Numerical Simulation Of The In-situ Remediation For The Saturated Zone Of The Soil Polluted By The Petroleum

Due to the rapid development of the industrialization,the soil problem from oil-pollution become much serious,this is very harmful to the human,animals and plants.How to remediate oil pollutants has become one of the environmental problems which should be soon solved.It is also important to develop the high-efficiency remediation methods.The soil remediation experiments are characterized by long time,high cost and complicated operating steps,while the numerical simulation method for the soil remediation is featured by low cost,high efficiency and adaptability to variable factors and therefore promoted and applied to many research fields.However,there are few studies on the numerical simulation of remediating the saturated soil polluted by the diesel.In this paper,the CFD software Fluent was used to build the mathematical models for the soil flushing(SF),surfactant enhanced remediation(SER)and in-situ bio-remediation(ISBR).The porous medium model was used for the soil,while the multiphase-flow model was adopted for the water and diesel.Based on previous models,the multiphase flow interaction model of and porous medium resistance model were integrated to simulate the migration and concentration variation of the petroleum pollutants under the interaction of the fluid and soil;then the interphase mass transfer model and multiphase flow interaction model were combined to simulate the mutual transformation mechanism among different phases,solubilizing mechanism of the surfactant enhanced remediation and transformation and mass transfer mechanism of the in-situ bio-remediation.For getting better simulated results,it is necessary to repeatedly adjust the porous media resistance function,the multiphase flow interaction forces and the function of interphase mass transfer model based on physical transformation mechanism.During the process of the simulation,the water acts as the primary phase,while the diesel and surfactant act as second phase.The simulation results indicated that: For the sandy soil,the diesel average removal rate was ~57.18% when the water flushing SF remediation last for 20 days,the diesel average removal rate was ~68.08% when the surfactant-drived SF remediation last for 20 days and the diesel average removal rate was ~72.1% when the ISBR remediation last for 50 days.For the sandy clay soil,the diesel average removal rate was ~32.35% when the water flushing SF remediation last for 20 days,the diesel average removal rate was ~46.57% when the surfactant-drived SF remediation last for 20 days and the diesel average removal rate was ~47.16% when the ISBR remediation last for 50 days.The simulation results are a little different from the experiment results,but their overall trends are similar.This study indicated that it is available to simulating how to remediate the saturated zone of the polluted soil with SF,SER and ISBR by the FLUENT software.