Study On The Characteristics And Mechanism Of Uranium (?) Removal From Water By Lactobacillus Plantarum

A large amount of waste uranium,tailings,and waste water containing uranium have been generated during uranium mining and uranium production and application.It poses a serious threat to human and ecological environment.Microbial remediation of U(?)contamination in water is one of the most effective environmental methods.In this study,Lactobacillus plantarum was used to remove U(?)from water,and the characteristics and mechanism of uranium removal were discussed.,in order to provide a theoretical basis for microbial treatment of radioactive uranium wastewater.The main work can be divided into the following three aspects:1.Through a static test,different experimental parameters such as contact time,biomass dosage,pH,initial U(?)concentration and temperatures on the adsorption of uranium by heat-killed Lactobacillus plantarum were investigated.The removal rate of heat-killed Lactobacillus plantarum to U(?)was up to 94.28% when the pH was 6,the temperature was 30°C,the biological dosage was 0.12g/L,and the initial concentration of U(?)was 10mg/L.The adsorption equilibrium time was 240 min.The adsorption process fit well with the pseudo-second-order kinetics adsorption model and the Freundlich model.2.The SEM-EDS,FTIR and other characterization methods revealed the mechanism of heat-killing Lactobacillus plantarum to remove U(?)from water.The results showed that the heat-inactivated cells removed U(?)from water mainly through adsorption mechanism.U(?)was mainly adsorbed on the cell wall and showed a gel-like shape.Coordination was the main mode of U(?)adsorption.The main functional groups interacted with U(?)included hydroxyl groups,protein amide groups,carboxyl groups,and phosphate ester groups.3.The comparative test and characterization comparison of the removal of U(?)in water by inactivated and non-inactivated Lactobacillus plantarum revealed the interaction mechanism between living cells and U(?)of water solution.The results showed that the living cells removed U(?)from the water through various mechanisms.SEM-EDS analysis showed that regular spherical nanoparticle uranium precipitated on the surface of living cells after interaction with U(?),but the surface of heat-killed cells did not;FTIR analysis showed that the functional groups of U(?)interaction between living cells and water were protein amide,hydroxyl group of protein and polysaccharide,phosphate group;XRD analysis showed that the crystals of uranyl phosphate existed on the surface of living cells after interaction with U(?),but not on the surface of heat-killed cells;XPS analysis showed that U(IV)and U(?)were deposited on the surface of living cells after interaction with U(?).On the contrary,there was only U(?)on the surface of the heat inactivated cells.It was concluded that the interaction between living cells and U(?)in water depended on their own metabolism.The living cells remove U(?)from water through various mechanisms such as adsorption,biomineralization and reduction.