Cementation rate and pollutant control of lead-contaminated soil solidified by microorganisms and gypsum
The microbial-gypsum single stirring method was used to treat lead-contaminated silt.Lead pol-lution concentration,calcium salt concentration,calcium salt type and stirring time were adopted as control parameters to investigate the engineering characteristics and pollutant leaching characteristics of solidified lead-contaminated silt.The results show that the unconfined compressive strength of lead-contaminated silt can be increased from less than 40 kPa to more than 120 kPa by using gypsum as calcium salt and being solidified and stabilized by microorganisms.When the stirring time increased from 30 min to 120 min,the strength of the sample increased by 30%.After solidification and stabilization treatment,the lead ion leac-hing value of the 200 mg/kg lead contaminated soil can be controlled below the TCLP limit of 5 mg/L,and the migration level of lead elements is significant reduced.The morphology of calcium carbonate formed in lead-contaminated silt is amorphous aggregates,symbiotic crystals of rosette calcite,with a small amount of lead carbonate crystals attached.The use of gypsum calcium source can effectively delay the ce-mentation rate of lead-contaminated silt,which could provide time conditions for the application of in-situ mixing technology in engineering applications.Meanwhile,the cementation effect of microbial mineraliza-tion on contaminated soil was improved.
lead-contaminated siltgypsumstirring timelead ion leaching valuepollutant control
NETL
NSTL
万方数据
