EGTA淋洗和KH2PO4钝化联合修复重金属污染土壤  

Remediation of heavy metal contaminated soil by combined EGTA washing and KH2PO4 immobilization

作　　者：王明新 张金永 肖扬 王世泽 WANG Minxing;ZHANG Jinyong;XIAO Yang;WANG Shize(School of Environmental and Safety Engineering,Changzhou University,Changzhou,213164,China)

机构地区：[1]常州大学环境与安全工程学院

出　　处：《环境化学》2019年第10期2366-2375,共10页Environmental Chemistry

基　　金：国家自然科学基金(41772240);江苏省“六大人才高峰”项目(JNHB-003);江苏省高校“青蓝工程”项目资助~~

摘　　要：为进一步削减螯合淋洗后土壤残留重金属的环境风险,采用淋洗与钝化相结合的方法修复重金属污染土壤.研究了乙二醇双(2-氨基乙基醚)四乙酸(EGTA)淋洗、磷酸二氢钾(KH2PO4)钝化及两者联合修复对土壤重金属洗脱率的影响,并分别采用TCLP法和BCR法分析重金属浸出浓度及化学形态分布,构建了涵盖土壤重金属残留量、生物有效性和毒性的环境风险评价方法,对淋洗、钝化及其联合修复效果进行了评价.结果表明,EGTA对Cu和Cd具有较好的洗脱效果,降低了土壤Cu、Zn和Cd浸出浓度,提高了Pb浸出浓度,削减了可还原态Cu残留量、弱酸提取态和可还原态Zn残留量、可还原态Pb残留量以及弱酸提取态、可还原态Cd残留量.随着KH2PO4投加量的增加,Pb、Cd和Cu浸出浓度呈下降趋势,Zn浸出浓度先上升后下降.KH2PO4对重金属形态分布的影响主要表现为降低弱酸态或可还原态重金属占比,提高残渣态重金属占比.EGTA和KH2PO4联合修复显著降低了4种重金属的可还原态残留量和弱酸提取态Pb、Cd残留量,大幅度削减了Cd和Cu的浸出浓度和环境风险.Zn污染土壤宜淋洗修复,Pb污染土壤宜钝化修复,Cd和Cu污染土壤深度修复宜淋洗/钝化联合处理.In order to further reduce the environmental risk of heavy metals remaining in the soil after chelation,a combination method of washing and immobilizatio was used to repair heavy metal contaminated soil.The washing rates,leaching concentration and chemical specification of heave metals in soil by ethylenebis(oxyethylenenitrilo)tetraacetic acid(EGTA)washing,potassium dihydrogen phosphate(KH2PO4)immobilization and their combination treatment were studied.The TCLP method and BCR method were used to analyze the leaching concentration and chemical form distribution of heavy metals.An environmental risk assessment method covering soil heavy metal concentration,bioavailability and toxicity was constructed to evaluate the remediation efficiency.The results showed that EGTA had higher removal rates of Cu and Cd.EGTA treatments reduced the leaching concentration of Cu,Zn and Cd in soil,and the increased the leaching concentration of Pb.Considering chemical specification of heavy metals,EGTA treatments reduced the reducible Cu,weak acid extractable and reducible Zn,the reducible and residual Pb,the weak acid extractable and reducible Cd residues in soil.With the increase of KH2PO4 dosage,the leaching concentration of Pb,Cd and Cu showed a downward trend,and the leaching concentration of Zn increased first and then decreased.The effect of KH2PO4 on the chemical specification of heavy metals was mainly reflected in the decrease of the proportion of the weak acid extractable fraction or the reducible fraction,and the increase of the residual fraction.The combination of EGTA and KH2PO4 significantly reduced the reducible heavy metals and the weak acid extractable Pb and Cd residues.Combined remediation had a synergistic effect on reducing cadmium leaching concentrations and environmental risks.Washing was suitable for Zn contaminated soil remediation,immobilization was suitable for Pb contaminated soil,and combined washing and immobilization was suitable for Cd or Cu contaminated soil deep remediation.

关 键 词：土壤 重金属 淋洗 钝化 环境风险 

分 类 号：X53[环境科学与工程—环境工程]