Matching Items (26)
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- All Subjects: Environmental engineering
- Creators: Perreault, Francois
- Creators: Fraser, Matthew
- Member of: ASU Electronic Theses and Dissertations
Description
The waterways in the United States are polluted by agricultural, mining, and industrial activities. Recovery of valuable materials, such as energy and nutrients, from these waste streams can improve the economic and environmental sustainability of wastewater treatment. A number of state-of-the-art anaerobic bioreactors have promise for intensified anaerobic biological treatment and energy recovery, but they have drawbacks. The drawbacks should be overcome with a novel anaerobic biological wastewater treatment process: the anaerobic biofilm membrane bioreactor (AnBfMBR). This research works aims to advance key components of the AnBfMBR. The AnBfMBR is a hybrid suspended growth and biofilm reactor. The two main components of an AnBfMBR are plastic biofilm carriers and membranes. The plastic biofilm carriers provide the surface onto which the biofilms grow. Membranes provide liquid-solid separation, retention of suspended biomass, and a solids-free effluent. Introducing sufficient surface area promotes the biofilm accumulation of slow-growing methanogens that convert volatile fatty acids into methane gas. Biofilms growing on these surfaces will have a mixed culture that primarily consists of methanogens and inert particulate solids, but also includes some acetogens. Biomass that detaches from biofilms become a component of the suspended growth. A bench-scale AnBfMBR was designed by the AnBfMBR project team and constructed by SafBon Water Technology (SWT). The primary objective of this thesis project was to evaluate the ability of plastic biofilm carriers to minimize ceramic-membrane fouling in the AnBfMBR setting. A systematic analysis of mixing for the bench-scale AnBfMBR was also conducted with the plastic biofilm carriers. Experiments were conducted following a ‘run to failure’ method, in which the ceramic membranes provide filtration, and the time it takes to reach a ‘failure transmembrane pressure (TMP)’ was recorded. The experiments revealed two distinct trends. First, the time to failure TMP decreased as mixed liquor suspended solids concentration (MLSS) concentration increased. Second, increasing the carrier fill extend the time to failure, particularly for higher MLSS concentrations. Taken together, the experiments identified an optimized “sweet spot” for the AnBfMBR: an operating flux of 0.25-m/d, a failure TMP of 0.3-atm pressure, MLSS of 5,000 – 7,500 mg/L, and 40% carrier fill.
ContributorsRoman, Brian Aaron (Author) / Rittmann, Bruce (Thesis advisor) / Boltz, Joshua (Committee member) / Perreault, Francois (Committee member) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2021
Description
Water quality assessment is essential for maintaining healthy ecosystems and protecting human health. Data interrogation and exploratory data analysis techniques are used to analyze the spatial and temporal variability of water quality parameters, identifying correlations, and to better understand the factors that impacts microbial and chemical quality of water. The seasonal dynamics of microbiome in surface waters were investigated to identify the factors driving these dynamics. Initial investigation analyzed two decades of regional water quality data from 20 various locations in Central Arizona, USA. Leveraging advanced data science techniques, the study uncovered correlations between crucial parameters, including dissolved organic carbon (DOC), ultraviolet absorbance (UVA), and specific ultraviolet absorbance (SUVA). These findings provide foundational insights into the dynamic of overall water quality. A comprehensive 12-month surface water sample collection and study was conducted to investigate potential bias in bacterial detection using EPA approved Membrane Filtration (MF) technique. The results underscore that while MF excels in recovering bacteria of public health significance, it exhibits biases, particularly against small and spore-forming bacteria and Archaea, such as Bacilli, Mollicutes, Methylacidiphilae, and Parvarchaea. This emphasizes the importance of complementing standard microbiology approaches to mitigate technological biases and enhance the accuracy of microbial water quality testing, especially for emerging pathogens. Furthermore, a complementary study of microbial dynamics within a model drinking water distribution systems (DWDSs) using treated water from the same source water as the above study. The influence of pipe material and water temperature on the microbiome and trace element composition was investigated. The research unveiled a preferential link between pipe material and trace elements, with water temperature significantly impacting the microbiome to a higher degree than the chemical composition of water. Notably, Legionellaceae and Mycobacteriaceae were found to be prevalent in warmer waters, highlighting the substantial influence of water temperature on the microbiome, surpassing that of pipe material. These studies provide comprehensive insights into the spatial and temporal variability of water quality parameters. Analyzing microbial data in depth is crucial in detecting bacterial species within a monitoring program for adjusting operational conditions to reduce the presence of microbial pathogens and enhance the quality of drinking water.
ContributorsAloraini, Saleh (Author) / Abbaszadegan, Morteza (Thesis advisor) / Fox, Peter (Committee member) / Perreault, Francois (Committee member) / Alum, Absar (Committee member) / Arizona State University (Publisher)
Created2023
Description
Plastics, when released into the environment, undergo surface weathering due to mechanical abrasion and ultraviolet (UV) exposure that leads to the formation of microplastics. Weathering also introduces oxygen functional groups on the surface, which will affect surface interactions compared to pristine plastics. In this study, the adsorption of selected model contaminants of high environmental relevance was evaluated at different level of abiotic and biotic transformation to understand how microplastics aging influences contaminant adsorption on high density polyethylene (HDPE) and polypropylene (PPE). Microplastics were aged through an accelerated weathering process using UV exposure with or without hydrogen peroxide. The effect of UV aging on the microplastics’ morphology and surface chemistry was characterized by Fourier Transform Infrared Spectroscopy, X-Ray Photoelectron Spectroscopy, streaming Zeta potential, Brunauer–Emmett–Teller Krypton adsorption analyses and Computed X-Ray Tomography. Sorption of organic contaminants was found to be higher on aged microplastics compared to pristine ones for all contaminants investigated. This increase in sorption affinity was found to be associated with a change in the surface chemistry and not in an increase in specific surface area after aging. Biological surface weathering (i.e., biofilm formation) was carried out at a lab-scale setting using model biofilm-forming bacteria followed by adsorption affinity measurement of biofilm-laden microplastics with the model organic contaminants. The amount of microbial biomass accumulated on the surface was also evaluated to correlate the changes in sorption affinity with the change in microplastic biofilm formation. The results of this study emphasize the need to understand how contaminant-microplastics interactions will evolve as microplastics are altered by biotic and abiotic factors in the environment.
ContributorsBhagat, Kartik (Author) / Perreault, Francois (Thesis advisor) / Westerhoff, Paul (Committee member) / Oswald, Jay (Committee member) / Arizona State University (Publisher)
Created2022
Description
The developing world has witnessed a rapid growth in crop production since the green revolution in the 1960s. Even though the population has almost doubled since then, food production
has tripled; most of this growth can be attributed to crop research, fertilizers, infrastructure, and
market development. Although the green revolution came with benefits, it has been widely
criticized for its negative impact on the environment. The excessive and inappropriate use of
fertilizers has led to human and livestock diseases, polluted waterways, loss of soil fertility, and
soil acidity. Even though the green revolution was started to ensure food security, it has
unintended consequences on human health and the surrounding environment.
This dissertation focuses on the surface characteristics of graphene nanomaterials
(GNMs) and their application in agriculture. Among the nutrients needed for crops, some can be
easily obtained from the environment (e.g., carbon, hydrogen, oxygen, etc.), while others, like
nitrogen (N), phosphorus (P), and potassium (K), often requires supplementation by fertilizers.
However, conventional fertilizers have caused problems associated with soil pH changes,
stunted plant growth, and disrupted beneficial microbial processes. Implementing
nano-fertilizers, which can act as controlled-release fertilizers, is important. GNMs have shown
some promising characteristics for the controlled release of drugs and other chemicals.
Therefore, in the first part of this study, the loading capacity of the three macronutrients (N, P,
and K) over GNMs of different surface chemistry was characterized. In the second part of this
thesis, the effect of graphene oxide (GO) addition on wheat germination was evaluated. Rapid
germination is essential for crop establishment to ensure low-cost and high-quality products and
keep in check the sustainable use of resources in commercial agriculture. The results of this
thesis indicated that the application of GO significantly enhanced the seed germination potential of the wheat crops. It not only increases the root weight but also improves its volume. Future work
should focus on the impact of surface chemistry of GNMs on germination, which, when
combined with the materials’ ability to bind nutrients, could help better guide the use of GNMs in
agriculture.
ContributorsKumar, Abhishek (Author) / Perreault, Francois (Thesis advisor) / Fox, Peter (Committee member) / Oukarroum, Abdallah (Committee member) / Arizona State University (Publisher)
Created2022
Description
This study investigated the difference in biofilm growth on pristine and aged polypropylene microplastics exposed to Tempe Town Lake water for 8 weeks. The research question here is, does the aging of microplastic (MPs) change the biofilm formation rate and composition of the biofilm in comparison with the pristine MPs. To answer this question, the biofilm formation was quantified using different methods over time for both pristine polypropylene and aged polypropylene using agar plate counts and crystal violet staining. Colony counts based on agar plating showed an increase in microbial growth over the 8 weeks of treatment, with the aged MPs accumulating higher microbial counts than the pristine MPs. The diversity of the biofilm decreased over time for both MPs and the aged MPs had overall less diversity in biofilm, based on phenotype enumeration, in comparison with the pristine MPs. Higher biofilm growth on aged MPs was confirmed using crystal violet staining, which stains the negatively charged biological compounds such as proteins and the extracellular polymeric substance matrix of the biofilm. Using this complementary approach to colony counting, the same trend of higher biofilm growth on aged MPs was found. Further studies will focus on confirming the phenotype findings using microbiome analysis following DNA extraction. This project created a methodology to quantify biofilm formation on MPs, which was used to show that MPs may accumulate more biofilms in the environment as they age under sunlight.
ContributorsMushro, Noelle (Author) / Perreault, Francois (Thesis advisor) / Hamilton, Kerry (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Arizona State University (Publisher)
Created2022
Description
Global shortages of urea and unsustainable production of synthetic urea have caused concerns over the future of food production, automobile operation, and other processes. Urine is a waste product that could supplement synthetic urea production. This study utilizes polyamide reverse osmosis (RO) and nanofiltration (NF) membranes in a cross-flow orientation to selectively recover urea from fresh human urine. Urea permeation experiments were conducted to determine the effects of urea stabilization via pH adjustment and membrane type on the production of a pure urea product. Fouling mitigation experiments were then conducted to determine the efficacy of microfiltration (MF) pretreatment on the reduction of the membrane fouling layer. The results showed that the NF90 membrane had advantageous performance to the BW30 RO and NF270 membranes, permeating 76% of the urea while rejecting 68% of the conductivity. Urine stabilization via acetic acid or sodium hydroxide addition did not inhibit membrane performance, signifying the use of pH 5 as a suitable pretreatment condition. Real fresh urine had higher rejection of constituents for NF90, suggesting the reduction of flux across the membrane due to interactions with organic material. MF pretreatment reduced foulant thickness and permeate flux loss but did not change the speciation of microorganisms. Finally, different urea-based products, such as fertilizers, biocement, and synthetic polymers, were suggested to show the potential of urine-recovered urea to reduce costs. The results from this work show the efficacy of using polyamide RO and NF membranes to supplement unsustainable synthetic production of urea with sustainably sourced urea from a waste product, human urine.
ContributorsCrane, Lucas Christopher (Author) / Boyer, Treavor H (Thesis advisor) / Perreault, Francois (Committee member) / Westerhoff, Paul (Committee member) / Arizona State University (Publisher)
Created2022
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
Nitrate leaching from agricultural systems poses a threat to ecosystems and human health. Integrating 2D carbon-based graphite nano additive (GNA) soil amendments previously demonstrated potential in mitigating nitrate loss, yet the responsible mechanism was unclear. To clarify the causal mechanism, this dissertation aimed to identify and understand mechanisms of how addition of graphite nano-additive (GNA) soil amendment reduces N leaching through agricultural soil by sequential investigation employing laboratory soil incubation tests, batch adsorption experiments, soil column experiments, and greenhouse pot study. Soil incubation tests were conducted with four commercially available graphene nanomaterials to establish that soil microbial activity indicated by respiration was significantly enhanced when soil was amended with graphene (e.g., GNA). Additionally, gene abundance assessment from the same incubation tests indicated a potentially slowed soil nitrification (ammonium to nitrate conversion) by GNA. Separate batch absorption tests indicated that GNA was unlikely to retain nitrate through adsorption. Soil column experiments were designed to probe the dependency of N retention in GNA-amended soil primarily due to altered microbial activity from assessing the impact of temperature, soil saturation, sterility, hydraulic retention time, GNA dose, and soil organic carbon. Finally, a greenhouse plant growth study was designed to assess how GNA impacts soil biology. Enzyme activity indicated GNA could stimulate soil carbon mineralization and improve soil bioavailable carbon. Gene abundance assessment showed total bacterial community size was unimpacted but selected and suppressed certain bacterial groups (e.g., suppressed bacterial amoA gene abundance).16S bacterial community sequencing showed that GNA significantly altered the bulk and rhizosphere soil microbiome composition. GNA-induced selection of certain bacterial classes (e.g., Bacilli) holds significant implications in aspects of plant growth and nutrient acquisition. This dissertation revealed mechanisms behind GNA-induced decrease of nitrate leaching in agricultural soil, aiding progress to its integration into conventional agriculture to improve nitrogen fertilizer efficiency for a food-secure future.
ContributorsDas, Partho (Author) / Westerhoff, Paul (Thesis advisor) / Penton, Christopher Ryan (Committee member) / Perreault, Francois (Committee member) / Arizona State University (Publisher)
Created2024
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