본 연구에서는 유해원소로 오염된 현장토양을 대상으로 물리적 및 화학적 토양세척공법을 적용하였을 경우, 유해원소의 처리효율과 더불어 토양세척공법에서 발생하는 폐수를 중화, 응집, 흡착 반응을 이용하여 처리할 경우를 고려하여 최적 토양세척공법의 선정방법을 평가하고자 하였다. 본 연구에서 사용한 토양에서 주된 유해원소인 비소제거에 수산화나트륨 수용액이 황산 수용액보다 효과적이었다. 반면, 폐수 처리의 경우 수산화나트륨 수용액으로 토양 세척 시 함께 추출되는 토양유기물로 인하여 폐수처리가 복잡하고 유해원소의 제거가 잘되지 않아 세척공정의 세척제로는 산을 이용하여 토양을 세척하는 것이 좋으며, 발생하는 세척액의 pH를 6.5 이상으로 중화시켜 대부분의 유해원소를 제거할 수 있었다. 흡착제로 GFO(Granular ferric oxide)를 이용하였을 경우 비소와 납의 제거율이 뛰어났으며, 중화공정과 결합하였을 경우 대부분의 유해원소를 제거할 수 있었다. 결과적으로, 토양세척 공법 적용 시 토양의 특성에 따라 유해원소의 제거율 및 세척액의 처리 및 재이용 방법이 차이가 있으므로, 세척효율 및 세척수 처리 공정을 고려한 체계적인 최적화를 진행하여야 할 것으로 판단된다.

This study evaluated the optimal soil washing conditions for toxic metals considering the removal efficiency of toxic metals from contaminated soils as well as from soil washing effluents. In the contaminated soils, As was the major contaminant and extracted by sodium hydroxide solution better than by sulfuric acid. However, in the case of the treatment of soil washing effluents, sodium hydroxide was less effective extractant because soil organic matter extracted by sodium hydroxide prevented the solid-liquid phase separation and toxic metal removal. In the treatment of_x000D_ soil washing effluents with sulfuric acid, toxic metals in the effluents were mostly precipitated at the pH above 6.5. In addition, granular ferric oxide (GFO) as an adsorbent enhanced the removal of As and Pb indicating that toxic metals in the washing effluents can be removed almost completely by the use of combined adsorption-neutralization process. This study suggests that soil washing techniques for toxic metals should be optimized based on the physical and chemical properties of the contaminated soils, the nature of chemical extractant, and the removal efficiency and effectiveness of toxic metals from the soils as well as soil washing effluents.

Adsorption Coagulation Heavy Metals Neutralization Precipitation

Mulligan CN, Yong RN, Gibbs BF, Eng. Geol., 60, 193 (2001)
Abumaizar RJ, Smith EH, J. Hazard. Mater., 70, 71 (1999)
Dermont G, Bergeron M, Mercier G, Richer-Lafleche M, J. Hazard. Mater., 152(1), 1 (2008)
Yang JW, Lee YJ, Korean Chem. Eng. Res., 45(4), 311 (2007)
Li F, Bade R, Oh S, Shin WS, Korean J. Chem. Eng., 29(10), 1362 (2012)
Demir A, Koleli N, Environ. Technol., 34, 799 (2013)
Lim M, Ahn JW, J. of Korean Inst. of Resources Recycling., 20, 28 (2011)
Pociecha M, Lestan D, J. Hazard. Mater., 174(1-3), 670 (2010)
Pociecha M, Lestan D, Environ. Pollut., 158, 2710 (2010)
Lee JH, Park KS, Economic and Environmental Geology., 43, 123 (2010)
Lee IH, Seol MS, Journal of Soil and Groundwater Environment., 15, 23 (2010)
Kim T, Kim MJ, J. of KSEE., 30, 808 (2008)
Kim HS, Choi SI, Journal of Soil and Groundwater Environment., 13, 60 (2008)
Han KW, Shin HM, Journal of the Environmental Sciences., 17, 185 (2008)
Baek K, Kim DH, Seo CI, Yang JS, Lee JY, Journal of Soil and Groundwater Environment., 12, 17 (2007)
Hwang SS, Lee NS, Namkoong W, J.of KSEE., 27, 1072 (2005)
Ko I, Lee CH, Lee KP, Kim KW, Journal of Soil and Groundwater Environment., 9, 52 (2004)
Hwang JS, Choi SI, Jang M, Journal of Soil and Groundwater Environment., 9, 104 (2004)
Voglar D, Lestan D, J. Hazard. Mater., 180(1-3), 152 (2010)
Pociecha M, Lestan D, J. Hazard. Mater., 165(1-3), 533 (2009)
Finzgar N, Lestan D, Chemosphere., 73, 1484 (2008)
Hasegawa H, Rahman IMM, Nakano M, Begum ZA, Egawa Y, Maki T, Furusho Y, Mizutani S, Water Res., 45, 4844 (2011)
Jung J, Yang JS, Kim SH, Yang JW, Desalination, 222(1-3), 202 (2008)
Jeong JH, Seo PS, Kong SH, Seo SW, Kim MK, Lee JY, Lee SS, J. of KSEE., 28, 1222 (2006)
Jang M, Hwang JS, Choi SI, Park JK, Chemosphere., 60, 344 (2005)
Jeon CS, Baek K, Park JK, Oh YK, Lee SD, J. Hazard. Mater., 163(2-3), 804 (2009)
Yang JS, Lee JY, Baek K, Kwon TS, Choi J, J. Hazard. Mater., 171(1-3), 443 (2009)