The Impact of Biofilms upon Surfaces Relevant to an Intermediate Level Radioactive Waste Geological Disposal Facility under Simulated Near-Field Conditions

Christopher Charles, Simon Rout, Andrew Laws, Brian Jackson, Sally Boxall, Paul Humphreys

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Abstract

The ability of biofilms to form on a range of materials (cementious backfill (Nirex Reference Vault Backfill (NRVB)), graphite, and stainless steel) relevant to potential UK intermediate level radioactive waste (ILW) disposal concepts was investigated by exposing these surfaces to alkaliphilic flocs generated by mature biofilm communities. Flocs are aggregates of biofilm material that are able to act as a transport vector for the propagation of biofilms. In systems where biofilm formation was observed there was also a decrease in the sorption of isosaccharinic acids to the NRVB. The biofilms were composed of cells, extracellular DNA (eDNA), proteins, and lipids with a smaller polysaccharide fraction, which was biased towards mannopyranosyl linked carbohydrates. The same trend was seen with the graphite and stainless steel surfaces at these pH values, but in this case the biofilms associated with the stainless steel surfaces had a distinct eDNA basal layer that anchored the biofilm to the surface. At pH 13, no structured biofilm was observed, rather all the surfaces accumulated an indistinct organic layer composed of biofilm materials. This was particularly the case for the stainless steel coupons which accumulated relatively large quantities of eDNA. The results demonstrate that there is the potential for biofilm formation in an ILW-GDF provided an initiation source for the microbial biofilm is present. They also suggest that even when conditions are too harsh for biofilm formation, exposed surfaces may accumulate organic material such as eDNA.
Original languageEnglish
Article number57
Number of pages11
JournalGeosciences (Switzerland)
Volume7
Issue number3
DOIs
Publication statusPublished - 12 Jul 2017

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radioactive waste
biofilm
backfill
steel
DNA
graphite
polysaccharide
waste disposal
carbohydrate
sorption
lipid

Cite this

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title = "The Impact of Biofilms upon Surfaces Relevant to an Intermediate Level Radioactive Waste Geological Disposal Facility under Simulated Near-Field Conditions",
abstract = "The ability of biofilms to form on a range of materials (cementious backfill (Nirex Reference Vault Backfill (NRVB)), graphite, and stainless steel) relevant to potential UK intermediate level radioactive waste (ILW) disposal concepts was investigated by exposing these surfaces to alkaliphilic flocs generated by mature biofilm communities. Flocs are aggregates of biofilm material that are able to act as a transport vector for the propagation of biofilms. In systems where biofilm formation was observed there was also a decrease in the sorption of isosaccharinic acids to the NRVB. The biofilms were composed of cells, extracellular DNA (eDNA), proteins, and lipids with a smaller polysaccharide fraction, which was biased towards mannopyranosyl linked carbohydrates. The same trend was seen with the graphite and stainless steel surfaces at these pH values, but in this case the biofilms associated with the stainless steel surfaces had a distinct eDNA basal layer that anchored the biofilm to the surface. At pH 13, no structured biofilm was observed, rather all the surfaces accumulated an indistinct organic layer composed of biofilm materials. This was particularly the case for the stainless steel coupons which accumulated relatively large quantities of eDNA. The results demonstrate that there is the potential for biofilm formation in an ILW-GDF provided an initiation source for the microbial biofilm is present. They also suggest that even when conditions are too harsh for biofilm formation, exposed surfaces may accumulate organic material such as eDNA.",
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AU - Rout, Simon

AU - Laws, Andrew

AU - Jackson, Brian

AU - Boxall, Sally

AU - Humphreys, Paul

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KW - Biofilm

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