固废基可渗透反应墙在砷污染地下水修复中的设计及应用

Design and Application of Solid Waste-based Permeable Reactive Barriers to Repair Arsenic-contaminated Groundwater

针对广西某冶炼废弃场地砷污染状况,以钢渣、脱硫石膏制备固废基可渗透反应墙(PRB)填充材料。探究污染源迁移扩散特征,优化PRB结构设计参数,并评估多工况下的原位阻隔-净化效果。结果表明,PRB混合填料主要通过生成钙钒石的类质同相置换和砷酸钙的沉淀实现砷(As)离子净化。PRB厚度是设计时需考虑的核心参数,当墙体厚度为3.6m时,对污染羽的有效截留可维持在10000d以上,滞留时间为1.27d。墙体厚度对滞留时间影响较大,但对捕获区宽度影响较小。地下水呈季节性变化,导致水质与流场相应变化,但PRB对As的净化率仍达到88%~94%,具有很好的净化效果。

In response to the Arsenic pollution situation at a smelting waste site in Guangxi,the solid waste-based permeable reaction barrier(PRB)fller was prepared using steel slag and desulfurization gypsum.Exploring the migration and dffusion characteristics of pollution sources,optimizing the design parameters of PRB,and evaluating the barrier purification effect under multiple working conditions.The results show that the PRB filler achieves arsenic(As)ion purification mainly through isomorphic replacement of ettringite and precipitation of calcium arsenate.The thickness of PRB is a critical parameter to be considered in the design,and when the thickness is 3.6 m,the effective retention of the contamination plume can be maintained above 10,000 d with a retention time of 1.27 d.The barrier thickness had a significant effect on retention time,but little influence on the capture zone width.The monitoring results showed that the groundwater shows seasonal variations,which led to corresponding changes in the quality of water and the flow field;however,the purification rate of As still maintained at 88%to 94%,which has a terrific purification effect.