Biofilm development and the dynamics of preferential flow paths in porous media

Abstract

A two-dimensional pore-scale numerical model was developed to evaluate the dynamics of preferential flow paths in porous media caused by bioclogging. The liquid flow and solute transport through the pore network were coupled with a biofilm model including biomass attachment, growth, decay, lysis, and detachment. Blocking of all but one flow path was obtained under constant liquid inlet flow rate and biomass detachment caused by shear forces only. The stable flow path formed when biofilm detachment balances growth, even with biomass weakened by decay. However, shear forces combined with biomass lysis upon starvation could produce an intermittently shifting location of flow channels. Dynamic flow pathways may also occur when combined liquid shear and pressure forces act on the biofilm. In spite of repeated clogging and unclogging of interconnected pore spaces, the average permeability reached a quasi-constant value. Oscillations in the medium permeability were more pronounced for weaker biofilms.

Keywords:

• biofilm
• porous media
• clogging
• channeling
• numerical model
• decay

Acknowledgments

The authors are grateful to DOW Microbial Control, Buffalo Grove, IL, USA, for the financial support. The work of C. Picioreanu was financially supported also by the Netherlands Organization for Scientific Research [NWO VIDI grant 864-06-003]. Conceptual discussions with Dr Robin Gerlach from Montana State University are kindly acknowledged.