Abstract
Silicate glasses are an accepted option for immobilizing nuclear waste and waste glass can be disposed in near-surface environments. It is important to understand glass alteration mechanisms under site-relevant conditions to predict glass corrosion rates upon disposal. Microbial activity near the glass surface may influence glass alteration. However, waste glass chemical durability is currently evaluated without consideration of microbial alteration. Here, four glass compositions were tested in three solutions, with and without a subsurface Paenibacillus bacterium, to compare the extent of glass leaching. Results indicate that the Paenibacillus cells increased glass alteration, resulting in higher concentrations of boron, iron, sodium, and silicon released into solution. The combination of microbially mediated organic acid production, which decreased pH, and glass dissolution, which increased pH, resulted in a net neutral or slightly acidic solution that could promote further glass alteration. The amount of each element released depended on glass composition and solution chemistry. This study revealed the dynamic relationship between microbial metabolism, elemental release, and corresponding changes to solution pH, showing that microbial processes can indirectly accelerate glass alteration. This work supports a greater understanding of microbially-influenced glass alteration and informs development of standardized durability tests to assess microbial influence at disposal facilities.
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Acknowledgements
This work is supported by the Waste Treatment and Immobilization Plant Project at the United States Department of Energy (US DOE) Hanford Field Office (HFO). This study is also supported in part by the US DOE, under Cooperative Agreement Number DE-FC01-06EW07053 entitled ‘The Consortium for Risk Evaluation with Stakeholder Participation III’ awarded to Vanderbilt University. A portion of the research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility, sponsored by the DOE’s Office of Biological and Environmental Research, located at Pacific Northwest National Laboratory under proposal number 60748. Pacific Northwest National Laboratory is operated for the US DOE by Battelle Memorial Institute under Contract DE-AC06–76RLO 1830. Graduate Fellow, A.R. Kennedy, was supported by the US DOE Office of Environmental Management – Minority Serving Institutions Partnership Program (EM MSIPP). We also thank Haluk Beyenal at Washington State University, Pullman, for providing Paenibacillus strain 300A.
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Hager, J.R., Kugler, A.J., Kennedy, A.R. et al. Evaluating the extent of microbially-induced glass alteration by a subsurface Paenibacillus bacterium. npj Mater Degrad (2026). https://doi.org/10.1038/s41529-026-00775-y
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DOI: https://doi.org/10.1038/s41529-026-00775-y
