Matching Items (50)
Description
This study investigated the difference in biofilm growth between pristine polypropylene microplastics and aged polypropylene microplastics. The microplastics were added to Tempe Town Lake water for 4 weeks. Each week the microplastic biofilms were quantified. Comparing the total biofilm counts, the results showed that the aged microplastic biofilms were larger than the pristine each week. By week 3 the aged microplastic counts had almost doubled in size increasing from 324 to 626 Colony Forming Units per gram in just one week. There was a significant difference in the diversity found from week 1 to week 4. About 40% of the diversity for the pristine microplastic biofilm was seen as light-yellow dots and about 60% of these dots were seen on the aged microplastic biofilms in both weeks. As the microplastics were submerged in the lake water, new phenotypes emerged varying from week 1 to week 4 and from pristine to aged microplastic biofilms. Generally, it was found that as the microplastics stay in the environment there is more biofilm on the particles. The aged microplastics have a larger amount of biofouling, and the pristine microplastic biofilms were found to have more diversity of phenotypes.
ContributorsMushro, Noelle Sararose (Author) / Perreault, Francois (Thesis director) / Jay, Oswald (Committee member) / Civil, Environmental and Sustainable Eng Program (Contributor) / School of Sustainable Engineering & Built Envirnmt (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Cerebral lateralization describes the asymmetries between the two halves of the brain which results in side-specialized processing of certain functions. This phenomenon provides a selective advantage by promoting enhanced cognitive abilities. However, due to the plastic nature of lateralization, an individual’s lateralization is highly subject to change by many external factors, such as pollution, throughout its life. Additionally, lateralized regions are dependent on different contexts, so lateralized elements do not all experience the same effects. A common pollutant found worldwide is bisphenol-A (BPA), a critical component of many plastics. BPA is a known endocrine disruptor that can agonize and antagonize the functions of sex steroids. Other studies have demonstrated the importance of sex steroids in regulating the development of cerebral lateralization; BPA may similarly affect lateralization. A popular research animal for studying toxicology is the zebrafish. Its advantages include a fully sequenced genome, many human orthologs, and more importantly, expresses lateralized behaviors that are indicative of the strength of its cerebral lateralization. This experiment analyzed the effects of BPA exposure on visual lateralization of zebrafish. Given the role that sex steroids play in moderating lateralization, it was hypothesized that exposing zebrafish to BPA would diminish the strength of lateralization in the brain which would translate into reduced behavioral lateralization. To test this, one group was exposed to 0.01 mg/L BPA for one week and compared against a control group in their eye preference when approaching a visual cue. Two settings, a foraging context and a social context, were utilized to examine the scope of impairment in lateralization. The control group in both settings displayed similar strengths in behavioral lateralization with a left eye preference. However, the lateralized response faded completely with BPA treatment. This experiment demonstrates that BPA induces loss of lateralization and possesses similar impacts on mechanisms controlling investigatory behavior in these two contexts. Wild populations may encounter higher concentrations of BPA, and although there is greater variability in these exposures, this experiment proves that exposure even beyond critical periods of development can impair lateralization. Additional research will have to be conducted to identify the effects of BPA on other lateralized behaviors and sensory modalities to pinpoint the exact mechanisms through which BPA influences lateralization.
ContributorsHuang, Alexander (Author) / Martins, Emilia (Thesis director) / Suriyampola, Piyumika (Committee member) / Conroy-Ben, Otakuye (Committee member) / School of Life Sciences (Contributor) / School of Molecular Sciences (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
To successfully launch and maintain a long-term colony on Mars, Martian agricultural systems need to be capable of sustaining human life without requiring expensive deliveries from Earth. There is a need for more studies on this topic to make this a feasible mission. This thesis aims to study from a high level one such agricultural system, specifically examining the requirements and flow of Nitrogen, Phosphorus and Potassium required to sustain a given human colony size. We developed a Microsoft Excel based model that relates human nutritional needs to the amount available in food crops and in turn the amount of Martian soil required for agriculture. The model works by inputting the number of humans, and then utilizing the built-in calculations and datasets to determine how much of each nutrient is needed to meet all nutritional needs of the colony. Using that information, it calculates the amount of plants needed to supply the nutrition and then calculates the amount of nutrients that would be taken from the soil. It compares the Martian regolith to the nutrient uptake, accounting for inedible biomass from the plants and human waste that can be added to the regolith. Any deficiencies are used to determine if and how much fertilizer should be added to the system initially and over time. Using the total amount of plants and the number of harvests, the amount of Martian land required for sustaining the colony is computed. These results can be used as a building block to enable the successful design of an agricultural system on Mars.
ContributorsGarland, Michael (Co-author) / Zinke, Sarah (Co-author) / Muenich, Rebecca (Thesis director) / Perreault, Francois (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
In order to produce efficient reverse osmosis membranes, it is necessary to minimize the effects of outside factors on the membrane surface that can reduce the flux of water through the membrane. One such problem is fouling. Fouling happens when particles are deposited on the membrane surface, blocking water flow through the membrane. Over time, the collection of foulants will prevent water through the membrane, increasing the amount of energy required in the system. Microgel, a heat-responsive colloidal gel, shows promise as an anti-foulant coating as it possesses functional groups similar to the membrane and compatible with common foulants and changes volume due to temperature differences. By coating the membrane with the microgel, foulants will attach to the functional groups of the microgel instead of those of the membrane Our hypothesis is that the change in volume of the microgel with different temperatures will help reduce and remove foulants. By functionalizing the surface of the membrane and the microgel, the microgel can covalently bond to the membrane surface and avoid detachment under reverse osmosis conditions. Microgel-coated reverse osmosis membranes have been fluorescently fouled to measure the decrease in foulants with heated crossflow under fluorescent microscopy. This process has shown a 50% decrease in fluorescence on the surface of the membrane indicating a decrease in foulants due to the presence of microgel. Under cross-flow conditions with a low flow rate, the microgel remains on the functionalized membrane for 8 hours with similar anti-fouling performance as the dip-coating process.
ContributorsKraetz, Andrea Nicole (Author) / Thomas, Marylaura (Thesis director) / Perreault, Francois (Committee member) / Chemical Engineering Program (Contributor) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Consumers purchase point-of-use (POU) devices to further improve the quality of water provided by the tap. As awareness increases of harmful contaminants, an emerging market of advanced POU with claims of removing beyond what a typical activated carbon filter is capable of, such as heavy metals. This research compares four commercially available pitcher filters; two that claim to remove arsenic and hexavalent chromium and two without such claims. Arsenate (As (V)) and hexavalent chromium (Cr (VI)) co-occur in natural geologic formations and are known to have harmful effects on humans when ingested. Pitcher filters Epic Water Filter and Aquagear had claims of removing both As (V) and Cr (VI) up to 99% with a capacity of nearly 200 gallons. In contrast, pitcher filters Brita and Pur had no claims for removal of As(V) and Cr(VI) with a 40-gallon lifespan. A series of experiments were conducted to first determine the efficiency of each filter, then to add the ability or improve removal of As(V) and Cr(VI) in one filter for future design implementations. Experiment 1 was conducted by treating 100 gallons of spiked tap water (50 ppb for As (V) and 100 ppb for Cr (VI)) with each filter. All four pitcher filters showed low performance, resulting in Pur with the lowest removal percentage of 2% and Aquagear with the highest percentage 16% for As (V). For Cr (VI) Pur performed the worst with a removal of 5% and Brita had the best performance of 15%. The functionality of Brita was improved by embedding a selective ion exchange media, which when nanotized successfully removed Cr (VI) in previous studies. The optimal mass of resin to add to the pitcher was experimentally determined as 18.9 grams through Experiment 2. Finally, Experiment 3 compared an alternative placement of the resin material using the same 18.9 grams. The performance in Experiment 3 was significantly worse than Experiment 2. The final recommendation for future design implementation was to add 18.9 grams of SIR-700 resin below the filter media for optimum performance. Overall, the results demonstrate the limited removal of As(V) and Cr(VI) by the four commercial pitcher filters and show that by adding selective ion exchange media, the POUs can be nano-enabled to effectively remove As(V) and Cr(VI) from water.
ContributorsDietrich, Lisa Keri (Author) / Westerhoff, Paul (Thesis director) / Perreault, Francois (Committee member) / Civil, Environmental and Sustainable Engineering Program (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
This report analyzes the potential for accumulation of boron in direct potable reuse. Direct potable reuse treats water through desalination processes such as reverse osmosis or nanofiltration which can achieve rejection rates of salts sometimes above 90%. However, boron achieves much lower rejection rates near 40%. Because of this low rejection rate, there is potential for boron to accumulate in the system to levels that are not recommended for potable human consumption of water. To analyze this issue a code was created that runs a steady state system that tracks the internal concentration, permeate concentration, wastewater concentration and reject concentration at various rejection rates, as well as all the flows. A series of flow and mass balances were performed through five different control volumes that denoted different stages in the water use. First was mixing of clean water with permeate; second, consumptive uses; third, addition of contaminant; fourth, wastewater treatment; fifth, advanced water treatments. The system cycled through each of these a number of times until steady state was reached. Utilities or cities considering employing direct potable reuse could utilize this model by estimating their consumption levels and input of contamination, and then seeing what percent rejection or inflow of makeup water they would need to obtain to keep boron levels at a low enough concentration to be fit for consumption. This code also provides options for analyzing spikes and recovery in the system due to spills, and evaporative uses such as cooling towers and their impact on the system.
ContributorsDoidge, Sydney (Author) / Fox, Peter (Thesis director) / Perreault, Francois (Committee member) / Civil, Environmental and Sustainable Engineering Program (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
Description
The purpose of this research was to produce reduced graphene oxides for the fabrication of desalination membranes. Graphene has typically been considered a way to create more energy efficient desalination membranes. However, graphene is expensive and unstable, while graphene oxide has similar properties, but is less expensive and more stable. Graphene oxide membranes have the potential to perform above the permeability-selectivity tradeoff that is typical in membranes through size-based exclusion. Reduction through heat or Vitamin C reduces the size of graphene oxide nanochannels so salt and organic materials can be rejected in higher numbers. Both reduced and unreduced graphene oxide membranes were created and evaluated by their ability to filter dye and salt in a pressurized membrane cell. The permeability and rejection of the graphene oxide membrane is found to be dependent on the oxidation level of the graphene oxide material and the concentration on the graphene oxide on the membrane. Unreduced graphene oxide membranes were created in three concentrations: 7.37, 14.74, and 29.47 μg/cm2. As graphene oxide concentration increased, dye rejection and salt rejection increased, while water flux decreased. Graphene oxide was reduced in solution using Vitamin C and was used to create a 14.74 μg/cm2 membrane. The reduction resulted in an increase in salt rejection from 12.59% to 100%, an increase in dye rejection from 30.44% to 100%, and a decrease in water flux from 9.502 to 0.198 L/(hr*m2*bar). Future research should focus on creating membranes using different methods of synthesizing graphene oxide from graphene and creating a reduced graphene oxide membrane with a higher water flux.
ContributorsAlbrecht, Alissa Marie (Author) / Perreault, Francois (Thesis director) / Laurin, Eric (Committee member) / Civil, Environmental and Sustainable Engineering Program (Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
Description
Nitrate contamination to groundwater and surface water is a serious problem in areas with high agricultural production due to over application of fertilizers. There is a need for alternative technologies to reduce nutrient runoff without compromising yield. Carbon nanoparticles have adsorptive properties and have shown to improve germination and yield of a variety of crops. Graphite nanoparticles (CNP) were studied under a variety of different fertilizer conditions to grow lettuce for the three seasons of summer, fall, and winter. The aim of this thesis was to quantify the effect of CNPs on nitrate leaching and lettuce growth. This was accomplished by measuring the lettuce leaf yield, formulating a nutrient balance using the leachate, plant tissue, and soil data, and changing the hydraulic conductivity of the soil to assess the effect on nutrient mobility. summer and fall experiments used Arizona soil with different amounts of nitrogen, phosphorus, and potassium (NPK) fertilizer being applied to the soil with and without CNPs. The winter experiments used three different soil blends of Arizona soil, Arizona soil blended with 30% sand, and Arizona soil blended with 70% sand with a constant fertilizer treatment of 30% NPK with and without CNPs. The results showed that the 70% NPK with CNP treatment was best at reducing the amount of nitrate leached while having little to no compromise in yield. The winter experiments showed that the effectiveness of CNPs in reducing nitrate leaching and enhancing yield, improved with the higher the hydraulic conductivity of the soil.
ContributorsPandorf, Madelyn (Author) / Westerhoff, Paul K (Thesis advisor) / Boyer, Treavor (Committee member) / Perreault, Francois (Committee member) / Arizona State University (Publisher)
Created2018
Description
Electrospinning is a means of fabricating micron-scale diameter fiber networks with enmeshed nanomaterials. Polymeric nanocomposites for water treatment require the manipulation of fiber morphology to expose nanomaterial surface area while anchoring the nanomaterials and maintaining fiber integrity; that is the overarching goal of this dissertation. The first investigation studied the effect of metal oxide nanomaterial loadings on electrospinning process parameters such as critical voltage, viscosity, fiber diameter, and nanomaterial distribution. Increases in nanomaterial loading below 5% (w/v) were not found to affect critical voltage or fiber diameter. Nanomaterial dispersion was conserved throughout the process. Arsenic adsorption tests determined that the fibers were non-porous. Next, the morphologies of fibers made with carbonaceous materials and the effect of final fiber assembly on adsorption kinetics of a model organic contaminant (phenanthrene, PNT) was investigated. Superfine powdered activated carbon (SPAC), C60 fullerenes, multi-walled carbon nanotubes, and graphene platelets were added to PS and electrospun. SPAC maintained its internal pore structure and created porous fibers which had 30% greater PNT sorption than PS alone and a sevenfold increase in surface area. Carbon-based nanomaterial-PS fibers were thicker but less capacious than neat polystyrene electrospun fibers. The surface areas of the carbonaceous nanomaterial-polystyrene composites decreased compared to neat PS, and PNT adsorption experiments yielded decreased capacity for two out of three carbonaceous nanomaterials. Finally, the morphology and arsenic adsorption capacity of a porous TiO2-PS porous fiber was investigated. Porous fiber was made using polyvinylpyrrolidone (PVP) as a porogen. PVP, PS, and TiO2 were co-spun and the PVP was subsequently eliminated, leaving behind a porous fiber morphology which increased the surface area of the fiber sevenfold and exposed the nanoscale TiO2 enmeshed inside the PS. TiO2-PS fibers had comparable arsenic adsorption performance to non-embedded TiO2 despite containing less TiO2 mass. The use of a sacrificial polymer as a porogen facilitates the creation of a fiber morphology which provides access points between the target pollutant in an aqueous matrix and the sorptive nanomaterials enmeshed inside the fiber while anchoring the nanomaterials, thus preventing release.
ContributorsHoogesteijn von Reitzenstein, Natalia Virginia (Author) / Westerhoff, Paul (Thesis advisor) / Hristovski, Kiril (Committee member) / Perreault, Francois (Committee member) / Herckes, Pierre (Committee member) / Arizona State University (Publisher)
Created2018
Description
C.C. Cragin Reservoir’s location in the Coconino National Forest, Arizona makes it prone to wild fire. This study focused on the potential impacts of such a wild fire on the reservoir’s annual thermal stratification cycle impacts and water quality. The annual thermal stratification cycle impacted the reservoir’s water quality by increasing hypolimnion concentrations of magnesium, iron, turbidity, and specific ultraviolet absorbance (SUVA) values, as well as resulting in the hypolimnion having decreased dissolved oxygen concentrations during stratified months. The scarification process did not affect the dissolved organic carbon (DOC) concentrations in the reservoir or the total/dissolved nitrogen and phosphorous concentrations. Some general water quality trends that emerged were that phosphorous was the limiting nutrient, secchi disk depth and chlorophyll a concentration are inversely related, and no metals were found to be in concentrations that would violate an EPA drinking water maximum contaminant level (MCL). A carbon mass model was developed and parameterized using DOC measurements, and then using historic reservoir storage and weather data, the model simulated DOC concentrations in the reservoir following four hypothetical wild fire events. The model simulated varying initial reservoir storage volumes, initial flush volumes, and flush DOC concentrations, resulting in reservoir DOC concentrations varying from 17.41 mg/L to 8.82 mg/L.
ContributorsFlatebo, Theodore (Author) / Westerhoff, Paul K (Thesis advisor) / Fox, Peter (Committee member) / Perreault, Francois (Committee member) / Arizona State University (Publisher)
Created2018