基于TMVOC的水位波动带土壤气相抽提模拟

为探究水位波动对土壤气相抽提（Soil Vapor Extraction,SVE）修复的影响,以西北某傍河石化场地为研究对象,利用TMVOC模拟苯系物的自然衰减过程及不同水位状态下SVE修复过程,从修复效果、相间转化、饱和度演变等方面比较不同条件下苯系物的衰减率.结果显示,该场地较佳的抽提井的压强为9.1×10⁴Pa,影响半径为8m;苯系物在自然衰减、水位稳定状态下SVE修复及水位波动状态下SVE修复12个月后的质量损失分别为17%、85%、96%;水位稳定和水位波动状态下SVE修复12个月后,非水相液体（Non-Aqueous Phase Liquids,NAPL）的饱和度最大可达到0.066和0.044;水位稳定状态下,苯系物在"气-液-NAPL"相去除率逐渐降低,水位波动状态下,在水位下降的阶段,更多的NAPL相苯系物转化为气相,并被抽提气流携带去除.

Numerical simulation of SVE in groundwater table fluctuation zone based on TMVOC

The effects of groundwater table fluctuation (GTF) on the remediation of a petrochemically polluted riverside in northwestern China by soil vapor extraction (SVE) were investigated. The migration and transformation of benzene, toluene, ethylbenzene, and o-xylene (BTEX) in cases of natural attenuation and SVE with GTF were simulated using TMVOC model. The remediation rates of BTEX were analyzed by remediation effect, transformation among phases, and saturation variation under different conditions. The results showed that the optimized extraction well pressure and influencing radius of the target site were 9.1×10⁴Pa and 8m, respectively. The removal rates of BTEX in cases of natural attenuation, SVE without GTF, and SVE with GTF were 17%, 85%, and 96%, respectively. The NAPL saturation can reach as high as 0.066 and 0.044 in case of SVE without GTF, and SVE with GTF, respectively. In case of SVE without GTF, the remediation rate of BTEX in gas, aqueous, and NAPL phase decreased gradually. In case of SVE with GTF, more NAPL phase contaminant was transported to gas phase contaminant, and extracted by SVE during the stage of falling groundwater tables.