Study On Restoring And Curing Technology Of Cr(?) Contaminated Soil

As the "Half astern into three" policy implemented by the government,many Cr electroplating factory moved out of the city,then the original industrial land is gradually developed as residential land or commercial land.Electroplating Cr polluted soil in great quantities was left all over the country,it's undoubtedly a potential health risks for residents.Based on a chrome plating factory,this study investigated the Cr(?)distribution in soil of the factory,then estimated the corresponding human health risk;Studied the effects of the reduction of Cr(?)to Cr(?)through the amount of Sodium Pyrosulfite doses,then studied the effects of the reduction of Cr(?)to Cr(?)through the mount of Portland cement doses based on this research,got the best dosing of Sodium Pyrosulfite and Portland cement;According to determine best dosing repair agent,used high pressure jet grouting technique,repaired this low permeability soil contaminated Cr(?),and provided a scientific basis and case support for similar Cr(?)polluted sites.First of all,studied the soil pollution of the chrome plating factory and estimated the human health risk,the results were as follows:(1)From top to bottom,the soil of the field,included a certain thickness of gravel backfill,gravel layer was about 0.8 to 1.5 meters below after filling,filling soil main was browns toner clay,mixed with partial gravel and silt.The lower original soil layer(about 5 meters underground area)mainly was brown silty clay;(2)The soil pH range was 3.12 to 7.62,and presented different pH distribution with different soil depth,the main show was the minimum pH between 3 and 4.was at 1.5 m,the highest pH was at a depth of 4.0 m,between 7 and 8,closed to neutral the control point;(3)The major pollutants in soil of this site was Cr(?),range of 1.9-10326 mg/kg,the Cr(?)concentration in the background soil control point was range of 1.2-3.5 mg/kg.The highest concentration of Cr(?)in soil was at the depth of 1.5 m,concentration of Cr(?)in soil was close to the control point at the depth of 4.0 m;And when the pH was smaller,the higher Cr(?)contented in the soil.When the pH was close to the background control,the Cr(VI)content in the soil also close to the background value;(4)It was found through the human health risk assessment that the Cr(?)cancer risk and non-cancer hazard of the field soil were beyond acceptable level,based on the risk control values of 15.6 mg/kg.Then,Studied the effects of the reduction of Cr(?)to Cr(?)through the amount of Sodium Pyrosulfite doses,and studied the effects of the reduction of Cr(VI)to Cr(III)through the mount of Portland cement doses based on this research,got the best dosing of Sodium Pyrosulfite and Portland cement and successfully repaired Cr(VI)soil of this field.(1)Experimental studied that five times theory amount of Sodium Pyrosulfite was added,5%of cement,curing 7 days later,the Cr(VI)content in the soil would below the repair target;(2)On the basis conclusion of experiment in laboratory,carried out actually the reduction-curing and repair experiment on the Cr(VI)contaminated sites,finally got the acceptance standard.