Matching Items (21)
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- All Subjects: Environmental engineering
- Genre: Masters Thesis
- Creators: Alum, Absar
- Creators: Torres, César I
- Member of: Theses and Dissertations
Description
DehaloR^2 is a previously characterized, trichloroethene (TCE)-dechlorinating culture and contains bacteria from the known dechlorinating genus, Dehalococcoides. DehaloR^2 was exposed to three anthropogenic contaminants, Triclocarban (TCC), tris(2-chloroethyl) phosphate (TCEP), and 1,1,1-trichloroethane (TCA) and two biogenic-like halogenated compounds, 2,6-dibromophenol (2,6-DBP) and 2,6-dichlorophenol (2,6-DCP). The effects on TCE dechlorination ability due to 2,6-DBP and 2,6-DCP exposures were also investigated. DehaloR^2 did not dechlorinate TCC or TCEP. After initial exposure to TCA, half of the initial TCA was dechlorinated to 1,1-dichloroethane (DCA), however half of the TCA remained by day 100. Subsequent TCA and TCE re-exposure showed no reductive dechlorination activity for both TCA and TCE by 120 days after the re-exposure. It has been hypothesized that the microbial TCE-dechlorinating ability was developed before TCE became abundant in groundwater. This dechlorinating ability would have existed in the microbial metabolism due to previous exposure to biogenic halogenated compounds. After observing the inability of DehaloR^2 to dechlorinate other anthropogenic compounds, DehaloR^2 was then exposed to two naturally occurring halogenated phenols, 2,6-DBP and 2,6-DCP, in the presence and absence of TCE. DehaloR^2 debrominated 2,6-DBP through the intermediate 2-bromophenol (2-BP) to the end product phenol faster in the presence of TCE. DehaloR^2 dechlorinated 2,6-DCP to 2-CP in the absence of TCE; however, 2,6-DCP dechlorination was incomplete in the presence of TCE. Additionally, when 2,6-DBP was present, complete TCE dechlorination to ethene occurred more quickly than when TCE was present without 2,6-DBP. However, when 2,6-DCP was present, TCE dechlorination to ethene had not completed by day 55. The increased dehalogenation rate of 2,6-DBP and TCE when present together compared to conditions containing only 2,6-DBP or only TCE suggests a possible synergistic relationship between 2,6-DBP and TCE, while the decreased dechlorination rate of 2,6-DCP and TCE when present together compared to conditions containing only 2,6-DCP or only TCE suggests an inhibitory effect.
ContributorsKegerreis, Kylie (Author) / Krajmalnik-Brown, Rosa (Thesis advisor) / Halden, Rolf U. (Committee member) / Torres, César I (Committee member) / Arizona State University (Publisher)
Created2012
Description
Bacteroides have been suggested as alternative indicators of fecal pollution since they are highly abundant in feces and are thought to have limited potential to grow in environment. However, recent literature suggests that Bacteroides can potentially survive within water distribution systems. The first objective of this study was therefore to investigate the validity of Bacteroides as a fecal indicator for drinking water through laboratory experiments and field studies. Experiments were performed using a laboratory scale PVC model water distribution system that was spiked with 109 Bacteroides. Samples were collected over the following four and analyzed by culture and molecular-based techniques. Second, field studies were performed by collecting water meters from two large chlorinated water distribution systems in central Arizona. Upon removal for repair by city personnel, meters were collected and biofilms samples were gathered within two hours. The biofilms were then analyzed using culture and molecular-based assays. The results from these studies support the hypothesis that Bacteroides DNA may be found in water distribution systems despite the difficulty of cultivating these bacterial cells. These experiments present the importance of considering biofilm interactions with fecal indicator bacteria when performing molecular assays on environmental samples, as biofilms may provide protection from high oxygen concentrations and grazing protozoa in bulk water that limit the persistence Bacteroides in the environment. Although the significance of biofilm interactions with surface or recreational waters may be small, they are likely important when considering drinking water delivered through distribution systems. The second objective of this study was to investigate alternative detection methodologies for the fecal indicator Bacteroides. In particular, this study focused on using a simplified protocol of Nucleic Acid Sequence Based Amplification (NASBA) and Thermophilic Helicase-Dependent Amplification (tHDA) to amplify the highly conserved 16s rRNA gene in the genomic DNA of fecal indicator Bacteroides. The results of this study show that the simplified NASBA procedure was not able to amplify the target, while continuous problems with tHDA exposed the methods lack of reliability. These results suggest higher reliability in the isothermal amplification methods needs to be achieved before application to environmental samples.
ContributorsDunkin, Nate (Author) / Abbaszadegan, Morteza (Thesis advisor) / Alum, Absar (Committee member) / Fox, Peter (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
The ongoing COVID pandemic has opened the doors for the development of effective surface disinfection technologies. UV technology is one of the most effective technique to be used in combination with different photocatalytic agents such as Titanium Dioxide (TiO2) for microbial inactivation. There are many bacteria and viruses which have the potential to infect humans via surface-oral/inhalation pathway. Thus, it is important to evaluate the effectiveness of these techniques used to inactivate microorganisms to minimize environmental transmission. UV light directly acts on bacteria and viruses by damaging their nucleic acids and protein structures. TiO2 acts as a photocatalyst, generates hydroxyl radicals under UV, leading to enhanced inactivation efficacy. This study focuses on the impact of UVC light at 254 nm wavelength in combination with spray formulations with TiO2 for the inactivation of E. coli (exposure times of 1, 5 and 10 minutes) and bacteriophages P22 (exposure times of 5 and 10 minutes) and MS2 (exposure times of 1 and 5 minutes). This study includes tests that explored the long-lasting impact of spray formulations on non-porous surface. Minimal inactivation of ~ 0.15 log inactivation of E. coli was resulted using TiO¬2 alone but when UV was added to the procedure on average 3 log inactivation was achieved. It was noted that MS2 was found to be more susceptible to UV as compared to P22 due to its higher inactivation rate. The spray formulation homogeneity is a critical factor in consistent microbial inactivation. In addition, the UV intensity of the handheld device is an important factor for total disinfection. However, the combined spray formulation and UV technology is an effective method of surface disinfection.
ContributorsBaxi, Dhatri Kamleshbhai (Author) / Abbaszadegan, Morteza (Thesis advisor) / Fox, Peter (Committee member) / Alum, Absar (Committee member) / Arizona State University (Publisher)
Created2021
Description
This research explores microbial chain elongation as a pathway for production of complex organic compounds in soils with implication for the carbon cycle. In chain elongation, simple substrates such as ethanol and short chain carboxylates such as acetate can be converted to longer carbon chain carboxylates under anaerobic conditions through cyclic, reverse β oxidation. This pathway elongates the carboxylate by two carbons. The chain elongation process is overall thermodynamically feasible, and microorganisms gain energy through this process. There have been limited insights into the versatility of chain elongating substrates, understanding the chain elongating microbial community, and its importance in sequestering carbon in the soils.
We used ethanol, methanol, butanol, and hydrogen as electron donors and acetate and propionate as electron acceptors to test the occurrence of microbial chain elongation in four soils with different physicochemical properties and microbial communities. Common chain elongation products were the even numbered chains butyrate, caproate, and butanol, the odd numbered carboxylates valerate and heptanoate, along with molecular hydrogen. At a near neutral pH and mesophilic temperature, we observed a stable and sustained production of longer fatty acids along with hydrogen. Microbial community analysis show phylotypes from families such as Clostridiaceae, Bacillaceae, and Ruminococcaceae in all tested conditions. Through chain elongation, the products formed are less biodegradable. They may undergo transformations and end up as organic carbon, decreasing the greenhouse gas emissions, thus, making this process important to study.
We used ethanol, methanol, butanol, and hydrogen as electron donors and acetate and propionate as electron acceptors to test the occurrence of microbial chain elongation in four soils with different physicochemical properties and microbial communities. Common chain elongation products were the even numbered chains butyrate, caproate, and butanol, the odd numbered carboxylates valerate and heptanoate, along with molecular hydrogen. At a near neutral pH and mesophilic temperature, we observed a stable and sustained production of longer fatty acids along with hydrogen. Microbial community analysis show phylotypes from families such as Clostridiaceae, Bacillaceae, and Ruminococcaceae in all tested conditions. Through chain elongation, the products formed are less biodegradable. They may undergo transformations and end up as organic carbon, decreasing the greenhouse gas emissions, thus, making this process important to study.
ContributorsJoshi, Sayalee (Author) / Delgado, Anca G (Thesis advisor) / Torres, César I (Committee member) / van Paassen, Leon (Committee member) / Arizona State University (Publisher)
Created2018
Description
The built environment is responsible for a significant portion of global waste generation.
Construction and demolition (C&D) waste requires significant landfill areas and costs
billions of dollars. New business models that reduce this waste may prove to be financially
beneficial and generally more sustainable. One such model is referred to as the “Circular
Economy” (CE), which promotes the efficient use of materials to minimize waste
generation and raw material consumption. CE is achieved by maximizing the life of
materials and components and by reclaiming the typically wasted value at the end of their
life. This thesis identifies the potential opportunities for using CE in the built environment.
It first calculates the magnitude of C&D waste and its main streams, highlights the top
C&D materials based on weight and value using data from various regions, identifies the
top C&D materials’ current recycling and reuse rates, and finally estimates a potential
financial benefit of $3.7 billion from redirecting C&D waste using the CE concept in the
United States.
ContributorsAldaaja, Mohammad (Author) / El Asmar, Mounir (Thesis advisor) / Buch, Rajesh (Committee member) / Kaloush, Kamil (Committee member) / Arizona State University (Publisher)
Created2019
Description
One of the two objectives of this dissertation is an investigation into the possible correlation between rainfall events and increased levels of E. coli and Mycobacterium using an existing data set. The literature states that levels of microbial concentrations do increase after rainfall events, but there are no studies to indicate this correlation applies in any Arizona water systems. The data analyzed for the bacterial concentrations project suggested the possibility of a correlation along one river but it is not conclusive to state that any correlation exists between rainfall events and the microbial concentration for many other sites included in the analysis. This is most likely due to the highly engineered water delivery systems that are not directly impacted.
The secondary objective was to determine if there are environmental variables collected from an ongoing project which would be a good candidate for making predictions about any of the project data parameters. Of the 79 possible opportunities for the model to accurately predict the dependent variable, it showed strong statistical favorability as well as experimentally favorable results towards Dissolved Organic Carbon as the best dependent variable from the data set, resulting in an accuracy of 41%. This is relevant since Dissolved Organic Carbon is one of the most important water quality parameters of concern for drinking water treatment plants where disinfection by-products are a limiting factor. The need for further analysis and additional data collection is an obvious result from both studies. The use of hydrograph data instead of rainfall would be a logical new direction for the heavily engineered water delivery systems.
The secondary objective was to determine if there are environmental variables collected from an ongoing project which would be a good candidate for making predictions about any of the project data parameters. Of the 79 possible opportunities for the model to accurately predict the dependent variable, it showed strong statistical favorability as well as experimentally favorable results towards Dissolved Organic Carbon as the best dependent variable from the data set, resulting in an accuracy of 41%. This is relevant since Dissolved Organic Carbon is one of the most important water quality parameters of concern for drinking water treatment plants where disinfection by-products are a limiting factor. The need for further analysis and additional data collection is an obvious result from both studies. The use of hydrograph data instead of rainfall would be a logical new direction for the heavily engineered water delivery systems.
ContributorsBuell, Andrew (Author) / Fox, Peter (Thesis advisor) / Abbaszadegan, Morteza (Thesis advisor) / Alum, Absar (Committee member) / Arizona State University (Publisher)
Created2018
Description
The application of microalgal biofilms in wastewater treatment has great advantages such as abolishing the need for energy intensive aerators and recovering nutrients as energy, thus reducing the energy requirement of wastewater treatment several-fold. A 162 cm2 algal biofilm reactor with good wastewater treatment performance and a regular harvesting procedure was studied at lab scale to gain an understanding of effectual parameters such as hydraulic retention time (HRT; 2.6 and 1.3 hrs), liquid level (LL; 0.5 and 1.0 cm), and solids retention time (SRT; 3 and 1.5 wks). A revised synthetic wastewater “Syntho 3.7” was used as a surrogate of domestic primary effluent for nutrient concentration consistency in the feed lines. In the base case (2.6 hr HRT, 0.5 cm LL, and 3 wk SRT), percent removals of 69 ± 2 for total nitrogen (TN), 54 ± 21 for total phosphorous (TP), and 60 ± 7 for chemical oxygen demand (COD) were achieved and 4.0 ± 1.6 g/m2/d dry biomass was produced. A diffusion limitation was encountered when increasing the liquid level, while the potential to further decrease the HRT remains. Nonlinear growth kinetics was observed in comparing SRT variations, and promoting autotrophic growth seems possible. Future work will look towards producing a mathematical model and further testing the aptness of this system for large-scale implementation.
ContributorsHalloum, Ibrahim (Author) / Torres, César I (Thesis advisor) / Popat, Sudeep C (Committee member) / Rittmann, Bruce E. (Committee member) / Arizona State University (Publisher)
Created2016
Description
Bioremediation of trichloroethene (TCE) using Dehalococcoides mccartyi-containing microbial cultures is a recognized and successful remediation technology. Our work with an upflow anaerobic sludge blanket (UASB) reactor has shown that high-performance, fast-rate dechlorination of TCE can be achieved by promoting bioflocculation of Dehalococcoides mccartyi-containing cultures. The bioreactor achieved high maximum conversion rates of 1.63 ± 0.012 mmol Cl- Lculture-1 h-1 at an HRT of 3.6 hours and >97% dechlorination of TCE to ethene while continuously fed 2 mM TCE. The UASB generated bioflocs from a microbially heterogeneous dechlorinating culture and produced Dehalococcoides mccartyi densities of 1.73x10-13 cells Lculture-1 indicating that bioflocculation of Dehalococcoides mccartyi-containing cultures can lead to high density inocula and high-performance, fast-rate bioaugmentation culture for in situ treatment. The successful operation of our pilot scale bioreactor led to the assessment of the technology as an onsite ex-situ treatment system. The bioreactor was then fed TCE-contaminated groundwater from the Motorola Inc. 52nd Street Plant Superfund site in Phoenix, AZ augmented with the lactate and methanol. The bioreactor maintained >99% dechlorination of TCE to ethene during continuous operation at an HRT of 3.2 hours. Microbial community analysis under both experimental conditions reveals shifts in the community structure although maintaining high rate dechlorination. High density dechlorinating cultures containing bioflocs can provide new ways to 1) produce dense bioaugmentation cultures, 2) perform ex-situ bioremediation of TCE, and 3) increase our understanding of Dehalococcoides mccartyi critical microbial interactions that can be exploited at contaminated sites in order to improve long-term bioremediation schemes.
ContributorsFajardo-Williams, Devyn (Author) / Krajmalnik-Brown, Rosa (Thesis advisor) / Torres, César I (Committee member) / Popat, Sudeep C (Committee member) / Arizona State University (Publisher)
Created2015
Description
Quagga Mussels (Dreissena bugensis) are an invasive species of mollusk that have established themselves within the Colorado River system of Arizona since 2007. However, despite close proximity and frequent travel by recreational boaters between reservoirs, they have not yet infested the Salt River or Verde River systems. Laboratory experimentation was done to test the survival rate of adult D. bugensis specimens in waters collected from Bartlett Lake (Verde River), Saguaro Lake (Salt River), and Salt River Project (SRP) canals (Salt River/Verde River/Colorado River blend) as well as Central Arizona Project (CAP) canals with the addition of turbidity to simulate high runoff storm events. Under each condition, adult survival for a time period of 21 days exceeded 98%, ruling out water chemistry or turbidity as a factor. Spawning was investigated using mussels collected from Lake Pleasant in August 2015. In 4 trials of serotonin dosage between 0.5 – 1.0 mMol, spawning was not successful. Calanoid copepod predation was also investigated by field sampling at Lake Pleasant, Saguaro Lake, and Bartlett Lake during September 2015. Calanoid copepods were identified in Lake Pleasant at a density of 104.22 individuals per cubic meter at a depth of 2 meters and 9.75 individuals per cubic meter at the surface. Calanoid copepods were not found in Bartlett Lake or Saguaro Lake, ruling out copepod predation as a factor. Finally, dissolved oxygen and temperature trends were analyzed in each reservoir. While temperature profiles are similar throughout the year, seasonal drops in dissolved oxygen below survivable concentrations for D. bugensis has been observed in both Saguaro Lake and Bartlett Lake but not Lake Pleasant, representing the most plausible explanation for no observed infestation.
ContributorsSokolowski, Matthew (Author) / Fox, Peter (Thesis advisor) / Abbaszadegan, Morteza (Thesis advisor) / Alum, Absar (Committee member) / Arizona State University (Publisher)
Created2015