Matching Items (3)
Description
Chloroform (CHCl3) is an important atmospheric pollutant by its direct health effects as well as by its contribution to photochemical smog formation. Chloroform outgassing from swimming pools is not typically considered a source of atmospheric CHCl3 because swimming pools are scarce compared to other sources. However, large urban areas in hot climates such as Phoenix, AZ contain a substantial amount of swimming pools, potentially resulting in significant atmospheric fluxes. In this study, CHCl3 formation potential (FP) from disinfection of swimming pools in Phoenix was investigated through laboratory experiments and annual CHCl3 emission fluxes from swimming pools were estimated based on the experimental data.
Swimming pool water (collected in June 2014 in Phoenix) and model contaminants (Pharmaceuticals and Personal Care Products (PPCPs), Endocrine Disrupting Compounds (EDCs), artificial sweeteners, and artificial human waste products) were chlorinated in controlled laboratory experiments. The CHCl3 production during chlorination was determined using Gas Chromatography-Mass Spectrometry (GC-MS) following solid-phase microextraction (SPME). Upon chlorination, all swimming pool water samples and contaminants produced measureable amounts of chloroform. Chlorination of swimming pool water produced 0.005-0.134 mol CHCl3/mol C and 0.004-0.062 mol CHCl3/mol Cl2 consumed. Chlorination of model contaminants produced 0.004-0.323 mol CHCl3/mol C and 0.001-0.247 mol CHCl3/mol Cl2 consumed. These numbers are comparable and indicate that the model contaminants react similarly to swimming pool water during chlorination. The CHCl3 flux from swimming pools in Phoenix was estimated at approximately 3.9-4.3 Gg/yr and was found to be largely dependent on water temperature and wind speed while air temperature had little effect. This preliminary estimate is orders of magnitude larger than previous estimates of anthropogenic emissions in Phoenix suggesting that swimming pools might be a significant source of atmospheric CHCl3 locally.
Swimming pool water (collected in June 2014 in Phoenix) and model contaminants (Pharmaceuticals and Personal Care Products (PPCPs), Endocrine Disrupting Compounds (EDCs), artificial sweeteners, and artificial human waste products) were chlorinated in controlled laboratory experiments. The CHCl3 production during chlorination was determined using Gas Chromatography-Mass Spectrometry (GC-MS) following solid-phase microextraction (SPME). Upon chlorination, all swimming pool water samples and contaminants produced measureable amounts of chloroform. Chlorination of swimming pool water produced 0.005-0.134 mol CHCl3/mol C and 0.004-0.062 mol CHCl3/mol Cl2 consumed. Chlorination of model contaminants produced 0.004-0.323 mol CHCl3/mol C and 0.001-0.247 mol CHCl3/mol Cl2 consumed. These numbers are comparable and indicate that the model contaminants react similarly to swimming pool water during chlorination. The CHCl3 flux from swimming pools in Phoenix was estimated at approximately 3.9-4.3 Gg/yr and was found to be largely dependent on water temperature and wind speed while air temperature had little effect. This preliminary estimate is orders of magnitude larger than previous estimates of anthropogenic emissions in Phoenix suggesting that swimming pools might be a significant source of atmospheric CHCl3 locally.
ContributorsRose, Christy J (Author) / Herckes, Pierre (Thesis advisor) / Fraser, Matthew (Committee member) / Hayes, Mark (Committee member) / Westerhoff, Paul (Committee member) / Arizona State University (Publisher)
Created2014
Description
Microbial fuel cells (MFCs) promote the sustainable conversion of organic matter in black water to electrical current, enabling the production of hydrogen peroxide (H2O2) while making waste water treatment energy neutral or positive. H2O2 is useful in remote locations such as U.S. military forward operating bases (FOBs) for on-site tertiary water treatment or as a medical disinfectant, among many other uses. Various carbon-based catalysts and binders for use at the cathode of a an MFC for H2O2 production are explored using linear sweep voltammetry (LSV) and rotating ring-disk electrode (RRDE) techniques. The oxygen reduction reaction (ORR) at the cathode has slow kinetics at conditions present in the MFC, making it important to find a catalyst type and loading which promote a 2e- (rather than 4e-) reaction to maximize H2O2 formation. Using LSV methods, I compared the cathodic overpotentials associated with graphite and Vulcan carbon catalysts as well as Nafion and AS-4 binders. Vulcan carbon catalyst with Nafion binder produced the lowest overpotentials of any binder/catalyst combinations. Additionally, I determined that pH control may be required at the cathode due to large potential losses caused by hydroxide (OH-) concentration gradients. Furthermore, RRDE tests indicate that Vulcan carbon catalyst with a Nafion binder has a higher H2O2 production efficiency at lower catalyst loadings, but the trade-off is a greater potential loss due to higher activation energy. Therefore, an intermediate catalyst loading of 0.5 mg/cm2 Vulcan carbon with Nafion binder is recommended for the final MFC design. The chosen catalyst, binder, and loading will maximize H2O2 production, optimize MFC performance, and minimize the need for additional energy input into the system.
ContributorsStadie, Mikaela Johanna (Author) / Torres, Cesar (Thesis director) / Popat, Sudeep (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
Description
The World Health Organization (WHO) has reported that water related diseases cause more than 3.4 million deaths every year across the globe (Berman 2009). Children are the most susceptible to becoming ill over contaminated water. Cases of childhood diarrheal disease, a common result of consuming contaminated water, are estimated at 1.7 billion every year, killing over 500,000 children under the age of five (WHO: Diarrhoeal Disease, 2017). Preventing consumption of contaminated drinking water is a complex issue. The process of identifying and purifying contaminants from water sources is an in-depth and costly endeavor. Often, communities do not receive ample support from municipal entities and are left to deal with the issue independently. This causes a lack of adequate resources and training for communities around the world dealing with contaminated water supplies. The ultimate result is the consumption of contaminated drinking water that creates foundational barriers to growth in areas like education, health, and overall quality of life. The primary purpose of this thesis report is to outline the proposed approach and technological elements for improving the usability and effectiveness of community-wide chlorination systems to remove bacterial pathogens to prevent consumption of contaminated drinking water.
While it may be complex, the prevention and treatment of contaminated water is possible. Founded in 2010, 33 Buckets is a registered 501(c)(3) nonprofit organization based out of Tempe, Arizona who partners with vulnerable communities and local partners to provide sustainable access to clean drinking water and WASH (Water and Sanitation for Health) training. Prior to 2018, 33 Buckets had completed drinking water projects in Bangladesh, the Dominican Republic, and Peru. In the summer of 2018, the 33 Buckets team returned to the Cusco region of Peru in an effort to assess more communities in need of clean drinking water infrastructure. In Cusco, 33 Buckets works closely with the Peruvian university, Universidad San Ignacio de Loyola (USIL). The primary purpose of this partnership is to identify communities in the Cusco region with contaminated water sources and a strong interest in improvement of current systems. Throughout this assessment trip, two communities were initially identified as potential partners, Occopata and Mayrasco. The results of bacteria tests showed a presence of Escherichia coli, commonly known as E. coli. When consumed, especially repeatedly, select strains of E. coli will cause severe diarrheal illness. Interviews with community members confirmed that common symptoms of water related disease are prevalent, especially in children. In Occopata and Mayrasco, there is an absence of support for water services from the municipality. Consequently, there is a volunteer-based water advisory board known as Junto Administración de Agua Sanitemeniento (JAAS). JAAS, in most nearby communities, currently utilizes a drip chlorination system in an attempt to disinfect bacterial pathogens from their water source. However, chlorine disinfection requires a precise dosing in order to be effective. In excessive amounts, chlorine will taste and smell of chemicals, likely producing negative feedback from community members. As a result, chlorine levels often are below the necessary level for disinfection. Chlorine tests performed by the 33 Buckets team confirmed that chlorine levels were insufficient to disinfect E. coli.
During the assessment trip, the 33 Buckets team provided a temporary solution to make chlorine disinfection more effective. Following the 2018 assessment trip, 33 Buckets formed a team of student engineers with the primary goal of furthering the technological development of a chlorine disinfection system to be implemented in communities with bacterial infected water sources. This student team was formed through the EPICS (Engineering Projects in Community Service) program at Arizona State University. The purpose of the program is providing a platform for undergraduate engineers to design solutions that create positive impact the greater community. From August of 2018 through April of 2019, the team developed the design for a continuous chlorine disinfection system that automatically tests for residual chlorine levels at multiple points throughout a community. The system is powered entirely from a low-cost solar panel, requiring a minimal amount of sunlight for full functionality. Moving forward, the goal of project development is to create an autonomous feedback loop that will adjust the amount of chlorine exposure to incoming water flows based on the results of the automatic residual chlorine test. The team also hopes to implement automatic data collection for remote monitoring of water quality in addition to onsite test results. The vision of the proposed solution is a network of chlorine disinfection systems around the Cusco region that ultimately will provide access to clean drinking water, indefinitely. This model of user-friendly purification, automatic testing, and data collection can be adjusted and applied to any region around the world experiencing health issues from consumption of contaminated water. A low-cost, scalable, and reliable water disinfection system has the potential to make significant increases in the quality of life for millions of people.
While it may be complex, the prevention and treatment of contaminated water is possible. Founded in 2010, 33 Buckets is a registered 501(c)(3) nonprofit organization based out of Tempe, Arizona who partners with vulnerable communities and local partners to provide sustainable access to clean drinking water and WASH (Water and Sanitation for Health) training. Prior to 2018, 33 Buckets had completed drinking water projects in Bangladesh, the Dominican Republic, and Peru. In the summer of 2018, the 33 Buckets team returned to the Cusco region of Peru in an effort to assess more communities in need of clean drinking water infrastructure. In Cusco, 33 Buckets works closely with the Peruvian university, Universidad San Ignacio de Loyola (USIL). The primary purpose of this partnership is to identify communities in the Cusco region with contaminated water sources and a strong interest in improvement of current systems. Throughout this assessment trip, two communities were initially identified as potential partners, Occopata and Mayrasco. The results of bacteria tests showed a presence of Escherichia coli, commonly known as E. coli. When consumed, especially repeatedly, select strains of E. coli will cause severe diarrheal illness. Interviews with community members confirmed that common symptoms of water related disease are prevalent, especially in children. In Occopata and Mayrasco, there is an absence of support for water services from the municipality. Consequently, there is a volunteer-based water advisory board known as Junto Administración de Agua Sanitemeniento (JAAS). JAAS, in most nearby communities, currently utilizes a drip chlorination system in an attempt to disinfect bacterial pathogens from their water source. However, chlorine disinfection requires a precise dosing in order to be effective. In excessive amounts, chlorine will taste and smell of chemicals, likely producing negative feedback from community members. As a result, chlorine levels often are below the necessary level for disinfection. Chlorine tests performed by the 33 Buckets team confirmed that chlorine levels were insufficient to disinfect E. coli.
During the assessment trip, the 33 Buckets team provided a temporary solution to make chlorine disinfection more effective. Following the 2018 assessment trip, 33 Buckets formed a team of student engineers with the primary goal of furthering the technological development of a chlorine disinfection system to be implemented in communities with bacterial infected water sources. This student team was formed through the EPICS (Engineering Projects in Community Service) program at Arizona State University. The purpose of the program is providing a platform for undergraduate engineers to design solutions that create positive impact the greater community. From August of 2018 through April of 2019, the team developed the design for a continuous chlorine disinfection system that automatically tests for residual chlorine levels at multiple points throughout a community. The system is powered entirely from a low-cost solar panel, requiring a minimal amount of sunlight for full functionality. Moving forward, the goal of project development is to create an autonomous feedback loop that will adjust the amount of chlorine exposure to incoming water flows based on the results of the automatic residual chlorine test. The team also hopes to implement automatic data collection for remote monitoring of water quality in addition to onsite test results. The vision of the proposed solution is a network of chlorine disinfection systems around the Cusco region that ultimately will provide access to clean drinking water, indefinitely. This model of user-friendly purification, automatic testing, and data collection can be adjusted and applied to any region around the world experiencing health issues from consumption of contaminated water. A low-cost, scalable, and reliable water disinfection system has the potential to make significant increases in the quality of life for millions of people.
ContributorsHoop, Daniel (Author) / Henderson, Mark (Thesis director) / Huerta, Mark (Committee member) / School of Sustainable Engineering & Built Envirnmt (Contributor) / Watts College of Public Service & Community Solut (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05