Engineering Commons^™

Urban Ecohydrology And The Watershed Microbial Continuum, Victoria C. Rexhausen

Doctoral Dissertations

A rapidly urbanizing world is adding unprecedented stress to water resources. Urbanization results in high rates of stream impairment, including but not limited to ecological stress, pollution, and flooding. A fully integrated and holistic perspective is necessary for effective remediation strategies for these wicked problems. This monitoring study from a heterogeneous urban watershed investigated the geospatial and seasonal interactions between urban hydrology and biological processes using stable isotope compositions, anions, and microbial.

This research found that nitrate concentrations in an urban watershed were ecologically driven. NO₃^- concentrations ranged from 0.4 to 12.7 mg/L throughout the watershed. Nitrate concentrations …

Integrated Approaches In Wastewater Surveillance Of Sars-Cov-2: Monitoring, Persistence, Sampling Optimization, And Impacts On Microbial Community Structure, Ye Li

Doctoral Dissertations

Wastewater-based epidemiology (WBE) serves as a crucial tool for monitoring SARS-CoV-2 prevalence on university campuses, yet concerns persist regarding its effectiveness as an early warning system for COVID-19 outbreaks. This study aimed to address these concerns through a comprehensive field trial conducted at the University of Tennessee, Knoxville. We investigated correlations between SARS-CoV-2 concentrations, both with and without normalization using Pepper Mild Mottle Virus (PMMoV), and various parameters. Significant positive correlations were observed between SARS-CoV-2 concentrations and active cases in the weeks prior to, during, and following the monitoring period, unaffected by PMMoV normalization. Concurrently, the persistence of SARS-CoV-2 RNA …

Enhanced Bioretention Modeling At The Catchment-Scale: An Integrated Drainmod-Urban And Swmm Approach, Ghada Diab

Doctoral Dissertations

Bioretention systems are increasingly being adopted in stormwater management as an effective measure to promote infiltration and restore more natural hydrology in urbanized watersheds. Given the significant financial investment in these practices, reliable bioretention models are necessary to predict the effectiveness of these practices prior to installation. One such model, DRAINMOD-Urban (DM-Urban), was recently developed to produce hydrographs with a high temporal resolution at the site-scale, showing substantial promise during initial testing. However, the dataset used for initial testing was limited, consisting of one bioretention area with minimal occasions of overflow. Additionally, DM-Urban is an input-heavy model and there is …

Exploring Soil Microbial Dynamics In Southern Appalachian Forests: A Systems Biology Approach To Prescribed Fire Impacts, Saad Abd Ar Rafie

Doctoral Dissertations

Prescribed fires in Southern Appalachian forests are vital in ecosystem management and wildfire risk mitigation. However, understanding the intricate dynamics between these fires, soil microbial communities, and overall ecosystem health remains challenging. This dissertation addresses this knowledge gap by exploring selected aspects of this complex relationship across three interconnected chapters.

The first chapter investigates the immediate effects of prescribed fires on soil microbial communities. It reveals subtle shifts in porewater chemistry and significant increases in microbial species richness. These findings offer valuable insights into the interplay between soil properties and microbial responses during the early stages following a prescribed fire. …

Advanced Air Quality Management With Machine Learning, Cheng-Pin Kuo

Doctoral Dissertations

Air pollution has been a significant health risk factor at a regional and global scale. Although the present method can provide assessment indices like exposure risks or air pollutant concentrations for air quality management, the modeling estimations still remain non-negligible bias which could deviate from reality and limit the effectiveness of emission control strategies to reduce air pollution and derive health benefits. The current development in air quality management is still impeded by two major obstacles: (1) biased air quality concentrations from air quality models and (2) inaccurate exposure risk estimations

Inspired by more available and overwhelming data, machine learning …

Performance Evaluation Of Sediment Basin Designs For Highway Construction Sites In Tennessee, Jeffery Cole Emmett Jr

Masters Theses

Performance of three sediment basin designs were tested; they were: 1) the TDEC standard design with a forebay, 2) the TDOT design with an inlet check dam, and 3) the TDOT standard design that does not include an inlet check dam. An 1/17 of an acre scaled physical model sediment basin, was constructed next to an elevated outdoor open flume used to mix known water volumes and sediment mass routed by gravity-flow into the basin. The measurement for performance was simply the percent sediment mass retained in the basin from the total input per experimental run (percent sediment removal). Three …

Joint Failure Probability Of Dams Based On Probabilistic Flood Hazard Analysis, Matthew G. Montgomery

Masters Theses

Probabilistic risk methods are becoming increasingly accepted as a means of carrying out risk-informed decision making regarding the design and operation of structures such as dams. Probabilistic risk calculations require the quantification of epistemic and aleatory uncertainties not investigated through deterministic methodologies. In this hydrological study, a stochastic sampling methodology is employed to investigate the joint failure probability of three dams in adjacent, similarly sized watersheds within the same Hydrologic Unit Code (HUC) 6 basin. A Probabilistic Flood Hazard Analysis (PFHA) framework is used to simulate the hydrologic loading of a wide range of extreme precipitation events across the combined …

Abiotic And Biotic Degradation Of Bisphenols, Yanchen Sun

Doctoral Dissertations

Bisphenol A (BPA), as well as its substitutes bisphenol S (BPS) and bisphenol AF (BPAF), are high production volume chemicals and potential endocrine disruptors. The oxidized manganese (Mn) species, soluble Mn(III) and solid Mn(IV) (i.e., MnO₂), are typically generated in Mn-cycling driven by Mn-oxidizing bacteria and Mn-reducing bacteria. MnO₂ is a strong oxidant capable of oxidizing a variety of organic contaminants including bisphenols. Soluble Mn(III) commonly occurs near oxic-anoxic interfaces and is an important environmental oxidant. Mn(III) is also associated with both biogenic and synthesized MnO₂. However, the effect of Mn(III) on the degradation of …

Environmental Design And Optimization Of Modular Hydropower Plants, Colin Sasthav

Doctoral Dissertations

This research aimed to understand the pathways to cost-effective and sustainable low-head hydropower. Designing viable hydropower projects requires optimization across many economic, environmental, and social outcomes. However, existing run-of-river hydropower design models often focus on economic performance and customizing technologies for high-head diversion schemes. Standard modular hydropower is a new design approach that uses standardized rather than custom-designed technologies to achieve economies of scale. Oak Ridge National Laboratory established a conceptual outline for module classes based on functions, such as generation modules and fish passage modules, but further research was needed to identify how modules should be selected and operated …

Hydropower System Design In Nazarét, Panama, Claudia M. Bible, Matthew J. Tolson, Andrew Houser, Aj Condra, Nathan Smith

Chancellor’s Honors Program Projects

No abstract provided.

Sustainable Underground Reactive Barrier To Attenuate Contaminants From Agricultural Drainage, Yuchuan Fan

Doctoral Dissertations

Denitrifying bioreactor (DNBR) has become a popular edge-of-field practice applied to reduce nitrate over the Mississippi river and to prevent a downstream hypoxic zone occurring at the Gulf of Mexico. Despite widespread field and laboratory studies, fewer investigations have been directed toward a systematic means of evaluating the nitrate removal performance achieved by various filling materials, abiotic factors, and other critical parameters. Our ultimate goal is to improve the nitrate removal by choosing the optimum fill materials and operate under optimal conditions, meanwhile, modeling the DNBR by critical variables. This study begins by establishing a global database. Forty filling materials …

A Connectivity Framework To Explore The Role Of Anthropogenic Activity And Climate On The Propagation Of Water And Sediment At The Catchment Scale, Christos Giannopoulos

Doctoral Dissertations

Anthropogenic disturbance in intensively managed landscapes (IMLs) has dramatically altered critical zone processes, resulting in fundamental changes in material fluxes. Mitigating the negative effects of anthropogenic disturbance and making informed decisions for optimal placement and assessment of best management practices (BMPs) requires fundamental understanding of how different practices affect the connectivity or lack thereof of governing transport processes and resulting material fluxes across different landscape compartments within the hillslope-channel continuum of IMLs. However, there are no models operating at the event timescale that can accurately predict material flux transport from the hillslope to the catchment scale capturing the spatial and …

Metabolomics, Genomics And Transcriptomics Unravel Fluoroalkane Metabolism In Pseudomonas Sp. Strain 273., Yongchao Xie

Doctoral Dissertations

Fluorinated organics have been developed and produced for various applications in the industrial, military, medical and agrochemical fields; they are now emerging as persistent organic pollutants with demonstrated adverse health impacts on mammals, including humans. The high bond dissociation energy of C-F bond hinders microbial degradation and defluorination. The present work demonstrates Pseudomonas sp. strain 273 can utilize the 1-fluoroalkanes (C₇ to C₁₀ and C₁₄) and 1,10-difluorodecane (DFD) as the sole carbon source in the presence of oxygen. In this study, fluorine mass balance analysis determined that the majority (> 90%) of the fluorine from the …

Impact And Application Of Real-Time Control On Stormwater Systems, Aaron A. Akin

Doctoral Dissertations

Stormwater control measures (SCMs) such as dry extended detention basins and wet ponds are common practices implemented by engineers and designers to mitigate the impact of stormwater runoff. These practices are designed based on historical rainfall data to attenuate runoff to pre-development conditions and, once they are installed, are unable to adapt to changing rainfall patterns or watershed restoration objectives. To solve these climate resiliency issues, several studies were conducted which investigated the impact of retrofitting such systems with a controllable outlet to increase or change detention times during rainfall events along with the novel instrumentation and methodologies necessary for …

Identifying And Assessing Bacterial Contamination In Stormwater Runoff And Receiving Streams, Songyi Liu

Doctoral Dissertations

Stormwater runoff has been recognized as a significant non-point source of pollution responsible for serious ecological impacts. Microbial pollutants represent one of the major contaminants of concern in stormwater runoff and the receiving streams. Traditionally, fecal indicator bacteria (FIB) have been used extensively to assess the microbial quality of water, particularly the extent of fecal contamination in water. However, the application of FIB as indicators of microbial contamination bears known disadvantages of cultivation-dependent techniques, such as the inability to identify the majority of microbial populations that are not amenable to cultivation under laboratory conditions. The effectiveness of a cultivation-independent sequencing …

Dissolved Organic Carbon And The Potential Role To Stream Acidity In The Great Smoky Mountains National Park, Jason R. Brown

Masters Theses

A substantial societal shift towards environmental awareness has focused research efforts on the impacts of pollution on natural landscapes. Improvements to pollutant regulations and technology have resulted in sizeable reductions of atmospheric deposition of anthropogenic acids, especially nitrates and sulfates, which has altered the role of these ions in the environment. As such, understandings of environmental chemistry dynamics have required regular updating.

Through the National Park Service Vital Signs monitoring program, increases in precipitation pH observed in Great Smoky Mountains National Park (GRSM) has been attributed to the reduction of inorganic acid concentrations. Unfortunately, these improvements have not been uniformly …

Terrestrial Laser Scanning Technology For Measuring Streambank Retreat Along East Fork Poplar Creek And Calculating The Effect On Mercury Release., José L. Martínez Collado

Masters Theses

Mercury (Hg) is a globally distributed inorganic pollutants of human concern. The high toxicity is mainly related to the capacity of Hg species to accumulate and biomagnify along aquatic food webs. Along East Fork Poplar Creek (EFPC), erosion represents the principal mercury input into the local waters, eventually reaching humans through the food chain. This research project aimed to monitor streambank erosion along a mercury-contaminated creek using Light Detention and Ranging (Lidar) technology and erosion pins. A Terrestrial Laser Scanner (TLS) was used to generate high-resolution point clouds from August 2020 to January 2021 across nine streambank locations to detect …

The Performance Impacts Of Real-Time Control On Bioretention, Padmini P. Persaud

Doctoral Dissertations

Bioretention is a green infrastructure practice used to restore natural hydrologic regimes and improve stormwater quality. Extreme weather combined with demands for treatment of a growing number of priority pollutants has put a strain on these systems, making meeting performance goals difficult. The addition of smart stormwater technology has the potential to help address these issues as more control is provided to modify internal conditions and optimize sometimes conflicting outcomes. The use of real-time control is tested in this research to determine how bioretention performance is impacted by this technology. Column studies incorporating forecasts and historic rainfall were used to …

Quantifying Tree Canopy Contributions To Stormwater Runoff Reductions In Urban Watersheds Of The Southeastern United States, Matthew C. Howard

Masters Theses

Urban stormwater is a major contributor to surface water degradation in the United States, prompting cities to invest in ways to naturally capture, store, and slowly release runoff through “Green Infrastructure” (GI). One often overlooked potential contributors to stormwater management are urban trees, an integral part of a given city’s GI. Interception is of particular interest and describes a tree’s ability to capture and store rainfall, reducing the volume of stormwater that can degrade urban streams during storm events. While rainfall interception for full canopy, forested environments is well studied, limited research is available that characterizes the interception of open-grown …

Bioretention Cell Performance Under Shifting Precipitation Patterns Across The Contiguous United States, Matthew Weathers

Masters Theses

As climate change produces shifts in precipitation patterns, communities will need to understand how the performance of green stormwater infrastructure (GSI) may be impacted. Bioretention cells are one of the most commonly implemented forms of GSI for their ability to reduce peak discharge and filter pollutants and are a vulnerable component of stormwater infrastructure. Projections in future climate indicate that bioretention cells may be at risk of losing their existing function due to deviations in precipitation frequency and intensity. General circulation models (GCMs) downscaled to regional climate models (RCMs) can provide climate change projections at a high spatial resolution but …

High-Resolution Timeseries Analysis Of Dynamic Geochemistry: A 27-Well Survey Of Contaminated Groundwater Downstream Of The Former S-3 Ponds, Oak Ridge, Tennessee, Emma Dixon

Masters Theses

Spatiotemporal variability of geochemistry of contaminated groundwater has large implications on overall water quality and ability to respond to remedial applications. Gaining knowledge of how geochemistry changes over time in an area can help establish response trends to changing external conditions like weather and level of contamination. In this study, a spatiotemporal survey was performed on 27 wells at the Y-12 Complex in Oak Ridge, Tennessee. This was completed to measure diurnal fluxes in geochemistry from seasonal changes and extreme weather conditions in three areas of historically different contamination levels from a single point contamination source. Measurements were gathered over …

Lagrangian Bedload Movement Prediction Using The Virtual Velocity Approach, Theodoros Kyriakopoulos

Masters Theses

The advances in particle tracking codes in the recent years has made possible to track the intermittent movement of a large number of sediment particles with precision and in an automated way. The present study used this technique to study the velocity of the particle while it is in motion, the length it travels once it gets mobilized until it deposits, and the time it rests once deposited until it gets mobilized again. New modeling equations were developed to predict these quantities for a wide range of flow conditions and sediment sizes. These equations were combined to predict the virtual …

Improving Stream Bank Erosion Estimates By Adjusting The Applied Shear Stress For Different Bank Characteristics, Justin Condon

Masters Theses

Stream bank erosion rates are commonly modeled using the excess shear stress equation ε_r = k_d(τ-τ_c)^a, where the exponent a is assumed to be unity. The coefficient of erodibility k_d, and the critical shear stress τ_c [Tau _c] are properties of the bank soil and the applied shear stress τ [Tau] is a function of the channel geometry and discharge. This equation appears to overstimate bank erosion likely due to effects of channel morphology and bank vegetation, among other factors. The objective of this study was to determine whether …

An Investigation Of Surface Water Sediment Source Tracking Using Bacterial Metagenomics And Elemental Fingerprinting, Yanchong Huangfu

Doctoral Dissertations

Excess suspended sediment in river systems commonly degrades surface water quality. A sediment source tracking approach is necessary to target management practices that will reduce significant sources of sediment in rainfall runoff and restore water quality. Sediment source tracking utilizes the biogeochemical characteristics of sediment, often paired with a mathematical model, to link eroding source materials and in-stream suspended sediment. However, there are still many questions left unanswered in using this approach, including simultaneously identifying fecal contamination sources, quantifying the reliability of sediment tracers, and methods to assess the accuracy of sediment source identification. The research herein utilized the microbial …

Sustainable Infrastructure Development: A Holistic System Based Decision Making Framework Integrating Vulnerability Indicators And Stakeholders Objectives, Mohamed Saeid Eid

Doctoral Dissertations

Infrastructure systems enable the host communities to expand, develop, and prosper in adequate socioeconomic conditions and healthy environment. Thus, the strategies for sustainable infrastructure development should aim to increase the individual utility of the local stakeholders, while reducing the vulnerability of the built environment to perturbations. Nevertheless, the available frameworks consider the development of the infrastructure systems as isolated projects and do not simultaneously address the needs of the stakeholders or the vulnerability of the built environment. The goal of this research is to provide decision makers and the research community with a novel infrastructure development framework that holistically balances …

Impact Of Transportation Infrastructure On Stream Water Quality: Contribution From Stormwater Runoff, Andrew James Steinman

Masters Theses

Stormwater runoff is a vital concern to the health of natural waterbodies and ecosystems within urban watersheds. While there is already ample research dedicated to understanding water quality from urban roadways, few of those studies have focused on measuring the dynamics of how stream water quality during storm conditions changes due to increased pollutant load from major urban roadways. With the goal to develop effective water resource management strategies for an impaired tributary watershed, water quality was monitored at four locations within a subwatershed to determine what impact pavement runoff of a major interstate has on the impaired receiving stream. …

A Bug’S Life: Integration Of Anaerobic Digestion And Bioelectrochemical Systems For Enhanced Energy Recovery From Wastewater Solids And Other Waste Substrates, Jeff Ryan Beegle

Masters Theses

Organic waste streams, like domestic wastewater and municipal solid waste, have the potential to be used as feedstocks for biotechnology processes to produce high value products and energy. This thesis investigated the technological, economical, and environmental potential for integrated anaerobic digestion (AD) and bioelectrochemical system (BES) platforms as they were theoretically and physically evaluated for energy recovery from domestic wastewater. The first chapter of this thesis compared the theoretical energy efficiencies of converting waste directly into electricity, using AD and BES alone and in various combinations. This chapter reviewed the experimentally demonstrated energy efficiencies reported in the literature with comparisons …

Wastewater Treatment Improvement For Rush Strong School, Christina R. Sanford Utk, Kelli M. Grissom, Katie Gipson, Sharon Counts

Chancellor’s Honors Program Projects

No abstract provided.

Bioremediation Of Chlorinated Ethenes: Ph Effects, Novel Dechlorinators And Decision-Making Tools, Yi Yang

Doctoral Dissertations

Chlorinated solvents have been widely used in different areas of modern society. Usage of these chlorinated solvents was not necessarily accompanied with proper handling and disposal of these hazardous compounds, which caused a variety of environmental problems and continues to affect human health. Remediation of chlorinated ethenes contaminated sites has high priority for state regulators and site owners. Among the available treatment technologies, bioremediation shows great promise as a cost-effective corrective strategy for a variety of environmental pollutants. Prerequisites are that the microbiology involved in contaminant degradation and geochemical factors, such as pH, are understood, so that bioremediation technologies can …

Potential Emissions And Exposures Of Toxic Organics From Storage Tanks For Chemical Additions In Hydraulic Fracturing: A Modeling Approach, Huan Chen

Doctoral Dissertations

Hydraulic fracturing has promoted the exploitation of natural gas in the United States (U.S.). However, the storing and emptying of chemical additives in hydraulic fracturing wells may pose adverse effects through inhalation exposures. Based on the information about hydraulic fracturing fluids, this study investigated: 1) water volumes used to mix chemical additives for making up the hydraulic fracturing fluids; 2) chemical species, concentrations and their degradability in the hydraulic fracturing fluids; 3) emissions of organics from chemical storage tanks; and 4) the occupational inhalation exposures by toxic and organic vapors.

Results shows for 80,047 wells fractured between 2008 and 2014 …