Desorption kinetics of thermal enhanced soil vapor extraction technology used in hydrocarbon contaminated soil
YANG Yujie1,2,, WANG Chunyu1,2, SHA Xuehua3, SONG Mingxin2, SANG Yimin2, ZHU Ling2,, 1.College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China 2.Department of Environmental Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617, China 3.Beijing Capital Sludge Disposal Technology Co. Ltd., Beijing 100044, China
Abstract:In order to study the mechanism of affecting the purification efficiency of thermal desorption of hydrocarbon contaminated soil, thermal enhanced soil vapor extraction (SVE) was used to treat hydrocarbon contaminated soil. The effects of ventilation rate, gas water content (GWC) of the extracted gas and soil water content (SWC) on the treatment efficiency of thermal enhanced SVE were studied, and the LDF and Freundlich kinetic equations were used to fit the desorption process. The results showed that when the treatment temperature was 120 ℃, the optimal treatment process was following: ventilation rate of 80 mL·min?1, 15% GWC in the extraction gas and 10% SWC, the mass transfer rate of gas was accelerated in soil pores, and the processing time of thermal enhanced SVE was significantly shorten. The aeration rate was reduced from 40 mL·min?1 to 80 mL·min?1, the processing time was shortened from 425 min to 350 min, and the water vapor concentration in the extracted gas increased from 0% to 15%, and the processing time was shortened from 350 min to 105 min. The GWC increased from 15% to 25% and the treatment time was prolonged from 105 min to 240 min. When the soil moisture content was 10%, the heat strengthening processing time was shortened to 290 min. When SWC changed from 10% to 15%, the treatment time was extended from 290 min to 390 min. The results showed that the LDF equation was suitable for data fitting under a simple condition system (ventilation rate). When the ventilation rate was 80 mL·min?1, the deviation rate was 4%. The Freundlich equation was more suitable for data fitting in a complex system (soil-water-gas). The deviation rates were 3.8% and 2.6% at GWC of 15% and SWC of 5%, respectively. Key words:hydrocarbon contaminated soil/ thermal enhanced soil vapor extraction technology/ desorption kinetics/ treatment time.
图1实验装置流程图 Figure1.Flow diagram of experimental device
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1.College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China 2.Department of Environmental Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617, China 3.Beijing Capital Sludge Disposal Technology Co. Ltd., Beijing 100044, China Received Date: 2019-05-22 Accepted Date: 2019-07-02 Available Online: 2019-10-11 Keywords:hydrocarbon contaminated soil/ thermal enhanced soil vapor extraction technology/ desorption kinetics/ treatment time Abstract:In order to study the mechanism of affecting the purification efficiency of thermal desorption of hydrocarbon contaminated soil, thermal enhanced soil vapor extraction (SVE) was used to treat hydrocarbon contaminated soil. The effects of ventilation rate, gas water content (GWC) of the extracted gas and soil water content (SWC) on the treatment efficiency of thermal enhanced SVE were studied, and the LDF and Freundlich kinetic equations were used to fit the desorption process. The results showed that when the treatment temperature was 120 ℃, the optimal treatment process was following: ventilation rate of 80 mL·min?1, 15% GWC in the extraction gas and 10% SWC, the mass transfer rate of gas was accelerated in soil pores, and the processing time of thermal enhanced SVE was significantly shorten. The aeration rate was reduced from 40 mL·min?1 to 80 mL·min?1, the processing time was shortened from 425 min to 350 min, and the water vapor concentration in the extracted gas increased from 0% to 15%, and the processing time was shortened from 350 min to 105 min. The GWC increased from 15% to 25% and the treatment time was prolonged from 105 min to 240 min. When the soil moisture content was 10%, the heat strengthening processing time was shortened to 290 min. When SWC changed from 10% to 15%, the treatment time was extended from 290 min to 390 min. The results showed that the LDF equation was suitable for data fitting under a simple condition system (ventilation rate). When the ventilation rate was 80 mL·min?1, the deviation rate was 4%. The Freundlich equation was more suitable for data fitting in a complex system (soil-water-gas). The deviation rates were 3.8% and 2.6% at GWC of 15% and SWC of 5%, respectively.
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