Advances in a Bioprocess for the Treatment of Nuclear Waste: Spent Ionic Exchange Resins

摘要

Development of a bioprocess intended to achieve a volume reduction of spent resins (either from research and power reactors) is the main purpose of this research project. Search is constrained to microorganisms that exhibit radioresistance, and which can be cultured in a heavy metal environment with additives of nuclear reactor waters such as boron, lithium and gadolinium compounds. Bacteria adapted to a radioactive environment were obtained by treating a RA-3 Reactor spent ionic exchange resin sample (kept at Area de Gestion Ezeiza: AGE) with sterile water; microorganisms suspended were isolated, subject to purity controls and characterized Experiments performed with these strains include: -Culture in a mineral-broth having polystyrene as source of both carbon and energy. The strain RMB 1200 gave the highest number of viable cells, then being tested with some aromatic compounds, and with some additives of nuclear reactor waters and other elements found in spent resins. -An anionic exchange resin sample was heated, yielding a chemical environment resembling to that of radiolysed resins, and then RMB 1200 strain was cultured with this solid. -A technique to stain polymers was developed in order to find morphological changes caused by microbiological activity. Microscopic examination of cultured polymer samples has been performed. Results obtained with RMB 1200 include metabolic capabilities to use aromatic carbon sources (benzoate, polyphenols), its growth with polystyrene and resin, and short-term tolerance to several xenobiotics assayed at higher concentration levels than the ones of spent resins.