• Open Access

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

Authors


  • Funding Information The research was supported with generous funding from the S.M. Blair Family Foundation, the Zandmer Estate, and Alberta Innovates Technology Futures. The original graphics display program was developed by Dr S. R. McDougall of Heriot-Watt University, Edinburgh, UK. Dr A. Grigoryan of the University of Calgary is also acknowledged for his insight into biocide related modes of disinfection.

For correspondence. E-mail cezeuko@ucalgary.ca; Tel. (+1) 403 479 1254; Fax (+1) 403 284 4852.

Summary

Biofilm growth in subsurface porous media, and its treatment with biocides (antimicrobial agents), involves a complex interaction of biogeochemical processes which provide non-trivial mathematical modelling challenges. Although there are literature reports of mathematical models to evaluate biofilm tolerance to biocides, none of these models have investigated biocide treatment of biofilms growing in interconnected porous media with flow. In this paper, we present a numerical investigation using a pore network model of biofilm growth, formation damage and biocide treatment. The model includes three phases (aqueous, adsorbed biofilm, and solid matrix), a single growth-limiting nutrient and a single biocide dissolved in the water. Biofilm is assumed to contain a single species of microbe, in which each cell can be a viable persister, a viable non-persister, or non-viable (dead). 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. Simulations demonstrate that biofilm tolerance to biocides can increase with biofilm maturity, and that biocide treatment alone does not reverse biofilm-induced formation damage. 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.

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