In a society where equality is sought as the norm, occupational gender representation is still skewed in some disciplines. One field where gender equality in representation has not yet been achieved is engineering, whether in college or at the professional level. This imbalance is not only a potentially vicious cycle...
Industrial waste heat composed of saturated liquid water can be redirected to charge a thermochemical energy storage (TCES) system. This energy can be stored long-term in the inherently energy-dense chemical bonds and used for space heating. Initial reactor scale cycling experiments were conducted in tandem with TCES material improvements. Hydration...
This work focuses primarily the development of methods for imaging microbial biofilms in opaque porous media using x-ray computed microtomography (CT). Two methods for evaluating biofilms in porous media are presented. The first focuses on the addition of silver-coated, hollow glass microspheres to a biofilm-containing micro-model. The silver-coated microspheres affix...
The integration of low-pressure membrane filtration and aerobic granular sludge (AGS) reactor leads to a novel environmental biotechnological process with strong potential to overcome membrane fouling and demonstrate excellent wastewater treatment performance. However, membrane fouling mechanisms in the AGS based membrane bioreactor (MBR) are lack of systematic elaboration. In the...
Trichloroethene (TCE) is a common groundwater contaminant. Bioremediation, or the enhancement of natural microbial processes for the transformation of toxic compounds in soil and groundwater, is an effective solution to this widespread problem. The organisms that transform TCE in the subsurface are sensitive to environmental conditions, especially to the presence...
Gender has been the subject of study in engineering education and science social research for decades. However, little attention has been given to transgender and gender nonconforming (TGNC) experiences or perspectives. The role of cisgender or gender conforming status has not been investigated nor considered in prevailing frameworks of gender...
The ability of Mycobacterium sp. ELW1, a novel microbe capable of alkene oxidation, to co-metabolize phenanthrene (PHE) was studied. ELW1 was able to completely co-metabolize PHE, at different concentrations below its water solubility limit, in an aqueous environment. The alkene monooxygenases in ELW1, used to initiate oxidation of PHE, were...
Carbon tetrachloride (CT) and chloroform (CF) were transformed in batch reactor experiments conducted with anaerobic dechlorinating cultures and supernatant (ADC+S) harvested from continuous flow reactors. The Evanite (EV-5L) and Victoria/Stanford (VS-5L) cultures capable of respiring trichloroethene (TCE), 1,2-cis-dichloroethene (cDCE), and vinyl chloride (VC) to ethene (ETH) were grown in continuous...
Stream chemistry studies conducted in the forested Watershed 1 of the HJ Andrews Experimental Forest show a contribution of CO2 from the hyporheic zone. Hyporheic CO₂ concentrations, measured as pCO₂, have a seasonal trend as well as a responsiveness to storm events. Concentrations are highest at the end of the...
Best Management Practices (BMP) are widely used as a method for stormwater volume control in urban areas to prevent an overload of water on receiving water bodies and treatment facilities. BMPs ability to treat stormwater has gone under critical review in the last few decades, and their performance varies both...
Engineered nanomaterials (ENMs) are small anthropogenic colloids with at least one length dimension <100 nanometers. Due to the nature of their use, ENMs are being increasingly released to the environment. Yet the environmental risks posed by ENMs are unknown due to a variety challenges, including limitations with detecting and quantifying...
The production of titanium dioxide (TiO2) nanoparticles has increased significantly in the past decades, which has generated concern due to their known toxicity in the environment. As a result of the production, use and disposal of productions containing TiO2, TiO2 nanoparticles are often received by wastewater treatment facilities. The adsorption...
This project determined how the presence of environmental biofilms on sand, granular activated carbon and biochar affected the sorption capacity and desorption quantity of copper, zinc, nutrients and organic carbon from stormwater. These contaminants have harmful and toxic environmental impacts on aquatic life, can lead to eutrophication of surface waters,...
Due to the effective antimicrobial properties of silver nanoparticles they represent a significant proportion of all consumer-‐related nanomaterials. The introduction of silver nanoparticles from these products into domestic and industrial wastewater streams poses potential complications for biological treatment systems. A critical component of biological treatment that is extremely sensitive to...
Methanotrophic bacteria are promising means of producing value-added products as they have the ability to transform methane under atmospheric temperature and pressure. Efforts to develop methanotrophs to produce value-added products are hoped to incentivize a decrease in methane flaring operations. The data collected during this study was used to inform...
Geologic CO₂ sequestration is a climate change mitigation strategy that involves the injection of supercritical CO₂ into deep underground rock formations. This thesis focuses on capillary trapping in which capillary forces immobilize CO₂ bubbles at the pore scale. During injection of supercritical CO₂, brine is displaced in what is known...
We do not fully understand reasons behind extinction of populations and species. Consequently, our ability to anticipate extinction (which can be considered a permanent type of an ecological threshold) has remained elusive. In particular, it is not clear how the attributes of episodic disturbance regimes can elicit extinction. In this...
Over the last two decades, urban stormwater management has grown to include green infrastructure, such as bioswales. These systems were primarily designed to mitigate hydraulic peaking during rainstorms but were also found to remove particulate and dissolved contaminants. However, little is known about the fate of these particulate contaminants after...
Several types of channel morphology measurement parameters used to
characterize fish habitat of small streams are refined, developed and evaluated in terms
of their accuracy, precision, and sensitivity to disturbance. Data for 74 stream reaches
in Oregon and Alaska are used in analysis. Over half the reaches are from a...
Natural stream systems contain a variety of flow geometries which contain flow separation, turbulent shear layers, and recirculation zones. This work focuses on streams with dead zones. Characterized by slower flow and recirculation, dead zones are naturally occurring cutouts in stream banks. These dead zones play an important role in...
The purpose of this research was to measure the copper-binding behavior of Dissolved Organic Matter (DOM) contained in Pulp and Paper (P&P) wastewater effluent and evaluate the Biotic Ligand Model’s (BLM) ability to quantify copper speciation in P&P influenced waters. A copper ion selective electrode was used to measure copper...
The production of the fullerene C60 and its emerging applications in consumer
products imply its ultimate release to the environment. Due to the molecule’s relative
novelty, the aqueous characteristics of C60 have not been fully assessed, though it may
potentially harm human or ecological health. C60 is highly insoluble in...
This work is a compilation of problems that deal with multiscale analysis of transport phenomena in environmental systems. A common feature among the problems studied here is the presence of non-negligible microscale structure in various forms. Each problem is approached from the perspective that a macroscopic observable encodes aspects of...
Wastewater treatment plants are considered one of the main sources and reservoirs of antimicrobial resistance (AMR). This study investigated the prevalence of 8 different phenotypes of AMR, multi-drug resistant (MDR), and extended-spectrum beta-lactamases (ESBL) producing E. coli in 17 wastewater treatment plants across Oregon in winter and summer of 2019...
Understanding the transport and retention of radionuclides in the environment is important for protecting freshwater supplies and minimizing impact to biologic systems. Technetium-99 (Tc⁹⁹) is a radionuclide of interest due to its long half-life (2.13 x 10⁵ years) and toxicity. In the form of pertechnetate (TcO₄⁻), Tc is expected to...
Stormwater picks up pollutants as it flows over impervious surfaces before ending up in water resources. Best management practices are implemented to remove pollutants from stormwater. Puralytics manufactures a stormwater treatment product called the LilyPad. The LilyPad consists of a titanium dioxide nanoparticle photocatalyst immobilized on polypropylene substrate. Treatment of...
At the beginning of the COVID-19 pandemic, the world was unprepared for such a massive challenge to global health. Individual testing kits and personal protective equipment were scarce. There were minimal ways to track the rapid spread of the disease, until researchers discovered that SARS-CoV-2, the virus that causes COVID-19,...
Atmospheric carbon reduction is arguably the most crucial facet among efforts to mitigate climate change. The Fifth International Panel of Climate Change report emphasizes a worldwide goal of maintaining global temperature elevation less than 1.5°C above pre-industrial temperatures. This report also acknowledges without the proper utilization of counteractive emission strategies...
Numerous studies have shown that some nanomaterials are highly toxic to aquatic organisms and can potentially disrupt overall community health; however, current methods to evaluate the nanomaterials environmental impacts rarely consider the environmental realism or provide sufficient detail on the impact at the community level. Here we demonstrate three approaches...
Heteroaggregation of nanoparticles with naturally occurring colloids has been shown to be an important process in nanoparticle fate and transport in the aquatic environment. The advent of a functional assay to measure heteroaggregation attachment efficiencies has opened the door for further mechanistic studies. It is well known that natural organic...
Anaerobic ammonium oxidation (anammox) has recently appeared as a promising approach for removing nitrogen from landfill leachates because it requires less oxygen and no organic carbon compared to traditional nitrification-denitrification system, and it produces low sludge volumes, thereby reducing operating and biological sludge disposal costs by over 60%. Anammox bacteria...
Agrivoltaics, which integrates photovoltaic power production with agriculture in the same plot of land, has the potential to reduce land competition and crop irrigation. To optimize agrivoltaic systems for crop growth, energy pathways must be characterized. While solar panels shade the crops, they also emit longwave radiation. At the end...
A dissertation describing the results of a series of greenhouse experiments conducted to better understand phytoremediation in stormwater bioretention systems.
1,4-Dioxane (dioxane) is a probable human carcinogen and is often found comingled with chlorinated aliphatic hydrocarbon (CAH) contamination since dioxane is used as a stabilizer in CAH solutions. Dioxane is miscible in water, has a low K[subscript ow], low H[subscript cc], and is highly recalcitrant in the environment. The presence...
Systems that contain multi-phase flow in porous media are of interest in diverse fields including environmental engineering, hydrogeology, and petroleum engineering etc. One of the main descriptors of multi-phase flow in porous media is the relationship between capillary pressure and fluid saturation. Capillary pressure is inherently a pore-scale variable and...
Engineering practice is aptly described as a unique culture, shaped by a long history of social learning, norms and values. As these systems and values have been constructed to the benefit of white men, it is unsurprising that the study of engineering culture has revealed many structures working against the...
Bioremediation of chlorinated ethenes by the augmentation of contaminated soils with microorganisms is a proposed method of reducing contaminant concentrations in groundwater. To determine the viability of using ELW-1 or R. rhodochrous for groundwater remediation, kinetic analyses of transformation rates must be performed. The focus of this research was to...
The flow of multiple immiscible fluids within a porous medium controls many natural and engineered systems in the environment including: geologic CO2 sequestration, enhanced oil recovery from underground reservoirs, and contaminant remediation of groundwater. The need to understand how fluids are transported and distributed in these processes is important for...
Identifying the inhibition of ammonia oxidizing bacteria (AOB) by emerging organic contaminants is crucial due to the importance of AOB in wastewater treatment, the widespread use of antibacterial agents such as triclosan (TCS) in consumer products, and the sensitivity of N. europaea to inhibitors. Triclosan inhibition of nitrification by AOB...
Despite decades of cleanup efforts, chlorinated solvents are some of the most common groundwater and subsurface contaminants of the industrialized world. These compounds include chlorinated ethenes (CEs) such as trichloroethene (TCE) and chlorinated methanes (CMs) such as carbon tetrachloride (CT). Dehalococcoides mccartyi belongs to a class of microorganisms called organohalide-respiring...
Nanoparticles are becoming increasingly important in numerous technological fields but evidence shows that they can be toxic to many organisms. To predict their fate and transport in the environment, nanoparticle attachment to naturally occurring colloids must be examined. This study investigated citrate-capped gold nanoparticle (Cit-AuNP) heteroaggregation with two model colloids...
Understanding the aggregation behavior of engineered nanomaterials (ENMs) in aqueous environments is essential to understanding their fate, transport, and toxicity. Because naturally occurring colloids will likely be present at much higher concentrations than ENMs in environmental systems, heteroaggregation and attachment with these natural colloids could significantly influence ENM fate and...
Anaerobic digestion is a biological process in which organic matter is decomposed by a community of microbes in the absence of oxygen. The end product of anaerobic digestion is biogas, composed of methane and carbon dioxide, which is often recovered and used to generate energy. Commonly, biogas is not produced...
An important goal of engineering educators is to prepare students to interact and communicate with other professionals, especially other engineers. Object and process scale is a crucial concept that engineers are required to communicate frequently and effectively. The goal of this study is to characterize how engineers communicate scale within...
Women are highly-underrepresented in undergraduate engineering majors, making up just over 15% of students in engineering and computer science at Oregon State University. High school girls' interest in pursuing engineering in college is affected by the way language frames engineering careers. The status-quo engineering frame is made up of terms...
Food waste (FW), brewery waste (BW), and fats, oils, and greases (FOG), are prevalent waste streams in municipalities across the country, particularly in the Pacific Northwest (PNW). Anaerobic digestion (AD), the microbial-mediated transformation of organic waste into methane-rich biogas, offers a sustainable, energy-generating, waste management solution for these wastes. Anaerobic...
Understanding the mechanisms controlling colloid transport and deposition in the vadose zone is an important step in protecting our water resources. Colloid transport in unsaturated porous media was studied using X-Ray Microtomography (XMT), which is a non-destructive imaging technique that provides three-dimensional images at a resolution on the order of...
Anammox (anaerobic ammonium oxidation) bacteria are capable of providing low-cost nitrogen removal for numerous types of wastewaters. However, low growth rates cause long startup-times and inhibition by oxygen and metabolic substrates necessitate close process control to maintain performance. Incorporation of Simultaneous Anammox and Denitrification (SAD) into constructed wetlands could provide...
1,4-dioxane, a probable human carcinogen at low (< 1ppb) concentrations, has emerged as a groundwater contaminant due to its historical use as a stabilizer for the chlorinated solvent 1,1,1-trichloroethane. Aerobic cometabolism, the use of a primary substrate to induce the production of microbial enzymes that fortuitously degrade other compounds, is...
Metal oxide nanoparticles (MONPs) are manufactured at the greatest rate of any class of nanomaterial due to their wide variety of industrial, commercial, and environmental applications. The sustainable use of MONPs requires a balance of careful consideration of their potential negative environmental impacts with the effective exploitation of their unique...