Environmental Engineering Commons^™

Evaluation And Calibration Of Coupled Low-Cost Particulate Matter Sensors, Tyler Cargill

McKelvey School of Engineering Graduate Student Theses & Dissertations

Low-cost sensors (LCS), if used appropriately, are useful instruments to elucidate human exposure to particles suspended in the air (i.e. particulate matter, PM). Characterizing this exposure is crucial, as exposure to PM2.5 (i.e. particles with aerodynamic diameter ≤ 2.5 μm) negatively affects the respiratory, cardiovascular, and other organ systems and is the leading environmental burden for global mortality. Similarly, exposure to particles with aerodynamic diameters greater than 2.5 μm and less than or equal to 10 μm, here forth termed as PMCoarse, is known to cause health ailments for the upper respiratory system. This dissertation focuses on the MODULAIRTM-PM (MOD-PM), …

Enhancing Aerosol Scattering Measurements: Performance Evaluation And Quality Assurance Of Airphoton Integrating Nephelometers In The Surface Particulate Matter Network, Kamlendra Singh Pathak

McKelvey School of Engineering Graduate Student Theses & Dissertations

Integrating nephelometers are key instruments for quantifying aerosol light scattering, a fundamental parameter governing the direct radiative effect of aerosols on climate and visibility, and for interpreting satellite observations of aerosol optical depth. The AirPhoton integrating nephelometer quantifies aerosol light scattering by measuring total scattering from the sample air and subtracting a clean-air reference that represents Rayleigh scattering, instrument wall scattering, and detector background noise. Measurement accuracy depends on rigorous calibration and regular performance evaluation to account for instrumental drift and environmental influences. This study presents a field performance evaluation of the AirPhoton integrating nephelometer within the global Surface Particulate …

Developing Aerosol Representation In Atmospheric Modeling, Inderjeet Singh

McKelvey School of Engineering Graduate Student Theses & Dissertations

Ambient aerosols affect climate and air quality in the Earth system. Global chemical transport models used to study these impacts require an accurate representation of aerosols in terms of shape, composition, and vertical distribution. For example, despite having a complex morphology, mineral dust is often treated as spherical particles in these models. This can lead to errors in optical properties calculations, trace gas retrievals, and heterogeneous chemistry. Similarly, inaccurate representation of the vertical distribution of smoke particles in these models can lead to uncertainties in air quality assessments. Aerosol composition also plays a critical role in determining radiative forcing and …

Photolysis Of Emerging Agricultural Applications Under Environmental Conditions, Kun-Pu Ho

McKelvey School of Engineering Graduate Student Theses & Dissertations

Novel agricultural applications are rapidly emerging to protect crops from weeds or pests in the US and worldwide. Isoxaflutole is a proherbicide considered agriculturally significant because it controls weeds that have developed resistance to other commonly used herbicides. In addition, RNA interference (RNAi) technology is regarded as a next-generation biopesticide because the technology has less toxicity to humans and more specificity to pests than traditional pesticides, which pose risks to the environment and the health of humans and livestock. However, we cannot disregard the possible risks of the emerging proherbicides and biopesticides to humans or non-target organisms. Therefore, the study …

Improving Particle-Phase Nitrate Measurement In Pm2.5 Filter Sampling: Evaluation Of A Denuder–Nylon Filter Modification In The Spartan Network, Wenyu Liu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Accurate measurement of PM_2.5 composition is of global importance. Evaporation-induced mass loss introduces potential bias in filter-based PM_2.5 measurements, with ammonium nitrate volatilization from Teflon filters being a major contributor to negative mass artifacts. Previous studies have demonstrated that using an acid gas denuder in combination with nylon filters can help recover the nitrate mass. This study evaluates design modifications to the AirPhoton sampling station setup within the globally distributed Surface Particulate Matter Network (SPARTAN) incorporating an additional acid gas denuder upstream and a nylon filter downstream of the existing Teflon filter.

Two co-located AirPhoton Sampling stations were …

Impacts Of Phosphate And Residual Free Chlorine On The Precipitation, Stability And Dissolution Of Lead Corrosion Products, Yao Ma

McKelvey School of Engineering Graduate Student Theses & Dissertations

Lead release from lead pipes into drinking water is a critical threat to public health. Orthophosphate addition is an established method of controlling lead concentrations in tap water. Many phosphate-based inhibitors currently used by utilities are blends of orthophosphate and polyphosphate. Orthophosphate can limit lead release from pipes by forming low-solubility lead phosphate solids on pipe inner surfaces. In contrast, polyphosphate can accelerate lead release by forming soluble lead-phosphate complexes. Due to the potential conversion from polyphosphate to orthophosphate in the distribution system and to complex dynamics of water chemistry in lead service lines (LSLs), the net impact of a …

Coupling Treatment Technologies With Bioelectrochemical Systems To Optimize Resource Recovery From Wastewater, Matthew Stephen Ferby

McKelvey School of Engineering Graduate Student Theses & Dissertations

Wastewater is a common waste produced from municipal, agricultural, and industrial processes. As the world’s population increases, the amount of wastewater produced globally is expected to reach approximately 450 billion m3 in the next two decades. Issues surrounding water, food, and energy accessibility will also become more imminent as the population grows. Interestingly, wastewater is an unconventional source of resources including water, nutrients (e.g., NH4+ and PO43-), and energy. However, conventional wastewater treatment processes focus primarily on the removal of containments rather than the recovery of resources. Bioelectrochemical systems (BES) have the ability to recover resources from wastewater. These engineered …

Exploring Applications Of Artificial Intelligence In Water And Wastewater Management Systems, Yanran Xu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Water and wastewater management systems play an essential role in satisfying residential, commercial, and industrial needs, but these systems suffer from undesired issues and high expenses, which stresses the need for sustainable development and system optimization. Modeling simulation is commonly used to optimize system performance through process prediction and precise control, and artificial intelligence (AI) technologies including machine learning (ML) and deep learning (DL) are showing their advantages in the application of water and wastewater management systems. A general framework was illustrated for optimized performance and enhanced explainability of ML models. Several analytical techniques were explored, including feature engineering, data …

Ammonia Recovery From Digester Centrate With Electrochemical Membrane Systems: Mechanism, Performance, And Application, Fubin Liu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Nitrogen plays an indispensable role in living organisms and thus is a key element for agricultural production. Ammonia (NH3), as an important part in nitrogen cycle, can be synthesized by nitrogen fixing bacteria and the Haber-Bosch process, the latter of which requires an extensive energy input. Wastewaters can contain a large amount of nitrogen compounds because of kitchen and toilet wastes being discharged to sewage. The concentration of ammonia nitrogen (NH4+-N) can be hundreds mg per liter in some wastewaters like anaerobic digester (AD) centrate. However, both Haber-Bosch process and conventional wastewater ammonia treatment process are energy intensive, which making …

Electrochemical Phosphorus Recovery From The Anaerobically Digested Sludge: Mechanism, Performance, Application, And Solids Disposal, Zixuan Wang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Phosphorus (P) is life’s bottleneck element and an essential nutrient for food production. However, phosphate rock is a non-renewable resource and its geological distribution is highly uneven, making P recovery a crucial step for a circular economy. Approximately 55% of mined phosphorus ends up in centralized wastewater treatment plants (WWTPs), where up to 90% is captured in the sludge. This sludge, treated in anaerobic digesters to produce anaerobically digested sludge (ADS), emerges as a viable secondary source for phosphorus recovery. Recovering phosphorus from ADS typically involves leaching and separation. Leaching mobilizes phosphates from sludge solid phase into a liquid phase, …

Commercial Adsorbents For Co2 Removal For Biogas Upgradation: An Experimental Study, Aakriti Bagla

McKelvey School of Engineering Graduate Student Theses & Dissertations

No abstract provided.

Real-Time Analysis Of Aerosol Size Distributions With The Fast Integrated Mobility Spectrometer (Fims), Daisy Wang

McKelvey School of Engineering Graduate Student Theses & Dissertations

The Fast Integrated Mobility Spectrometer (FIMS) has emerged as an innovative instrument in the aerosol science domain. It employs a spatially varying electric field to separate charged aerosol particles by their electrical mobilities. These separated particles are then enlarged through vapor condensation and imaged in real time by a high-speed CCD camera. FIMS achieves near 100% detection efficiency for particles ranging from 10 nm to 600 nm with a temporal resolution of one second. However, FIMS’ real-time capabilities are limited by an offline data analysis process. Deferring analysis until hours or days after measurement makes FIMS' capabilities less valuable for …

Persistence Of Dna From Biocontained Genetically Engineered Microbes, Wentao Dai

McKelvey School of Engineering Graduate Student Theses & Dissertations

The utilization of genetically engineered microbes in environmental systems requires effective biocontainment mechanisms to ensure their safe operation. CRISPR-based kill switches are a promising solution, inducing cell death through site-specific DNA cleavage under specific environmental conditions. In this study, we aimed to assess the impact of CRISPR-based kill switches on the abundance and persistence of bacterial DNA. Our results revealed that while CRISPR-based kill switches were capable of achieving high reductions in viable Escherichia coli Nissle 1917 (EcN); the DNA largely remained intact. This was observed in two strains of EcN: one enabled with multi-locus genome cleavage, and the other …

Fate Of Metals In Presence Of Minerals And Mineral-Organic Assemblages, Neha Sharma

McKelvey School of Engineering Graduate Student Theses & Dissertations

Metals can enter aquatic systems from natural and anthropogenic processes associated with weathering, sediment re-suspension, industrial activities, and atmospheric deposition. Metals pose health and environmental risks at high concentrations due to their potential toxicity and bioaccumulation, but many trace metals also serve as essential micronutrients for biogeochemical processes in natural aquatic systems. Biogeochemical processes such as methanogenesis, denitrification, and mercury methylation require transition metals such as nickel (Ni), cobalt (Co), copper (Cu), and molybdenum (Mo) for completion. These biogeochemical processes can be substantial contributors of greenhouse gases, such as methane (CH4) and nitrous oxide (N2O), into the atmosphere. The behavior, …

Advanced Nanomaterials And Module Designs For Efficient Photothermal Water Treatment, Deoukchen Ghim

McKelvey School of Engineering Graduate Student Theses & Dissertations

Water scarcity is one of the most serious challenges that human beings face, and the demand for clean water will continuously increase as populations grow. Creating potable water from saline water is an important way to meet global freshwater demands. However, current desalination techniques require high energy consumption and a large scale to be efficient, restricting their utilization in remote and underdeveloped areas. These constraints motivate the development of sustainable water treatment methods that can be used with less energy input, in small modular configurations, and in off-grid water treatment systems. As an abundant and renewable energy source, sunlight has …

The Generation And Transport Of Charged Aerosols: Fundamental Study And Applications In Medicine And Energy Conversion, Hao Zhou

McKelvey School of Engineering Graduate Student Theses & Dissertations

Charged aerosols have significant implications in the field of functional material synthesis, pharmaceutical coating, and drug delivery. Electrospray systems are an effective methodology for generating highly charged monodispersed droplets in the size range from nanometer to micrometer. The prediction of surface charge, size and morphology of nanoparticles resulting from charged droplets are highly required for the precise control of nanoparticle properties and their effective utilization. However, the evolution of charged droplet is not well understood due to the existence of coulombic fission and ion evaporation processes. Thus, the goal of this dissertation is to elucidate how the precursor properties and …

Nanoscale Interfacial Control Of Ion Behaviors And Caco3 Formation In Environmental Systems, Yaguang Zhu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Interfaces in environmental systems can change the distribution of pollutants and nutrients, determine the fate and transport of nanoparticles, and affect the efficiency of engineering projects. Complex interactions, including electrostatic interactions, Van der Waals interactions, chemical interactions, and ion-surface specific interactions, can all contribute to different ion, ion-pair, and nanoparticle formations near interfaces. Although environmental interfaces play critical roles, only a limited number of studies have considered the nanoscale picture of how they control ions and nanoparticles. Thus, this dissertation addresses three research questions: (1) How does sulfate chemically interact with calcium carbonate (CaCO3) during its heterogeneous formation on quartz …

Role Of Water Chemistry In Lead Release During Drinking Water Supply And Augmentation, Anushka Mishrra

McKelvey School of Engineering Graduate Student Theses & Dissertations

Lead is a toxic heavy metal and legacy contaminant in drinking water that can be released from lead service lines and lead-containing premise plumbing. Lead concentrations in water are sensitive to changes in water chemistry. The extent of lead release is often driven by the solubility of the corrosion products formed on the interior of the pipes. Therefore, it is critical to advance our understanding of the extent of lead released from different lead-based plumbing materials at equilibrium and the ability to control lead when it exceeds the regulatory levels. Lead measured in the 1st liter of water collected from …

Photochemical Formation Mechanisms And Applications Of Mn Oxide Nanomaterials, Zhenwei Gao

McKelvey School of Engineering Graduate Student Theses & Dissertations

Manganese (Mn) oxides are ubiquitous in aquatic and terrestrial environments, and the rich redox chemistry of manganese is of interest in engineered systems, such as batteries and water oxidation catalysts. Mn oxides have large surface areas and are highly active in adsorption and redox reactions. Our research group recently reported photochemically-assisted abiotic inorganic oxidation of Mn2+(aq) to δ-MnO2 nanosheets in the presence of nitrate and without a microorganism, demonstrating that abiotic Mn oxidation processes are not negligible. My doctoral work focuses on investigating the effects of various aquatic chemistry parameters, including reactive oxygen species (ROS), peroxyl radical (ROO•), reactive halogen …

Nano-Bio Interactions: Implications And Applications, Anushree Ghosh

McKelvey School of Engineering Graduate Student Theses & Dissertations

Rapid expansion of technology development at the nanoscale has underpinned a promising industry. Towards this, there remain significant information gaps which are critical with regard to decision making processes and ultimate industrial sustainability. From an implication point of view, understanding how common biological macromolecules, including glycolipids and/or biopolymers produced by bacteria and fungi, which are ubiquitous in the environment, is fundamental to predicting the behavior of released/produced nanoparticles. Conversely, other bio-based tailored macromolecules, including mussel foot protein (MFP), have significant potential as functional material coatings for advanced applications.This PhD thesis is focused on interfacial processes related to superparamagnetic iron oxide …

Calcium Bearing Mineral-Hydrogel Composites For Phosphate Removal And Recovery, Albern Xuan-Wei Tan

McKelvey School of Engineering Graduate Student Theses & Dissertations

The millions of tons of phosphate rock ore mined every year for use as phosphorus fertilizer have created two challenges. First, phosphate rock is a mined, non-renewable resource that is also heavily geographically concentrated, raising concerns about the long-term sustainability and availability of phosphorus. Second, after it is applied as a fertilizer, phosphorus will also be released to the broader environment. There, it contributes to harmful algal blooms and eutrophication, which threaten surface water quality and can harm aquatic ecosystems and the communities and industries that rely on them. These considerations motivate the coupled development of techniques for removing and …

Advancements In Pressurized Oxy-Combustion Process: Pollutant Control And Process Development, Piyush Kumar Verma

McKelvey School of Engineering Graduate Student Theses & Dissertations

The emission of carbon dioxide from the power industry is one of the major causes of climate change. However, it is well established that the development of human societies across the globe depends on reliable and dispatchable power, which are generally the source of these emissions. There has been a recent growth in the integration of intermittent sources such as wind and solar which are carbon free. But these intermittent sources have significant temporal changes in power production and thus lack reliability and dispatchablity. This is a complicated problem to solve. However, flexible power plants with carbon capture and storage, …

Droplet And Particle Dynamics In Aerosol Reactors And Environmental System, Sukrant Dhawan

McKelvey School of Engineering Graduate Student Theses & Dissertations

Aerosol science and engineering is an enabler for continual advances in nanomaterial synthesis. The spray-based techniques have been used extensively for the large-scale production of nanoparticles. Synthesis of particles with a desired the size and morphology is of key importance for exploiting their properties for their use in several emerging technologies. In contrast to useful nanomaterials, the aerosols from industrial flue gas, dust, indoor cooking, pathogens, and wildfire etc. are harmful to human health. It is important to understand how these harmful aerosols travel through the environment and potentially impact the health. It is also very critical to improve the …

Interaction Of Aqueous U(Vi) With Goethite, Montmorillonite, And Uo2(S), Anshuman Satpathy

McKelvey School of Engineering Graduate Student Theses & Dissertations

Uranium contamination in subsurface environments is a matter of great concern throughout the world. Fate and transport of uranium in the subsurface can be controlled by U(VI) adsorption and reduction onto common iron (oxy)hydroxides and clay minerals. Aqueous U(VI) can also exchange uranium atoms with solids comprised of uranium which can potentially lead to changes in the morphology of the uranium-containing solids and affect their stability. First, the performance of multiple surface complexation models (SCMs) on adsorption of U(VI) onto goethite was analyzed for a broad range of input conditions. Individual models could fit the data for which they were …

Advanced Materials For Air Pollutants Removal In A Combustion System, Sungyoon Jung

McKelvey School of Engineering Graduate Student Theses & Dissertations

Air pollutants directly or indirectly impact human health and the environment. Large quantities of CO2, volatile organic compounds (VOCs), and particulate matter are emitted from combustion systems, and cause climate change, smog formation, and pose serious health risks. The increasing demand for the remediation of air pollutants at the source has drawn much attention to the use of advanced materials due to their high reactivities and special properties. In order to achieve the successful application of advanced materials for the remediation of problematic emissions, three aspects, (1) synthesis method, (2) characterization of materials’ structural properties, and (3) evaluation of materials’ …

Particle Studies In The Lab And Pilot-Scale Coal Combustion Systems, Dishant Khatri

McKelvey School of Engineering Graduate Student Theses & Dissertations

In the past century, coal contributed more to the global electricity supply than any other source. Currently, it alone accounts for over 35% of the global electricity supply. Though coal is globally well-distributed and can provide cheap, stable, and reliable energy on demand, it emits a large amount of carbon dioxide—a greenhouse gas responsible for global warming. Additionally, it is a major source of particulate matter (PM) pollution. Thus, in recent years, to reduce the impact of coal on climate, several policies have been introduced to phase out coal. However, replacing coal with intermittent renewables has led to a reduction …

Development Of Novel Instrumentation And Methods To Investigate The Composition And Phase Partitioning Of Semivolatile And Intermediately Volatile Organic Compounds In Atmospheric Organic Aerosol, Claire Fortenberry

McKelvey School of Engineering Graduate Student Theses & Dissertations

Atmospheric particulate matter (PM) is ubiquitous in both indoor and outdoor air and is generally detrimental to human health. PM composed of particles with aerodynamic diameters less than 2.5 um (PM2.5) are related to adverse health outcomes including heart disease and respiratory disease. Fundamentally, particle physical properties such as size and hygroscopicity are dictated by chemical composition, which can be highly complex, particularly for organic aerosol (OA). In both outdoor and indoor air, OA is composed substantially of intermediately volatile and semivolatile organic compounds (I/SVOCs), which exist in both gas and particle phases under typical atmospheric conditions. The distribution of …

Chemistry Of Nanoscale Solids And Organic Matter In Sustainable Water Management Systems, Xuanhao Wu

McKelvey School of Engineering Graduate Student Theses & Dissertations

To alleviate global water scarcity and improve public health, engineered water treatment and management systems have been developed for purifying contaminated water and desalinating brackish or ocean water. These engineered systems provide substantial amounts of potable water and lessen environmental concerns about the release of contaminated water. Wastewater treatment plants (WWTPs), water desalination plants (WDPs), and managed aquifer recharge systems (MARs) are three representative sustainable water management (SWM) systems. But the operation of all three poses two fundamental questions: (1) What is the fate of nanoscale solids (e.g., engineered nanomaterials, naturally occurring nanoparticles) in SWM systems and how will their …

Contemporary Problems In Aerosol Aggregation And Gelation, Pai Liu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Aggregation of nanoparticles in aerosols is a fundamental phenomenon with important implications to diverse fields ranging from material synthesis to pollutant control. The past few decades have witnessed extensive research on investigating the structure and growth mechanism of aerosol aggregates with sizes spanning across several orders of magnitude. This dissertation focuses on some contemporary problems that remain unaddressed in this topical area. Aerosol aggregates in sub-micron regimes, which are formed via the irreversible collision and aggregation of solid nanoparticle monomers, are fractal-like in their morphology. A mathematical description of this seemingly random structure dates to the seminal works by Forest …

Modeling The Effects Of Distribution System Topology On Water Quality, Chun-Ying Chao

McKelvey School of Engineering Graduate Student Theses & Dissertations

Inadequate treatment of drinking water causes the formation of disinfection by-products and the regrowth of harmful microbial species. Various studies have addressed the problem of water quality monitoring, but very few have employed topological analysis, a valuable mathematical tool widely applied in biological, business, and social research. This thesis examines the relationship between the topological properties of water distribution systems and water-quality models. In particular, the research proposes a novel framework for mapping network topological attributes to water-quality models. This research adopts topological metrics to assess the accuracy of the predictions of chlorine concentrations in dead ends. It examines four …