黏性土壤淋洗修复过程中粒径高效分级系统的研发及应用

传统淋洗技术针对黏性重金属污染土壤修复效率偏低，因此可将污染土壤进行分级减量化，以提高淋洗效率。通过研发一种土壤的高效分级系统，使得土壤颗粒实现快速筛分，以提高土壤污染淋洗修复的工作效率。该系统利用过滤分离原理，通过泵的主动加压和筛网表面的旋转，使得堆积在筛网表面的颗粒受到离心力、重力以及液体剪切力的作用，固液体系充分扰动，极大地降低土壤颗粒在筛网表面的架桥堆积现象，强化筛分过程，将土壤水溶液中的大小颗粒按目标粒径进行高效分级。通过多级粒径的实际验证（250~35μm）可知:与常规气流分离系统相比，该系统筛分速率明显提升，筛分效率和收率均可得到保证，能很好地达到土壤粒径分级的目的。此外，基于该筛分系统进行分级淋洗实验，粒径分级后需淋洗修复的土壤质量减少20%左右，并确定EDTA淋洗Pb污染土壤的最优工艺参数为淋洗液浓度为0.01~0.05 mol/L，pH=7，淋洗时间为10 h。

AN EFFICIENT SCREENING SYSTEM OF CLAY SOIL PARTICLES IN THE SOIL WASHING REMEDIATION PROCESS

The traditional leaching technology for heavy metal contaminated soil remediation efficiency was low, and the contaminated soil could be classified and reduced to improve the leaching efficiency. Through the development of an efficient soil classification system, soil particles could be quickly screened to improve the efficiency of soil pollution leaching remediation. The system used the principle of filtration separation, through the active pressure of the pump and the rotation of the screen surface, the particles accumulated on the screen surface were subjected to centrifugal force, gravity and liquid shear force, and the solid-liquid system was fully disturbed, which greatly reduced the bridging accumulation of soil particles on the screen surface, strengthened the screening process, and then classified the particles in the soil water solution according to the target particle size. Through the practical verification of multi-stage particle size(250~35 μm), compared with the conventional air separation system, the screening rate of the system was significantly improved, the screening efficiency and yield could be guaranteed, and the purpose of soil particle size classification was well achieved. In addition, based on the screening system, the grading leaching experiment was carried out, and the quality of the soil leached after particle size classification was reduced by about 20%. The optimal process parameters of EDTA leaching Pb contaminated soil were determined as follows:leaching solution concentration of 0.01~0.05 mol/L, pH value of 7, and leaching time of 10 h.