Monitoring and analysis of key indicators in the process of electrickinetic remediation of Cr(Ⅵ) contaminated groundwater
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摘要:
电动修复是去除地下水中重金属污染物的有效方法。采用电动修复方法对Cr(Ⅵ)初始浓度为1 000 mg/kg的污染浅层地下水进行为期4 d的处理，研究不同电压梯度（1、2、3 V/cm）对饱和带地下水中Cr(Ⅵ)去除率的影响。此外，对修复过程中的相关指标包括电流、阴阳极电解液pH、氧化还原电位（Eh）和不同位置地下水Cr(Ⅵ)浓度进行监测，并且对电动修复前后饱和带介质的pH、Eh和Cr(Ⅵ)去除率进行分析。结果表明：Cr(Ⅵ)的平均去除率随电压梯度升高而升高，当电压梯度为2 V/cm时去除效率和经济性较好，去除率提升与能耗提升比值为0.52，最高去除率91.41%出现在电压梯度为3 V/cm时，但此时相应能耗较高。修复过程中Cr(Ⅵ)会在阳极附近富集，特别是当电压梯度较低（1 V/cm）时，反应结束后近阳极地下水Cr(Ⅵ)富集浓度高达2 170.95 mg/L，介质中Cr(Ⅵ)浓度为1 497.45 mg/kg，此时去除率为负值；阳极电解液Cr(Ⅵ)浓度呈先增长后稳定的趋势，当Cr(Ⅵ)浓度接近4 000 mg/L时，已接近装置的最大迁移值，增加反应时间对Cr(Ⅵ)的回收率提升不大。修复过程中介质Eh降低、pH升高会促进Cr(Ⅵ)的还原和解吸，对Cr(Ⅵ)的去除具有促进作用。
Abstract:Electrokinetic remediation is an effective method to remove heavy metal contaminants from groundwater. The effect of different voltage gradients (1, 2, 3 V/cm) on the removal rate of saturated zone groundwater Cr(Ⅵ) was studied with an initial content of 1 000 mg/kg for 4 days by the electrokinetic remediation method. In addition, the relevant factors in the repair process, including current, pH and redox potential (Eh) of anode and cathode electrolytes, and the concentrations of Cr(Ⅵ) in different positions were monitored. PH, the removal rates of Cr(Ⅵ) and Eh of the saturated zone medium before and after treatments were analyzed The results showed that: 1) The average removal rates of Cr(Ⅵ) increased with the increase of voltage gradient. When the voltage gradient was set at 2 V/cm, the removal efficiency and economy were better. The removal rate increase/energy consumption increase ratio was 0.52. The highest removal rate of 91.41% was observed when the voltage gradient was set at 3 V/cm, and the higher corresponding energy consumption was observed. 2) During the repair process, Cr(Ⅵ) would be enriched near the anode, especially when the voltage gradient was low (1 V/cm). The Cr(Ⅵ) concentration in groundwater near the anode after the reaction was up to 2170.95 mg/L, and the concentration of Cr(Ⅵ) in the medium was 1497.45 mg/kg, with negative removal rate. The concentration of Cr(Ⅵ) in the anolyte showed a tendency to increase first and then stabilize. When the Cr(Ⅵ) concentration was close to 4000 mg/L, it was close to the maximum migration value of the device. Increasing the reaction time had little effect on the recovery rate of Cr(Ⅵ). 3) The decrease of Eh and the increase of pH during the repair process would promote the reduction and desorption of Cr(Ⅵ), which could promote the removal of Cr(Ⅵ).
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Key words:
- electrodynamic remediation /
- hexavalent chromium /
- groundwater pollution /
- heavy metal
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图 2 取样点示意
注：a1~a3为阳极室取样点；b1~b3为阴极室取样点；G1~G3为地下水取样点；S1~S5为反应结束后土壤介质取样点。
Figure 2. Schematic diagram of sampling points
图 4 电动处理后含水层中残留的Cr(Ⅵ)
Figure 4. Remaining Cr(Ⅵ) in the aquifer after electrokinetic process
图 5 土壤室地下水中Cr(Ⅵ)浓度变化
Figure 5. Variation of Cr(Ⅵ) concentrations in the groundwater in the soil chamber
图 9 电动修复过程中的累积能耗
Figure 9. Accumulated energy consumption during electrokinetic remediation
表 1 土壤样品的理化性质
Table 1. Physical and chemical properties of the soil sample
土壤粒径占比/% 土壤质地 pH Eh/mV 溶解性有机碳浓度/(mg/kg) 含水率/% 碳酸盐浓度/% 0.002 mm 0.002～0.0 5 mm 0.05～2 mm 13.5 44.1 42.4 中壤土 7.98 232 10.13 22 6.2 
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表 2 土壤中Cr(Ⅵ)浓度随机采样结果
Table 2. Random sampling results Cr(Ⅵ) concentration in soil
mg/kg 采样点 平均值 标准差 1 2 3 4 5 1 005.06 938.58 936.80 989.00 1 018.00 977.49 37.76
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表 3 电压提高与Cr(Ⅵ)去除率和能耗的关系
Table 3. Relationship between voltage increase and Cr(Ⅵ) removal rate and energy consumption
项目 电压梯度/(V/cm) 1→2 2→3 去除率提升/% 21.50 15.27 能耗提升/% 41.05 80.60 去除率提升/能耗提升 0.52 0.19
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[1] 陈志良, 周建民, 蒋晓璐, 等.典型电镀污染场地重金属污染特征与环境风险评价[J]. 环境工程技术学报,2014,4(1):80-85. doi: 10.3969/j.issn.1674-991X.2014.01.014CHEN Z L, ZHOU J M, JIANG X L, et al. Pollution characteristics and environmental risk assessment of heavy metals in typical electroplating contaminated site[J]. Journal of Environmental Engineering Technology,2014,4(1):80-85. doi: 10.3969/j.issn.1674-991X.2014.01.014 [2] 关峰. 化学淋洗法修复工业场地铬污染土壤的过程控制及效果研究[D]. 青岛: 青岛科技大学, 2018. [3] REDDY K R, PARUPUDI U S, DEVULAPALLI S N, et al. Effects of soil composition on the removal of chromium by electrokinetics[J]. Journal of Hazardous Materials,1997,55(1/2/3):135-158. [4] 莫慧敏. 改性纳米零价铁对Cr(Ⅵ)的还原固定及机理研究[D]. 南宁: 广西大学, 2020. [5] EYVAZI B, JAMSHIDI-ZANJANI A, DARBAN A K. Immobilization of hexavalent chromium in contaminated soil using nano-magnetic MnFe2O4[J]. Journal of Hazardous Materials,2019,365:813-819. doi: 10.1016/j.jhazmat.2018.11.041 [6] 何俊昱. 土壤六价铬的污染特性、生物可给性及风险评估[D]. 杭州: 浙江大学, 2015. [7] 焦芳芳, 马振民, 侯玉松.焦作地区浅层地下水铬(Ⅵ)污染机理及迁移预测[J]. 煤田地质与勘探,2014,42(6):82-86. doi: 10.3969/j.issn.1001-1986.2014.06.017JIAO F F, MA Z M, HOU Y S. Pollution mechanism and migration prediction of Cr(Ⅵ) in shallow groundwater in Jiaozuo area[J]. Coal Geology & Exploration,2014,42(6):82-86. doi: 10.3969/j.issn.1001-1986.2014.06.017 [8] DHERI G S, BRAR M S, MALHI S S. Heavy-metal concentration of sewage-contaminated water and its impact on underground water, soil, and crop plants in alluvial soils of northwestern India[J]. Communications in Soil Science and Plant Analysis,2007,38(9/10):1353-1370. [9] 易玲, 高柏, 丁小燕, 等.鄱阳湖流域上游铀尾矿库周边水体中铬形态及健康风险评估[J]. 湖泊科学,2020,32(1):79-88. doi: 10.18307/2020.0108YI L, GAO B, DING X Y, et al. Species and health risk assessment of chromium around uranium tailing pond in the upper reaches of Lake Poyang Basin[J]. Journal of Lake Sciences,2020,32(1):79-88. doi: 10.18307/2020.0108 [10] 崔永高.铬污染土壤和地下水的修复技术研究进展[J]. 工程地质学报,2017,25(4):1001-1009.CUI Y G. Research progress on remediation technology of chromium contaminated soils and groundwater in Shanghai[J]. Journal of Engineering Geology,2017,25(4):1001-1009. [11] WENG C H, LIN Y T, LIN T Y, et al. Enhancement of electrokinetic remediation of hyper-Cr(Ⅵ) contaminated clay by zero-valent iron[J]. Journal of Hazardous Materials,2007,149(2):292-302. doi: 10.1016/j.jhazmat.2007.03.076 [12] 叶斌晖, 罗亚婷, 龙碧波, 等.草酸青霉SL2对高浓度铬污染土壤的生物淋洗及胞内铬形态转化研究[J]. 环境科学学报,2018,38(7):2825-2832.YE B H, LUO Y T, LONG B B, et al. Research on bioleaching of soils contaminated by high concentration of chromium with Penicillium oxalicum SL2 and the intracellular speciation transformation of chromium[J]. Acta Scientiae Circumstantiae,2018,38(7):2825-2832. [13] 闫鹏飞. 电动修复技术处理铬污染粘土试验研究[D]. 青岛: 青岛理工大学, 2010. [14] 喻旭. 化学强化剂协同可渗透反应墙强化电动修复铬污染土壤实验研究[D]. 重庆: 重庆大学, 2019. [15] 张瑞华, 孙红文.电动力和铁PRB技术联合修复铬(Ⅵ)污染土壤[J]. 环境科学,2007,28(5):1131-1136. doi: 10.3321/j.issn:0250-3301.2007.05.035ZHANG R H, SUN H W. Remediation of chromate contaminated soils by combined technology of electrokinetic and iron PRB[J]. Environmental Science,2007,28(5):1131-1136. doi: 10.3321/j.issn:0250-3301.2007.05.035 [16] 储陆平, 周书葵, 荣丽杉, 等.电动修复重金属污染土壤的研究进展[J]. 应用化工,2020,49(11):2853-2858. doi: 10.3969/j.issn.1671-3206.2020.11.040CHU L P, ZHOU S K, RONG L S, et al. Research progress on electric remediation of heavy metal contaminated soil[J]. Applied Chemical Industry,2020,49(11):2853-2858. doi: 10.3969/j.issn.1671-3206.2020.11.040 [17] 王业耀, 孟凡生, 陈锋.阴极pH控制对污染土壤电动修复效率的影响[J]. 环境科学研究,2007,20(2):36-40. doi: 10.3321/j.issn:1001-6929.2007.02.008WANG Y Y, MENG F S, CHEN F. Effect of pH control at the cathode for the electrokinetic remediation efficiency[J]. Research of Environmental Sciences,2007,20(2):36-40. doi: 10.3321/j.issn:1001-6929.2007.02.008 [18] 贺亚雪, 代朝猛, 苏益明, 等.地下水重金属污染修复技术研究进展[J]. 水处理技术,2016,42(2):1-5.HE Y X, DAI C M, SU Y M, et al. Research progress of remediation technologies on heavy metal pollution in groundwater[J]. Technology of Water Treatment,2016,42(2):1-5. [19] CAMESELLE C. Enhancement of electro-osmotic flow during the electrokinetic treatment of a contaminated soil[J]. Electrochimica Acta,2015,181:31-38. doi: 10.1016/j.electacta.2015.02.191 [20] LU P, FENG Q Y, MENG Q J, et al. Electrokinetic remediation of chromium-and cadmium-contaminated soil from abandoned industrial site[J]. Separation and Purification Technology,2012,98:216-220. doi: 10.1016/j.seppur.2012.07.010 [21] WU J N, ZHANG J, XIAO C Z. Focus on factors affecting pH, flow of Cr and transformation between Cr(Ⅵ) and Cr(Ⅲ) in the soil with different electrolytes[J]. Electrochimica Acta,2016,211:652-662. doi: 10.1016/j.electacta.2016.06.048 [22] TANG J, HE J G, LIU T T, et al. Removal of heavy metal from sludge by the combined application of a biodegradable biosurfactant and complexing agent in enhanced electrokinetic treatment[J]. Chemosphere,2017,189:599-608. doi: 10.1016/j.chemosphere.2017.09.104 [23] FU R B, WEN D D, XIA X Q, et al. Electrokinetic remediation of chromium (Cr)-contaminated soil with citric acid (CA) and polyaspartic acid (PASP) as electrolytes[J]. Chemical Engineering Journal,2017,316:601-608. doi: 10.1016/j.cej.2017.01.092 [24] HE J Y, HE C Q, CHEN X P, et al. Comparative study of remediation of Cr(Ⅵ)-contaminated soil using electrokinetics combined with bioremediation[J]. Environmental Science and Pollution Research,2018,25(18):17682-17689. doi: 10.1007/s11356-018-1741-8 [25] LEI H Y, CHEN K, LI Y J, et al. Electrokinetic recovery of copper, nickel, and zinc from wastewater sludge: effects of electrical potentials[J]. Environmental Engineering Science,2012,29(6):472-478. doi: 10.1089/ees.2010.0467 [26] LIU J, JIAO B Q, XU Z H. The effect of voltage gradient on removal efficiency and energy consumption during electrokinetic remediation of Zinc[J]. Disaster Advances,2011,4:69-72. [27] YUAN C, CHIANG T S. Enhancement of electrokinetic remediation of arsenic spiked soil by chemical reagents[J]. Journal of Hazardous Materials,2008,152(1):309-315. doi: 10.1016/j.jhazmat.2007.06.099 [28] NASIRI A, JAMSHIDI-ZANJANI A, KHODADADI DARBAN A. Application of enhanced electrokinetic approach to remediate Cr-contaminated soil: effect of chelating agents and permeable reactive barrier[J]. Environmental Pollution,2020,266:115197. [29] 李院. 电动-PRB联合修复复合污染土壤箱体实验研究[D]. 北京: 中国地质大学(北京), 2018. [30] 徐磊, 刘国, 许文来.低污染浓度重金属Cd污染土壤的电动修复研究[J]. 工业安全与环保,2015,41(3):4-6. doi: 10.3969/j.issn.1001-425X.2015.03.002XU L, LIU G, XU W L. Research on low pollution concentrations of Cd soil contamination by electrokinetic remediation[J]. Industrial Safety and Environmental Protection,2015,41(3):4-6. doi: 10.3969/j.issn.1001-425X.2015.03.002 [31] REDDY K R, CHINTHAMREDDY S. Electrokinetic remediation of heavy metal-contaminated soils under reducing environments[J]. Waste Management,1999,19(4):269-282. doi: 10.1016/S0956-053X(99)00085-9 [32] 江兆霞. 中国东部森林土壤降水脉冲效应的空间格局分布及影响因素[D]. 长春: 东北师范大学, 2021. [33] 蔡晔, 林怡雯, 李月娥, 等.土壤和底泥中六价铬提取与检测方法[J]. 实验室研究与探索,2015,34(1):21-25. doi: 10.3969/j.issn.1006-7167.2015.01.006CAI Y, LIN Y W, LI Y E, et al. Extraction and detection of chromium(Ⅵ) in soil and sediment[J]. Research and Exploration in Laboratory,2015,34(1):21-25. doi: 10.3969/j.issn.1006-7167.2015.01.006 [34] 王业耀, 孟凡生.铬(Ⅵ)污染高岭土电动修复实验研究[J]. 生态环境,2005,14(6):855-859.WANG Y Y, MENG F S. Experimental study on electrokinetic remediation of chromium-polluted kaolin[J]. Ecology and Environmental Sciences,2005,14(6):855-859. [35] 李敏, 孙照明, 马聪, 等.以牺牲阳极强化的电化学联用方法修复铬污染土壤[J]. 环境工程,2020,38(9):224-230.LI M, SUN Z M, MA C, et al. Electrochemical combined remediation of chromium contaminated soil based on strengthening by anode consumption[J]. Environmental Engineering,2020,38(9):224-230. [36] 万龙. 微电流-Fe0-PRB还原地下水中Cr(Ⅵ)研究[D]. 北京: 中国地质大学(北京), 2018. [37] 邵惟俊.汞、镉、钛、铬化合物的Eh-pH图[J]. 长安大学学报(地球科学版),1980(2):27-35. [38] DIAS-FERREIRA C, KIRKELUND G M, OTTOSEN L M. Ammonium nitrate as enhancement for electrodialytic soil remediation and investigation of soil solution during the process[J]. Chemosphere,2015,119:889-895. doi: 10.1016/j.chemosphere.2014.08.064 [39] 张鑫, 孙汝东.准平衡法测量水中溶解氧的研究[J]. 现代化工,2014,34(4):170-173.ZHANG X, SUN R D. Determination of dissolved oxygen in water by quasi-equilibrium method[J]. Modern Chemical Industry,2014,34(4):170-173. [40] 王成文, 许模, 张俊杰, 等.土壤pH和Eh对重金属铬(Ⅵ)纵向迁移及转化的影响[J]. 环境工程学报,2016,10(10):6035-6041. doi: 10.12030/j.cjee.201505010WANG C W, XU M, ZHANG J J, et al. Influence of soils pH and Eh on vertical migration and transformation of Cr(Ⅵ)[J]. Chinese Journal of Environmental Engineering,2016,10(10):6035-6041. doi: 10.12030/j.cjee.201505010 [41] 韩娟娟, 孟凡生, 王业耀, 等.电动修复硝酸盐污染高岭土的影响因素[J]. 环境工程技术学报,2014,4(4):269-274. doi: 10.3969/j.issn.1674-991X.2014.04.044HAN J J, MENG F S, WANG Y Y, et al. Influence factors of electrokinetic remediation for nitrate-polluted kaolin[J]. Journal of Environmental Engineering Technology,2014,4(4):269-274. doi: 10.3969/j.issn.1674-991X.2014.04.044 [42] REDDY K R, CHINTHAMREDDY S. Effects of initial form of chromium on electrokinetic remediation in clays[J]. Advances in Environmental Research,2003,7(2):353-365. doi: 10.1016/S1093-0191(02)00005-9 [43] 尹晋, 马小东, 孙红文.电动修复不同形态铬污染土壤的研究[J]. 环境工程学报,2008,2(5):684-689.YIN J, MA X D, SUN H W. Study on electrokinetic remediation of soil contaminated by chromium[J]. Chinese Journal of Environmental Engineering,2008,2(5):684-689. [44] ZHANG P, JIN C J, ZHAO Z H, et al. 2D crossed electric field for electrokinetic remediation of chromium contaminated soil[J]. Journal of Hazardous Materials,2010,177(1/2/3):1126-1133. ⊗ -
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