可生物降解螯合剂GLDA土柱淋洗修复镉锌污染土壤

Remediation of Cd and Zn contaminated soil by soil column leaching with biodegradable chelator GLDA

为了降低重金属污染土壤的风险,需要研究有效的修复技术.采用可生物降解螯合剂谷氨酸N,N-二乙酸(GLDA)为淋洗剂,通过开展土柱淋洗实验,考察了GLDA对Cd和Zn的修复效果和对土壤理化性质的影响.研究结果表明:GLDA对Cd、Zn的淋出率(61.7%、22.3%)与乙二胺四乙酸(EDTA)的相近,酸可提取态和可还原态的Cd和Zn显著减少,Cd、Zn迁移性和环境风险有效降低.FeS沉淀淋洗液中的Cd和Zn,可以实现GLDA回收利用,再生与新鲜的GLDA对Cd、Zn具有相近的提取能力.GLDA淋洗后采用水冲洗土壤,可以减少GLDA的使用量,也会降低GLDA在土壤中的残留.GLDA淋洗对土壤pH、速效磷、速效钾均有不同程度的改变,并显著增加土壤细颗粒的比例,对土壤结构和质地会造成一定的影响.

In order to reduce the risk of heavy metal contaminated soil,it is necessary to study effective remediation technology.The biodegradable chelator N,N-bis(carboxymethyl)-L-glutamic acid(GLDA)is used as the leaching eluent,through the soil column leaching experiment,the remediation effects of GLDA on Cd and Zn and the effects on soil physical and chemical properties are investigated.The results show that the leaching efficiencies(61.7%,22.3%)of Cd and Zn by GLDA are similar to those by ethylene diamine tetraacetic acid(EDTA).The acid-soluble and reducible Cd and Zn are significantly reduced,which indicates that the mobility and environmental risks of Cd and Zn could be effectively reduced.FeS can precipitate Cd and Zn in the leaching liquid,which can realize the recovery of GLDA,and the regenerated GLDA has similar Cd and Zn extraction ability to the fresh GLDA.Using water to wash the soil after GLDA leaching can reduce the amount of GLDA applied and residual GLDA in soil.GLDA leaching changes soil pH,available phosphorus and available potassium,significantly increases the proportion of soil fine particles,and has certain effects on soil structure and texture.