Study On The Remediation Method Of Contaminated Soil By Gasoline With SVE

Contamination of soil by gasoline and other petroleum-derived hydrocarbons released from underground storage tanks (USTs) is a serious and widespread environmental problem. Soil vapor extraction (SVE) is gaining acceptance as a remediation technology for unsaturated soils contaminated with volatile organic compounds (VOCs). On the basis of quantitative analysis for many components in gasoline, designing column experiment and field experiment studied the removal law of different components, and discussed the influence factor of gasoline contamination. During the study, the conclusions that are drawn are followed.1. In this report, a set of analytical methods were described for use in monitoring volatile organic compounds in gas and soil. This provided a basement for mechanism discuss and risk- based evaluation. The precision of GC measurement is the gas sample's RSD between 1.36% and 6.64%, the soil sample's RSD between 2.77% and 19.14%. The veracity of GC measurement is the gas sample's recovery between 101.33% and 109.19%, the soil sample's recovery between 80.59% and 113.18%. The RSD of TVOC measurement is 12.83%. The correlativity of GC measurement and TVOC measurement of Gas sample is linearity.2. Through the column study, it was found that under the soil condition of Tongzhou field site, the gasoline in the soil could be removed effectively. The TVOC in the soil gas could reflect the gasoline's change in the soil. Under the experiment condition of this study, the main influence factor of contamination removal rate was aeration flux. The removal rate became bigger as the bigger of aeration flux.3. Under the experiment condition of this study, the law of contamination remove was the remove of the easy volatilization components were before the difficult volatilization components. In this study, the main reason of SVE"tailing"was the bigger molecular weight components is difficult to be quickly removed by the method of ventilated. These components were the controlling factor of phases'mass transfer, because of the high boiling point and low volatility.4. In soil and gas, the main influence factor of different components content was the components'volatility difference. And the secondary influence factor of different components content was the content difference in the gasoline. When the spill oil mass is the mass of soil's 7%, the mostly contaminant components in the gas included butane, 2-methyl butane, 2-pentene, 2- methyl-2-butene, and 2- methyl pentane. The the mostly contaminant components in the soil included toluene, 1,2,4-TMB, m+p-xylenzene, benzene, isooctane and ethyl-benzene.5. When the oil contaminated the subsurface heterogeneity stratum, the distribution of TPH was affected by the soil lithology and the O.M. content of soil. When the spill oil mass is the mass of soil's 7%, the soil content is 1.323×104mg/kg in the viscid powdery soil, 5993mg/kg in arenaceous powdery soil, and 3365mg/kg in the grit. When the O.M. content of soil is 1.3‰, the soil content is 1.081×10~4 mg/kg. When the O.M. content of soil is 0.3‰, the soil content is 5993 mg/kg.6. Through the measurement of TVOC in the gas, it was found the airflow of SVE could pass the contaminant zone. As the depth of 3.1m, the value of TVOC was decrease. The decrement was between 20ppm and 200ppm. Using the variety of TVOC can show the form process of airflow. When the airflow was near stabilization, the variety of TVOC was very small, near zero. The subsurface heterogeneity stratum could influence the airflow on the level. The air flow would avoid low penetrate stratum, and flow to high penetrate stratum.