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- Creators: Arizona State University
- Creators: Byrd, Andrew
Description
As the use of engineered nanomaterials (ENMs) in consumer products becomes more common, the amount of ENMs entering wastewater treatment plants (WWTPs) increases. Investigating the fate of ENMs in WWTPs is critical for risk assessment and pollution control. The objectives of this dissertation were to (1) quantify and characterize titanium (Ti) in full-scale wastewater treatment plants, (2) quantify sorption of different ENMs to wastewater biomass in laboratory-scale batch reactors, (3) evaluate the use of a standard, soluble-pollutant sorption test method for quantifying ENM interaction with wastewater biomass, and (4) develop a mechanistic model of a biological wastewater treatment reactor to serve as the basis for modeling nanomaterial fate in WWTPs. Using titanium (Ti) as a model material for the fate of ENMs in WWTPs, Ti concentrations were measured in 10 municipal WWTPs. Ti concentrations in pant influent ranged from 181 to 3000 µg/L, and more than 96% of Ti was removed, with effluent Ti concentrations being less than 25 µg/L. Ti removed from wastewater accumulated in solids at concentrations ranging from 1 to 6 µg Ti/mg solids. Using transmission electron microscopy, spherical titanium oxide nanoparticles with diameters ranging from 4 to 30 nm were found in WWTP effluents, evidence that some nanoscale particles will pass through WWTPs and enter aquatic systems. Batch experiments were conducted to quantify sorption of different ENM types to activated sludge. Percentages of sorption to 400 mg TSS/L biomass ranged from about 10 to 90%, depending on the ENM material and functionalization. Natural organic matter, surfactants, and proteins had a stabilizing effect on most of the ENMs tested. The United States Environmental Protection Agency's standard sorption testing method (OPPTS 835.1110) used for soluble compounds was found to be inapplicable to ENMs, as freeze-dried activated sludge transforms ENMs into stable particles in suspension. In conjunction with experiments, we created a mechanistic model of the microbiological processes in membrane bioreactors to predict MBR, extended and modified this model to predict the fate of soluble micropollutants, and then discussed how the micropollutant fate model could be used to predict the fate of nanomaterials in wastewater treatment plants.
ContributorsKiser, Mehlika Ayla (Author) / Westerhoff, Paul K (Thesis advisor) / Rittmann, Bruce E. (Committee member) / Hristovski, Kiril D (Committee member) / Arizona State University (Publisher)
Created2011
Description
Several decades of research have concluded that child social functioning is a critical predictor of wellbeing across various developmental domains. Most scientists agree that both genetic and environmental influences play defining roles in social behavior; the processes by which they concurrently affect child development, however, has been the subject of less research. This work examines distinct mechanisms that shape child prosociality by examining genetic and environmental influences on development, via two empirical studies. The first study analyzed the evocative-reactive and the evocative-socially-mediated hypotheses as gene-environment correlation (rGE) mechanisms connecting the arginine vasopressin receptor 1a (AVPR1a) and dopamine receptor D2 (DRD2) genes, child prosocial behavior, and parent differential treatment (PDT). Findings present modest evidence for the evocative-reactive rGE hypothesis; specifically, AVPR1a marginally influenced child prosociality, which subsequently predicted mother preference in adolescence. The second study examined several gene-environment interactions (GxEs) in exploring how social environmental variables- positive and negative parenting- predicted child prosociality, as moderated by socially-implicated child genes, DRD2 and dopamine receptor D4 (DRD4). Findings indicated that while positive parenting was predictive of child prosociality regardless of genetic variants, the effects of negative parenting on child prosociality were dependent on child genetic variants. Together, findings from these studies suggest modest genetic and environmental influences on child behavior in middle childhood and adolescence, consistent with previous research and theory. Directions for future research are offered, and intervention and policy implications are discussed.
ContributorsMeek, Shantel E (Author) / Jahromi, Laudan B (Thesis advisor) / Lemery-Chalfant, Kathryn (Thesis advisor) / Valiente, Carlos (Committee member) / Iida, Masumi (Committee member) / Arizona State University (Publisher)
Created2013
Description
The Santa Cruz River, in southern Arizona, receives steady inputs of nutrient-enriched treated wastewater (effluent). Previous studies have documented reduced infiltration of surface water in the river. This disruption of hydrologic connectivity, or clogging, can have consequences for groundwater recharge, flows of wastewater in unwanted locations, and potentially even survivorship of floodplain riparian vegetation. Clogging can result from biotic processes (microbial or algal growth), abiotic processes (siltation of interstitial spaces), or both. Little is known about clogging in rivers and the environmental factors that regulate their dynamics, so natural field experiments along the Santa Cruz and San Pedro Rivers were used to answer: 1) Are there spatial patterns of hydraulic conductivity in the riverbed downstream from the effluent point-source? 2) Is there temporal variability in hydraulic conductivity and microbial abundance associated with flooding? 3) Are there environmental variables, such as nutrients or stream flow, related to differences in hydraulic conductivity and microbial abundance? To address these questions, a series of sites at increasing distance from two municipal effluent discharge points with differing water quality were selected on the Santa Cruz River and compared with non-effluent control reaches of the San Pedro River. Physical, chemical, and biological parameters were monitored over one year to capture seasonal changes and flood cycles.
ContributorsCase, Natalie (Author) / Stromberg, Juliet (Thesis advisor) / Rock, Channah (Committee member) / Meixner, Thomas (Committee member) / Arizona State University (Publisher)
Created2012
Description
ABSTRACT Fruit and vegetable intake is not uniform across levels of socioeconomic status (SES) and researchers have identified low SES as a risk factor for poor intake of fruits and vegetables. In an effort to eliminate public health disparities and increase fruit and vegetable intake, the Women, Infant, and Children (WIC) program implemented additional food assistance programs, with a specific emphasis on fresh fruits and vegetables. The Farmers' Market Nutrition Program (FMNP) provides pre-existing WIC clients with coupons to purchase fresh, locally grown produce at farmers' markets. In addition, Congress also approved the WIC Cash Value Voucher (CVV) program, which provides WIC participants with vouchers to purchase fresh fruits and vegetables at farmers' markets or grocery stores. The purpose of this thesis was to investigate the relation of FMNP coupon use with accessibility and WIC CVV redemption rates at farmers' markets. Furthermore, this thesis addressed whether WIC shoppers redeemed a higher percentage of their WIC CVV value at farmers' markets or grocery stores. WIC CVV and FMNP issuance and redemption data were analyzed to establish overall redemption rates and total perecent of WIC CVV value redeemed. Accessibility was assessed using the Geographic Information System, which allowed me to calculate the distance that WIC participants would have to travel to redeem their FMNP coupons at FMNP-approved farmers' markets. The results showed that less than 1% of WIC shoppers redeem their WIC CVVs at farmers'markets in Arizona. However, the redemption of WIC CVV was significantly higher during the months when shoppers had the option of using both WIC CVV and FMNP coupons at farmers' markets. Furthermore, the percent of total CVV value redeemed at farmers' markets was 99%, significantly higher than grocery stores (93.5%). Average FMNP coupon redemption rates for 2008-2010 was 43.3%, well below the national average of 59%. However, my spatial analysis revealed that there was no significant association between the distance traveled to farmers' markets and FMNP redemption rates. This indicates that the distance traveled to farmers' markets is not a major barrier to redemption of FMNP coupons in Arizona.
ContributorsTucker, Wesley Jack (Author) / Wharton, Christopher (Christopher Mack), 1977- (Thesis advisor) / Vaughan, Linda (Committee member) / Johnston, Carol S (Committee member) / Arizona State University (Publisher)
Created2012
Description
Corrosion is known to have severe infrastructure integrity implications in a broad range of industries including water and wastewater treatment and reclamation. In the U.S. alone, the total losses due to corrosion in drinking water and wastewater systems can account for economic losses as high as $80 billion dollars a year. Microbially induced corrosion is a complex phenomenon which involve various phases; 1) formation of biofilms on submerged surfaces, 2) creation of micro-environmental niches associated with biofilm growth, 3) altered availability nutrients, 4) changes in the pH and oxygen concentrations. Biofilms can harbor opportunistic or pathogenic bacteria for a long time increasing the risk of pathogen exposure for the end users. The focus of this thesis research was to study the kinetics of microbially induced corrosion of various materials in water and reclaimed water systems. The specific objective was to assess the biofilms formation potential on stainless steel 304, stainless steel 316, galvanized steel, copper, cPVC, glass, carbon steel, and cast iron in water and reclaimed water systems. Experiments were conducted using bioreactor containers, each bioreactor housed four sampling boxes with eight partitions, dedicated to each material type coupon. One bioreactor was stationed at ASU, and one at Vistancia Aquifer Storage and Recovery (ASR) well; while three bioreactors were stationed at Butler facility, at pre-disinfection, post-UV and post-chlorination. From each location, one submerged sampling box was retrieved after 1, 3, 6 and 12 months. Time series of biofilm samples recovered from various types of coupons from different locations were analyzed using physical and culture-based techniques for quantification of biofilms and detection of heterotrophic plate count (HPC) bacteria, Legionella, Mycobacterium, and sulfate reducing bacteria (SRB).
After one-year, galvanized steel had the highest concentration of HPC at 4.27 logs while copper had the lowest concentration of 3.08 logs of HPC. Bacterial growth data collected from the SRB tests was compiled to develop a numerical matrix using growth potential, biofilm formation potential and metal reduction potential of SRB isolates. This risk assessment matrix can be a useful tool for the water industry to evaluate the potential risk of MIC in their systems.
ContributorsNeal, Amber (Author) / Abbaszadegan, Morteza (Thesis advisor) / Fox, Peter (Committee member) / Alum, Absar (Committee member) / Arizona State University (Publisher)
Created2022
Description
With the acceleration of urbanization in many parts of the world, transportation challenges such as traffic congestion, increasing carbon emissions, and the “first/last-mile” connectivity problems for commuter travel have arisen. Transport experts and policymakers have proposed shared transportation, such as dockless e-scooters and bike-sharing programs, to solve some of these urban transportation issues. In cities with high population densities, multimodal mobility hubs designed to integrate shared and public transportation can be implemented to achieve faster public connections and thus increase access to public transport on both access and egress sides. However, haphazard drop-offs of these dockless vehicles have led to complaints from community members and motivated the need for neighborhood-level parking areas (NLPAs). Simultaneously, concerns about the equitable distribution of transportation infrastructure have been growing and have led to the Biden Administration announcing the Justice40 Initiative which requires 40% of certain federal investments to benefit disadvantaged communities. To plan a system of NLPAs to address not only the transportation shortcomings while elevating these recent equity goals, this thesis develops a multi-objective optimal facility location model that maximizes coverage of both residential areas and transit stations while including a novel constraint to satisfy the requirements of Justice40. The model is applied to the City of Tempe, Arizona, and uses GIS data and spatial analyses of the existing public transportation stops, estimates of transit station boardings, population by census block, and locations of disadvantaged communities to optimize NLPA location. The model generates Pareto optimal tradeoff curves for different numbers of NLPAs to find the non-dominated solutions for the coverage of population nodes and boardings. The analysis solves the multi-objective model with and without the equity constraint, showing the effect of considering equity in developing a multimodal hub system, especially for disadvantaged communities. The proposed model can provide a decision support tool for transport and public authorities to plan future investments and facilitate multimodal transport.
ContributorsQuan, Hejun (Author) / Kuby, Michael (Thesis advisor) / Frazier, Amy (Thesis advisor) / Tong, Daoqin (Committee member) / Arizona State University (Publisher)
Created2022
Description
Pathogens can proliferate in the built environment and can cause disease outbreaks if water and wastewater are not properly managed. Understanding pathogens that grow in engineered systems is crucial to protecting public health and preventing disease. Using dynamic computational models can reveal mechanistic insights into these systems to aid in understanding risk drivers and determining risk management strategies. The first research chapter of this thesis investigates tradeoffs for reducing the cost associated with Legionnaire’s Disease, hot water scalding, and energy use using a computational framework for evaluating an optimal water heater temperature set point. The model demonstrated that the optimal temperature set point was highly dependent on assumptions made regarding the dose response parameter for a common configuration of an electric water heater in a hospital setting. The optimal temperature was 55°C or 48°C for subclinical vs. clinical severity dose response, respectively, compared with current recommendations of 60°C to kill bacteria and 49°C to prevent scalding and conserve energy.
The second research chapter models the population dynamics of antibiotic-susceptible Escherichia coli (E. coli) and antibiotic-resistant E. coli with a population ecology-exposure assessment model in surface water to quantify the risk of urinary tract infection from recreational swimming activities. Horizontal gene transfer (HGT) was modeled in the environment and the human gastrointestinal tract for several scenarios. HGT was generally not a dominant driver of exposure estimates compared to other factors such as growth and dilution, however, the rank order of factors was scenario-dependent.
The final research chapter models pathogen transport from wastewater treatment plant (WWTP) exposures and assesses the risk to workers based on several exposure scenarios. Case studies were performed to investigate infection risk drivers across different scenarios, including adjustments for the timing of exposure and personal protective equipment. A web application was developed for use by WWTP risk managers to be used with site-specific data.
The proposed modeling frameworks identified risk drivers across several microbial risk scenarios and provide flexible tools for risk managers to use when making water treatment and use decisions for water management plans used for premise plumbing as well as for wastewater treatment practices.
ContributorsHeida, Ashley (Author) / Hamilton, Kerry (Thesis advisor) / Garcia, Margared (Committee member) / Muenich, Rebecca (Committee member) / Wilson, Amanda (Committee member) / Arizona State University (Publisher)
Created2023
Description
Energy can be harvested from wastewater using microbial fuel cells (MFC). In order to increase power generation, MFCs can be scaled-up. The MFCs are designed with two air cathodes and two anode electrodes. The limiting electrode for power generation is the cathode and in order to maximize power, the cathodes were made out of a C-N-Fe catalyst and a polytetrafluoroethylene binder which had a higher current production at -3.2 mA/cm2 than previous carbon felt cathodes at -0.15 mA/cm2 at a potential of -0.29 V. Commercial microbial fuel cells from Aquacycl were tested for their power production while operating with simulated blackwater achieved an average of 5.67 mW per cell. The small MFC with the C-N-Fe catalyst and one cathode was able to generate 8.7 mW. Imitating the Aquacycl cells, the new MFC was a scaled-up version of the small MFC where the cathode surface area increased from 81 cm2 to 200 cm2. While the MFC was operating with simulated blackwater, the peak power produced was 14.8 mW, more than the smaller MFC, but only increasing in the scaled-up MFC by 1.7 when the surface area of the cathode increased by 2.46. Further long-term application can be done, as well as operating multiple MFCs in series to generate more power and improve the design.
ContributorsRussell, Andrea (Author) / Torres, Cesar (Thesis advisor) / Garcia Segura, Sergio (Committee member) / Fraser, Matthew (Committee member) / Arizona State University (Publisher)
Created2022
Description
Over thirty years after the passage of the landmark Americans with Disabilities Act (ADA), the meaning of disability accessibility and justification for accessibility measures remains unclear. Connecting work in social and political philosophy to scholarship in disability studies and disability law, this project offers an account of what access is and why access is often owed to disabled people. This project argues that disability access is necessary both for the same reasons access is considered necessary for the non-disabled, and for counteracting harmful narratives about disability and disabled people. These narratives and stereotypes originate from a particular ideology, termed “the ideology of abledness.” This ideology informs the way policies are formed and the ways they are received; it also explains why considerations of disability are often absent in general policies, and why unique provisions for disability accessibility are necessary. In its effort to clarify disability access, the project tackles difficult questions such as the nature of accessibility, issues of cost and who is obligated to pay for accessibility measures, how all people with disabilities can be included in a social contract theory, and how disability accessibility relates to and can even expand the way non-discrimination is understood.
ContributorsLevit Ades, Rachel (Author) / McGregor, Joan (Thesis advisor) / Calhoun, Cheshire (Committee member) / de Marneffe, Peter (Committee member) / Francis, Leslie (Committee member) / Arizona State University (Publisher)
Created2023
Description
Microscopic algae have been investigated extensively by researchers for decades for their ability to bioremediate wastewater and flue gas while producing valuable biomass for use as feed, fuel, fertilizer, nutraceutical, and other specialty products. Reports of the exciting commercial potential of this diverse group of organisms started appearing in the literature as early as the 1940’s. However, nearly 80 years later, relatively few successful commercial microalgae installations exist and algae have not yet reached agricultural commodity status. This dissertation examines three major bottlenecks to commercial microalgae production including lack of an efficient and economical cultivation strategy, poor management of volatile waste nutrients, and costly harvesting and post processing strategies. A chapter is devoted to each of these three areas to gain a better understanding of each bottleneck as well as strategies for overcoming them.
The first chapter demonstrates the capability of two strains of Scenedesmus acutus to grow in ultra-high-density (>10 g L-1 dry weight biomass) cultures in flat panel photobioreactors for year-round production in the desert Southwest with record volumetric biomass productivity. The advantages and efficiency of high-density cultivation are discussed. The second chapter focuses on uptake and utilization of the volatile components of wastewater: ammonia and carbon dioxide. Scenedesmus acutus was cultured on wastewater from both municipal and agricultural origin and was shown to perform significantly better on flue gas as compared to commercial grade CO2 and just as well on waste nutrients as the commonly used BG-11 laboratory culture media, all while producing up to 50% lipids of the dry weight biomass suitable for use in biodiesel. The third chapter evaluates the feasibility of using gravity sedimentation for the harvesting of the difficult-to-separate Scenedesmus acutus green algae biomass followed by microfluidization to disrupt the cells. Lipid-extracted biomass was then studied as a fertilizer for plants and shown to have similar performance to a commercially available 4-6-6 fertilizer. Based on the work from these three chapters, a summary of modifications are suggested to help current and future microalgae companies be more competitive in the marketplace with traditional agricultural commodities.
The first chapter demonstrates the capability of two strains of Scenedesmus acutus to grow in ultra-high-density (>10 g L-1 dry weight biomass) cultures in flat panel photobioreactors for year-round production in the desert Southwest with record volumetric biomass productivity. The advantages and efficiency of high-density cultivation are discussed. The second chapter focuses on uptake and utilization of the volatile components of wastewater: ammonia and carbon dioxide. Scenedesmus acutus was cultured on wastewater from both municipal and agricultural origin and was shown to perform significantly better on flue gas as compared to commercial grade CO2 and just as well on waste nutrients as the commonly used BG-11 laboratory culture media, all while producing up to 50% lipids of the dry weight biomass suitable for use in biodiesel. The third chapter evaluates the feasibility of using gravity sedimentation for the harvesting of the difficult-to-separate Scenedesmus acutus green algae biomass followed by microfluidization to disrupt the cells. Lipid-extracted biomass was then studied as a fertilizer for plants and shown to have similar performance to a commercially available 4-6-6 fertilizer. Based on the work from these three chapters, a summary of modifications are suggested to help current and future microalgae companies be more competitive in the marketplace with traditional agricultural commodities.
ContributorsWray, Joshua (Author) / Dempster, Thomas (Thesis advisor) / Roberson, Robert (Thesis advisor) / Bingham, Scott (Committee member) / Neuer, Susanne (Committee member) / Arizona State University (Publisher)
Created2019