Novel Remediation Approaches Of Hexavalent Chromium Contaminated Soil Based On Leaching Method

Hexavalent chromium(Cr(VI))contaminated soil has drawn increasing attention due to its high environmental toxicity and strong migration ability.Among the various remediation technologies,the leaching technology has the advantages of fast removal speed,simple operation process,strong practicability and large removal amount,so it has been widely investigated and applied.However,the migration and removal of Cr(VI)in practical applications is still limited by the permeability of the soil,and Cr(VI)in the leachate has not been removed.The electrochemical technology can efficiently treat the fine density soil with low permeability coefficient and enhance the migration of charged ions.Therefore,this study uses the external electric field to achieve the enhancements to the original leaching technology.By analyzing the effects of the electric field strength,the nature of the eluent,the concentration of pollutants and the relative position of the pollutants during the experiment,the mechanism and environmental changes during the strengthening process were investigated.The use of microbial sensor means to quickly analyze the soil toxicity.The various enhanced leaching methods lay the theoretical foundation for the treatment and restoration of heavy metal Cr(VI)contaminated soil and inspire the further development of novel treatment technology.The main research conclusions are as follows:(1)The electro-enhanced leaching system can effectively remove Cr(VI)in contaminated soil,which can reach up to 99.9%under 20V.Within the concentration range of 20-120 mg/kg Cr(VI),the pollutants can be eliminated to safety standards.The increased salt content of the environment will have a slight inhibitory effect on the leaching performance.And in the application of simulation of the actual contaminated site,this method achieved a final removal efficiency of 85.7%.(2)A double-chamber microbial fuel cell enhanced leaching reactor was constructed.This method achieved the utilization of waste biomass,and 40%of Cr(VI)pollutants were reduced to Cr(III)and fixed in the surface of deciduous humus.This reactor maintained the power generation performance of about 400mV without direct input of external energy.(3)In order to achieve the effective recovery of the eluent and the microenvironment control,the hollow fiber membrane artificial root system was used to enhance the electro-enhanced leaching technology.The micro-electrode strengthened the desorption process of pollutants from soil particles,and the artificial root channel enhanced the collection of eluent.This method can be used as a potential treatment approach for further research.(4)The combination of hollow fiber membrane artificial root system and sensor cell DH5?_V_recA_lux was used to analyze the genetic toxicity of Cr(VI)contaminated soil.The genotoxicity dose-effect relationship curve of the aqueous solution and the sample soil have practical application value for the preliminary screening of the genotoxicity of the Cr(VI)contaminated site.