Internal Biofilm Heterogeneities Enhance Solute Mixing and Chemical Reactions in Porous Media

Abstract

Bacterial biofilms can form in porous media that are of interest in industrial applications ranging from medical implants to biofilters as well as in environmental applications such as in situ groundwater remediation, where they can be critical locations for biogeochemical reactions. The presence of biofilms modifies porous media topology and hydrodynamics by clogging pores and consequently solutes transport and reactions kinetics. The interplay between highly heterogeneous flow fields found in porous media and microbial behavior, including biofilm growth, results in a spatially heterogeneous biofilm distribution in the porous media as well as internal heterogeneity across the thickness of the biofilm. Our study leverages highly resolved three-dimensional X-ray computed microtomography images of bacterial biofilms in a tubular reactor to numerically compute pore-scale fluid flow and solute transport by considering multiple equivalent stochastically generated internal permeability fields for the biofilm. We show that the internal heterogeneous permeability mainly impacts intermediate velocities when compared with homogeneous biofilm permeability. While the equivalent internal permeability fields of the biofilm do not impact fluid–fluid mixing, they significantly control a fast reaction. For biologically driven reactions such as nutrient or contaminant uptake by the biofilm, its internal permeability field controls the efficiency of the process. This study highlights the importance of considering the internal heterogeneity of biofilms to better predict reactivity in industrial and environmental bioclogged porous systems.

Assessing the Fate of Benzophenone-Type UV Filters and Transformation Products during Soil Aquifer Treatment: The Biofilm Compartment as Bioaccumulator and Biodegrader in Porous Media

“…These conclusions are illustrated in Figure , which summarizes the mass balance of the various processes controlling the UVF fate of BP-3 and its TPs in the CT (a similar figure for the ST is shown in Figure S5), which underscores the central role of biofilm in the fate of UVFs. This aligns perfectly with the findings in the recent study by Markale et al, where they observed a significant impact of biofilm permeability heterogeneity on biologically driven reactions …”

“…This aligns perfectly with the findings in the recent study by Markale et al, where they observed a significant impact of biofilm permeability heterogeneity on biologically driven reactions. 48 Overall, this study demonstrates that implementing a reactive barrier in an infiltration basin improves the degradation of benzophenone-type UVFs and, especially, of BP-3 and its TPs, and that biofilm acts as an additional environmental compartment favoring the retention and degradation of UVFs in porous media. It does not sway us that these processes can be assumed for other hydrophobic compounds.…”

“…This aligns perfectly with the findings in the recent study by Markale et al, where they observed a significant impact of biofilm permeability heterogeneity on biologically driven reactions. 47 …”

Microscale advection governs microbial growth and oxygen consumption in macroporous aggregates

“…This is an important distinction to microbial growth in porous media (such as soils, sediments, aquifers, or engineered systems like packed bed reactors or trickling filter systems in wastewater treatment) where numerical studies of the interaction between the biofilm surface roughness and mass transport ( 27 ) and simulations of coupled microbial growth and flow in porous media ( 28 – 32 ) have provided key insights on how flow can shape localized growth conditions. However, in contrast to the microenvironments we focus on in this study, microbial communities in porous media attach to the solid structures and create streamers that can clog macropores ( 33 , 34 ) and alter preferential flow paths within the porous media with consequences for nutrient supply ( 35 , 36 ). Thus, although similarities exist between the systems, caution needs to be exerted when extrapolating insights from our analysis to other porous media.…”

A Novel Mathematical Model for Repairing Rough Cracks Using the Microbially Induced Carbonate Precipitation (MICP)

“…Most of prior investigations have selected theoretical methods about fine aggregate cementation based on the MICP technique. According to the MICP process, these methods can be categorized into four parts: the distribution and transport of biomass, biochemical reaction, MICP solidification, and CaCO 3 precipitation [33][34][35][36][37][38][39]. These parts can affect the ultimate impact of biocementation.…”