基于粒径分布的不同异位修复工艺除Cr特性

Characteristics of chromium removing using different ex-situ remediations based on particle size distribution

以我国某铬盐厂的铬污染土壤为研究对象,采用改进的BCR顺序提取法研究了粒径对不同修复工艺(异位淋洗、异位稳定化、湿法解毒)去除土壤中各形态Cr的影响。实验结果表明:粒径是影响铬渣污染土壤总铬和Cr(VI)去除的关键影响因素之一,粒径越细,越有利于3种异位修复工艺对土壤中Cr(Ⅵ)的去除或还原,粒径越细越有利于异位淋洗工艺对总铬的消减。粒径对水溶态Cr、酸溶态Cr的去除影响显著,粒径越细,水溶态Cr、酸溶态Cr的去除率越高,水溶态Cr和酸溶态Cr的分离或去除是不同异位修复工艺实现铬渣污染土壤中Cr(Ⅵ)高效去除的有效手段;粒径对可还原态Cr的去除影响不显著,pH是影响可还原态Cr去除的主要影响因素;粒径对可氧化态Cr含量提升显著,尤其是对异位稳定化和湿法解毒工艺,粒径越细,可氧化态Cr增大倍数越高;粒径对残渣态Cr的去除影响不显著。

This paper takes the chromium contaminated soil from one of chromate plants in china as the object of study. Different chromium forms removal efficiencies were investigated to find the optical technology and influence factors by using the modified BCR method. Experimental results showed that particle size was one of the key factors affecting the removal of total Cr and Cr（Ⅵ）. The Cr（Ⅵ） removal rate or reduction efficiency was increased with decreasing particle size by three kinds of ex-situ remediation technologies. For soil washing, the removal rate of total Cr was also increased with decreasing particle size. Particle size was one of the key factors affecting the removal of soluble Cr and acid soluble Cr. The removal rates of soluble Cr and acid soluble Cr increased with decreasing particle size. The separation and removal of soluble Cr and acid soluble Cr is an effective way to remove Cr（Ⅵ） from chromium contaminated soil by different ex-itu remediation technologies. The effect of particle size on the removal of reducible Cr was not significant, and pH was the main influencing factor on the removal of reducible Cr. The effect of particle size on oxidizable Cr was significant. With the decrease of particle size, the Oxidizable Cr increased significantly, especially for ex-situ stabilization technology and wet-process detoxication technology. The smaller the particle size is, the higher the increase of oxidized Cr is. The effect of particle size on the removal of residual Cr was not significant. The residual Cr is difficult to release in the natural environment, and generally does not cause environmental risks.