Microbial transformation of bentonite


Microbial transformation of bentonite

Matschiavelli, N.; Steglich, J.; Kluge, S.; Cherkouk, A.

For the storage of highly radioactive waste in a deep geological repository a multi-barrier concept is favoured, which combines a technical barrier (canister including the highly radioactive waste), a geotechnical barrier (e.g. Bentonite) and the geological barrier (host rock). Due to their properties, namely a high swelling capacity and a low hydraulic conductivity, Bentonites fulfil in this system a sealing and buffering function. For the potential repository of nuclear waste the microbial mediated transformation of Bentonite could influence its properties as a barrier material. To elucidate the microbial potential within selected Bentonites, microcosms were set up, which contain 20g Bentonite and 40ml anaerobic synthetic Opalinus-clay-pore water solution under an N2/CO2-gas-atmosphere. Substrates like acetate and lactate were supplemented to stimulate potential microbial activity. Microcosms were incubated in the dark, without shaking at 30°C. Within an indefinite time scale samples were taken at different time-points of incubation and were analysed regarding geochemical parameters like pH, O2-concentration, redox potential, iron-concentration and sulphate-concentration as well as biological parameters like the consumption and formation of metabolites. First results show that bentonites represent a source for microbial life, demonstrated by the consumption of lactate and the formation of acetate and pyruvate. Furthermore, microbial iron-reduction was determined. The results reveal the importance of the selection of the best suitable Bentonite in order to avoid transformation of the mineral structure by indigenous microbes.

  • Poster
    16th International Clay Conference - Clays, from the oceans to space - Granada 17-21 July 2017, 17.-21.07.2017, Granada, Spain

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Publ.-Id: 25689