Biomineralization of Uranium-Phosphates Fueled by Microbial Degradation of Isosaccharinic Acid (ISA)

Geological disposal is the globally preferred long-term solution for higher activity radioactive wastes (HAW) including intermediate level waste (ILW). In a cementitious system, cellulosic items present in ILW may undergo alkaline hydrolysis, producing significant quantities of isosaccharinic acid (ISA), chelating agent radionuclides. Although microbial degradation ISA has been demonstrated, its impact upon fate radionuclides geological facility (GDF) topic ongoing research. This study investigates U(VI) pH-neutral, anoxic, enrichment cultures, approaching conditions similar to far field GDF, containing as sole carbon source, and elevated phosphate concentrations, incubated both (i) under fermentation (ii) Fe(III)-reducing conditions. ISA-fermentation experiment, was precipitated insoluble U(VI)-phosphates, whereas conditions, majority uranium reduced U(IV)-phosphates, presumably formed via enzymatic reduction mediated by metal-reducing bacteria, Geobacter species. Overall, this suggests establishment microbially bio-barrier extending into geosphere surrounding GDF possible biobarrier potential evolve response evolution can have controlling on