Experimental Study Humus Reduction U (Ⅵ) Efficacy And Mechanism Of Uranium Mining And Milling Waste Water To Remove Bacteria

The migration and release of uranium in uranium tailings is a complexinteraction process of physical,chemical and biological. Microorganisms exists widelyin natural environment,and they has great potential in the bioremediation of uraniumcontamination.Current microbial reduction of U (Ⅵ) is of great concern, and humicrespiratory metabolism model of humic-reducing bacteria(HRB) is a hot researchtopic. Results indicated that humic substances could act as electros mediators betweenthe HRB and reducible pollutants (such as U(Ⅵ)), and contributed significantly to thereduction of these pollutants.In the experiment, the bottom sediment of lotus pool was domesticated to get thesludge enriched with HRB, and further isolated HRB. The characteristics andperformance of the HRB to remove U(Ⅵ) in wastewater were examined.Single factortests investigate the effects of temperature, pH values, the dosage ofanthraquinone-2-sulfonate (AQS), initial U(Ⅵ) concentrations, electron donor and thecoexisting ions on U(Ⅵ) removal Through orthogonal test, the effects of temperature,pH values, the dosage of anthraquinone-2-sulfonate (AQS), sodium lactate (electrondonor) and initial U(Ⅵ) concentrations on U(Ⅵ) removal were investigated. Theresults of tests showed that in low concentration of U(Ⅵ) the U(Ⅵ) removalefficiency is higher,the optimum condition of U(Ⅵ) reduction was as the following:temperature of30℃, pH value of6.0, AQS of1.0m mol/L,and sodium lactateconcentration of5m mol/L.The continuous U(Ⅵ) removal test results showed thatHRB was efficient to remove low concentration U(Ⅵ).The removal efficiency ofU(Ⅵ) was more than93%in the first phases within80hrs, while it still closed to60%in the second phases within96hrs, and the removal capacity of U(Ⅵ) had greatlyincreased, and the total removal capacity of U(Ⅵ) was about300mg/g. Resultsindicated that HRB was suitable for bioremediation and immobilization of solubleU(Ⅵ) in contaminated water.Research work to further explore the mechanism of HRB reduction of U (Ⅵ).The results indicated that enrichment bacterial liquid could remove about85%of theU(Ⅵ) in60hrs, while electron transfer approach about61%and EPS adsorptionapproach about41%, and the electron transfer approach was the main way to reduce U(Ⅵ) by HRB. The whole IR spectroscopic analysis implys that carboxyl,amide andphosphate groups of HRB are the dominant functional groups involved in bacteria toremove uranium.