Matching Items (4)
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- All Subjects: P22
- Genre: Academic theses
- Creators: Abbaszadegan, Morteza
Description
Mexico City has an ongoing air pollution issue that negatively affects its citizens and surroundings with current structural disconnections preventing the city from improving its overall air quality. Thematic methodological analysis reveals current obstacles and barriers, as well as variables contributing to this persistent problem. A historical background reveals current programs and policies implemented to improve Mexico’s City air quality. Mexico City’s current systems, infrastructure, and policies are inadequate and ineffective. There is a lack of appropriate regulation on other modes of transportation, and the current government system fails to identify how the class disparity in the city and lack of adequate education are contributing to this ongoing problem. Education and adequate public awareness can potentially aid the fight against air pollution in the Metropolitan City.
ContributorsGarcia, Lucero (Author) / Duarte, Marisa E. (Thesis advisor) / Arzubiaga, Angela (Committee member) / Richter, Jennifer (Committee member) / Arizona State University (Publisher)
Created2018
Description
Advanced oxidation processes (AOP’s) are water/wastewater treatment processes simultaneously providing disinfection and potential oxidation of contaminants that may cause long-term adverse health effects in humans. One AOP involves injecting peracetic acid (PAA) upstream of an ultraviolet (UV) irradiation reactor. Two studies were conducted, one in pilot-scale field conditions and another under laboratory conditions. A pilot-scale NeoTech UV reactor (rated for 375 GPM) was used in the pilot study, where a smaller version of this unit was used in the laboratory study (20 to 35 GPM). The pilot study analyzed coliform disinfection and also monitored water quality parameters including UV transmittance (UVT), pH and chlorine residual. Pilot study UV experiments indicate the unit is effectively treating flow streams (>6 logs total coliforms) twice the 95% UVT unit capacity (750 GPM or 17 mJ/cm2 UV Dose). The results were inconclusive on PAA/UV inactivation due to high data variability and field operation conditions creating low inlet concentrations.Escherichia coli (E. coli) bacteria and the enterobacteria phage P22—a surrogate for enteric viruses—were analyzed. UV inactivated >7.9 and 4 logs of E. coli and P22 respectively at a 16.8 mJ/cm2 UV dose in test water containing a significant organics concentration. When PAA doses of 0.25 and 0.5 mg/L were injected upstream of UV at approximately the same UV Dose, the average E.coli log inactivation increased to >8.9 and >9 logs respectively, but P22 inactivation decreased to 2.9 and 3.0 logs, respectively. A bench-scale study with PAA was also conducted for 5, 10 and 30 minutes of contact time, where 0.25 and 0.5 mg/L had <1 log inactivation of E. coli and P22 after 30 minutes of contact time. In addition, degradation of the chemical N-Nitrosodimethylamine (NDMA) in tap water was analyzed, where UV degraded NDMA by 48 to 97% for 4 and 0.5 GPM flowrates, respectively. Adding 0.5 mg/L PAA upstream of UV did not significantly improve NDMA degradation.
The results under laboratory conditions indicate that PAA/UV have synergy in the inactivation of bacteria, but decrease virus inactivation. In addition, the pilot study demonstrates the applicability of the technology for full scale operation.
The results under laboratory conditions indicate that PAA/UV have synergy in the inactivation of bacteria, but decrease virus inactivation. In addition, the pilot study demonstrates the applicability of the technology for full scale operation.
ContributorsCooper, Samantha (Author) / Abbaszadegan, Morteza (Thesis advisor) / Alum, Absar (Committee member) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2017
Description
This study was designed to provide insight into microbial transport kinetics which might be applied to bioremediation technology development and prevention of groundwater susceptibility to pathogen contamination. Several pilot-scale experiments were conducted in a saturated, 2 dimensional, packed porous media tank to investigate the transport of Escherichia coli bacteria, P22 bacteriophage, and a visual tracer and draw comparisons and/or conclusions. A constructed tank was packed with an approximate 3,700 cubic inches (in3) of a fine grained, homogeneous, chemically inert sand which allowed for a controlled system. Sampling ports were located at 5, 15, 25, and 25 vertical inches from the base of the 39 inch saturated zone and were used to assess the transport of the selected microorganisms. Approximately 105 cells of E. coli or P22 were injected into the tank and allowed to move through the media at approximately 10.02 inches per day. Samples were collected intermittently after injection based off of an estimated sampling schedule established from the visual tracer.
The results suggest that bacteriophages pass through soil faster and with greater recovery than bacteria. P22 in the tank reservoir experienced approximately 1 log reduction after 36 hours. After 85 hours, P22 was still detected in the reservoir after experiencing a 2 log reduction from the start of the experiment. E. coli either did not reach the outlet or died before sampling, while P22 was able to be recovered. Bacterial breakthrough curves were produced for the microbial indicators and illustrate the peak concentrations found for each sampling port. For E. coli, concentrations at the 5 inch port peaked at a maximum of 5170 CFU/mL, and eventually at the 25 inch port at a maximum of 90 CFU/mL. It is presumed that E. coli might have experienced significant filtration, straining and attachment, while P22 might have experienced little adsorption and instead was transported rapidly in long distances and was able to survive for the duration of the experiment.
The results suggest that bacteriophages pass through soil faster and with greater recovery than bacteria. P22 in the tank reservoir experienced approximately 1 log reduction after 36 hours. After 85 hours, P22 was still detected in the reservoir after experiencing a 2 log reduction from the start of the experiment. E. coli either did not reach the outlet or died before sampling, while P22 was able to be recovered. Bacterial breakthrough curves were produced for the microbial indicators and illustrate the peak concentrations found for each sampling port. For E. coli, concentrations at the 5 inch port peaked at a maximum of 5170 CFU/mL, and eventually at the 25 inch port at a maximum of 90 CFU/mL. It is presumed that E. coli might have experienced significant filtration, straining and attachment, while P22 might have experienced little adsorption and instead was transported rapidly in long distances and was able to survive for the duration of the experiment.
ContributorsAcosta, Jazlyn Cauren (Author) / Abbaszadegan, Morteza (Thesis advisor) / Dahlen, Paul (Committee member) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2017
Description
Since its first report in 1976, many outbreaks linked to Legionella have been reported in the world. These outbreaks are a public health concern because of legionellosis, which is found in two forms, Pontiac fever and Legionnaires disease. Legionnaires disease is a type of pneumonia responsible for the majority of the illness in the reported outbreaks of legionellosis. This study consists of an extensive literature review and experimental work on the aerosolization and UV inactivation of E.coli and Legionella under laboratory conditions. The literature review summarizes Legionella general information, occurrence, environmental conditions for its survival, transmission to human, collection and detection methodologies and Legionella disinfection in air and during water treatment processes.
E. coli was used as an surrogate for Legionella in experimentation due to their similar bacterial properties such as size, gram-negative rod-shaped, un-encapsulated and non-spore-forming bacterial cells. The accessibility and non-pathogenicity of E. coli also served as factors for the substitution.
Three methods of bacterial aerosolization were examined, these included an electric spray gun, an air spray gun and a hand-held spray bottle. A set of experiments were performed to examine E. coli aerosolization and transport in the aerosolization chamber (an air tight box) placed in a Biological Safety Cabinet. Spiked sample was sprayed through the opening from one side of the aerosolization chamber using the selected aerosolization methods. The air sampler was placed at the other side to collect 100 L air sample from the aerosolization chamber. A Tryptic Soy Agar plate was placed inside the air sampler to collect and subsequently culture E. coli cells from air. Results showed that the air spray gun has the best capability of aerosolizing bacteria cells under all the conditions examined in this study compared to the other two spray methods. In this study, we provide a practical and efficient method of bacterial aerosolization technique for microbial dispersion in air. The suggested method can be used in future research for microbial dispersion and transmission studies.
A set of experiments were performed to examine UV inactivation of E. coli and Legionella cells in air. Spiked samples were sprayed through the opening from one side of the aerosolization chamber using the air spray gun. A UV-C germicidal lamp inside the Biological Safety Cabinet was turned on after each spray. The air samples were collected as previously described. The application of UV-C for the inactivation of bacterial cells resulted in removing aerosolized E. coli and Legionella cells in air. A 1 log reduction was achieved with 5 seconds UV exposure time while 10 seconds UV exposure resulted in a 2 log bacterial reduction for both bacteria. This study shows the applicability of UV inactivation of pathogenic bacterial cells in air by short UV exposure time. This method may be applicable for the inactivation of Legionella in air ducts by installing germicidal UV lamps for protecting susceptible populations in certain indoor settings such as nursing homes or other community rooms.
E. coli was used as an surrogate for Legionella in experimentation due to their similar bacterial properties such as size, gram-negative rod-shaped, un-encapsulated and non-spore-forming bacterial cells. The accessibility and non-pathogenicity of E. coli also served as factors for the substitution.
Three methods of bacterial aerosolization were examined, these included an electric spray gun, an air spray gun and a hand-held spray bottle. A set of experiments were performed to examine E. coli aerosolization and transport in the aerosolization chamber (an air tight box) placed in a Biological Safety Cabinet. Spiked sample was sprayed through the opening from one side of the aerosolization chamber using the selected aerosolization methods. The air sampler was placed at the other side to collect 100 L air sample from the aerosolization chamber. A Tryptic Soy Agar plate was placed inside the air sampler to collect and subsequently culture E. coli cells from air. Results showed that the air spray gun has the best capability of aerosolizing bacteria cells under all the conditions examined in this study compared to the other two spray methods. In this study, we provide a practical and efficient method of bacterial aerosolization technique for microbial dispersion in air. The suggested method can be used in future research for microbial dispersion and transmission studies.
A set of experiments were performed to examine UV inactivation of E. coli and Legionella cells in air. Spiked samples were sprayed through the opening from one side of the aerosolization chamber using the air spray gun. A UV-C germicidal lamp inside the Biological Safety Cabinet was turned on after each spray. The air samples were collected as previously described. The application of UV-C for the inactivation of bacterial cells resulted in removing aerosolized E. coli and Legionella cells in air. A 1 log reduction was achieved with 5 seconds UV exposure time while 10 seconds UV exposure resulted in a 2 log bacterial reduction for both bacteria. This study shows the applicability of UV inactivation of pathogenic bacterial cells in air by short UV exposure time. This method may be applicable for the inactivation of Legionella in air ducts by installing germicidal UV lamps for protecting susceptible populations in certain indoor settings such as nursing homes or other community rooms.
ContributorsYao, Wei (Author) / Abbaszadegan, Morteza (Thesis advisor) / Fox, Peter (Committee member) / Alum, Absar (Committee member) / Arizona State University (Publisher)
Created2015