Biofilm growth occurs in a variety of random porous media in a range of industrial processes; prediction of its growth and subsequent influence on hydrodynamics is hence desirable. In this study, we present the first numerical 3D pore‐scale model of biofilm growth in porous media, based on a lattice Boltzmann simulation platform complemented with an individual‐based biofilm model (IbM). We use it to explore the coupled interaction between nutrient mass transport, biofilm growth, and hydrodynamics. Biofilm is shown to be very effective at reducing the permeability of porous media, particularly under nutrient limited conditions. We conclude with a direct comparison of 3D and 2D biofilm growth simulations in porous media and show the necessity of performing the simulations in 3D. © 2008 American Institute of Chemical Engineers AIChE J, 2009

A 3D Biofilm model, appropriate for complex porous media support structures, is successfully modified such that non-zero permeability of biofilms structures is enabled. A systematic study is then conducted into the influence of biofilm permeability on overall biomass growth rate. This reveals a significant influence at large biofilm concentrations; even when the permeability of the biomass is 1.25% of that of the free pore space, biomass accumulation increased by a factor of ∼3 over 40 h. The effect is shown to be retained when allowing for biomass detachment or erosion as a consequence of adjacent velocity shear. We conclude that biofilm permeability should be included in biofilm models and that further experimental work is required to better describe the link between biofilm permeability and local microstructure.

While biological clogging of porous systems can be problematic in numerous processes (e.g., microbial enhanced oil recovery-MEOR), it is targeted during bio-barrier formation to control sub-surface pollution plumes in ground water. In this simulation study, constant pressure drop (CPD) and constant volumetric flow rate (CVF) operational modes for nutrient provision for biofilm growth in a porous system are considered with respect to optimum (minimum energy requirement for nutrient provision) permeability reduction for bio-barrier applications. Biofilm growth is simulated using a Lattice-Boltzmann (LB) simulation platform complemented with an individual-based biofilm model (IbM). A biomass detachment technique has been included using a fast marching level set (FMLS) method that models the propagation of the biofilm-liquid interface with a speed proportional to the adjacent velocity shear field. The porous medium permeability reduction is simulated for both operational modes using a range of biofilm strengths. For stronger biofilms, less biomass deposition and energy input are required to reduce the system permeability during CPD operation, whereas CVF is more efficient at reducing the permeability of systems containing weaker biofilms.

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The increasing demand for drinking water and its stricter quality requirements have resulted in an exponentially expanding industry of membrane filtration processes. Currently, reverse osmosis (RO) is the most common method of desalination, able to produce water that is virtually free of pollutants and pathogenic micro-organisms. Biofouling of these devices however is a significant limitation. Here we present a 3D simulation of RO membrane biofouling based on a lattice Boltzmann (LB) platform that we subsequently favorably compare with experimental data. This data consists of temporally (and spatially) resolved velocity measurements acquired for a RO membrane using magnetic resonance techniques. The effect of biofilm cohesive strength on system pressure drop is then explored; weaker biomass is observed to have a reduced impact on pressure drop (per unit biomass accumulated).

in Wiley Online Library (wileyonlinelibrary.com).Carbon dioxide sequestration in aquifers is seen as a potential climate change mitigation technique. One physical mechanism by which this could occur is capillary trapping of discrete pore-scale CO 2 bubbles (referred to as ganglia) in the pore space. Nuclear magnetic resonance (NMR) techniques were used to quantify the spatial distribution and pore environment of such CO 2 entrapment in a model porous medium (random glass bead packing). 3D images revealed a relatively macroscopically homogeneous CO 2 entrapment, even though the image resolution is insufficient to resolve individual CO 2 ganglia. Quantification of the pore environment of the CO 2 ganglia was achieved using NMR displacement propagators (displacement probability distributions), acquired both before and after CO 2 entrapment. Lattice Boltzmann (LB) simulations were used to facilitate interpretation of the propagator statistics by considering various pore environments in which CO 2 could become trapped. Comparison with the experimental data suggests that CO 2 is preferentially entrapped in comparatively larger pores.