污染土壤与稳定剂均匀搅拌可有效确保重金属污染土壤原地异位稳定化实施效果.本文开展污染土壤原地异位稳定化现场试验,基于测试获取的污染土壤和稳定剂混拌料的重金属及特征元素全量、含水率、重金属浸出浓度提出搅拌均匀度的概念;研究污染土壤和稳定剂混拌用的设备类型、搅拌次数对搅拌均匀性的影响规律,并通过相关性分析,研究污染土壤和稳定剂搅拌均匀性的快捷评价方法.结果表明,相较于筛分斗,混合机在控制稳定剂在污染土壤中的分散性方面优于筛分斗,而筛分斗搅拌后的土壤砷和锑全量的均匀度显著提高,筛分斗混合范围更大;稳定化污染土壤元素全量、含水率、砷和锑浸出浓度的均匀度随筛分斗搅拌次数的增加而增大,当搅拌次数大于3次时,砷和锑浸出浓度均低于修复目标值;砷和锑浸出浓度均匀度与砷、锑全量均匀度显著相关.基于此,建议污染土壤稳定化施工期可通过现场快速测定重金属全量,并结合均匀度分析评价污染土壤和稳定剂的搅拌均匀性.
Abstract
Thorough mixing of contaminated soil and stabilizer is essential for effective ex-situ stabilization for heavy metals-contaminated soils. Field tests of ex-situ soil stabilization was conducted, and the total elements, moisture content, and leaching concentrations of target heavy metals (including arsenic(As) and antimony(Sb)) in the stabilized soils were measured. The influence of mixing equipment type, and soil-stabilizer mixing frequency on the ex-situ stabilization efficiency was evaluated. Based on the measured total elemental content and moisture content, a concept termed 'mixing uniformity' was proposed. The results showed the multi-function mixing equipment performed better than screening crushing bucket in controlling the uniformity of stabilizers in the contaminated soil. In contrast, the screening crush bucket significantly improved the uniformity of total As and Sb in the soil, with a larger mixing range. The mixing uniformities of total element content, moisture content, and As and Sb leaching concentrations increased with the number of mixing using the screening crushing bucket. When the number of mixing exceeded three, As and Sb leaching concentrations fell below remediation target values. Additionally, the uniformity of As and Sb leaching concentrations showed a good correlation with the uniformity of total contents. Based on the results, it is recommended that on-site rapid testing of total heavy metal content, combined with uniformity analysis, can be used to evaluate the mixing uniformity of contaminated soil and stabilizers during stabilization processes.
关键词
重金属 /
污染土壤 /
原地异位稳定化 /
搅拌均匀性 /
浸出浓度
Key words
heavy metal /
contaminated soil /
ex-situ stabilization /
mixing uniformity /
leaching concentration
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基金
国家重点研发计划项目(2023YFC3709604)国家自然科学基金资助项目(42177133,42477178);江苏省重点研发计划项目(BE2022830)
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