Microbial activity in bentonite buffers

Literature study

Marjaana Rättö, Merja Itävaara

Research output: Book/ReportReportProfessional

Abstract

The proposed disposal concept for high-level radioactive wastes involves storing the wastes underground in copper-iron containers embedded in buffer material of compacted bentonite. Hydrogen sulphide production by sulphate-reducing prokaryotes is a potential mechanism that could cause corrosion of waste containers in repository conditions. The prevailing conditions in compacted bentonite buffer will be harsh. The swelling pressure is 7-8 MPa, the amount of free water is low and the average pore and pore throat diameters are small. This literature study aims to assess the potential of microbial activity in bentonite buffers. Literature on the environmental limits of microbial life in extreme conditions and the occurrence of sulphate-reducing prokaryotes in extreme environments is reviewed briefly and the results of published studies characterizing microbes and microbial processes in repository conditions or in relevant subsurface environments are presented. The presence of bacteria, including SRBs, has been confirmed in deep groundwater and bentonite-based materials. Sulphate reducers have been detected in various high-pressure environments, and sulphate-reduction based on hydrogen as an energy source is considered a major microbial process in deep subsurface environments. In bentonite, microbial activity is strongly suppressed, mainly due to the low amount of free water and small pores, which limit the transport of microbes and nutrients. Spore-forming bacteria have been shown to survive in compacted bentonite as dormant spores, and they are able to resume a metabolically active state after decompaction. Thus, microbial sulphide production may increase in repository conditions if the dry density of the bentonite buffer is locally reduced.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages34
ISBN (Electronic)978-951-38-7833-7
Publication statusPublished - 2012
MoE publication typeNot Eligible

Publication series

NameVTT Technology
PublisherVTT
No.20
ISSN (Print)2242-1211
ISSN (Electronic)2242-122X

Fingerprint

bentonite
microbial activity
repository
sulfate
prokaryote
spore
bacterium
dry density
hydrogen sulfide
literature study
radioactive waste
swelling
corrosion
sulfide
hydrogen
copper
iron
water
groundwater
nutrient

Keywords

  • bentonite
  • nuclear waste
  • microorganisms
  • piezophiles
  • sulphate reducers

Cite this

Rättö, M., & Itävaara, M. (2012). Microbial activity in bentonite buffers: Literature study. Espoo: VTT Technical Research Centre of Finland. VTT Technology, No. 20
Rättö, Marjaana ; Itävaara, Merja. / Microbial activity in bentonite buffers : Literature study. Espoo : VTT Technical Research Centre of Finland, 2012. 34 p. (VTT Technology; No. 20).
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Rättö, M & Itävaara, M 2012, Microbial activity in bentonite buffers: Literature study. VTT Technology, no. 20, VTT Technical Research Centre of Finland, Espoo.

Microbial activity in bentonite buffers : Literature study. / Rättö, Marjaana; Itävaara, Merja.

Espoo : VTT Technical Research Centre of Finland, 2012. 34 p. (VTT Technology; No. 20).

Research output: Book/ReportReportProfessional

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T1 - Microbial activity in bentonite buffers

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AU - Itävaara, Merja

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N2 - The proposed disposal concept for high-level radioactive wastes involves storing the wastes underground in copper-iron containers embedded in buffer material of compacted bentonite. Hydrogen sulphide production by sulphate-reducing prokaryotes is a potential mechanism that could cause corrosion of waste containers in repository conditions. The prevailing conditions in compacted bentonite buffer will be harsh. The swelling pressure is 7-8 MPa, the amount of free water is low and the average pore and pore throat diameters are small. This literature study aims to assess the potential of microbial activity in bentonite buffers. Literature on the environmental limits of microbial life in extreme conditions and the occurrence of sulphate-reducing prokaryotes in extreme environments is reviewed briefly and the results of published studies characterizing microbes and microbial processes in repository conditions or in relevant subsurface environments are presented. The presence of bacteria, including SRBs, has been confirmed in deep groundwater and bentonite-based materials. Sulphate reducers have been detected in various high-pressure environments, and sulphate-reduction based on hydrogen as an energy source is considered a major microbial process in deep subsurface environments. In bentonite, microbial activity is strongly suppressed, mainly due to the low amount of free water and small pores, which limit the transport of microbes and nutrients. Spore-forming bacteria have been shown to survive in compacted bentonite as dormant spores, and they are able to resume a metabolically active state after decompaction. Thus, microbial sulphide production may increase in repository conditions if the dry density of the bentonite buffer is locally reduced.

AB - The proposed disposal concept for high-level radioactive wastes involves storing the wastes underground in copper-iron containers embedded in buffer material of compacted bentonite. Hydrogen sulphide production by sulphate-reducing prokaryotes is a potential mechanism that could cause corrosion of waste containers in repository conditions. The prevailing conditions in compacted bentonite buffer will be harsh. The swelling pressure is 7-8 MPa, the amount of free water is low and the average pore and pore throat diameters are small. This literature study aims to assess the potential of microbial activity in bentonite buffers. Literature on the environmental limits of microbial life in extreme conditions and the occurrence of sulphate-reducing prokaryotes in extreme environments is reviewed briefly and the results of published studies characterizing microbes and microbial processes in repository conditions or in relevant subsurface environments are presented. The presence of bacteria, including SRBs, has been confirmed in deep groundwater and bentonite-based materials. Sulphate reducers have been detected in various high-pressure environments, and sulphate-reduction based on hydrogen as an energy source is considered a major microbial process in deep subsurface environments. In bentonite, microbial activity is strongly suppressed, mainly due to the low amount of free water and small pores, which limit the transport of microbes and nutrients. Spore-forming bacteria have been shown to survive in compacted bentonite as dormant spores, and they are able to resume a metabolically active state after decompaction. Thus, microbial sulphide production may increase in repository conditions if the dry density of the bentonite buffer is locally reduced.

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Rättö M, Itävaara M. Microbial activity in bentonite buffers: Literature study. Espoo: VTT Technical Research Centre of Finland, 2012. 34 p. (VTT Technology; No. 20).