Identifier

etd-01142015-153345

Degree

Master of Science in Civil Engineering (MSCE)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

Modeling of biofilms in porous media at pore scale resolution has been hindered by the lack of available experimental techniques to non-destructively image biofilm structure at these resolutions. Researchers have relied upon simulation rather than experimentation to produce pore-scale biofilm models, using simplifying assumptions governing microbial growth such as Monod kinetics and random biofilm seeding locations to generate biofilms in simulated environments. This study investigated the use of absorption-edge synchrotron X-ray computed microtomography (SXCMT) in combination with a contrast agent, Lugol’s iodine solution (10% KI/5% I2), to nondestructively obtain three-dimensional images of biofilms at pore-scale resolution. The study examined and quantified the preferential absorption of contrast agent into biofilm and demonstrated the ability of SXCMT to determine the concentration of contrast agent in solution. Three-dimensional maps of X-ray mass linear attenuation were converted to SXCMT-determined contrast agent concentration maps that contain the average contrast agent concentration of each pore in the images. Averaging the large number of individual concentration values in each pore results in a high level of confidence in the SXCMT-determined mean concentrations. The pore mean concentration maps were used to identify and differentiate biofilm and abiotic pore spaces. Large spheroid granular biofilms were used to provide qualitative confirmation of the imaging technique. The novel imaging technique developed in the study provides a useful tool to develop three-dimensional measurements of biofilms in porous media that better represent actual in situ biofilm structure and distribution.

Date

2014

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Willson, Clinton

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