ABSTRACT

The environmental contaminations occurred by exploration, drilling, extraction, transportation and storage of different substances for using in industries have serious effects on soils and their properties. This research examined the effects of phytoremediation on the removal of total petroleum hydrocarbons (TPHs) and geotechnical properties of a silty clayey sand contaminated by 3%, 5%, and 7% crude oil. Ophiopogon japonicus and Platycladus orientalis were two types of plants used to determine the phytoremediation effects within 30 and 60 days of operation. The scanning electron microscopy (SEM) images indicated that with increase in crude oil content at 0, 30, and 60 days of investigations, the soil particles become more flocculated. Comparison of the soil samples that experienced phytoremediation and without phytoremediation showed that flocculation of the soil particles became less during phytoremediation process. Use of Platycladus orientalis reduced soil flocculation more compared to Ophiopogon japonicus. The test results also showed that the TPHs removal rate using Platycladus orientalis was more than Ophiopogon japonicus. The addition of more crude oil contents caused enhancement of permeability while liquid limit, plastic limit, maximum dry density, optimum moisture content and CBR decreased. Investigation of the geotechnical properties of soil at different crude oil contents in 30 and 60 days of phytoremediation revealed that soil samples that experienced phytoremediation had more CBR and lower permeability compared to other ones without phytoremediation. It was also observed that upon more days of phytoremediation the liquid limit, plastic limit, optimum moisture content and permeability increased while the maximum dry density decreased. Using Platycladus orientalis compared to Ophiopogon japonicus yielded higher liquid limit, plastic limit, maximum dry density, and CBR along with lower optimum moisture content and permeability.

摘要

工业用不同物质的勘探、钻探、提取、运输和储存所产生的环境污染对土壤及其性质产生严重影响。本研究考察了植物修复对被 3%、5% 和 7% 原油污染的粉质粘土砂的总石油烃 (TPH) 和岩土工程特性的去除效果。麦冬和侧柏是用于确定操作后 30 天和 60 天内植物修复效果的两种植物。扫描电子显微镜 (SEM) 图像表明，随着研究 0、30 和 60 天原油含量的增加，土壤颗粒变得更加絮凝。对经过植物修复和未经过植物修复的土壤样品的比较表明，在植物修复过程中土壤颗粒的絮凝减少。与麦冬相比，使用侧柏更能减少土壤絮凝。试验结果还表明，侧柏对TPHs的去除率高于麦冬. 原油含量增加导致渗透率提高，而液限、塑限、最大干密度、最佳含水率和CBR降低。对 30 天和 60 天植物修复后不同原油含量土壤的岩土特性的调查表明，与其他未进行植物修复的土壤样品相比，经过植物修复的土壤样品具有更高的 CBR 和更低的渗透性。还观察到，经过更多天的植物修复，液限、塑限、最佳含水量和渗透性增加，而最大干密度降低。使用侧柏与麦冬相比 产生了更高的液限、塑限、最大干密度和 CBR，以及较低的最佳含水量和渗透率。