3种含铁材料对重金属和砷复合污染底泥稳定化处理

选用3种含铁材料FeCl3、Fe(OH)3和FePO4,开展重金属和砷(As)复合污染底泥的稳定化处理实验,并用毒性浸出测试(TCLP)的结果和底泥交换态重金属(Pb、Cd、Cu、Zn)及As的含量来评价其稳定化效果。结果表明,(1)FeCl3和FePO4降低了底泥pH值,Fe(OH)3轻微地提高了底泥pH值。(2)FeCl3活化了底泥中Pb、Cd、Cu、Zn,使其浸出量和交换态含量增加,对As浸出量的影响不大,但使底泥中As交换态含量明显降低,且在最大添加量(8.00 g/kg)时As交换态含量未检测出;Fe(OH)3降低了Cd交换态和浸出量,稍增加了As交换态和浸出量,但对Pb、Cu、Zn交换态和浸出量影响不明显;FePO4明显降低了Pb的浸出量和交换态含量,略微降低了交换态Cd、Zn含量,对交换态Cu影响不大,但明显增加了As的浸出量和交换态含量。综上,FeCl3对As具有较好的稳定化效果,但明显活化了底泥中的4种重金属;Fe(OH)3亦对底泥中Cd有一定稳定化效果;FePO4对Pb的稳定化效果较好,但明显活化了底泥中的As。显然,3种含铁材料都不能实现底泥中重金属和As的同时稳定化。

Stabilization of multi-metals and arsenic in combined contaminated sediment by three iron-based materials

Laboratory batch experiments were conducted to study the stabilization effects of FeCl₃, Fe(OH)₃ and FePO₄ on multi-metals and arsenic in sediment sampled from Hengyang Section of Xiangjiang. The contents of exchangeable and leachable multi-metals (Pb, Cd, Cu, Zn) and arsenic (As) were detected. The results showed that: (1) FeCl₃, FePO₄ reduced sediment pH, Fe (OH)₃ slightly increased sediment pH. (2) FeCl₃ activated Pb, Cd, Cu, Zn in sediment, and increased the contents of Pb, Cd, Cu, Zn exchange states and leaching concentrations, but significantly reduced exchangeable As and declined it to below the detection limits at maximum dosage (8.00 g/kg). However, it had no significant effect on As leaching concentration. Fe(OH)₃ treatment reduced Cd exchange state and leaching concentration, increased slightly As, but had no significant effects on Pb, Cu, Zn exchange states and leaching concentrations.FePO₄ stabilized^Pb but activated As. It also slightly decreased the contents of exchange Cd, Zn, but had insignificant effect on Cu. In summary, FeCl₃ had good stabilization effect on As, but activated Pb, Cd, Cu, Zn; Fe(OH)₃ had certain effect on Cd; FePO₄ had obvious effect on Pb, but activated As remarkably. However, any of the three multi-metals could not stabilize Pb, Cd, Cu, Zn and As simultaneously in combined contaminated sediment.