生物表面活性剂及其与柠檬酸联合用于污泥重金属电动修复

Electrokinetic Repair of Heavy Metals in Sludge by Biosurfactant and Its Combination with Citric Acid

选择城市污泥作为修复对象,通过添加槐糖脂、鼠李糖脂、皂角苷3种生物表面活性剂及其与柠檬酸复配溶液,从电流密度、排出液重金属浓度、试验后土体各区域重金属含量等角度,研究添加剂对重金属污染污泥电动修复的增强效果,从添加剂作用机理上进行分析,并从微观层面进行补充解释.试验结果表明:重金属的迁移主要发生在污泥中,排出液重金属浓度很低;阳极区处理效果最好,阴极次之,中部有重金属积聚效应;单独添加生物表面活性剂,在阳极区对Zn、Cu、Ni、Cd去除率最高的分别是槐糖脂(53.85%)、鼠李糖脂(44.26%)、鼠李糖脂(56.33%)、槐糖脂(34.43%);复配柠檬酸后,阳极重金属去除率相较于单独添加生物表面活性剂普遍可提升0.90%~16.08%,柠檬酸可显著改善中部重金属积聚效应.基于试验结论,在实际工程中对于Zn、Cd含量高的污泥推荐采用槐糖脂或配合使用柠檬酸,而对于Cu、Ni含量高的则推荐鼠李糖脂与柠檬酸的复配溶液.

Taking the municipal sludge as the remediation objects and aiming at studying the effects of electrokinetic remediation of heavy metals from municipal sludge,model tests were carried out with different reagents,which were sophorolipid,rhamnolipid,saponin and composite reagents of biosurfactants and citric acid.Current density and heavy metal concentration in discharge liquid and sludge were examined and analyzed in order to explore the mechanism of reagents from the perspective of microstructure.The results demonstrated that the migration of heavy metals was mainly in the sludge and the concentration of heavy metals was very low in the discharge liquid.Best treatment was achieved around anode area and then followed by the cathode region,while heavy metals were accumulated in middle region.By comparing the removal effect of four biosurfactants,the highest removal rates of Zn,Cu,Ni and Cd were sophorolipid(53.85%),rhamnolipid(44.26%),rhamnolipid(56.33%)and sophorolipid(34.43%),respectively in anode region.Citric acid promoted the migration of heavy metals significantly in middle region,so that the removal rate with composite reagents of biosurfactants and citric acid were increased by 0.90%~16.08%.Based on the test results,it is recommended to apply sophorolipid or composite reagents with citric acid for high concentration of Zn and Cd in sludge treatment.As for high concentration of Cu and Ni,rhamnolipid or composite reagents with citric acid is a better choice.