Research And Application Of In-situ Chemical Leaching Reagents Contaminated By Product Oil

As important global energy resources,petroleum and its derivatives are widely used in various industries such as medical,transportation,and industrial production,and the demand for petroleum products increase rapidly.However,the improper disposal of petroleum extraction,refining,processing,transportation and other links will trigger a series of petroleum pollution incidents and cause serious environmental problems.A series of remedial measures were proposed for the soil pollution caused by the leakage of refined oil pipelines.First,the soil texture,hydrogeology and distribution of underground pipelines on the repair site were mastered by way of field surveys of contaminated sites,secondly the two-phase vacuum suction technology and surfactant leaching were determined as the main technologies to repair the contaminated site.The400m~2area of the repair site was used as a suction test area to explore the feasibility and removal effect of dual-phase vacuum suction technology on the repair of product oil pollution;the surfactants were screened according to the actual site requirements,and the solubilization experiment and adsorption experiment were carried out exploring the solubilizing ability of each surfactant and the amount of adsorption in the soil medium;the impact of various influencing factors was studied on the surfactant leaching effect,and the most suitable leaching conditions for each surfactant was determined,and finally the experimental results of soil column simulation of single type and compound surfactant were compared to define the leaching agent used for on-site repair.The resrarch results are shown as below:1.A test area of about 400 m~2 was established and 12 suction wells were evenly arranged.After 7 months of two-phase vacuum pumping test,the results showed that the thickness of the free phase generally decreased from about 0.8 meters to less than0.3 meters,and the removal rate of the free phase was more than 85%.2.At room temperature,the solubilizing ability of nonionic surfactants to petroleum pollutants is stronger than anionic surfactants;the lg Km of nonionic surfactants to solubilize petroleum pollutants is positively correlated with the HLB value of surfactants;the adsorption capacity of non-ionic surfactants in sand is significantly higher than that of anionic surfactants;clean water rinse and natural drying can remove some of the pollutants,which can not meet the requirements.3.During the surfactant leaching process,increasing the surfactant concentration,increasing the temperature,and increasing the solid-liquid ratio can all improve the removal rate of contaminants.There is a non-positive correlation between the removal rate and each influencing factor,and there is an optimal value within a specific range.4.During the soil column simulation experiment,except for Tween80,the other three surfactants all showed clogging to varying degrees,making the experiment unable to continue.This is inconsistent with the results of the solubilization experiment,so the screening of surfactants cannot be carried out solely through the solubilization experiment.The leaching ability of the surfactant is related to its actual effective concentration.Both adsorption and natural degradation will affect the surfactant.5.After the field application experiment of surfactants,the concentration of petroleum pollutants in the soil of the demonstration area was reduced from 25326mg/kg to 4507mg/kg,the average removal rate of total petroleum hydrocarbons reached89.5%,and the remediation effect was ideal.