电动联合法对复合重金属污染底泥的修复

Electrokinetic combination remediation of sediment contaminated with complex heavy metals

河流与湖泊底泥中重金属污染物的清除是实现水体彻底净化及底泥工程利用的关键。以增加了电解液循环的电动联合装置为修复设备,以Cu、Zn、Pb、Cr、Ni污染底泥为研究对象,结合小试模拟和中试模拟实验,明确修复装置对复合污染底泥的净化修复效果,并优化污染物回收的技术参数。结果表明,增设电解液循环有助于增强复合污染底泥中重金属离子的迁出,在小试模拟和中试模型实验中,底泥污染物的去除率分别达到了74%~84%和52%~60%;中试模型实验修复后底泥中的Cr、Cu、Ni和Zn含量分别为140.31、314.47、250.93、464.17 mg·kg^(-1),低于《土壤环境质量-建设用地土壤污染风险管控标准》(GB 36600-2018)的筛选值。在两极电解液增设pH调节装置和斜板沉淀池有助于以Cr(OH)_(3)、Cu(OH)_(2)、Ni(OH)_(2)和Zn(OH)_(2)沉淀物的方式对重金属离子进行回收,阳极电解液pH控制在5.0~6.5,阴极电解液pH控制在10时,阴阳极两侧电解液中重金属沉淀回收率均达99%。增加了电解液循环的电动联合修复技术可同步实现底泥污染物的净化及回收。

The removal of heavy metal contaminations from sediments is the key to purify river water and utilize in engineering.The electrokinetic combination method with electrolyte circulation was designed to remediate sediment polluted with combined heavy metals like Cu,Zn,Pb,Cr and Ni.The bench-scale and pilotscale experimentation were carried out simultaneously to clarify the purification effect of the remediation technology and to optimize the technical parameters of recovery.The results indicate that the removement of heavy metal ions from sediments is enhanced with the help of electrolyte circulation.The removal rate of pollutions in the bench-scale and pilot-scale experimentation can reach to 74%~84%and 52%~60%.In pilotscale experimentation,the residual content of Cr,Cu,Ni and Zn is 140.31、314.47、250.93、464.17 mg·kg^(-1)respectively.These values are all lower than the screening value of Soil Environmental Quality-Risk Control Standard for Soil Contamination of development land Standard(GB 36600-2018).With the help of pH adjustment and the inclined plate sedimentation device,the heavy mental ions in electrolyte can be recycled by precipitation like Cr(OH)_(3),Cu(OH)_(2),Ni(OH)_(2)and Zn(OH)_(2).The precipitation rate of heavy metals on both sides are all up to 99%when the pH value of anolyte and catholyte is controlled between 5.0~6.5 and 10 respectively.The electrokinetic combination method can synchronously realize the purification and recovery of sediment pollutants.