Environmental Engineering Commons^™

Assessing Diffusive Gradients In Thin Films Passive Samplers For Pfas Quantitation In Aqueous Systems, Brianna Harris

Graduate Theses and Dissertations

Diffusive gradients in thin-films (DGT) passive samplers are an alternative to grab sampling for quantifying time-weighted average (TWA) concentrations of per- and polyfluoroalkyl substances (PFAS) in aqueous systems. DGTs may enable long-term PFAS site characterization in a more time and cost-effective manner compared to grab sampling, but critical information is lacking in PFAS diffusion coefficient (DGel) uncertainty, PFAS quantitation limits, and environmental impacts on DGT performance. This work provides a thorough evaluation of DGT performance for a suite of 32 PFAS through (i) determining gel-layer PFAS diffusion coefficients and their associated error (i.e., 95 % confidence intervals (CIs)), (ii) assessing …

Monitoring Streambank Morphology Using Iphone Lidar Technology, Lily C. Stitt

Biological and Agricultural Engineering Undergraduate Honors Theses

Monitoring stream morphology is crucial for maintaining the health and safety of fluvial environments, particularly as these naturally dynamic systems are shifted out of equilibrium due to climate and land-use change. Quantifying changes in stream geometry are useful for infrastructure design, water quality assessment, water resource management, and stream restoration, among other applications. Traditional stream surveying methods contain numerous cost limitations that inhibit affordable and accessible stream surveying needed for evaluating stream geometry with high accuracy and larger spatial scales (>100s of ). In recent years, several advancements have been made in the use of Light Detection and Ranging …

Dried Water Treatment Residuals Might Be An Option To Reduce Soluble Reactive Phosphorus Release From Soils, Katie B. Mckay

Biological and Agricultural Engineering Undergraduate Honors Theses

Nonpoint source pollution from agricultural landscapes contributes to freshwater eutrophication, with legacy phosphorus (P) in soils potentially driving soluble reactive phosphorus (SRP) losses to surface waters. The objectives of this study were to evaluate SRP adsorption by dried water treatment residuals (WTRs) produced by Beaver Water District, quantify reductions in soil SRP release across increasing WTR application rates, and compare dried WTR performance to prior WTR studies.

Dried WTRs (~98% solids) were assessed using batch sorption experiments and soil core incubations. Phosphorus sorption was measured by mixing WTRs with CaCl₂ solutions containing increasing SRP concentrations and fitting results to …

Assessing The Fate Of Antibiotic Resistance Genes In Wastewater Treatment Processes, Gunter A. Campbell

Civil Engineering Undergraduate Honors Theses

The increasing need for clean water has paved the way for the creation of systems for reusing water, such as wastewater treatment plants (“WWTPs”), to provide potable water. But in recent years, such systems have raised concerns about the distribution of antibiotic resistance genes (“ARGs”). Bacteria are adapting to antibiotics by the evolution of resistance mechanisms, such as high mutation rates and horizontal transfer. The presence of ARGs, particularly tetracycline ("tetA") resistance genes, in wastewater effluents is of concern, as they can survive treatment, spread to bodies of water, and pose a threat to human health. In this study, the …

Feasibility Of Liquid Carbon Sources For Algae Growth, Brady S. Jones

Chemical Engineering Undergraduate Honors Theses

This thesis explores the use of electrochemically produced aqueous bicarbonate as a novel liquid-phase carbon source for enhancing algal biomass productivity. Targeting the freshwater microalgae Chlorella Saccharophila, the study investigates its growth response to varying bicarbonate concentrations and compares the efficacy of liquid bicarbonate delivery with traditional gaseous CO₂ bubbling methods. Results demonstrate that Chlorella Saccharophila can sustain growth solely on bicarbonate, and that bicarbonate-fed cultures yielded higher biomass than those supplied with gaseous CO₂ or hybrid systems. These findings validate the potential of bicarbonate-based carbon delivery for scalable algae cultivation, offering key advantages such as gas-free operation, improved …

Cytotoxicity And Genotoxicity Of Glyphosate And Roundup Quickpro On Chinese Hamster Ovary Cells, Tasnimul Ferdous

Graduate Theses and Dissertations

Glyphosate and Roundup products have become the most used herbicide worldwide. However, previous bans in Europe and recent reversal have caused confusion over their safety. This study aims to investigate the cytotoxic and genotoxic effects of Roundup QuickPro and its main ingredient glyphosate using Chinese hamster ovary (CHO) cells. Cytotoxicity was calculated by measuring CHO cell viability with 72 hours of exposure to each toxicant. Roundup exhibited higher cytotoxicity with LC50 of 511.2 μg/mL than glyphosate’s LC50 of 3389 μg/mL. The recommended application concentration (11,233.7 μg/mL) of Roundup QuickPro is much higher than the measured LC50, which caused complete cell …

Closing Dichloramine Decomposition Nitrogen And Oxygen Mass Balances: Relative Importance Of End-Products From The Reactive Nitrogen Species Pathway, Huong T. Pham, David G. Wahman, Julian L. Fairey

Civil Engineering Faculty Publications and Presentations

In drinking water chloramination, monochloramine autodecomposition occurs in the presence of excess free ammonia through dichloramine, the decay of which was implicated in N-nitrosodimethylamine (NDMA) formation by (i) dichloramine hydrolysis to nitroxyl which reacts with itself to nitrous oxide (N₂O), (ii) nitroxyl reaction with dissolved oxygen (DO) to peroxynitrite or mono/dichloramine to nitrogen gas (N₂), and (iii) peroxynitrite reaction with total dimethylamine (TOTDMA) to NDMA or decomposition to nitrite/nitrate. Here, the yields of nitrogen and oxygen-containing end-products were quantified at pH 9 from NHCl₂ decomposition at 200, 400, or 800 μeq Cl₂·L …

Diffusive Gradients In Thin-Films Passive Samplers For Quantitation Of Per- And Polyfluoroalkyl Substances In Water: Kinetic Modeling, Experimental Methods, And Outlook For Regulatory Monitoring, Samuel Hodges

Graduate Theses and Dissertations

Environmental sampling is the backbone of regulatory compliance in public water systems. Coupled with continuously improving analytical capabilities, grab sampling has revealed the ubiquity of emerging contaminants in water resources such as per- and polyfluoroalkyl substances (PFAS). The Environmental Protection Agency’s (EPAs) Method 533 and 537.1 specify 0.25 L grab samples undergo a solid phase extraction (SPE) to enrich PFAS up to 250-fold in 1 mL of methanol prior to analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS). This process can achieve lowest concentration minimum reporting levels (LCMRLs) between 0.53–16 ng•L−1 for the twenty-nine prioritized PFAS in drinking waters. However, toxicity …

Exploring The Potential Of Tesla Valve For Filtering And Sorting Microscale Active Swimmers: A Computational Study, Ariel Rogers, Zhiyao He, Yong Wang

Physics Faculty Publications and Presentations

It is well-known that a Tesla valve allows fluids to flow unidirectionally without moving parts; however, how Tesla valves interact with active matters and the potential applications of Tesla valves in biology remain largely unexplored. Here, we present a computational study on the potential use of Tesla valves for filtering and sorting microscale active swimmers such as bacteria. We investigated the behavior of microscale swimmers passing through the Tesla valve at different linear and angular velocities using numerical simulations and quantified the diodicity of the Tesla valve for active swimmers. Our results demonstrate that the Tesla valve can effectively filter …

Non-Steady-State Fickian Diffusion Models Decrease The Estimated Gel Layer Diffusion Coefficient Uncertainty For Diffusive Gradients In Thin-Films Passive Samplers, Samuel D. Hodges, David G. Wahman, Levi M. Haupert, Huong T. Pham, Margaret K. Bozarth, Michael B. Howland, Julian L. Fairey

Civil Engineering Faculty Publications and Presentations

Mass transport in diffusive gradients in thin-film passive samplers is restricted to diffusion through a gel layer of agarose or agarose cross-linked polyacrylamide (APA). The gel layer diffusion coefficient, D_Gel, is typically determined using a standard analysis (SA) based on Fick’s first law from two-compartment diffusion cell (D-Cell) tests. The SA assumes pseudo-steady-state flux, characterized by linear sink mass accumulation–time profiles with a typical threshold R² ≥ 0.97. In 72 D-Cell tests with nitrate, 63 met this threshold, but the SA-determined D_Gel ranged from 10.1 to 15.8 × 10^_–6 cm²·s^–1 (agarose) and …

Photocatalytic Nanoparticle Treatment Of Cyanotoxins In Harmful Algal Blooms, Brian Baird

Civil Engineering Undergraduate Honors Theses

Harmful Algal Blooms (HAB) have the ability to cause detriment to water bodies, ecosystems, and human health. Furthermore, current evidence suggests that these events are becoming increasingly common due to factors such as increased pollution and global warming. While there are current methods to treat water that is negatively impacted by the bacteria and toxins associated with HABs, these methods are often costly and inefficient. The purpose of this research is to explore a potential treatment option that uses titanium dioxide photocatalytic nanoparticles attached to a retractable net to treat toxins produced by HABs in situ. Specifically, the toxin …

Plural Communities: A Cultural Mapping Project + A Framework Plan For Cherokee Village, Arkansas, Community Design Center

Community Design Center Project Reports

What do urban designers do with culture? How might we redevelop a mid-century modern planned community through the mapping of cultural influences that shaped it? We explored memory and heritage central to cultural mapping and its participatory-based forms of public inquiry. 54 drawings integrate maps, folklore materials, archived media, photographs, and new drawings into five synchronic cultural frameworks that shaped Cherokee Village—Native American heritage, Ozark pioneer and folk heritage, camping and scouting, midcentury planned communities, and regional modernism in design and planning.

Cherokee Village was developed within a mid-twentieth century planning ethos that valued uniformity …

Sustainability And Health Impacts Of Pulse Crops In The United States Using Life Cycle Assessment, Prathamesh A. Bandekar

Graduate Theses and Dissertations

Environmental sustainability and human health impact of pulses produced and consumed in the United States was assessed using life cycle assessment (LCA). The study included three objectives 1) to estimate environmental impact of current production and consumption practices in the United States using attributional LCA; 2) to estimate environmental and human health impact of iso-caloric diets containing varying amounts of pulses using Hybrid-LCA and Combined Nutritional and Environmental-LCA (CONE-LCA); and 3) to estimate environmental impact of increased demand for pulses using consequential LCA. Scope of the study varied for each objective with system boundary encompassing cradle-to-grave activities for objective 1 …

A Snapshot Of Sars-Cov-2 In Wastewater Treatment Plants In Northwest Arkansas, Katie Loethen

Biological and Agricultural Engineering Undergraduate Honors Theses

Because SARS-CoV-2, a coronavirus, is released in the fecal shedding of covid-positive patients, the virus enters the municipal waste stream and flows to wastewater treatment plants (WWTPs). The goal of this research is to quantify the effectiveness of wastewater treatment processes at removing SARS-CoV-2 from wastewater and preventing its release into the environment. Sampling at Paul R. Noland and West Side WWTPs in Fayetteville, Arkansas, took place from August 2020 to May 2021, and samples were tested for the presence of SARS-CoV-2 using N1 and N2 primers via RT-qPCR. Sampling days which returned positive detection of one or both of …

The Effect Of Changing Land Use On Streamflow Statistics And Flood Flows Across Select Gages In Northwest Arkansas, Timothy Mcmullen

Civil Engineering Undergraduate Honors Theses

Since 1901, heavy rainfall events have increased in the United States in both intensity and frequency, and population in the United States has increased, resulting in significant land use changes. Both of these trends could explain an increase in observed flood magnitude and frequency. In order to determine if a relationship exists between land use/land cover and changing stream flows in northwest Arkansas, this study analyzed temporal changes in various flow statistics for fourteen stream gages and compared the rates of change in flow statistics from gages on streams with watersheds that have varying land uses, i.e. urban, agricultural, and …

Sustainability In Construction Practices As Emphasis On Environmental Investing In Esg Model Grows, Maddie Heal

Management Undergraduate Honors Theses

The purpose of this research is to emphasize the importance of growing investment on environmental initiatives in business ESG models in regard to sustainable practices in construction. The ESG acronym is known as the environmental, social, and governance efforts that businesses strive to incorporate in their models to increase the responsibility of operations.

Investors continue to seek out responsible businesses when choosing which ventures to pursue. The analysis of the current construction crisis, current investments in the right direction of Eco-friendly design regarding construction, and the threats and benefits incentivizing those investments elucidates the need to emphasize socially responsible investment …

Port Infrastructure Resilience Through Combined Wind-Surge Demand Characterization, Kaley Callaway

Graduate Theses and Dissertations

The United States economy is reliant on maritime transportation for 70% of imports and exports. Structures that are integral to the operation of ports, such as cranes, are jeopardized when tropical storms approach land. While wind is the only environmental load used to design dockside container cranes, storm surge often accompanies severe wind events and can create large structural loads. This study focuses on determining coupled storm-surge demands and the effect of waves on dockside container cranes. A damage index prediction tool that considers both maximum wind speed and storm surge height is developed and applied to historical hurricane data …

Community Transportation Needs And Willingness To Use Shared Micromobility: A Case Study Of Fort Smith, Arkansas, Anthony Michael Kammerer

Civil Engineering Undergraduate Honors Theses

Shared micromobility is utilized in “targeted service areas with the usage generally intended for short trips such as "first- and last-mile" connections to complete trips made via other modes, including transit” (Price et al., 2021). In the United States, this practice has especially taken off with the implementation of sharing-based systems. This is evidenced by ridership numbers in the United States growing from 84 million riders nationwide in 2018 to 136 million riders in 2019 (NACTO, 2020). Users often use their smart phone or another similar device to unlock the vehicle after paying a fee on the device through their …

Exploring The Effects Of Varied Land Use On Elemental Concentrations Within Streams, Logan Jennings

Biological and Agricultural Engineering Undergraduate Honors Theses

It is well documented that human activity influences the chemistry of surrounding waters. As such, it is possible that there is a link between land use within a watershed and the chemical composition of the stream. The objectives of this study are to determine if varied land use does affect the concentrations of macronutrients and trace elements present in the streams of Northwest Arkansas, and if so, to determine what extent urban and agricultural development are responsible for these changes. Water samples were collected across 19 streams in the Northwest Arkansas region between January and March of 2022. Water samples …

Formation Of Reactive Nitrogen Species During Dichloramine Decay And Their Impact On N Nitrosodimethylamine Formation Under Drinking Water Conditions, Huong Thu Pham

Graduate Theses and Dissertations

NDMA occurrence and formation pathways in drinking water systems are reviewed and NDMA yields are compared on the basis of disinfectant type, water chemistry, and precursor category. In chloramination, despite monochloramine being the predominant species between pH 7-9, evidence suggests that dichloramine is the primary species involved in NDMA formation. This is somewhat confounding as NDMA yields are maximal at pH 9, yet at pH 9 dichloramine decays faster than it forms and hence is present at trace levels; additionally, the proposed mechanism involves a spin-forbidden incorporation of dissolved oxygen as a triplet, which is presumably kinetically slow. This review …

Identification Of Phosphorous Loading Point Source Facilities To 303(D) Listed Nutrient Impaired Waters Through Watershed Delineation Using Arcgis For Life Cycle Assessment Applications, John Zimmerman

Chemical Engineering Undergraduate Honors Theses

The work done for this project is part of a larger “life cycle assessment (LCA) of novel electrochemical phosphorus recovery technology at the wastewater treatment plant and U.S. watershed scales” (Morrissey 2019). The goal of that LCA is to determine “environmental impacts of implementing electrochemical struvite recovery at the wastewater treatment plant, U.S watershed, and global scales” (Morrissey 2019). This project’s goal is to identify locations deemed more sensitive to eutrophication impacts. The results will be used as part of the life cycle inventory (LCI) accounting for geographically explicit phosphorus flows. The waters identified as impaired were sourced from the …

Comparison Of The Resistance Of Belitic Calcium Sulfoaluminate Cement And Portland Cement To Sulfate Attack And Sulfuric Acid, Rilye Dillard

Graduate Theses and Dissertations

Microbially induced corrosion (MIC) is a fairly common concrete deterioration mechanism with many negative effects. MIC is a complex chemical and biological process that occurs in sewage systems and is nearly impossible to replicate in a laboratory setting. For this study, sulfate and sulfuric acid attack on concrete were studied to mimic two stages of the MIC process. The ASTM C1012, Standard Test Method for Length Change of Hydraulic-Cement Mortars Exposed to a Sulfate Solution and a modified ASTM C1012 accelerated method were used to compare the sulfate resistance of belitic calcium sulfoaluminate (BCSA) cement, portland cement (PC), and PC-fly …

Analysis Of Shear-Strength In Weathered Shale Strata Along A Highway Slope Failure Site In Northwest Arkansas, Olivia Overton

Civil Engineering Undergraduate Honors Theses

Slope failures cost millions of dollars per year to repair and can be deadly. Accurate modeling of slope conditions, including soil parameters, water table locations, and depth to bedrock, are essential to determining the overall stability of a slope. This project is a continuation of the work completed in 2019 by a former University of Arkansas researcher, Vanessa LeBow. LeBow RocScience used Slide2 modeling software to model two highway embankment slopes in Northwest Arkansas that experienced slope movement to determine whether increased use of geophysical data could increase the accuracy of slope stability models. A parametric study of shear strengths …

Low Impact Development: Low-Maintenance Design To Encourage Residential Adoption Of Sustainable Systems, Haley Ellis

Biological and Agricultural Engineering Undergraduate Honors Theses

Residential adoption of low-impact development (LID) technology can positively impact downstream watershed hydrology by reducing total volumetric discharge from the residential site. This reduction can provide economic, environmental, and social benefits for the residents as well as the community at large. Additionally, homeowners are often affected by stormwater related issues, like flooding or washout, that could be easily mitigated with a sustainably engineered LID structure or network. Engineering for sustainability often includes the blending of several objectives to provide greater overall benefit. This thesis compares the outflow characteristics of three low-maintenance residential LID design scenarios differing in rain garden soil …

Surface Modified Polypropylene Membranes For Treating Hydraulic Fracturing Produced Waters By Membrane Distillation, Tharaka Hawpe Gamage

Graduate Theses and Dissertations

Membrane distillation is an emerging technology for treating hydraulic fracturing flowback and produced waters. Suppression of membrane fouling by inorganic and polar and non-polar organic compounds is a challenge. Here polyhydroxyethyl methacrylate, polyacrylic acid, polvinylallyl imidazolium bromide and polyvinylhexyl imidazolium bromide chains have been grafted from the membrane surface. Fouling is initially due to adsorption of organic compounds followed by scale formation. When challenged with produced water, membranes modified with polvinylallyl imidazolium bromide chains provided the greatest resistance to fouling. For EC pretreated produced water and synthetic produced water that contained mainly inorganic species, the flux decline was much less.

Moisture Monitoring Of A Clt Structure In A Southern Climate, Elizabeth Poblete

Graduate Theses and Dissertations

Understanding of moisture behavior in cross laminated timber (CLT) is critical to the widespread use of CLT in construction in the United States. Currently, very little data exists on the long-term impact of moisture on CLT. The objective of this research is to collect data regarding the long-term moisture variation in the CLT panel at the University of Arkansas Adohi Hall residence hall. The climate of Northwest Arkansas is different from previously monitored buildings, as they were in the Pacific Northwest. Comparatively, Northwest Arkansas has a warmer climate with higher average annual precipitation. Waterproofing efforts are usually employed to prevent …

Irrigation Design In Montana: Accommodating Varying Water Accessibility Across The Continental Divide., John Garrett Lampson

Biological and Agricultural Engineering Undergraduate Honors Theses

The design work performed in this project was conducted over two summers (2018, 2019) of internship experience with the Natural Resources Conservation Service (NRCS) across the state of Montana. The first summer’s design work was based out of Glendive, MT, in Dawson County, approximately 50 kilometers from the North Dakota border. The second summer was in Missoula, MT, in Missoula County, near the Idaho border. The two areas differ significantly in topography, weather, and water availability with the main separating geographic influence being the Rocky Mountains.

This paper focuses on the design process and requirements for two farms located outside …

Discovering Synergies Among Sustainable Rating Systems In Green Roof Analysis, Kanaan Hardaway

Biological and Agricultural Engineering Undergraduate Honors Theses

As awareness has grown of the impacts the built environment has on the natural environment and the human psyche, methods to create more sustainable living environment have been developed. Green infrastructure is well-known for its environmental benefits. Emerging literature suggests green infrastructure have aesthetic qualities conducive to mental restoration, as well. To analyze the multi-benefits of green infrastructure, a green roof is studied for its aesthetic qualities and its impact on LEED, SITES, and WELL certification. A questionnaire was administered to individuals on the University of Arkansas campus to quantify human perceptions and attitudes toward a green roof on a …

Cytotoxicity And Mutagenicity Of Disinfection Byproduct Mixtures Formulated Using Free Chlorine And Monochloramine, Yonas Ghebremedhin

Graduate Theses and Dissertations

Bioassays have been used extensively to assess various toxicity endpoints of drinking water disinfection byproducts (DBPs), but an emphasis on single compounds prevails. In this research, DBP mixtures were assessed using a cytotoxicity test with Chinese Hamster Ovary (CHO) cells and an Ames fluctuation test with Salmonella typhimurium TA-98 and TA-100 with and without S9 rat liver homogenate. Seven whole mixture DBP concentrates were formulated using reconstituted natural organic matter (NOM) extracts from the Upper Mississippi River using scaled disinfectant dosing protocols with free chlorine and monochloramine in the presence and absence of added bromide. DBPs were identified by gas …

Silver-Based Microbial Check Valve For Spacecraft Potable Water Systems, Tanner Burns

Chemical Engineering Undergraduate Honors Theses

As human space exploration increases, the development of a more efficient potable water treatment system suited for spacecraft becomes crucial. This Waste-management Education Research Consortium (WERC) challenge was designed to explore the viability of microbial control through the utilization of silver ions as a biocide for possible integration into the Tranquility Node 3 water purification system aboard the International Space Station (ISS). Current systems using iodine risk causing hyperthyroidism from overexposure; however, silver can be safely ingested without this side effect. After researching silver delivery methods including electrochemical ion production, controlled release, or a combination of the two, our team …