College of Environmental Science and Engineering, Dalian Maritime University, Dalian, 116026, China.
College of Environmental Science and Engineering, Dalian Maritime University, Dalian, 116026, China.
Chemosphere. 2019 Dec;236:124319. doi: 10.1016/j.chemosphere.2019.07.050. Epub 2019 Jul 6.
Thermally enhanced remediation of n-alkanes-contaminated silty soil mixed with coarse quartz sands was demonstrated in a laboratory cylindrical tank with diameter of 40 cm and depth of 30 cm. The removal kinetics of semi-volatile n-alkanes (C, C, C) under three pulsed heating operations of soil vapor extraction (SVE) was investigated. CMG-STARS software was adopted to simulate the dynamics of heat transfer within the soil column. The results indicated the dramatic increase of air permeability of soil and acceleration of heat transfer after introduction of sand, with the result of achieving rapid soil remediation. Gas-phase transfer of n-alkanes mainly occurred when average soil temperature was ≥100 °C. At the end of remediation with soil subjected to heating for 30.8 h (total running time), the average soil concentration of total n-alkanes was reduced from initial 3106.5 to 202.4 mg/kg, corresponding to 93.4% of mass removal. The residual n-alkanes of C, C, C and C in all collected soil samples were declined to levels of lower than 10 mg/kg. Most of the soil concentration-gradient curves for n-alkanes tested almost coincided with their isothermal contours, indicating the key impact of thermal drive force on contaminant transfer.
实验室圆柱形罐（直径 40 厘米，深度 30 厘米）中展示了受污染的粉质土壤与粗砂混合后，经热强化修复去除其中长链正烷烃（C、C、C）的过程。研究了土壤蒸汽抽提（SVE）三次脉冲加热操作下半挥发性长链正烷烃（C、C、C）的去除动力学。采用 CMG-STARS 软件模拟了土壤柱内的传热动力学。结果表明，引入砂后土壤透气性显著提高，传热加速，从而实现了快速土壤修复。当平均土壤温度≥100°C 时，长链正烷烃主要以气相形式迁移。在加热 30.8 小时（总运行时间）后，受加热土壤中总长链正烷烃的平均浓度从初始的 3106.5 毫克/千克降低到 202.4 毫克/千克，去除率为 93.4%。所有采集土壤样品中 C、C、C 和 C 的残留长链正烷烃均下降至低于 10 毫克/千克的水平。测试的长链正烷烃的大部分土壤浓度梯度曲线几乎与等温线重合，表明热驱动力对污染物迁移的关键影响。
