Remediation Of Heavy Metal Contaminated Soil By Biochar Coupled MICP

In recent years,the problem of soil pollution caused by heavy metals has become more and more serious,which has caused great threats to ecosystems and human health.The task of controlling heavy metal pollution is imminent.Biochar(BC)as an excellent adsorption and stabilization material has been widely studied and applied to the remediation of heavy metal contaminated soil.In addition,microbial induced calcium carbonate precipitation(MICP)in mineralized soil heavy metals is also a research hotspot in the field of heavy metal pollution control.If BC and MICP can be used together,it is of great significance for the remediation of heavy metal contaminated soil.In this study,a strain of Lysinibacillus strain(KWS-1)with high urea decomposition capacity was isolated and screened.The strain has a pH tolerance range of 5-12 and an optimal growth pH of about 9;the highest tolerance is Cr(VI)The concentration is 80 mg/L;Pb(II)concentration is 1000 mg/L.Biochar with a pyrolysis temperature of 300? can promote the growth and reproduction of strain KWS-1;biochar with a pyrolysis temperature higher than 300? will have an inhibitory effect on the strain;proper addition of BC300 can significantly increase the production of CaCO3,Conducive to MICP.In the MICP process,after adding BC300,the crystal forms of calcium carbonate are calcite and vaterite;after adding BC400,BC500,BC600,and BC700,the crystal forms of calcium carbonate are mainly calcite.Biochar has different effects on the Cr(?)and Pb(?)in the soil stabilized by MICP.Adding BC300 can increase the stabilizing effect of MICP on Cr(?)and Pb(?).After biochar and MICP repaired the soil,the exchangeable binding state of heavy metals decreased,the carbonate binding state increased significantly,and the organic matter binding state and iron-manganese oxidation state did not change significantly.The results of this study can provide a technical reference for the actual remediation of heavy metal contaminated soil in the northwest region.