Experimental Study On Remediation Of Diesel Contaminated Soil Using Thermally Enhanced Soil Vapor Extraction Technology

With the rapid social economic development, Due to backward technology, poor management and many other reasons, some leakage and pollution accidents are produced in the process of oil exploitation, refining, storage, transportation and use, oil-contaminated soil is getting worse, which brings some harm to the ecological environment and human health, it has become one of the major environmental problems to be solved.Owing to small damage to soil, simple and easy operation, low investment cost, no secondary pollution and so on some advantages, soil vapor extraction(SVE) has been the most widely used soil remediation technology. In this paper, 0 # diesel as target pollutant, by designing the experiment of remediation of contaminated soil using SVE, The effects of different factors on the remediation of SVE were studied, in addition, by establishing the SVE system thermally enhanced by hot air, the influencing factors of soil temperature rises were discussed, the removal regularity of different diesel components were analyzed, the operating conditions of technology were optimized, the resulting conclusions were as follows:Soil depth, soil texture, ventilation velocity, initial content of oil, moisture had great influences on the remediation effect of SVE. The closer the distance from the air inlet, the higher diesel removal rate achieved; sandy soil has significantly higher diesel removal rate and shorter purification time than which in loam; the higher ventilation velocity, lower initial content of diesel in soil and lower moisture content would lead to higher diesel removal rate and shorter purification time.For SVE enhanced thermally, we found that ventilation temperature, moisture content, ventilation velocity and soil texture had effects on temperature rise of soil. The closer soil from the heat source, the faster the temperature rises; the higher ventilation temperature, lower moisture content and greater ventilation rate would result to greater rate of temperature rise; the temperature in sand rised faster than which in loam; improving ventilation temperature and ventilation rate had great effects on temperature improvement of soil closer to the heat source, but had little effects on the entire soil in column. The increase of ventilation temperature would lea d to higher diesel removal rate and shorter purification time. and reduced the organic matter content, which might change the basic physical and chemical properties of the soil, which affecting use after restoration. The increase of water content can promote the removal of pollutants in the process of thermally enhanced SVE. The lower saturated vapor pressure of diesel components, the lower removal rate.The optimal operating conditions of SVE obtained in this experiment were, ventilation rate of 3L / min, moisture content of <1%, ventilation temperature of 85℃, after running 168 h, the average removal rate of diesel was 54.80%.