Improving washing efficiency of heavy metal-contaminated clayey soils based on repeated ice-segregation in seasonal frozen areas
-
摘要: 基于程国栋院士的“厚层地下冰的重复分凝机制”理论,提出利用重复分凝成冰作用以提高重金属污染黏性土的淋洗效率。以Cd、Pb污染黏性土为研究对象,选用EDTA、酒石酸为淋洗液,通过室内振荡淋洗试验和冻融–淋洗土柱试验,比较分析了不同工况下重金属的去除效果。结果表明,通过融化速率控制为正融土中水分迁移和重复分凝成冰提供有利条件,较单一冻结–吸水模式淋洗液的摄入量约增加20%,而且冻–融界面的反复波动,有助于淋洗液与土壤中重金属充分接触,两者的协同作用能够显著提高重金属去除率,Cd、Pb的去除率分别提高了43.95%和171.74%。该方法在实际工程应用上具有一定的现实性和普适性,对季冻区重金属污染黏性土修复提供了一个新的思路。Abstract: The scheme to improve the washing efficiency of heavy metal-contaminated clayey soil is proposed by using the repeated ice-segregation based on the theory of "repeated segregation mechanism of thick ground ice". The laboratory batch washing tests and freezing-thawing and washing tests are performed on Cd- and Pb-contaminated clayey soils with EDTA, tartaric acid as eluents. Subsequently, the removal effects of heavy metals under different working conditions are analyzed. The results show that it provides advantages for water migration in thawing soils and repeated ice-segregation by controlling the thawing rate. Compared with that of the single freezing-water intaking mode, the eluent intaking amount of the freezing-thawing and washing tests with repeated ice-segregation increases by about 20%. The repeated fluctuations of the freezing-thawing interface will promote the eluent to fully contact with the heavy metal in the soils. Their synergistic effects can effectively increase the removal effeciency of heavy metals. The removal efficiency of Cd and Pb increases by 43.95% and 171.74%, respectively. It is of certain reality and universality in practical engineering application and provides a new idea for the remediation of heavy metal-contaminated clayey soils in seasonal frozen areas.
-
-
表 1 土样的基本性质
Table 1 Basic properties of test soil samples
土颗粒密度ρs/(g·cm-3) 界限含水率 击实参数 粒径分布 Pb含量/(mg·kg-1) Cd含量/(mg·kg-1) wL/% wP/% ρdmax/(g·cm-3) wopt/% ≥0.25 mm 0.075~0.25 mm ≤0.075 mm 2.70 29.9 16.0 1.7 19.0 24.2 22.08 53.72 128.3 5.5 表 2 试验方案
Table 2 Test schemes
试验编号 淋洗液补给* 冻结速率 融化速率 重复分凝成冰 冻融次数 补水 FTW1-1 0.05 mol/L EDTA+0.05 mol/L TA 0.2℃/h 分步升温:1℃/5 h 有 1 有 FTW1-2 0.05 mol/L EDTA+0.05 mol/L TA 直线升温 无 无 FTW1-3 0.05 mol/L EDTA 分步升温:1℃/5 h 有 有 FTW1-4 0.05 mol/L EDTA 直线升温 无 无 FTW3-1 1:0.05 mol/L EDTA+0.05 mol/L TA 分步升温:1℃/5 h 有 3 有 2:0.01 mol/L EDTA 有 3:0.02 mol/L TA 有 FTW3-2 1:0.05 mol/L EDTA+0.05 mol/L TA 分步升温:1℃/5 h 有 无 2:0.01 mol/L EDTA+0.02 mol/L TA 有 3:0.01 mol/L EDTA 有 注:* FTW3-1为例,冻融第1次补给0.05 mol/L EDTA+0.05 mol/L TA,第2次补给0.01 mol/L EDTA,第3次补给0.02 mol/L TA,共3个冻融循环。 -
[1] 王菲, 徐汪祺. 固化/稳定化和软土加固污染土的强度和浸出特性研究[J]. 岩土工程学报, 2020, 42(10): 1955–1961. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC202010028.htm WANG Fei, XU Wang-qi. Strength and leaching performances of stabilized/solidified(S/S) and ground improved (GI) contaminated site soils[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(10): 1955–1961. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC202010028.htm
[2] DASSEKPO J B M, NING J Q, ZHA X X. Potential solidification/stabilization of clay-waste using green geopolymer remediation technologies[J]. Process Safety and Environmental Protection, 2018, 117: 684–693. doi: 10.1016/j.psep.2018.06.013
[3] DERMONT G, BERGERON M, MERCIER G, et al. Soil washing for metal removal: a review of physical/chemical technologies and field applications[J]. Journal of Hazardous Materials, 2008, 152(1): 1–31. doi: 10.1016/j.jhazmat.2007.10.043
[4] GRIFFITHS R A. Soil-washing technology and practice[J]. Journal of Hazardous Materials, 1995, 40(2): 175–189. doi: 10.1016/0304-3894(94)00064-N
[5] CHANG B V, CHIANG B W, YUAN S Y. Biodegradation of nonylphenol in soil[J]. Chemosphere, 2007, 66(10): 1857–1862. doi: 10.1016/j.chemosphere.2006.08.029
[6] ASH C, TEJNECKÝ V, ŠEBEK O, et al. Redistribution of cadmium and lead fractions in contaminated soil samples due to experimental leaching[J]. Geoderma, 2015, 241/242: 126–135. doi: 10.1016/j.geoderma.2014.11.022
[7] FEDJE K K, YILLIN L, STRÖMVALL A M. Remediation of metal polluted hotspot areas through enhanced soil washing- evaluation of leaching methods[J]. Journal of Environmental Management, 2013, 128: 489–496. doi: 10.1016/j.jenvman.2013.05.056
[8] SEMER R, REDDY K R. Evaluation of soil washing process to remove mixed contaminants from a sandy loam[J]. Journal of Hazardous Materials, 1996, 45(1): 45–57. doi: 10.1016/0304-3894(96)82887-1
[9] 芮大虎, 武迎飞, 陈雪, 等. 复合冻融与淋洗方法修复重金属污染黏性土的研究[J]. 岩土工程学报, 2019, 41(2): 286–293. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201902007.htm RUI Da-hu, WU Ying-fei, CHEN Xue, et al. Remediation of heavily metal-contaminated clayey soils by composite freeze-thaw and soil washing method[J]. Chinese Journal of Geotechnical Engineering, 2019, 41(2): 286–293. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201902007.htm
[10] RUI D H, WU Z P, JI M, et al. Remediation of Cd- and Pb- contaminated clay soils through combined freeze-thaw and soil washing[J]. Journal of Hazardous Materials, 2019, 369: 87–95. doi: 10.1016/j.jhazmat.2019.02.038
[11] CHENG K T. The mechanism of repeated-segregation for the formation of thick layered ground ice[J]. Cold Regions Science and Technology, 1983, 8(1): 57–66. doi: 10.1016/0165-232X(83)90017-4
[12] MING F, LI D Q. A model of migration potential for moisture migration during soil freezing[J]. Cold Regions Science and Technology, 2016, 124: 87–94. doi: 10.1016/j.coldregions.2015.12.015
[13] ZHOU J Z, WEI C F, LI D Q, et al. A moving-pump model for water migration in unsaturated freezing soil[J]. Cold Regions Science and Technology, 2014(104/105): 14–22. http://www.onacademic.com/detail/journal_1000036125878410_8173.html
[14] 王洋, 刘景双, 王国平, 等. 冻融作用与土壤理化效应的关系研究[J]. 地理与地理信息科学, 2007, 23(2): 91–96. https://www.cnki.com.cn/Article/CJFDTOTAL-DLGT200702021.htm WANG Yang, LIU Jing-shuang, WANG Guo-ping, et al. Study on the effect of freezing and thawing action on soil physical and chemical characteristics[J]. Geography and Geo-Information Science, 2007, 23(2): 91–96. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-DLGT200702021.htm
[15] 王家澄, 程国栋, 张宏鼎, 等. 饱水砂土反复冻融时成冰条件的试验研究[J]. 冰川冻土, 1992, 14(2): 101–106, 191. https://www.cnki.com.cn/Article/CJFDTOTAL-BCDT199202001.htm WANG Jia-cheng, CHENG Guo-dong, ZHANG Hong-ding, et al. Experimental study on conditions for ice formation of saturated sand in freezing and thawing cycles[J]. Journal of Glaciology and Geocryology, 1992, 14(2): 101–106, 191. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-BCDT199202001.htm
[16] 李述训, 程国栋, 张宏鼎, 等. 冰水系统中的砖在融化过程中水分迁移实验研究[J]. 冰川冻土, 1991, 13(4): 323–329. https://www.cnki.com.cn/Article/CJFDTOTAL-BCDT199104006.htm LI Shu-xun, CHENG Guo-dong, ZHANG Hong-ding, et al. Experimertal reseach on moisture migration of brick in ice-water system during thawing[J]. Journal of Glaciology and Geocryology, 1991, 13(4): 323–329. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-BCDT199104006.htm
-
期刊类型引用(3)
1. 张明,胡栋科,谢敬礼,王赵明,李小明,周方亮,赵留义. 基于机器学习算法的高放废物处置库屏障材料膨胀性能演化研究. 辐射防护. 2025(02): 157-166 . 百度学术
2. 谈云志,魏康旭,祝雨,张金生,明华军. 球状石墨–膨润土压实后的导热与防渗性能. 岩石力学与工程学报. 2025(05): 1340-1348 . 百度学术
3. 郝丰富,马田田,于海文,韦昌富,田慧会,伊盼盼. 阳离子交换量对膨润土层间水化影响的试验研究. 岩土力学. 2024(09): 2611-2620 . 百度学术
其他类型引用(2)