河流重金属污染底泥的稳定化实验研究

以实现河道疏浚底泥中富含的重金属Cu、Zn、Ni的稳定化为目标,选用EDTA、DTCR、Na2S、Na2S2O3、膨润土、水泥及自主研发的特殊胶凝材料作为稳定剂,对底泥中的重金属进行固化稳定,通过分析稳定后重金属浸出液浓度及赋存形态变化,探讨各药剂稳定效果,并寻求稳定剂的最佳投加量.研究表明,7种稳定剂对3种重金属的综合稳定化效果由好到差依次为:水泥> 胶凝材料> 膨润土> DTCR> 硫化钠> 硫代硫酸钠> EDTA;对Cu、Zn、Ni单种重金属而言,稳定效果最好的药剂分别为膨润土、胶凝材料及DTCR,而EDTA则使重金属浸出液浓度升高.除EDTA外,其他药剂对重金属Cu和Zn的稳定效果要明显优于Ni.根据稳定后重金属赋存形态变化结果,EDTA可使重金属可交换态比例升高,而膨润土对重金属4种形态分布基本无影响,其他药剂使重金属可交换态比例降低.

Stabilization of heavy metals in contaminated river sediment

To stabilize the heavy metals Cu, Zn and Ni in dredged river sediment, seven chemical agents, including EDTA, DTCR, Na2S, Na2S2O3, bentonite, cement and special cementing material, were used as stabilizers in this study. Though analyzing the change of the speciation and leachate toxicity of heavy metals, both the stabilization efficiency of chemical agents and their optimum dosage were studied. According to the results, the stabilization effects of seven agents on the three heavy metals were as follows: cement > cementing material > bentonite> DTCR> Na2S> Na2S2O3> EDTA; with regard to the single metal, bentonite, cementing material and DTCR showed the best stabilization effects for Cu, Zn and Ni, respectivelly. But, EDTA could increase the leachate concentration of heavy metal. Except EDTA, the stabilization effects of other agents on Cu and Zn were better than that on Ni. According to the change of the stabilized heavy metal, EDTA could increase the interchangeable ratio of heavy metals, but bentonite had no obvious effects on the four speciations of heavy metals, and other chemical agents could decrease the ratio.