摩擦清洗修复铅污染土壤的参数优化及清洗效率评价

Parameters Optimization and Cleaning Efficiency Evaluation of Attrition Scrubbing Remediation of Pb-Contaminated Soil

采用摩擦清洗法修复铅污染场地土壤,主要目的是将细颗粒和铅污染物从砂粒表面去除.通过正交实验优化清洗参数,并对3份不同铅含量土壤进行摩擦清洗实验.优化的清洗参数为:水土比70%干物质、温度25℃、搅拌时间30 min、搅拌速率1 200 r.mim-1.摩擦清洗前土壤经过筛分化验分析表明,3份土壤铅主要富集在砂粒和粉黏粒中;铅的分布与有机质有极大相关性.结果表明,经过摩擦清洗后,3份原状铅污染土壤砂粒的清洗效率分别为:67.61%、31.71%、41.01%,摩擦清洗从砂粒表面去除一部分细粒土壤和铅污染物,使铅浓缩至粉黏粒中;扫描电镜(SEM)分析表明,摩擦清洗后砂粒表面变光滑.以上结论说明摩擦清洗对于铅污染场地的砂粒土壤具有较好的清洗效果.

Attrition scrubbing was used to remediate lead contaminated-site soil,and the main purpose was to remove fine particles and lead contaminants from the surface of sand.The optimal parameters of attrition scrubbing were determined by orthogonal experiment,and three soil samples with different lead concentration were subjected to attrition scrubbing experiments.The results showed that the optimal scrubbing parameters were： a solid ratio of 70% dry matter,a temperature of 25℃,an attrition time of 30 min,and an attrition speed of 1 200 r.min-1.Before attrition scrubbing,the screening and analysis of soil showed that in all three soil samples,lead was mainly enriched on sand and fine particles,and the distribution of lead was highly correlated to the organic matter.After attrition scrubbing,the washing efficiency of the original state lead contaminated sand soil in triplicates was 67.61%,31.71% and 41.01%,respectively,which indicates that attrition scrubbing can remove part of the fine soil and lead contaminants from the surface of sand,to accomplish the purpose of pollutants enrichment.Scanning electron microscopy（SEM） analysis showed that the sand surface became smooth after attrition scrubbing.The results above show that attrition scrubbing has a good washing effect for the remediation of lead contaminated sand soil.