The Experimental Study Of Surfactant-enihanced Air Sparging Remediation Of Nitrobenzene

Groundwater is widely distributing, stably water-supply and the quality ofgroundwater is excellent. It has been becoming an important source of water in life,irrigation, industrial and mining enterprises, and it has a great significance to developmentof economic. However, due to the impact of human activities, groundwater contaminationincidents take place frequently in recent years, various contaminants get into the soil andgroundwater through different channels. Once the groundwater is contaminated, it isdifficult to be remedied in a short period of time through the nature itself, and its damageon environment is sustained and irreversible, which cause a great threat to the ecologicalenvironment and human health. In view of this situation, the developed countries takeactive part in technology research and application of site remediation, and have a wealthof theoretical support and practical experience already. Air sparging stand out from thecrowd quickly for the advantages of economy, effectiveness and easy to use, it can beapplied in conjunction of SVE, repairing the volatile organic compounds in the soil vadoseand groundwater.This paper studies the influence of aeration flow and medium size in removingvolatile organic compounds by AS. The results show that: the air flow has a greatinfluence on residual rate of contamination, the removal efficiency of pollutant increaseswith the increase in the amount of aeration. However, the removal efficiency increasesonly a little when the aeration gets to0.10m3/h. when we taking into economic factorsaccount, the optimum air flow is0.10m3/h with the experimental conditions. Theremediation effect of AS is very sensitive to the permeability coefficient: in general, theparticle size of dielectric is greater, the permeability is stronger, and the removal efficiencyis higher.By optimizing the surfactant and researching the strengthening mechanism ofsurfactant-enhanced air sparging(SEAS), what we can know are that: contamination plumeis not easy to control since the Tween80has a great solubilization on nitrobenzene, theadsorption amount of Tween80is much larger than SDBS on medium, and the precipitation amount of SDBS in the underground environment is so small that it can beneglected. When the surface tension reduces, the air saturation increases to variousdegrees, and the surface tension is lower, the influence of air saturate because of air flowis larger. After the surface tension reduces, the air easily gets into medium. In addition,with the reduction in surface tension, the number of air flow passage in the medium issignificantly increased, and the air saturation is improved observably.By the experimental study of surfactant-enhanced air sparging remedy thenitrobenzene, what we can get from the experiment are that: the existing lens willseriously degrade the remediation effect of pollutants and prolong the remediation time;After adding the surfactant, the reduction of surface tension will lead to the release andmigration of the residual saturation state pollutant in groundwater, it may expand thecontamination plume, but benefit to the pollution contact with the airflow which canpromote the volatilization of pollution, reduce the threat of the residue pollution as asource of pollution in the pores, reduce the concentration of tailing.