重金属污染土壤旋流洗脱设备的设计及性能评估

Design and performance evaluation of soil washing on heavy metal contaminated soil by hydrocyclone

针对高浓度重金属污染土壤,尤其是污染负荷较高的黏土土壤,传统的物化方法难以实现其高效的洗脱。利用旋流场中土壤颗粒高速自转/公转,实现土壤颗粒污染物的强化快速脱附。土壤旋流洗脱实验分为旋流器的分离性能和单一/复合污染物的脱附性能2部分。在土壤-水体系下,旋流器的最优操作条件为:进口流量0.7 m^3·h^(-1),分流比0.12,固液比为1:20。对于Pb污染物,底流脱附效率均能达到近85%,溢流也能够达到70%,对于Cu污染物,底流和溢流脱附均能达到90%左右。对于Cr(Ⅵ)污染物,底流脱附最高能达到60%左右,但溢流洗脱效率极低。复合污染能够在单次通过后脱除Pb、Cu、Cr(Ⅵ)等多种重金属污染,且洗脱效果与单一污染洗脱时基本一致。对实际的场地修复具有指导意义。

For heavy metal contaminated soil, especially the highly polluted clay soil, it is difficult to achieve efficient desorption by traditional physical or chemical method. In this study, the rotation/revolution of soil particles in a swirling flow field is used to achieve strenthened and rapid desorption of contaminated soil. The experiment of soil washing is divided into two parts of the separation performance of the hydrocyclone and the desorption performance of single/compound pollutants. In the soil-water system, the optimal operation conditions of the hydrocyclone are the inlet flow rate of 0.7 m^3·h^（-1）, the split ratio of 0.12, and the ratio of solid to liquid of 1 ：20. For the desorption of Pb pollutants, the efficiency of underflow can reach nearly 85%, the overflow also can reach 70%. For Cu pollutants,both of overflow and underflow desorption can reach about 90%. For Cr（VI） pollutants, underflow desorption can reach a maximum of about 60%, but the overflow desorption efficiency is very low. The compound pollution can remove many kinds of heavy metal pollution of Pb, Cu and Cr（VI） after a single pass, and the desorption effect is basically the same as that of single pollution desorption. It is of guiding significance to the actual field remediation.