Research On Application Of New Complex Oxidants In Petroleum Contaminated Site

The remediation and treatment of petroleum-contaminated soil has become the focus of social attention.The technology of chemical remediation of petroleum-contaminated soil has obvious advantages in terms of reducing consumption and quick results.At present,the research on the remediation of total petroleum hydrocarbon(TPH)contaminated soil is mostly limited to laboratory analysis,and system performance evaluation is lacking.Therefore,systematic screening,performance evaluation and in-situ practical application are of great practical significance for the efficient remediation of TPH contaminated soil.This paper takes the petroleum contaminated site in eastern Gansu Province as the research object.Through sampling and analysis of the contaminated site,the target pollutant is determined to be TPH;through indoor experiments,small-scale device simulations,and on-site in-situ remediation experiments.The chemical properties and degradation performance of oxidants are clarified;the control process mechanism of in-situ remediation of oxidants is proposed,and the main results are as follows:1)The screening of chemical oxidants and degradation performance analysis for remediation of TPH contaminated soil were carried out.Using a batch experiment method,with the aid of a reaction kinetic model,comprehensive analysis of the degradation performance of the pre-selected oxidants,the results show that:Compared with H₂O₂,KMn O₄ and Na₂S₂O₈,Na₂FeO₄ has a fast reaction rate,a short half-life,weak disturbing soil structure,and a strong ability to remove TPH.Comprehensive high performance without residue.Therefore,it is determined that Na₂FeO₄ is the main repair agent.2)Equipped with a new type of composite oxidant and determine its stable and efficient control parameters.Two kinds of stabilizers,one intensifier,and three concentration levels of the orthogonal experiment method are used.The results are as follows:the compound oxidant formula is 0.1%KIO₄,0.15%Na HCO₃ and 0.05mol/L Na₂FeO₄.The best control parameters for high efficiency performance are 0.4mmol/g soil composite oxidant solution,0.3 mmol/g soil Na₂S₂O₈ solution,1:1water-soil ratio and 20?temperature.Under these conditions,the removal rate of TPH in the soil is 89.76%,The final reaction product is Fe(OH)₃,H₂O and CO₂.3)A simulation experiment of a small device for chemical remediation of TPH contaminated soil was run.Three different pressures of 0.2 MPa,0.4 MPa,0.6 MPa were used for the injection experiment in soil.The results showed that the flow direction and radial injection distance were fitted,and it was found that the injection pressure and the flow direction injection radius were locally linear,and the comprehensive comparison was nonlinear.relationship.The injection pressure has a linear relationship with the radial injection radius.After pilot experiments and Fluent simulations,it was finally determined that the ratio of jet nucleus,turbulence zone,and seepage zone was approximately 1:4:2.Under three different pressures,the average removal rate of soil TPH can reach 87%.4)Implemented field experiments on chemical remediation of TPH contaminated soil.Through the response surface optimization design and Fluent software simulation,the optimal operating parameters of the high-pressure jet grouting equipment and the formation law of the boundary layer under the jet environment were determined,and the feasibility of modeling was determined by comparing with the results of field experiments.The results show that according to the quadratic regression equation,the best operating conditions of the high-pressure rotary jet machine are injection pressure:30 MPa,rotation speed:23 r/min,and lifting speed:30cm/min.The best injection diameter is:147.3 cm.Comparison of field experiment and simulation experiment can confirm that the ratio of jet core,turbulence zone and seepage zone is about 1:4:2.Through field repair experiments,the highest removal rate can reach87.1%,which is concentrated near the jet core.The minimum removal rate is 76.3%,which is concentrated near the seepage area.The problem of the decrease of TPH removal rate in the seepage area can be solved by the plum pattern.The seepage area of adjacent injection points overlaps,and the removal rate can be stabilized at83.77%.The above content is for the soil quality of the Loess Plateau,the above content has found an oxidant that is efficient,safe,environmentally friendly and suitable for nutrient-poor soils.At the same time,it provides a theoretical reference for the restoration of the high-pressure jet grouting process in the Loess Plateau region,and verifies the in-situ chemical oxidation of high-pressure jet grouting The process is feasible,efficient and economical for repairing petroleum-contaminated soil in the Loess Plateau.The results of simulation,pilot experiment and field experiment are similar.Using this method can provide a certain theoretical reference and actual repair experience for the repair work.