregnated woods. A preliminary visit for site recognition and
sampling was carried out. Sampling was performed in an open area while the
SFWRS test was carried out closer to the main entrance of the site for practical
reasons. Soil samples collected during the sampling campaign were used for soil
treatability studies and to design the wastewater treatments for the reuse of soil
leachates. The soil porosity and apparent density were 0.182 Æ 0.073 and 1.33,
respectively. Its intrinsic water permeability was 4 D and its pH was 5.5. The details
of soil and contamination characteristics obtained for the collected samples are
reported in Table 1.3. The main targeted contaminants were PAHs and C 10–40 total
petroleum hydrocarbons index (TPH).
Several anionic (SDS) and zwitterionic (cocamidopropylbetaine, CB and
laurylbetaine, LB) surfactants were assessed for TPH extraction in soil leachates at
C S ¼ 2%w, much larger than their CMC. Betaines-derivative surfactants were
selected based on their biodegradability and low toxicity (Holmberg et al. 2002).
In lab tests, surfactant foams were used to flush the contaminated soil in order to
improve HOCs extraction during the treatment (Mulligan and Eftekhari 2003; Wang
and Chen 2012). In the best case, flushing in soil columns at the lab scale required a
minimum of 20–50 pore volumes (PV) of surfactant solution injected for the full
extraction of petroleum hydrocarbons; three quarters of the extracted TPH were
removed in the foam gas phase (Table 1.4).
The loss of betaines surfactants in soils was much lower than for SDS (Fig. 1.13).
Finally, LB was selected for field tests, because it produced low-persistent foams
required for SF and cross-flow UF operations. The linear part for the exponential
extraction rate corresponding to the most productive part has been observed up to
5 PV, which has been the targeted level for injections in field-scale tests.
An in situ field test was carried out at the pilot scale by excavating a contaminated
plot (dimensions: 2 m long, 2 m large, 3 m depth). A 2 mm-thick PET sheet was set
at the bottom and folded vertically on sides (0.5 m high) to make the cell impervious.
Then a central well was installed to collect soil leachates and the soil was set back
and compacted using a mechanical shovel. Finally, the top soil was clad with a
2 mm-thick PET sheet folded down on sides (0.3 m) and 16 injection–extraction
wells were set. Considering the dimensions of the cell and soil characteristics, the PV
was estimated to be 2.4 m
3 . All the steps and details about the setup of the cell are
shown in Fig. 1.14, while details for wastewater treatments are shown in Fig. 1.15.
44
N. Fatin-Rouge
with Reused Solutions (SFWRS)
SF tests with reused fluids were performed in Solec Kujawski (Poland) at the
EU-project Timbre test site with the aim of assessing technological efficiencies
and
costs
(http://www.timbre-project.eu/news-volltext/items/timbre-in-soleckujawski.html). The site was a former wood impregnation industrial plant operated
from 1876 to 2001. It had a surface of about 13 ha, while about 4 ha were heavily
polluted. The GW level was lower than 3.5 m below the soil surface. The soil was
sandy and the plot of land used for experiments was contaminated because of
dripping from impregnated woods. A preliminary visit for site recognition and
sampling was carried out. Sampling was performed in an open area while the
SFWRS test was carried out closer to the main entrance of the site for practical
reasons. Soil samples collected during the sampling campaign were used for soil
treatability studies and to design the wastewater treatments for the reuse of soil
leachates. The soil porosity and apparent density were 0.182 Æ 0.073 and 1.33,
respectively. Its intrinsic water permeability was 4 D and its pH was 5.5. The details
of soil and contamination characteristics obtained for the collected samples are
reported in Table 1.3. The main targeted contaminants were PAHs and C 10–40 total
petroleum hydrocarbons index (TPH).
Several anionic (SDS) and zwitterionic (cocamidopropylbetaine, CB and
laurylbetaine, LB) surfactants were assessed for TPH extraction in soil leachates at
C S ¼ 2%w, much larger than their CMC. Betaines-derivative surfactants were
selected based on their biodegradability and low toxicity (Holmberg et al. 2002).
In lab tests, surfactant foams were used to flush the contaminated soil in order to
improve HOCs extraction during the treatment (Mulligan and Eftekhari 2003; Wang
and Chen 2012). In the best case, flushing in soil columns at the lab scale required a
minimum of 20–50 pore volumes (PV) of surfactant solution injected for the full
extraction of petroleum hydrocarbons; three quarters of the extracted TPH were
removed in the foam gas phase (Table 1.4).
The loss of betaines surfactants in soils was much lower than for SDS (Fig. 1.13).
Finally, LB was selected for field tests, because it produced low-persistent foams
required for SF and cross-flow UF operations. The linear part for the exponential
extraction rate corresponding to the most productive part has been observed up to
5 PV, which has been the targeted level for injections in field-scale tests.
An in situ field test was carried out at the pilot scale by excavating a contaminated
plot (dimensions: 2 m long, 2 m large, 3 m depth). A 2 mm-thick PET sheet was set
at the bottom and folded vertically on sides (0.5 m high) to make the cell impervious.
Then a central well was installed to collect soil leachates and the soil was set back
and compacted using a mechanical shovel. Finally, the top soil was clad with a
2 mm-thick PET sheet folded down on sides (0.3 m) and 16 injection–extraction
wells were set. Considering the dimensions of the cell and soil characteristics, the PV
was estimated to be 2.4 m
3 . All the steps and details about the setup of the cell are
shown in Fig. 1.14, while details for wastewater treatments are shown in Fig. 1.15.
44
N. Fatin-Rouge