Uranium removal from complex mining waters by alginate beads doped with cells of Stenotrophomonas sp. Br8: Novel perspectives for metal bioremediation Sánchez Castro, Iván Martínez Rodríguez, Pablo Abad Ortega, María del Mar Descostes, Michael Merroun, Mohamed Larbi Mining waters Bioremediation Biomineralization Uranium Bacteria immobilization Alginate beads This work was supported by ORANO Mining (France) [collaborative research contract no 3022 OTRIUGR] . It results from a Joint Research Project between Orano Mining R&D Department and the Department of Microbiology of the University of Granada. We acknowledge the assis-tance at the ESEM of Isabel Sanchez Almazo and Concepcion Hernandez Castillo (Centro de Instrumentacion Cientifica, University of Granada, Spain) . Funding for open access charge: Universidad de Granada/CBUA. Uranium-containing effluents generated by nuclear energy industry must be efficiently remediated before release to the environment. Currently, numerous microbial-based strategies are being developed for this purpose. In particular, the bacterial strain Stenotrophomonas sp. Br8, isolated from U mill tailings porewaters, has been already shown to efficiently precipitate U(VI) as stable U phosphates mediated by phosphatase activity. However, the upscaling of this strategy should overcome some constraints regarding cell exposure to harsh environmental conditions. In the present study, the immobilization of Br8 biomass in an inorganic matrix was optimized to provide protection to the cells as well as to make the process more convenient for real-scale utilization. The use of biocompatible, highly porous alginate beads for Br8 cells immobilization resulted the best alternative when investigating by a multidisciplinary approach (High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM), Environmental Scanning Electron Microscopy (ESEM), Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance, etc.) several consolidated entrapment methods. This biomaterial was applied to complex real U mining porewaters (containing 47 mg/L U) in presence of an organic phosphate source (glycerol-2-phosphate) to produce reactive free orthophosphates through Br8 phosphatase activity. Uranium immobilization rates around 98 % were observed after one cycle of 72 h. In terms of U removal ability as a function of biomass, Br8-doped alginate beads were determined to remove up to 1199.5 mg U/g dry biomass over two treatment cycles. Additionally, optimized conditions for storing Br8-doped beads and for a correct application were assessed. Results for U accumulation kinetics and HAADF-STEM/ESEM analyses revealed that U removal by the immobilized cells is a biphasic process combining a first passive U sorption onto bead and/or cell surfaces and a second slow active biomineralization. This work provides new practical insights into the biological and physico-chemical parameters governing a high-efficient U bioremediation process based on the phosphatase activity of immobilized bacterial cells when applied to complex mining waters under laboratory conditions. 2021-10-04T08:54:30Z 2021-10-04T08:54:30Z 2021-07-28 info:eu-repo/semantics/article Iván Sánchez-Castro... [et al.]. Uranium removal from complex mining waters by alginate beads doped with cells of Stenotrophomonas sp. Br8: Novel perspectives for metal bioremediation, Journal of Environmental Management, Volume 296, 2021, 113411, ISSN 0301-4797, [https://doi.org/10.1016/j.jenvman.2021.113411] http://hdl.handle.net/10481/70605 10.1016/j.jenvman.2021.113411 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España Elsevier