Using Indirect Measurement Techniques to Evaluate the Effect of Nutrient Flow Rate on Biofilm Growth in Porous media
Abstract
We use micro-imaging to study the effects of flow rate on three-dimensional growth of biofilm in porous media. The images allow us to gain a better understanding of how biofilms grow and interact with the pore geometry, nutrients, and the fluid flow environment in the subsurface. In this particular study, three flow rates were applied to evolving biofilms in model packed-bed columns, and observed after a growth period of 11 days. At the end of the growth period, all columns were scanned using x-ray computed microtomography and a barium sulfate-based contrast agent to distinguish the biofilm. We used differential pressure transducer and effluent dissolved oxygen measurements to complement and validate the image-based findings. Reduction in permeability due to biofilm growth was studied using both transducer-based pressure drop measurements and image-based calculations using the Kozeny-Carman model. A combination of results from these different measurements suggest that biofilm growth was oxygen limited at the lowest flow rate, and affected by shear stresses at the highest flow rate. We hypothesize that the interplay between these two factors drives the spatial distribution and quantity of biofilm growth in the class of porous media studied here.
Our approach opens the way to more systematic studies of the structure-function relationships involved in biofilm growth in porous media and the impact that such growth may have on physical properties such as hydraulic conductivity. Opportunities exist to extend these types of findings to larger scale by combining the pore-scale information obtained through micro-imaging with geophysical techniques, such as complex conductivity measurements, that can probe larger domains and more easily track temporal changes.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B53F2462W
- Keywords:
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- 0406 Astrobiology and extraterrestrial materials;
- BIOGEOSCIENCES;
- 0418 Bioremediation;
- BIOGEOSCIENCES;
- 1505 Biogenic magnetic minerals;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1835 Hydrogeophysics;
- HYDROLOGY