The Soil Restoration Of Heavy Metal Chromium Residue Contaminated Site And Risk Assessment

As one of the largest producers of chromium salts in the world,the annual amount of chromium salts is huge.But at the same time,because of the backwardness of equipment and management,chromium-containing waste droplets and chromium slag are piled up randomly in the production process of chromium salts,causing severe environmental pollution problems.Chromium salt pollution poses a major threat to human health.In this paper,chromium slag was used to contaminate the soil in the site.Based on the relevant national laws,regulations and industry norms,the feasibility of the restoration technology was evaluated.The optimal program was selected to restore the chromium slag contaminated sites.In order to find the optimal reduction-immobilization/stabilization drugs,batch experiments were conducted.The contents were contained as follows:the effect of pharmaceuticals on the removal of hexavalent chromium,the exploration of the best pharmaceuticals and the best dosage,the site investigation of the actual contaminated sites in-depth analysis,and repair operations at the same time.According to the requirements of risk assessment,the risk assessment of the rehabilitated soil will be provided to provide guidance for the subsequent planning and use.The research content and conclusions of this article mainly include as follows:According to a series of laws,regulations and policy standards of retrieving soil remediation and environmental pollution,actual cases and engineering experiences were collected and stored in the field of soil remediation among developed countries as well as China.The innovative,rational and economic analysis of soil remediation technologies were conducted.To determine the suitable solution for heavy metal contaminatedsoil,namely reducingagent-curingstabilizationandrepair technology.The effects of eight different reduction-immobilization/stabilization drugs on the removal of chromium from soil were studied,including FeSO₄,K₂HPO₄,FeCl₂,Na₂S,CaO,cement,bentonite and fly ash.The results showed that FeSO₄,Na₂S and cement had the most obvious effect on the removal of chromium at the best dosing amount?5%?.The investigation and analysis of the contaminated sites of the actual chromium salt production enterprises were conducted.The special areas of the enterprise were carried out the remediation of the chromium-contaminated sites.Takingintoaccountthelocalenvironmentalandconditions,the remediation-immobilization/stabilization technology was designed to remediate the contaminated site.The results of risk assessment showed that the non-carcinogenic hazards of trivalent chromium in the field soil were within an acceptable range and did not affect human health under normal circumstances.According to the risk characterization calculation results,when the carcinogenic risk of a single pollutant exceeded the acceptable risk level,the soil limit value of the pollutant shall be calculated according to the specific conditions of the site.