Journal of Soil and Groundwater Environment (한국지하수토양환경학회지:지하수토양환경)

Korean Society of Soil and Groundwater Environment (한국지하수토양환경학회)
권호 표지

Removal of NAPL from Aquifer Using Surfactant-enhanced Air Sparging at Elevated Temperature

승온조건의 SEAS(surfactant-enhanced air sparging) 기술을 이용한 대수층 NAPL(n-decane)의 휘발제거

  • Song, Young-Su (Dept. of Environmental Sciences and Biotechnology, Hallym University, Institute of Energy and Environment, Hallym University) ;
  • Kwon, Han-Joon (Dept. of Environmental Sciences and Biotechnology, Hallym University, Institute of Energy and Environment, Hallym University) ;
  • Kim, Heon-Ki (Dept. of Environmental Sciences and Biotechnology, Hallym University, Institute of Energy and Environment, Hallym University)
  • 송영수 (한림대학교 환경생명공학과, 한림대학교 에너지환경 연구소) ;
  • 권한준 (한림대학교 환경생명공학과, 한림대학교 에너지환경 연구소) ;
  • 김헌기 (한림대학교 환경생명공학과, 한림대학교 에너지환경 연구소)
  • Received : 2009.11.03
  • Accepted : 2009.11.26
  • Published : 2009.12.31
Download PDF
⟨ Previous Next ⟩

Abstract

Surfactant-enhanced air sparging (SEAS) was developed to suppress the surface tension of groundwater prior to air sparging resulting in higher air saturation and larger contact area between NAPL and gas during air sparging. Larger contacting interface between NAPL and gas means faster mass transfer of contaminants from NAPL to gas phase. This new technique, however, is limited to relatively volatile contaminants because vaporization is its basic mechanism of mass transfer. In this study, SEAS was tested at an elevated temperature for a semi-volatile n-decane, which is expected not to be a good candidate of SEAS application due to its low vapor pressure at ambient temperature. Three sparging experiments were conducted using 1-dimensional column (5 cm id, 80 cm length) packed with sand; (1) ambient temperature ($23^{\circ}C$), column saturated with distilled water, (2) SEAS at ambient temperature ($23^{\circ}C$), for n-decane contaminated sand, (3) SEAS at elevated temperature ($73^{\circ}C$), for n-decane contaminated sand. Higher air saturation was achieved by SEAS compared to that by air sparging without surfactant application. The n-decane removal efficiency of SEAS at elevated temperature was significantly higher(> 10 times) than that of ambient SEAS. The n-decane concentrations in the gas effluent from column during SEAS at $73^{\circ}C$ are found to be 10 times of those measured at ambient temperature. Thus, SEAS technique can be applied for removal of semi-volatile contaminants provided that an appropriate technique for elevating aquifer temperature is available.

대수층에 존재하는 휘발성 오염물질을 제거하는 새로운 공법으로서 Surfactant-enhanced air sparging(SEAS)은 지하수의 표면장력을 감소함으로써 지하수 폭기효율의 증대를 도모한다. 그러나 SEAS기술도 기본적으로 오염물질의 휘발에 의한 물질이동에 의존함으로써 휘발성이 낮은 오염물질의 제거에는 매우 제한적이다. 본 연구는 승온된 조건에서 SEAS기술을 준휘발성 물질인 n-decane에 대하여 적용함으로써 SEAS기술의 확장여부를 시험하였다. 지하수 폭기실험은 내경 5 cm, 길이 80 cm의 1차원 토양(모래)컬럼을 사용하여 실시하였다. 실험은 총 3회 실시하였으며, 상온에서 증류수로 포화된 조건에서 1회, 상온($23^{\circ}C$)에서 음이온계 계면활성제(sodium dodecylbenzene sulfonate, SDBS) 수용액으로 포화된 조건에서 1회(상온 SEAS), 그리고 승온상태($73^{\circ}C$)에서 SDBS수용액으로 포화된 조건에서 1회(승온 SEAS) 실시하였다. 계면활성제가 적용된 경우의 폭기에 의한 공기포화율(57%)은 증류수로 포화된 조건의 공기포화율(10%)보다 높게 측정되었다. 승온 및 상온조건에서의 공기포화율은 거의 차이가 없었으나 n-decane의 제거속도는 현저한 차이를 나타내었다. 토양유출 가스에 포함된 n-decane의 농도는 상온조건에 비하여 승온조건에서 10배 이상 높았으며, 따라서 제거속도도 10배 이상의 차이를 나타내었다. 본 연구 결과에 따라 상온에서 휘발성이 낮으나 수 십도의 온도상승으로 증기압이 획기적으로 늘어날 수 있는 준휘발성 물질에 대하여 SEAS 기술이 효과적으로 응용될 수 있을 것으로 보인다.

Keywords

References

  1. Adams, J.A. and Reddy, K.R., 2000, Removal of dissolved- and free-phase benzene pools from ground water using in situ air sparging, J. Envir. Engrg., 126, 697-707 https://doi.org/10.1061/(ASCE)0733-9372(2000)126:8(697)
  2. Brooks, R.H. and Corey, A.T., 1966, Properties of porous media affecting fluid flow, J. Irrig. Drain., 92, 61-68
  3. Lide, D.R., 2000, Vapor pressure, In: Lide, D. R(ed.), CRC Handbook of Chemistry and Physics 81st Edition, CRC Press, Washington D.C., p. 6-88
  4. Heron, G., van Zutphen, M., Christensen, T.H., and Enfield, C.G., 1998, Soil heating for enhanced remediation of chlorinated solvents: A laboratory study on resisteve heating and vapor extraction in a silty, low-permeable soil contaminated with trichloroethylene, Environ. Sci. Technol., 32, 1474-1481 https://doi.org/10.1021/es970563j
  5. Johnson, R.L., Johnson, P.C., McWhorter, D.B., Hinchee, R.E., and Goodman, I., 1993, An overview of in situ air sparging, Ground Water Monit. Rev., 13, 127-135 https://doi.org/10.1111/j.1745-6592.1993.tb00456.x
  6. Johnston, C.D., Rayner, J.L., and Briegel, D., 2002, Effectiveness of in situ air sparging for removing NAPL gasoline from a sandy aquifer near Perth, Western Australia, J. Contam. Hydrol., 59, 87-111 https://doi.org/10.1016/S0169-7722(02)00077-3
  7. Kawala, Z. and Atamanczuk, T., 1998, Microvave-enhanced thermal decontamination of soil, Environ. Sci. Technol., 32, 2602-2607 https://doi.org/10.1021/es980025m
  8. Kim, H. and Annable, M.D., 2006, Effect of surface reduction on VOC removal during surfactant-enhanced air sparging, J. Environ. Sci. Health Part A, 41, 2799-2811 https://doi.org/10.1080/10934520600966946
  9. Kim, H., Annable, M.D., Rao, P.S.C., and Cho, J., 2009, Laboratory Evaluation of Surfactant-Enhanced Air Sparging for Perchloroethene Source Mass Depletion from sand, J. Environmental Sci. Health, Part A, 44, 406-413 https://doi.org/10.1080/10934520802659786
  10. Kim, H., Choi, K.-M., Moon, J.-W., and Annable, M.D., 2006, Changes in air saturation and air-water interfacial area during surfacatant-enhanced air sparging in saturated sand, J. Conatam. Hydrol., 88, 23-35 https://doi.org/10.1016/j.jconhyd.2006.05.009
  11. Kim, H., Choi, K.-M., and Rao, P.S.C., 2007, Measurement of gas-accessible NAPL saturation in soil using gaseous tracers, Environ. Sci. Technol., 41, 235-241 https://doi.org/10.1021/es060992u
  12. Kim, H., Soh, H.-E., Annable, M.D., and Kim, D.-J., 2004, Surfactant-enhanced air sparging in saturated sand, Environ. Sci. Technol., 38, 1170-1175 https://doi.org/10.1021/es030547o
  13. Lundegard, P.D. and LaBrecque, D., 1995, Air sparging in a sandy aquifer (Florence, Oregon, USA): Actual and apparent radius of influence, J. Contam. Hydrol., 19, 1-27 https://doi.org/10.1016/0169-7722(95)00010-S
  14. Marley, M.C., Hazebrouck, D.J., and Walch, M.T., 1992, The application of in situ air sparging as an innovative soils and ground water remediation technology, Gound Water Monit. Rev. 12, 137-145 https://doi.org/10.1111/j.1745-6592.1992.tb00044.x
  15. Rabiduar, A.J., Blayden, J.M., and Ganguly, C., 1999, Field performance of air-sparging system for removing TCE from groundwater, Environ. Sci. Technol., 33, 157-162 https://doi.org/10.1021/es980538t
  16. Reddy, K.R. and Adams, J.A., 1998, System effect on benzene removal from saturated soils and groundwaterusing air sparging, J. Environ. Engrg., 124, 288-299 https://doi.org/10.1061/(ASCE)0733-9372(1998)124:3(288)
  17. Reddy, K.R., Kosgi, S., and Zhou, J., 1995, A review of in-situ air sparging for the remediation of VOC-contaminated saturated soils and groundwater, Haz. Waste and Haz. Mat., 12, 97-118 https://doi.org/10.1089/hwm.1995.12.97
  18. Tse, K.K.C., Liou, T.-S., and Lo, S.-L., 2006, Numerical simulation of steam injectioin pilot study for a PCE-contaminated aquifer, Environ. Sci. Technol., 40, 4292-4299 https://doi.org/10.1021/es051784p