Experimental Study On The Remediation Of Low Concentration Uranium Wastewater By Sporosarcina Pasteurii Induced Carbonate-uranium Co-precipitation

In the process of uranium mining and smelting,a large amount of wastewater containing uranium is produced,which poses a potential threat to the environment and human health.Therefore,the remediation of uranium contamination has become a focus of research in the field of environment.Uranium is usually present in soil and water in the form of UO₂²⁺,which is soluble and migratory.In addition,as a common alpha nuclide,it is highly biological/chemical toxic and very radioactive.In recent years,due to the advantages of low cost,simple operation and less environmental interference,microbial remediation has provided a greener,economic and stable means for the remediation of uranium contamination.Microbial-induced carbonate precipitation has been widely used in the remediation of heavy metal pollution in the environment in recent years.Microorganism that can induce carbonate precipitation usually have certain enzyme-producing properties.This group of microorganism is collectively known as carbonate mineralized microorganism,including fungi and bacteria.Among them,a kind of carbonate mineralized bacteria with the characteristic of producing urease can provide urease and crystal nucleus.In the process of carbonate precipitation,some heavy metals and radioactive elements in the environment are replaced to the position of Ca²⁺in Ca CO₃by means of isomorphic substitution,so as to realize the purpose of fixing heavy metals in the precipitation products.The application of microbial-induced carbonate precipitation to remediation of uranium-contaminated wastewater by hydrolyzing urea was analyzed to evaluate the feasibility of in-situ remediation of uranium-contaminated water by carbonate mineralizing bacteria.In the presence of a large number of calcium sources,Sporosarcina pasteurii was used to induce carbonate precipitation and repair uranium pollution in water with the characteristic of producing urease hydrolyzing urea.This article demonstrated that Sporosarcina pasteurii can rapidly decompose urea and promote the co-precipitation of uranium with microbial-induced carbonate.Under the initial p H of 4.5,the maximum removal rate of uranium in water can reach 95.38%.The analysis indicated that Sporosarcina pasteurii was able to tolerate high concentration of uranium,while low concentration of uranium had a slight promotion effect on bacterial growth.In addition,the decrease of uranium concentration was directly related to the concentration of Ca²⁺.High concentration of Ca²⁺can remove uranium better.The temperature at about 30℃and alkaline environment are favorable to the co-precipitation of uranium and calcite.X-ray diffraction analysis showed that the precipitate was composed of calcite.Scanning electron microscope-Energy dispersive spectrometer analysis further suggested that the precipitated component contains uranium element.The continuous extraction method proved that the chemical form of uranium in the precipitation is mainly carbonate bound state.Combined with the results of determination of uranium content in the precipitated samples by digestion,it could be inferred that the uranium in the solution is bound to the precipitated products by co-precipitation in the process of calcite formation.The research results show that the Sporosarcina pasteurii induced carbonate-uranium co-precipitation can effectively fix the uranium in water,and has a significant effect on the remediation of low concentration uranium contaminated wastewater.The experimental study shows that Sporosarcina pasteurii induced carbonate-uranium co-precipitation has a potential application prospect in the remediation of low concentration uranium wastewater.