The Effect Of Combine Attapulgite-Electrokinetics With ChromiumReducing Bacteria On The Remediation Of Cr(?)Contaminated Soil

With the continuous adjustment of urban industrial structure and land use planning,more and more original industrial land properties have been gradually developed into public construction land or residential land.Unrepaired contaminated sites will bring safety and health risks,and the safe reuse of contaminated sites has become a hot issue at present.Therefore,it is of great significance to study the remediation of heavy metal contaminated soil.In this paper,the effect of attapulgite(ATP)as an immobilized carrier on soil remediation was explored,and the means of Shewanella oneidensis MR-1 and Microbacterium sp.Y2 was studied.The effect of combined removal of Cr(?)by microorganism and electrokinetic repair(EK).The effect of HS as a natural enhancer on EK,and the effect and feasibility of synergistic effect of HSand microorganism EK on EK were discussed,which were polluted by heavy metal Cr(?).The results we acquired were as follows:(1)The effect of removing Cr(?)from soil of exogenous microorganism MR-1 are better than Y2,and the removal rate of free MR-1 was 34.49%.The immobilized microorganism with biological charcoal as carrier is better than modified attapulgite soil as carrier and free microorganism.The removal rate of Y2(BAY)treatment group with biological carbon as carrier is the highest,and 24 days later is 92.33%;(2)HS significantly increase the reduction rate of microorganisms,but also increase about 460%of the removal rate after 8 days of culture.HS combined with immobilized Y2 pellet(HBAY)with biochar as carrier was the best.After 24 days,Cr(?)in soil was almost completely reduced,and the removal rate was 98.43%.In the EK process,HS can increase the current density of soil,and promote the removal of pollutants,and effectively improve the removal eff-iciency of Cr(?).The Cr(?)concentrations at S1-S5 were 137.84 mg kg-1?5.27mg kg-1?3.5mg kg-1?1.76 mg kg-1 ? 0 mg kg-1,respectively;(3)In the EK process,Cr(?)migrate to the anode under the action of electric field at a speed of about 6×10-7 m s-1.Both Fe3O4 and ATP can effectively mitigate soil acidification and alkalization as PRB medium materials.The adsorption property of Fe3O4 is slightly higher than that of TCr,and the content of TCr in the cathode is 875.48 mg kg-1,and in the anode is 1464.82 mg kg-1 which is about 2.5 times of ATP,but the surface of Fe3O4 is liable to be covered by the product.(4)MR-1 and Y2 can not only effectively activate Cr in soil through metabolic activity,but also effectively reduce Cr(?)to Cr(?)by increasing the number of removable Cr(?)ions.After remediation,78%of residual Cr in soil is Cr(?).After combined EK with the Y2,the removal rate of Cr(VI)increased from 68.36%to 92.59,and the removal rate of Cr(?)combined with MR-1 was 73.74%.(5)Almost all Cr(?)were removed in the best treatment when HS,microorganism and EK working together.When EK,HS and Y2 are combined,the concentration of Cr(?)at S1-S5 were 22.91 mg kg-1?11.57 mg kg-1?8.69 mg kg-1?5.82 mg kg-1?0.00 mg kg-1 respectively.The removal rate of Cr(?)was 96.93%,and removal rate of TCr increased from 25.0%to 82.72%.Besides,the removal rate of Cr(?)combined with MR-1 is 73.74%.