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Modelling biofilm-induced formation damage and biocide treatment in subsurface geosystems.

Ezeuko CC, Sen A, Gates ID - Microb Biotechnol (2012)

Bottom Line: Persisters describe small subpopulation of cells which are tolerant to biocide treatment.Biofilm tolerance to biocide treatment is regulated by persister cells and includes 'innate' and 'biocide-induced' factors.Also, a successful application of biological permeability conformance treatment involving geologic layers with flow communication is more complicated than simply engineering the attachment of biofilm-forming cells at desired sites.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada. cezeuko@ucalgary.ca

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Time evolution of spatial nutrient concentration (upper images) and biofilm morphology (lower images) for Cases L1 and L2 layered network in 2.5 × 2.5 cm model. In each network, pore sizes of the bottom layer have been multiplied by 70. Nutrient concentration is dimensionless with respect to injected nutrient concentration. The principal flow direction is from left (inlet) to right (outlet). Aqueous phase pores are shown in black whereas biofilm-saturated pores are shown in white [seeded biofilm sites = 60, in top layer only; β = 1.0 × 10−5 s−1].A. Case L1.B. Case L2.
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fig08: Time evolution of spatial nutrient concentration (upper images) and biofilm morphology (lower images) for Cases L1 and L2 layered network in 2.5 × 2.5 cm model. In each network, pore sizes of the bottom layer have been multiplied by 70. Nutrient concentration is dimensionless with respect to injected nutrient concentration. The principal flow direction is from left (inlet) to right (outlet). Aqueous phase pores are shown in black whereas biofilm-saturated pores are shown in white [seeded biofilm sites = 60, in top layer only; β = 1.0 × 10−5 s−1].A. Case L1.B. Case L2.

Mentions: As shown in Fig. 8, the nutrient front in a layered network exhibits a dominant finger after 0.19 h of simulated time. However, the whole network eventually becomes saturated with nutrient. Figure 8 shows nutrient concentration and biofilm occupancies for case L1 (i.e. biocide injection commencing after 2.5 h) while Fig. 8 shows results for case L2 (i.e. biocide injection commencing after 6 days). In cases L1 and L2, biofilm is seeded in both the top and bottom layers. The results show that the biofilm enlarges and clogs the upstream region of both layers, causing nutrient-limited growth in the downstream region of each layer. The effect is preferential growth towards the nutrient supply which increases bioclogging towards the inlet of each layer. Biofilm accumulation however occurs at a faster rate within the higher permeability bottom layer. Results here indicate that for conformance problems where the aim of the process is to reduce flow from the high permeability bottom layer (as may be desirable during waterflooding in oil fields or bioremediation by bioclogging to minimize the transport rate of underground contaminants), then permeability damage of the bottom layer will be considered an improvement in process productivity (i.e. water is channelled to the lower permeability layer). However, permeability damage of the top layer for such a case will represents a decline in productivity and can be described as formation damage.


Modelling biofilm-induced formation damage and biocide treatment in subsurface geosystems.

Ezeuko CC, Sen A, Gates ID - Microb Biotechnol (2012)

Time evolution of spatial nutrient concentration (upper images) and biofilm morphology (lower images) for Cases L1 and L2 layered network in 2.5 × 2.5 cm model. In each network, pore sizes of the bottom layer have been multiplied by 70. Nutrient concentration is dimensionless with respect to injected nutrient concentration. The principal flow direction is from left (inlet) to right (outlet). Aqueous phase pores are shown in black whereas biofilm-saturated pores are shown in white [seeded biofilm sites = 60, in top layer only; β = 1.0 × 10−5 s−1].A. Case L1.B. Case L2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3815385&req=5

fig08: Time evolution of spatial nutrient concentration (upper images) and biofilm morphology (lower images) for Cases L1 and L2 layered network in 2.5 × 2.5 cm model. In each network, pore sizes of the bottom layer have been multiplied by 70. Nutrient concentration is dimensionless with respect to injected nutrient concentration. The principal flow direction is from left (inlet) to right (outlet). Aqueous phase pores are shown in black whereas biofilm-saturated pores are shown in white [seeded biofilm sites = 60, in top layer only; β = 1.0 × 10−5 s−1].A. Case L1.B. Case L2.
Mentions: As shown in Fig. 8, the nutrient front in a layered network exhibits a dominant finger after 0.19 h of simulated time. However, the whole network eventually becomes saturated with nutrient. Figure 8 shows nutrient concentration and biofilm occupancies for case L1 (i.e. biocide injection commencing after 2.5 h) while Fig. 8 shows results for case L2 (i.e. biocide injection commencing after 6 days). In cases L1 and L2, biofilm is seeded in both the top and bottom layers. The results show that the biofilm enlarges and clogs the upstream region of both layers, causing nutrient-limited growth in the downstream region of each layer. The effect is preferential growth towards the nutrient supply which increases bioclogging towards the inlet of each layer. Biofilm accumulation however occurs at a faster rate within the higher permeability bottom layer. Results here indicate that for conformance problems where the aim of the process is to reduce flow from the high permeability bottom layer (as may be desirable during waterflooding in oil fields or bioremediation by bioclogging to minimize the transport rate of underground contaminants), then permeability damage of the bottom layer will be considered an improvement in process productivity (i.e. water is channelled to the lower permeability layer). However, permeability damage of the top layer for such a case will represents a decline in productivity and can be described as formation damage.

Bottom Line: Persisters describe small subpopulation of cells which are tolerant to biocide treatment.Biofilm tolerance to biocide treatment is regulated by persister cells and includes 'innate' and 'biocide-induced' factors.Also, a successful application of biological permeability conformance treatment involving geologic layers with flow communication is more complicated than simply engineering the attachment of biofilm-forming cells at desired sites.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada. cezeuko@ucalgary.ca

Show MeSH
Related in: MedlinePlus