Research On The Migration Patterns And Remediation Technology Of Petroleum Pollutant In The Soil

With the great deal number of extraction and production of crude oil oily-waste water,ground and mud began to accumulate.These oil-made pollutants permeated soil by all means,changed the nature of soil,reduced the fertility and aggravated salinization,migrated to deeper strata under gravity,precipitation and infiltration.In those area with heavy polluted,contaminants would infiltrate over time,which affect the local agriculture and vegetation.Thus,the research on the migration rule of oil fomites is of significance to protect the environment,with scatter shot of recovery mothod.Daqing oilfield consists of Lamadian,Saertu,Xingshugang and the other 45 fids in vary range.Annual average precipitation is 434 mm.The main types of soil are chemozems and aeolian-sand soil.Surface vegetation is dwarf saline alkali plant.The density of Daqing oil is 0.8629g/mL,wax content is 20%³0%?solidification is 29?,viscosity is 22.2mm²/s.The process of oilfield development and production has created damaging pollutants,which are mainly ground oil,oily-waste water and mud.Via the desk research,three methods extraction,homoiothermy oscillation,ultrasound and Soxhlet,have been compared,and the optimum efficiency,ultrasound extraction,under the condition?40?,20 min,100W?has been confirmed,which gets the highest extraction rate of 79.02%.By orthogonal sifting test of extraction agent among CCl₄,CCl₂H₂,n-C₆H₁₄ and C₃H₆ O formulating with the sift result,the best solvent has been chosen,which is dichloromethane-acetone 4:1 mixed solution with extraction rate 85.73%.Installing soil-column lab research,imitating homogeneous and heterogeneous soil-column moving,the disciplinarian of shifting has been confirmed after compared.In the same condition,leaching amount and polluted time,the heavy polluted column gets a higher initial oil-content,when counterpoising,5cm gets lower while the 10 cm gets the highest,and accumulating oil reaches the top.Besides,in condition of same polluted and time,the more leaching,the more origin oil-content,and the balance-content is that 5cm¹0cm are the lowest while the under 10 cm are little distinct.Moreover,the condition of same lixiviation and pollutant,the origin content in 5cm is less than 10 cm,and as time accumulates,the 5cm content gathers,but the deeper,under 10 cm,gradually decrease,in the pattern of negative exponent.For the origin column infancy,the oil content decreases from shallow to deep,pollutants focusing on the 5cm.Increasing over time,oil-content at 10 cm is risen,while the 5cm one is little,which is quite different from the homo column.The main effect area is upper 15 cm,otherwise the under area contains little oil.This phenomenon shows that the more oil-fouled,the more oil-content acquired,yet the higher filtrating,the lower the concentration will be.The direction of oil-drifting is rarely affected by polluted condensation and seeping.The homo-column shows that the contraction at 5cm is raising over time,though 10 cm is declining.In regard of hetero-column,the essence of oil over time is minor at 5cm,although the 10 cm raising.As the difference of soil porosity,the hetero-migrate speed is slower than homo-migrate.Comparative analysis of the columns between homogeneous and heterogeneous show that homo-column gets more condensation than the hetero-one,which being scattered from C₁₂ to C₂₈ with higher range on each component.The origin-column gets few component,mainly dispels at C₁₂^C₂₂ with smaller peak on each.The laminae superficialis of homo-column are major of light components(<C₁₉).However,the light components reeducated gradually,the heavy parts accumulating underground.None of light components(<C₁₆)exist,mainly heavy parts(>C₂₀),and the relative amount changes little.Hetero-column mainly contains C₁₂^C₂₂,and the relative amount of C₁₉ and C₂₀ are much higher.In deeper area,light components rare exist,the major of components are C₁₇^C₂₀,which suggests that the heavy groups(< C₂₂)are not move into the under part.The change discipline over depth of four components in crude oil between homo-and hetero-column are quite same,that with the depth of columns accelerated,the relative content of aromatic hydrocarbon adding as well,but non-hydrocarbon relatively decreasing,saturated hydrocarbon and asphalt keep still.Oil migration rules in the soil,base on the porous medium characterization,come under convection,diffusion effect and oil,water and soil interaction,therefore,establishing soil-petroleum pollutant transport model by porous media of thermodynamic equilibrium and kinetic equations.In the vertical direction,on any layer of soil,the surface adsorption of oil add those flow in the cavity is equal to the amount from the top down into the target layer minus the outflow component.The physical meaning of the method can be calculated by determining the boundary conditions,which can make the initial value of the three point concentration in the shallow soil as the initial value to calculate the concentration of the pollutants in the deep soil.Adsorption desorption experiments were set up to study the retention and elution capacity of pollutants in soil,and the adsorption equilibrium constants of petroleum hydrocarbons Kcal is calculated as 31.922.After the experimental data,the simulation error o????t??%2,ground oil can be used to calculate the concentration of oil pollutants in the soil of different depths.In view of high content of oily soil on the field,and slow migration rate,the main group moving into shallow depth,the research uses microwave as the heat source,with the influence factors of effect on sensitizer,microwave power and time,oily soil content for microwave thermal remediation technology of soil remediation.When the soil and sensitizer quality rate is 5:1,the power of microwave thermal remediation is 700 W,takes 20 min and exceeds up to 900?,the removal rate oil pollutant in soil reaches 95.7%.Most of the pollutants are removed,with generation of non-condensable gas group pointing to C₂H₄,C₃H₆,C₃H₈,C₄H₈,C₄H₁₀,recovery condensate mainly contains saturated hydrocarbon.The results show that microwave has viability to accomplish the remediation of oil contaminated soil,with certain economic benefit.Via the analysis of oil pollutants in soil migration rules,petroleum pollutant transportation model has been established.By using the pollutant concentrations in the surface,the concentration value in deeper soil could be approximately obtained,to provide theoretical concentration values on pollution controlling.According to the concentration of pollutants,the method of microwave-pyrolysis recovery is chosen,gets a higher removal rate of pollutant,and a shorter treatment time,the product being able to recycled,which is an effective method of soil remediation.