Abstract
Accumulation of microbial biomass and its influence on porous media flow were investigated under saturated flow conditions. Microfluidic experiments were performed with model organisms, and their accumulation was observed in the pore space and on the sub-pore scale. Time-lapse optical imaging revealed different modes of biomass accumulation through primary colonization, secondary growth, and filtration events, showing the formation of preferential flow pathways in the flooding domain as result of the increasing interstitial velocity. Navier–Stokes–Brinkmann flow simulations were performed on the segmented images—a digital-twin approach—considering locally accumulated biomass as impermeable or permeable based on optical biomass density. By comparing simulation results and the experimental responses, it was shown that accumulated biomass can be considered as a permeable medium. The average intra-biomass permeability was determined to be 500 ± 200 mD, which is more than a factor of 10 larger than previously assumed in modeling studies. These findings have substantial consequences: (1) a remaining interstitial permeability, as a result of the observed channel formation and the intra-biomass permeability, and (2) a potential advective nutrient supply, which can be considered more efficient than a purely diffusive supply. The second point may lead to higher metabolic activity and substrate conversion rates which is of particular interest for geobiotechnological applications.
Highlights
The presence and metabolic activity of microbial life in the subsurface are likely to influence the hydrodynamic properties of porous aquifers and reservoir rocks
Part of the cells attached to solid surfaces and deposited as aggregates in the pore space
The influence of biomass accumulation on the permeability of porous media was investigated using microfluidic under saturated flow conditions
Summary
The presence and metabolic activity of microbial life in the subsurface are likely to influence the hydrodynamic properties of porous aquifers and reservoir rocks. Microbiological processes can be used deliberately in subsurface engineering, e.g., (i) for remediating contaminated soils and groundwater bodies by breaking down toxic chemicals (MacQuarrie et al 1990), (ii) for geo-methanation processes by in situ conversion of gases like carbon dioxide and hydrogen to methane (Götz et al 2016; Strobel et al 2020), and (iii) for microbial enhanced oil recovery (MEOR) through the production of in situ surfactants to reduce the interfacial tension between oil and water, or through the production of bio-polymers to establish flow barriers in exploited zones of oil fields (Surasani et al 2013; Baveye et al 1998; Lazar et al 2007) In all these applications, products of microbial metabolism including bacterial cells themselves modify the hydraulic reservoir properties and the mobility of fluids or substances dissolved therein. Excessive enrichment of biomass may lead to a reduction in porosity and permeability, i.e., injectivity of the porous medium
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
