The Combined Immobilization Of Sr²⁺,Pb²⁺ By Montmorillonite And Carbonate Mineralization Bacteria

Soil heavy metal pollution is becoming increasingly serious, the task of controlling heavy metal pollution is imminent. Sr²⁺ and Pb²⁺ were represented common heavy metal ions in this study. Based on the rapid adsorption of montmorillonite and efficient mineralization of carbonate mineralization bacteria to heavy metal ions, the system with two functions of buffer retention and mineralization fixation was built including montmorillonite and typical mineralization bacteria. Our research will focus on the behavior during the adsorption-dissolution-mineralization process of the system to discuss the characteristics of rapid retention/fixation of heavy metal ion.Through the research on the mineralization characteristics of Sr²⁺ and Pb²⁺ by carbonate mineralization bacteria isolated from non contaminated soil, it is found that final mineralization rate of Sr²⁺ and Pb²⁺ were above 94.0% and 34.4% respectively, the main mineralization products were carbonate crystals.Through curve fitting by Sr²⁺, Pb²⁺ adsorption experimental data, optimal content of montmorillonite in different adsorption rate were calculated under different concentrations of the target ions. The results can provide certain reference data for the actual treatment of heavy metal pollution.Through the analysis of combined retention/fixation effect on Sr²⁺, Pb²⁺ by montmorillonite- carbonate mineralization bacteria system, the results showed that the effect of montmorillonite-Klebsiella sp. system was better. Finally, the removal rates of Sr²⁺ and Pb²⁺ were 94.5% and 90%, respectively. The mineralization rates by Klebsiella sp. of Sr²⁺ and Pb²⁺ were 79.2% and 87.3%, respectively.According to the fitting curve of Sr²⁺, Pb²⁺ adsorption experiment, strontium / lead montmorillonite were prepared. The system was built including strontium / lead montmorillonite and carbonate mineralization bacteria. The dissolution characteristics of Sr²⁺, Pb²⁺ in strontium/lead montmorillonite and mineralization characteristics of carbonate mineralization bacteria on the target ions were studied.The results showed that the dissolution rate and cure rate of Sr-M2-Klebsiella sp. system were up to 89.1% and 88.9% respectively. The dissolution rate and cure rate of Pb-M2-Klebsiella sp. system were both higher than 92.0%. It is obvious that the vast majority dissolution of Sr²⁺, Pb²⁺ in strontium/lead montmorillonite could be mineralized. Moreover, the addition of carbonate mineralization bacteria would promote the rapid dissolution of Sr²⁺ and Pb²⁺.This study discussed the fast adsorption of heavy metal ions by montmorillonite and mineralization by carbonate mineralization bacteria. The montmorillonite-carbonate mineralization bacteria system was built by combination of the two and the retention/fixation mechanism of heavy metal ions in the system was studied. The results will be expected to provide fundamental reference to the fast and in-situ govern of real sudden pollution of heavy metals and nuclides.