Mineralization-Activation Regulation Of Cd And Sr By Two Strains Of Soil Bacteria

The problem of soil heavy metal pollution is particularly prominent in many types of soil pollution,which not only restricts the further development of the economy,but also seriously endangers the health of the people.So green treatment of heavy metal pollution is imminent.In recent years,bioremediation of heavy metal pollution technology has become a research hotspot at home and abroad due to its low cost and high efficiency.This study is mainly aimed at the emergency repair of higher concentration of soil heavy metal pollution,and achieves the goal of in-situ non-polluting repair through the rational use of biological remediation technology.Carbonate-mineralization microbe?Klebsiella quasipneumoniae?and Sulfate-reducing bacteria?SRB?were selected from the soil as experimental strains.The passivation behavior and removal effect of bacteria on Cd²⁺were investigated by analyzing its growth characteristics,Cd²⁺concentration changes and mineralization products.The results showed that the removal efficiency of the two strains decreased with the increase of Cd²⁺concentration.Through analysis of SEM-EDS and XRD,it was confirmed that the mineralized product of carbonate-mineralization microbe and Cd²⁺was CdCO₃,and the mineralized product of SRB and Cd²⁺was CdS.By analyzing the characteristics of Cd²⁺mineralized by two strains in series,it was found that Cd²⁺was mineralized to form CdCO₃ under the action of CO₃^2--producing of carbonate-mineralization microbe,but the crystallinity was poor and it was easy to decompose and transform.SRB can be used to transform CdCO₃ to CdS?color changed from white to yellow?.Through SEM analysis,it was found that the strains and minerals interacted,that is,the strains interacted with heavy metal ions to produce minerals,and the mineral aggregates wrapped a large number of strains to form a larger group,which made the new clusters produced by tandem mineralization more stable.At the same time,minerals produced from biomineralization/chemical passivation for remediation of soil heavy metal pollutionl can be converted into sulfide minerals to be more stable in the soil.By analyzing the activation characteristics of SrSO₄ and SrCO₃ on SRB,minerals were activated to dissolve Sr²⁺.And most sulfides in the liquid phase existed in the form of S^2-accompanied by the dissolution of Sr²⁺.Compared with the concentration of Sr²⁺extracted from scindapsus,it was found that the dissolved Sr²⁺concentration of SrSO₄ and SrCO₃activated by SRB at 7 d was 6.17 and 3.61 mg/L,respectively.At the same time,the growth of scindapsus at 5 and 10 mg/L Sr²⁺concentration for 7 d absorbed Sr²⁺concentration were4.61 and 8.54 mg/L,respectively.It can be seen that the occurrence of Sr is regulated by the action of microorganisms,so that the environmental pollution is less,and it can provide extraction for plants.That is,the occurrence of Sr can be regulated by the action of microorganisms,so that the environmental pollution is less,and it can be used for plant extraction.In this study,construct a mineralization-activation regulation system for plant extraction,laying a foundation for the rapid and non-polluting removal of heavy metal pollution.This study will build a bioremediation mineralization-activation control system,which is a new idea for assisting plants to extract heavy metals:through microorganisms to control the occurrence state of heavy metals to enhance plant repair efficiency.It will lay the foundation for efficient and pollution-free removal of heavy metal pollution.