Pore‐network modeling of biofilm evolution in porous media

Abstract

The influence of bacterial biomass on hydraulic properties of porous media (bioclogging) has been explored as a viable means for optimizing subsurface bioremediation and microbial enhanced oil recovery. In this study, we present a pore network simulator for modeling biofilm evolution in porous media including hydrodynamics and nutrient transport based on coupling of advection transport with Fickian diffusion and a reaction term to account for nutrient consumption. Biofilm has non-zero permeability permitting liquid flow and transport through the biofilm itself. To handle simultaneous mass transfer in both liquid and biofilm in a pore element, a dual-diffusion mass transfer model is introduced. The influence of nutrient limitation on predicted results is explored. Nutrient concentration in the network is affected by diffusion coefficient for nutrient transfer across biofilm (compared to water/water diffusion coefficient) under advection dominated transport, represented by mass transport Péclet number >1. The model correctly predicts a dependence of rate of biomass accumulation on inlet concentration. Poor network connectivity shows a significantly large reduction of permeability, for a small biomass pore volume.

A Network Model for the Kinetics of Bioclogged Flow Diversion for Enhanced Oil Recovery

“…Several numerical models have been developed to describe biofilm growth. There exist continuum Darcy models [23], bacterially-based models [12], Lattice-Boltzmann-based simulations [13,17] and Pore Network Models (PNM) [6,22,20,5,7]. Frequently, in biofilm growth models, the porous media consists of three components: the grains, the biofilm which grows on the walls of the solid grains and the liquid in the pore space.…”

“…The bacterial population will determine the development of biofilm in the pores of the medium. This biofilm will grow and will change the radii of the pores, leading to a modification in the dynamics of the fluid that carries the nutrients through the network [6,22,20,5]. The geometric properties of the network such as connectivity, coordination number or coordination number distribution have an influence on transport of solute and in multiphase flow in porous systems [15].…”

“…Thullner et al [21] considered that the flow in each of the tubes is described by a modified form of the Poiseuille flow where the flux through the biofilm and through the void space is taken into account. Considering that nutrients can also flow through the biofilm phase, Ezeuko et al [6] used two different diffusion coefficients, one for diffusion through the water-water interface and another for the water-biofilm interface.…”

Solute Mass Exchange Between Water Phase and Biofilm for a Single Pore

“…It not only sheds light on physical fundamentals of flow and transport at the pore scale, but also can provide constitutive relationships which appear in upscaled macroscale transport equations, like effective dispersive tensor, effective reaction rate, and relationship between permeability and biofilm volume fraction (Ezeuko et al 2011;Graf von der Schulenburg et al 2009;Hesse et al 2009;Kim and Fogler 2000;Li et al 2006;Stewart and Kim 2004;Suchomel et al 1998a, b;Thullner et al 2002;Thullner and Baveye 2008). Graf von der developed a Lattice-Boltzmann (LB) model to study the coupled interactions between nutrient transport, biofilm growth, and hydrodynamics.…”

“…Biofilm growth was assumed to occur uniformly around the pore walls. Inside a cylindrical pore, either local mass equilibrium (Ezeuko et al 2011) or a first-order kinetic model with a constant mass exchange coefficient was used (e.g., Thullner and Baveye 2008). But, it is worth noting that even in the tubes of a pore network we still need to distinguish non-equilibrium from equilibrium conditions.…”