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Field application of modified in situ soil flushing in combination with air sparging at a military site polluted by diesel and gasoline in Korea.

Lee H, Lee Y, Kim J, Kim C - Int J Environ Res Public Health (2014)

Bottom Line: The discharged TPH and BTEX (benzene, toluene, ethylbenzene, and xylenes) concentrations in the water were highest at 20 min and at a rate of 350 L/min, which was selected as the volume of air for the full-scale operation in the pilot air sparging test.The hydraulic conductivity (3.13 × 10-3 cm/s) increased 4.7 times after the serial operation of both processes relative to the existing condition (6.61 × 10-4 cm/s).The total TPH and BTEX mass removed during the full-scale operation was 5109 and 752 kg, respectively.

View Article: PubMed Central - PubMed

Affiliation: Department of Technical Development, Daeil E&C, 114-9 Samseong-dong, Gangnan-gu, Seoul 135-509, Korea. jaeykim@snu.ac.kr.

ABSTRACT
In this study the full-scale operation of soil flushing with air sparging to improve the removal efficiency of petroleum at depths of less than 7 m at a military site in Korea was evaluated. The target area was polluted by multiple gasoline and diesel fuel sources. The soil was composed of heterogeneous layers of granules, sand, silt and clay. The operation factors were systemically assessed using a column test and a pilot study before running the full-scale process at the site. The discharged TPH and BTEX (benzene, toluene, ethylbenzene, and xylenes) concentrations in the water were highest at 20 min and at a rate of 350 L/min, which was selected as the volume of air for the full-scale operation in the pilot air sparging test. The surfactant-aid condition was 1.4 times more efficient than the non-surfactant condition in the serial operations of modified soil flushing followed by air sparging. The hydraulic conductivity (3.13 × 10-3 cm/s) increased 4.7 times after the serial operation of both processes relative to the existing condition (6.61 × 10-4 cm/s). The removal efficiencies of TPH were 52.8%, 57.4%, and 61.8% for the soil layers at 6 to 7, 7 to 8 and 8 to 9 m, respectively. Therefore, the TPH removal was improved at depth of less than 7 m by using this modified remediation system. The removal efficiencies for the areas with TPH and BTEX concentrations of more than 500 and 80 mg/kg, were 55.5% and 92.9%, respectively, at a pore volume of 2.9. The total TPH and BTEX mass removed during the full-scale operation was 5109 and 752 kg, respectively.

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Variations in the TPH and BTEX concentrations during the soil flushing operation. (a) TPH removal efficiency at 0.1, 0.3, 0.5, and 1.0 L/min∙m2 in the column test, (b) the TPH and BTEX concentrations during the pilot scale soil flushing operation with and without the surfactant.
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ijerph-11-08806-f005: Variations in the TPH and BTEX concentrations during the soil flushing operation. (a) TPH removal efficiency at 0.1, 0.3, 0.5, and 1.0 L/min∙m2 in the column test, (b) the TPH and BTEX concentrations during the pilot scale soil flushing operation with and without the surfactant.

Mentions: In this test, a gravity dose was introduced during soil flushing based on the results of the lab scale column test shown in Figure 5a. Previously, significant TPH and BTEX concentrations were reduced by soil flushing at 0.16 L/(min∙m2) for 10 pore volumes at this site [14]. However, after soil flushing, the residue was still detected at concentrations that were greater than the legal limit. The removal efficiencies of TPH and BTEX in the subsurface layer at depths of less than 7 m were low, which corresponded to the weathered soil layer that is generally less permeable. In the column test, the removal efficiency of TPH decreased as the injection velocity of the surfactant was increased during soil flushing. The removal efficiencies of 10 pore volumes at 0.1, 0.3, 0.5, and 1.0 L/(min∙m2) were 54.7%, 45.2%, 42.7% and 40.0%, respectively. The removal efficiency at 50 pore volumes at 0.1 L/(min∙m2) was 14.7% greater than at 1 L/(min∙m2). This finding is consistent with the results of Choi et al. [16], which showed that lower flux enhanced the removal effect at the same pore volume in the column test. The surfactant solution flow-rate was shown to have a detrimental effect on TPH removal efficiency. Another similar result was reported by Couto et al. in the remediation of a sandy soil contaminated with commercial diesel oil, supplied by Petrobras S.A using SDS solution as a remediation surfactant [17]. Based on these results, a low flux dose method was adopted in the following pilot scale test with soil flushing.


Field application of modified in situ soil flushing in combination with air sparging at a military site polluted by diesel and gasoline in Korea.

Lee H, Lee Y, Kim J, Kim C - Int J Environ Res Public Health (2014)

Variations in the TPH and BTEX concentrations during the soil flushing operation. (a) TPH removal efficiency at 0.1, 0.3, 0.5, and 1.0 L/min∙m2 in the column test, (b) the TPH and BTEX concentrations during the pilot scale soil flushing operation with and without the surfactant.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4198992&req=5

ijerph-11-08806-f005: Variations in the TPH and BTEX concentrations during the soil flushing operation. (a) TPH removal efficiency at 0.1, 0.3, 0.5, and 1.0 L/min∙m2 in the column test, (b) the TPH and BTEX concentrations during the pilot scale soil flushing operation with and without the surfactant.
Mentions: In this test, a gravity dose was introduced during soil flushing based on the results of the lab scale column test shown in Figure 5a. Previously, significant TPH and BTEX concentrations were reduced by soil flushing at 0.16 L/(min∙m2) for 10 pore volumes at this site [14]. However, after soil flushing, the residue was still detected at concentrations that were greater than the legal limit. The removal efficiencies of TPH and BTEX in the subsurface layer at depths of less than 7 m were low, which corresponded to the weathered soil layer that is generally less permeable. In the column test, the removal efficiency of TPH decreased as the injection velocity of the surfactant was increased during soil flushing. The removal efficiencies of 10 pore volumes at 0.1, 0.3, 0.5, and 1.0 L/(min∙m2) were 54.7%, 45.2%, 42.7% and 40.0%, respectively. The removal efficiency at 50 pore volumes at 0.1 L/(min∙m2) was 14.7% greater than at 1 L/(min∙m2). This finding is consistent with the results of Choi et al. [16], which showed that lower flux enhanced the removal effect at the same pore volume in the column test. The surfactant solution flow-rate was shown to have a detrimental effect on TPH removal efficiency. Another similar result was reported by Couto et al. in the remediation of a sandy soil contaminated with commercial diesel oil, supplied by Petrobras S.A using SDS solution as a remediation surfactant [17]. Based on these results, a low flux dose method was adopted in the following pilot scale test with soil flushing.

Bottom Line: The discharged TPH and BTEX (benzene, toluene, ethylbenzene, and xylenes) concentrations in the water were highest at 20 min and at a rate of 350 L/min, which was selected as the volume of air for the full-scale operation in the pilot air sparging test.The hydraulic conductivity (3.13 × 10-3 cm/s) increased 4.7 times after the serial operation of both processes relative to the existing condition (6.61 × 10-4 cm/s).The total TPH and BTEX mass removed during the full-scale operation was 5109 and 752 kg, respectively.

View Article: PubMed Central - PubMed

Affiliation: Department of Technical Development, Daeil E&C, 114-9 Samseong-dong, Gangnan-gu, Seoul 135-509, Korea. jaeykim@snu.ac.kr.

ABSTRACT
In this study the full-scale operation of soil flushing with air sparging to improve the removal efficiency of petroleum at depths of less than 7 m at a military site in Korea was evaluated. The target area was polluted by multiple gasoline and diesel fuel sources. The soil was composed of heterogeneous layers of granules, sand, silt and clay. The operation factors were systemically assessed using a column test and a pilot study before running the full-scale process at the site. The discharged TPH and BTEX (benzene, toluene, ethylbenzene, and xylenes) concentrations in the water were highest at 20 min and at a rate of 350 L/min, which was selected as the volume of air for the full-scale operation in the pilot air sparging test. The surfactant-aid condition was 1.4 times more efficient than the non-surfactant condition in the serial operations of modified soil flushing followed by air sparging. The hydraulic conductivity (3.13 × 10-3 cm/s) increased 4.7 times after the serial operation of both processes relative to the existing condition (6.61 × 10-4 cm/s). The removal efficiencies of TPH were 52.8%, 57.4%, and 61.8% for the soil layers at 6 to 7, 7 to 8 and 8 to 9 m, respectively. Therefore, the TPH removal was improved at depth of less than 7 m by using this modified remediation system. The removal efficiencies for the areas with TPH and BTEX concentrations of more than 500 and 80 mg/kg, were 55.5% and 92.9%, respectively, at a pore volume of 2.9. The total TPH and BTEX mass removed during the full-scale operation was 5109 and 752 kg, respectively.

Show MeSH
Related in: MedlinePlus