Study on Microbial Cure and Stabilization Effect and Mechanisms of Zinc-Contaminated Silt
With the rapid development of industry,the problem of soil contaminated by heavy metals,re-presented by Zn,has been becoming more and more prominent,and it is important to study the treatment methods and cured effects on Zn-contaminated silt.Based on the microbial induced calcium carbonate pre-cipitation(MICP)technique,a series of indoor experiments on microbial-cemented Zn-contaminated soil were conducted to reveal the mechanism of microbial cementation of Zn-contaminated soil from the perspec-tive of microstructural evolution.The results showed that microbial mineralization significantly improved the mechanical properties of Zn-contaminated soil,and reduced the permeability coefficient of Zn-contaminated soil by an order of magnitude,significantly reduced the leaching concentration of Zn ions and the percent-age of the exchangeable Zn content.It mainly might produce calcite crystals with colloidal properties during the microbial mineralization process,and zinc ions were fixed and tranfered to zinc carbonate,which made the microbial-cemented Zn-contaminated soil achieve the dual objectives of contaminant control and strength enhancement simultaneously.The microbial cure and stabilization of Zn-contaminated silt were most effec-tive when the cementitious solution concentration was 1 mol/L,the cementitious solution ratio(CaCl2∶Ure-a)was 1∶2,and the curing age was 28 d.
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