EDTA/腐殖酸去除腐殖土中典型重金属效果研究

Study on the Effect of the Removal of Heavy Metal Pollution in Residual Garbage Humus from Old Landfill Using EDTA Combined with Humic Acid

该研究以垃圾填埋场存余垃圾筛分后的腐殖土为研究对象,针对常见的Cu、Zn、Mn含量高的问题,考察了EDTA、腐殖酸(HA)单一淋洗以及EDTA/HA混合淋洗的淋洗效果,使用响应面法对参数进行优化,采用处理后的腐殖土进行绿化实验。结果显示,在相同条件下,EDTA淋洗对Cu、Zn、Mn的去除率分别为29.63%、36.53%、33.75%,HA淋洗对Cu、Zn、Mn的去除率分别为40.23%、25.46%、21.45%,EDTA/HA混合淋洗体系对3种重金属的去除率分别为43.14%、35.13%和24.32%,EDTA/HA混合淋洗体系提高了Cu的去除率。对淋洗后重金属的形态进行分析,与单一EDTA淋洗相比,HA的加入提高了可交换态金属的去除率,对可还原态金属的去除效果更为均衡,因此混合淋洗可降低腐殖土中残留重金属毒性和对环境的危害。淋洗剂浓度越高、淋洗时间越长、固液比越小、pH值越小,越有利于重金属的去除。当淋洗后腐殖土质量分数为50%时,测量黑麦草、长春花、千日红体内的重金属含量,发现试验植物体内的重金属含量均小于规范值。

The effect of the removal of heavy metal pollution in residual garbage humus from old landfill using EDTA combined with humic acid was investigated.The extraction performance of high content of Cu,Zn and Mn using single leaching of EDTA,humic acid(HA)and mixed leaching of EDTA/HA were studied,and response surface methodology was used to optimize parameters.Under the same conditions,the removal efficiency of Cu,Zn and Mn by EDTA leaching was29.63%,36.53%and 33.75%,and the removal efficiency of Cu,Zn and Mn by HA leaching was 40.23%,25.46%and 21.45%.The removal efficiency of three heavy metals by the EDTA/HA mixed leaching system was 43.14%,35.13%and 24.32%.The form of heavy metals after leaching was analyzed,and it is found that the addition of HA improved the removal efficiency of exchangeable metals,and the removal effect of reducible metals was more balanced,compared with single EDTA leaching,Therefore,mixed leaching could reduce the toxicity of residual heavy metals in humus and the harm to the environment.And it is found that increasing the concentration of the eluent,prolonging the elution time,reducing the solid-liquid ratio,and maintaining acidic conditions would be beneficial to the removal of heavy metals.The heavy metals in ryegrass,periwinkle,and Qianrihong with the addition of 50%of the eluent were determined,and it was found that they could meet the greening requirements.