电化学循环井驱动模拟含水层化学氧化降解三氯乙烯

doi:10.13745/j.esf.sf.2021.2.1

摘要/Abstract

摘要：

传统原位化学氧化地下水修复技术存在氧化剂迁移距离短和利用率低等问题。本研究在双井循环模式促进传质的基础上,通过注水井中的地下水电解原位提供O₂和H₂,配合乙二胺四乙酸(ethylenediamine tetraacetic acid,EDTA)络合溶解出含水层Fe(Ⅱ),活化O₂产生羟基自由基(•OH),实现地下水三氯乙烯(TCE)的氧化降解。在填充了砂土和黏土互层的二维砂槽中,设置电流为0.2 A、流速为72 cm/d、初始TCE浓度为3 mg/L,经过9 d的连续通电处理后,TCE浓度降低到1 mg/L,降解率达到67%。通电前投加0.5 mmol/L EDTA,经过1 d水流循环后含水层中溶解态Fe(Ⅱ)浓度从02 mg/L增加到414 mg/L,黏土区域较高。通电过程中,循环井促进O₂、Fe(Ⅱ)-EDTA和TCE的有效接触与反应,使TCE氧化降解。通电初期,黏土区域Fe(Ⅱ)氧化速率、TCE降解速率较周围慢,后期差异逐渐减小。未通电时加入醋酸钠可促进Fe(Ⅲ)还原,使含水层中铁循环利用。该修复过程通过循环井提升了氧化剂迁移距离,使用源于含水层的Fe(Ⅱ)-EDTA和稳定性较好的O₂提高了氧化剂利用率,有望应用于有机污染地下水修复。

关键词: 电化学, 循环井, 化学氧化, 二价铁, 三氯乙烯

Abstract:

Traditional groundwater remediation by in-situ chemical oxidation has the problem of short transport distance and low utilization efficiency for oxidants. In this study, a two-well groundwater circulation mode was applied to enhance mass transfer; and electrolysis in the injection well was utilized to generate O₂ and H₂ in-situ. In order to use Fe(Ⅱ) in sediments for TCE degradation, ethylenediamine tetraacetic acid (EDTA) was added to chelate Fe(Ⅱ) and increase •OH production. The system performance was evaluated in a two-dimensional sandy tank filled with interlayers of sand and clay. The current was set to 0.2 A and the flow rate was 72 cm/d. Results from a 9-day experiment showed that 3 mg/L TCE was degraded down to 1 mg/L (67% removal). Addition of 0.5 mmol/L EDTA before electrolysis increased the dissolved Fe(Ⅱ) concentration in the aquifer from 0-2 mg/L to 4-14 mg/L after a day of hydraulic circulation, with the higher concentrations around clay fillings. During electrolysis, groundwater circulation promoted the effective contacts and reactions of O₂, Fe(Ⅱ)-EDTA and TCE for TCE degradation. In the early stage, the rates of Fe(Ⅱ) oxidation and TCE degradation were slower around clay fillings than in other areas, but the gap gradually decreased in the later stage. Adding acetate upon completion of electrolysis promoted Fe cycling and utilization in the aquifer. This remediation process improved the oxidant transport distance through groundwater circulation and the oxidant utilization efficiency through use of relatively stable O₂and Fe(Ⅱ)-EDTA from aquifer, demonstrating its potential application in the remediation of organic pollution in groundwater.

Key words: electrochemistry, circulation well, chemical oxidation, ferrous iron, trichloroethylene

中图分类号:

X523
X505

刘洋, 谢雯静, 郑云松, 张耀强, 蔡其正, 袁松虎. 电化学循环井驱动模拟含水层化学氧化降解三氯乙烯[J]. 地学前缘, 2021, 28(5): 197-207.

LIU Yang, XIE Wenjing, ZHENG Yunsong, ZHANG Yaoqiang, CAI Qizheng, YUAN Songhu. Electrolytic circulation well drives chemical oxidation of TCE in a simulated aquife[J]. Earth Science Frontiers, 2021, 28(5): 197-207.

图/表 8

图1 二维砂槽实验装置示意图图中圆圈表示取样孔,4排(14)7列(A-G);含水层中深色长条为黏土填充区域,其余浅色部分为砂土填充区域。

Fig.1 Schematic diagram of two-dimensional sand tank experiment

图2 动态体系运行过程中DO(a)、溶解态Fe(Ⅱ)(b)和TCE(c)的浓度变化以靠近注水管A3和靠近抽水管G3作为模拟含水层代表点。

Fig.2 Variations of DO (a), dissolved Fe(Ⅱ) (b) and TCE (c) concentrations during dynamic operation

图3 动态体系运行过程中EDTA(a)和溶解态总Fe(b)的浓度变化以靠近注水管A3和靠近抽水管G3作为模拟含水层代表点。

Fig.3 Variations of EDTA (a) and total dissolved Fe (b) concentrations during dynamic operation

图4 第2组实验过程中溶解态Fe(Ⅱ)浓度时空变化

Fig.4 Temporospatial variations of dissolved Fe(Ⅱ) concentration during the second EGCW treatment

图5 第2组实验过程中TCE浓度时空变化

Fig.5 Temporospatial variations of TCE concentration during the second EGCW treatment

图6 静态体系中TCE的降解(a)、EDTA浓度的变化(b)和溶解态Fe(Ⅱ)与溶解态总铁浓度的变化(c)

Fig.6 Temporal profile of TCE degradation (a), and variations of EDTA (b) and dissolved Fe(Ⅱ) and total dissolved Fe (c) concentrations in static system

图7 槽体系TCE降解机理示意图

Fig.7 Schematic diagram of TCE degradation mechanism in tank system

图8 动态体系运行过程中DH(a)和N O 3 -与N O 2 -浓度(b)的变化以靠近注水管A3和靠近抽水管G3作为模拟含水层代表点。

Fig.8 Variations of DH (a) and N O 3 - and N O 2 - (b) concentrations during dynamic operation

参考文献 33

[1]	李海明, 陈鸿汉, 郑西来. 某城市工业区浅层地下水CAHs污染特征[J]. 地学前缘, 2005, 12(增刊1):132-138.
[2]	中华人民共和国国土资源部和水利部, 全国国土资源标准化技术委员会. 地下水质量标准: GB/T 14848—2017[S]. 北京: 中国标准出版社, 2018.
[3]	吴嘉茵, 方战强, 薛成杰, 等. 我国有机物污染场地土壤修复技术的专利计量分析[J]. 环境工程学报, 2019, 13(8):2015-2024.
[4]	SIEGRIST R L, CRIMI M, SIMPKIN T J, et al. ISCO status and future directions[M]//SERDP/ESTCP environmental remediation technology. New York: Springer, 2010: 535-545.
[5]	杨乐巍, 张岳, 李书鹏, 等. 原位化学氧化高压注射修复优化设计与应用案例分析[J]. 环境工程, 2019, 37(8):185-189.
[6]	WHITE B C, WONG R, COLLINS W E, et al. Draft removal action closeout report time-critical removal action installation restoration Site 5 - Unit 2 Naval Air Station North Island San Diego, California[R]. San Diego: Shaw Environmental & Infrastructure,Inc, 2003.
[7]	WEST O R, CLINE S R, HOLDEN W L, et al. A full-scale demonstration of in-situ chemical oxidation through recirculation at the X-701B site[R]. Oak Ridge: Office of Scientific and Technical Information(OSTI), 1997.
[8]	GAVASKAR A, CONDIT W, HARRE K. Cost and performance report for a persulfate treatability study at naval air station north island[R]. Columbus: Defense Technical Information Center, 2008.
[9]	PETRI B G, WATTS R J, TEEL A L, et al. Fundamentals of ISCO using hydrogen peroxide[M]//SERDP/ESTCP environmental remediation technology. New York: Springer, 2010: 33-88.
[10]	SIMPKIN T J, PALAIA T, PETRI B G, et al. Oxidant delivery approaches and contingency planning[M]//SIEGRIST R L, CRIMI M, SIMPKIN T J. In-situ chemical oxidation for groundwater remediation. New York: Springer, 2011. DOI: 10.1007/978-1-4419-7826-4-11. DOI
[11]	KREMBS F J, CLAYTON W S, MARLEY M C. Evaluation of ISCO Field applications and performance[M]//SIEGRIST R L, CRIMI M, SIMPKIN T J. In-situ chemical oxidation for groundwater remediation. New York: Springer, 2011. DOI: 10.1007/978-1-4419-7826-4-8. DOI
[12]	TSITONAKI A, PETRI B, CRIMI M, et al. In-situ chemical oxidation of contaminated soil and groundwater using persulfate: a review[J]. Critical Reviews in Environmental Science and Technology, 2010, 40(1):55-91. DOI URL
[13]	TONG M, YUAN S, MA S, et al. Production of abundant hydroxyl radicals from oxygenation of subsurface sediments[J]. Environmental Science & Technology, 2016, 50(1):214-221. DOI URL
[14]	YUAN S H, LIU X X, LIAO W J, et al. Mechanisms of electron transfer from structrual Fe(Ⅱ) in reduced nontronite to oxygen for production of hydroxyl radicals[J]. Geochimica et Cosmochimica Acta, 2018, 223:422-436. DOI URL
[15]	YUAN S H, LIU Y, ZHANG P, et al. Electrolytic groundwater circulation well for trichloroethylene degradation in a simulated aquifer[J]. Science China Technological Sciences, 2021, 64(2):251-260. DOI URL
[16]	JONES A M, GRIFFIN P J, WAITE T D. Ferrous iron oxidation by molecular oxygen under acidic conditions: the effect of citrate, EDTA and fulvic acid[J]. Geochimica et Cosmochimica Acta, 2015, 160:117-131. DOI URL
[17]	WANG N, JIA D Q, JIN Y Y, et al. Enhanced Fenton-like degradation of TCE in sand suspensions with magnetite by NTA/EDTA at circumneutral pH[J]. Environmental Science and Pollution Research International, 2017, 24(21):17598-17605. DOI URL
[18]	JIA D Q, SUN S P, WU Z X, et al. TCE degradation in groundwater by chelators-assisted Fenton-like reaction of magnetite: sand columns demonstration[J]. Journal of Hazardous Materials, 2018, 346:124-132. DOI URL
[19]	ZHANG Y, ZHOU M H. A critical review of the application of chelating agents to enable Fenton and Fenton-like reactions at high pH values[J]. Journal of Hazardous Materials, 2019, 362:436-450. DOI URL
[20]	WEATHERILL J J, ATASHGAHI S, SCHNEIDEWIND U, et al. Natural attenuation of chlorinated ethenes in hyporheic zones: a review of key biogeochemical processes and in-situ transformation potential[J]. Water Research, 2018, 128:362-382. DOI URL
[21]	LAINE P, MATILAINEN R. Simultaneous determination of DTPA, EDTA, and NTA by UV-visible spectrometry and HPLC[J]. Analytical and Bioanalytical Chemistry, 2005, 382(7):1601-1609. DOI URL
[22]	YUAN S H, CHEN M J, MAO X H, et al. Effects of reduced sulfur compounds on Pd-catalytic hydrodechlorination of trichloroethylene in groundwater by cathodic H₂ under electrochemically induced oxidizing conditions[J]. Environmental Science & Technology, 2013, 47(18):10502-10509.
[23]	YUAN S H, CHEN M J, MAO X H, et al. A three-electrode column for Pd-catalytic oxidation of TCE in groundwater with automatic pH-regulation and resistance to reduced sulfur compound foiling[J]. Water Research, 2013, 47(1):269-278. DOI URL
[24]	YUAN S H, XIE S W, ZHAO K Y, et al. Field tests of in-well electrolysis removal of arsenic from high phosphate and iron groundwater[J]. Science of the Total Environment, 2018, 644:1630-1640. DOI URL
[25]	YOU X J, LIU S G, DAI C M, et al. Acceleration and centralization of a back-diffusion process: effects of EDTA-2Na on cadmium migration in high- and low-permeability systems[J]. Science of the Total Environment, 2020, 706.
[26]	刘雅莉, 刘菲, 黄伟英. 菱铁矿催化过氧化氢-过硫酸钠修复地下水中TCE时对微生物的影响[J]. 地学前缘, 2014, 21(4):186-190.
[27]	BUXTON G V, GREENSTOCK C L, HELMAN W P, et al. Critical review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (·OH/·O- in aqueous solution[J]. Journal of Physical and Chemical Reference Data, 1988, 17(2):513-886. DOI URL
[28]	WANG H Y, WANG J, ZHANG W, et al. Comparison of performance in a bioelectrochemical system for simultaneous denitrification and vanadate (V) removal using hydrogen as the sole electron donor[J]. Geomicrobiology Journal, 2020, 37(4):301-307. DOI URL
[29]	CARERE C R, MCDONALD B, PEACH H A, et al. Hydrogen oxidation influences glycogen accumulation in a verrucomicrobial methanotroph[J]. Frontiers in Microbiology, 2019, 10:1873. DOI URL
[30]	YOU X J, LIU S G, DAI C M, et al. Acceleration and centralization of a back-diffusion process: effects of EDTA-2Na on cadmium migration in high- and low-permeability systems[J]. Science of the Total Environment, 2020, 706:135708.
[31]	刘洋, 袁松虎, 张耀强, 等. 电化学循环井耦合氧化-还原降解地下水中三氯乙烯[J]. 水文地质工程地质, 2020, 47(3):44-51.
[32]	李玮, 王明玉, 韩占涛, 等. 棕地地下水污染修复技术筛选方法研究: 以某废弃化工厂污染场地为例[J]. 水文地质工程地质, 2016, 43(3):131-140.
[33]	苗竹, 吕正勇, 魏丽, 等. 地下水循环井技术概述[C]//2018中国环境科学学会科学技术年会论文集. 北京: 中国环境科学学会, 2018: 714-719.