The Research On Biochar-Mediated Microbial Reduction And Immobilization Of U(?)

During the process of uranium mining and smelting,a certain amount of uranium will be released into the environment,such as radiological hazard and heavy metal toxicity,will cause a series of ecological security problems.Based on the hazard of uranium pollution,the reduction behavior of U??? by microorganisms was explored.The adsorption of U??? and the microbial reduction U???,what is more,the effect of iron oxide on the biochar-mediated microbial reduction uranium in the environment by biochar was studied.,the following conclusions were drawn.?1?When pH is neutrality.the results shew the NaHCO₃ significantly inhibited the adsorption of U???by biochar.The higher the concentration of NaHCO₃,the adsorption of U??? by biochar be lower.?2?Under the condition of low adsorption rate,biochar can as electron transporter promote the reduction by microorganisms.The higher the concentration of biochar,the better the effect of uranium reduction and fixation.?3?The microbial concentration is less than 1×10⁷ cells·mL^-1,and the effect of biochar on the reduction of uranium by microbial reduction is not obvious.The rate of uranium reduction is increasing when the concentration of microorganisms exceeds 1×10⁷ cells·mL^-1.?4?The biochar prepared by different pyrolysis temperature has effect on microbial reduction uranium.The reduction rate of uranium is k_{biochar?700??}>k_biochar?900??>kbiochar?500??>kbiochar?300??>Kno biochar.In the biochar-mediated reduction mechanism,the conductivity mechanism is main reduction mechanism when the temperature is over 700?,while the biochar intermedia theory is main reduction mechanism in the low temperature?T<700??region.?5?The iron oxide in the environment promotes the biochar-mediated microbial reduction uranium.The rate of biochar-mediated microbial reduction uranium is 15.25umol·L^-1·h^-1 in presence of goethite.The rate of biochar-mediated microbial reduction of uranium is 14.75 umol·L^-1·h^-1 in absence of goethite,and the rate of microbial direct reduction of uranium is 14 umol·L^-1·h^-1.