Modeling transport of contaminants influenced by complex microbial processes

Persistent Link:
http://hdl.handle.net/10150/279907
Title:
Modeling transport of contaminants influenced by complex microbial processes
Author:
Li, Li
Issue Date:
2001
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Many current models that describe biodegradation and transport of contaminants in porous media do not include provisions for nonideal (nonlinear, rate-limited) sorption, microbial lag, inhibition, microbial community heterogeneity, and cell transport. Therefore, a more complete model was developed that incorporates bacterial lag, inhibition effects, and cell transport/elution, as well as nonlinear, rate-limited sorption. The performance of the new model was evaluated by using the model to simulate the results of a series of miscible-displacement experiments conducted using a range of porewater velocities, substrate concentrations, and initial cell densities. The results show that the model can simulate the substrate breakthrough curves very well. The model was also able to predict the total biomass growth. The calibrated values obtained for the maximum specific growth-rate coefficient, the mean lag time, and lag-time variance were within the range of values obtained from batch experiments. These results suggest that the model performed well and that it successfully describes the system. The model was used to investigate the coupled interactions among sorption, biodegradation, and transport, and the results show that biodegradation can significantly influence the first, second, and third spatial moment when sorption is nonlinear or rate-limited depending on initial/boundary conditions, residence time, biomass growth dynamics, and time-dependent sorption/desorption processes. The influence of heterogeneous microbial communities on biodegradation and transport of contaminants was investigated in the last part of the study. A one-dimensional mathematical model was developed that incorporates multiple populations, each subject to its own set of growth-related coefficients. Breakthrough curves produced for different combinations of growth rates, half-saturation constants and initial biomass concentrations for multiple species exhibit oscillatory behavior under certain conditions, which is attributed to competition between different species. The results suggest that the existence of heterogeneous microbial communities can have a significant influence on biodegradation and transport. The results presented herein illustrate the significant impact that factors such as microbial lag, microbial community heterogeneity, and nonideal sorption/desorption can have on the transport of biodegradable contaminants in porous media. One product of this dissertation is the development and evaluation of a more comprehensive model that represents many important processes involved in transport of biodegradable contaminants. The use of this type of model should enhance our ability to investigate and hopefully understand the complex systems inherent to the subsurface wherein multiple coupled processes influence contaminant transport and fate.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Hydrology.; Biology, Microbiology.; Environmental Sciences.; Engineering, Environmental.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Soil, Water and Environmental Science
Degree Grantor:
University of Arizona
Advisor:
Brusseau, Mark L.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleModeling transport of contaminants influenced by complex microbial processesen_US
dc.creatorLi, Lien_US
dc.contributor.authorLi, Lien_US
dc.date.issued2001en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractMany current models that describe biodegradation and transport of contaminants in porous media do not include provisions for nonideal (nonlinear, rate-limited) sorption, microbial lag, inhibition, microbial community heterogeneity, and cell transport. Therefore, a more complete model was developed that incorporates bacterial lag, inhibition effects, and cell transport/elution, as well as nonlinear, rate-limited sorption. The performance of the new model was evaluated by using the model to simulate the results of a series of miscible-displacement experiments conducted using a range of porewater velocities, substrate concentrations, and initial cell densities. The results show that the model can simulate the substrate breakthrough curves very well. The model was also able to predict the total biomass growth. The calibrated values obtained for the maximum specific growth-rate coefficient, the mean lag time, and lag-time variance were within the range of values obtained from batch experiments. These results suggest that the model performed well and that it successfully describes the system. The model was used to investigate the coupled interactions among sorption, biodegradation, and transport, and the results show that biodegradation can significantly influence the first, second, and third spatial moment when sorption is nonlinear or rate-limited depending on initial/boundary conditions, residence time, biomass growth dynamics, and time-dependent sorption/desorption processes. The influence of heterogeneous microbial communities on biodegradation and transport of contaminants was investigated in the last part of the study. A one-dimensional mathematical model was developed that incorporates multiple populations, each subject to its own set of growth-related coefficients. Breakthrough curves produced for different combinations of growth rates, half-saturation constants and initial biomass concentrations for multiple species exhibit oscillatory behavior under certain conditions, which is attributed to competition between different species. The results suggest that the existence of heterogeneous microbial communities can have a significant influence on biodegradation and transport. The results presented herein illustrate the significant impact that factors such as microbial lag, microbial community heterogeneity, and nonideal sorption/desorption can have on the transport of biodegradable contaminants in porous media. One product of this dissertation is the development and evaluation of a more comprehensive model that represents many important processes involved in transport of biodegradable contaminants. The use of this type of model should enhance our ability to investigate and hopefully understand the complex systems inherent to the subsurface wherein multiple coupled processes influence contaminant transport and fate.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectHydrology.en_US
dc.subjectBiology, Microbiology.en_US
dc.subjectEnvironmental Sciences.en_US
dc.subjectEngineering, Environmental.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineSoil, Water and Environmental Scienceen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorBrusseau, Mark L.en_US
dc.identifier.proquest3040120en_US
dc.identifier.bibrecord.b42455649en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.