Grantee Research Project Results
Final Report: Nano-Silver and Zeolite for Ceramic Water Filters
EPA Grant Number: SU836762Title: Nano-Silver and Zeolite for Ceramic Water Filters
Investigators: Saleh, Navid
Institution: The University of Texas at Austin
EPA Project Officer: Page, Angela
Phase: I
Project Period: November 1, 2016 through October 31, 2017
Project Amount: $14,998
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2016) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources
Objective:
Access to safe drinking water is an essential 'social capability' and has been enshrined as a right for all in the Universal Declaration of Human Rights. A very large portion of the globe, particularly those situated at the lower economic bracket, is deprived of this right. Mesoamerica inhabits a major fraction of such a population, within which, Mexico inhabits nearly 8.9 million people lacking access to improved drinking water. In Mexico, Oaxaca is one of the poorest states, where more than 40% of the population lacks access to an improved water supply and these communities source water from off-grid alternatives, such as shallow groundwater, rivers, and in some cases natural springs. Lack of information on the quality of water in the region forces this population to purchase drinking water, which is the only, and unfortunately an expensive and undesirable option. Collection and storage of the collected water often cause microbial contamination and also introduce uncertainty in water quality (e.g., high mineral content and turbidity). Point-of-use (POU) treatment solutions that are appropriate for the needs of the community, can be manufactured locally, and also can be used with little to no maintenance requirement, are desirable alternatives to address this acute water crisis.
Novel ceramic water filters (CWFs) enabled with silver nanoparticles and zeolites, can be a promising POU treatment option, which can be engineered for a target community with the necessary attributes to arrive at a sustainable solution. CWFs are recognized worldwide for improving water quality in low-income communities with the use of inexpensive materials. One of the key limitations of these POUs is lack of disinfection effectiveness for waters with high mineral content, which are known to cause fluctuation in ionic silver release and potentially reduce the longevity of the devices. Locally available zeolites can be used in the filter device to soften the water and allow a continuous but sustained release of ionic silver for a long-term effective disinfection. This project takes an innovative community-centered approach, where nano-silver (AgNP)-enabled CWFs, enhanced with locally available zeolites, are being developed as per the need of three target communities in Oaxaca.
Phase I aimed to utilize the existing partnership between the University of Texas (UT) and several academic institutions in Oaxaca. lnstituto Politecnico Nacional's (IPN's) Interdisciplinary Research Center for Regional Integral Development Unit Oaxaca (CIIDIR) is a local graduate research center, and both Technological Institution of Oaxaca (ITO) and La Salle University Oaxaca (LSUO) are undergraduate academic institutions. Instituto Blaise Pascale (IBP) is a local high school, which was involved as a strong outreach partner in the area. Phase I also has gathered detailed information on socioeconomic and health status as well as on the water sourcing and water use practices from the target communities, while designed and laboratory tested nano-enabled CWF cartridges. Based on the assessed community needs, appropriate CWF device prototypes are designed. One of the key lessons learned during the Phase I of this project is that differences in water sourcing and storage practices between the communities will likely render deployment of a CWF device with a single design, ineffective. Thus Phase II aims to take a community-based design approach, where multiple appropriate device designs will be utilized to enhance ease of use, reduce the need for maintenance, while preserving disinfection efficiency of the devices. To ensure an immediate impact to the well-being of the community, the Phase II project will develop and distribute water management guides, customized to the water use practices of each of the community. The long-term solution will be achieved by detailed laboratory testing of the devices, followed by field deployment in selected houses at Oaxaca. Subsequent modification will be done by interim and long-term assessments of the device performance and water quality. The project also aims to expand the reach of this treatment solution to other communities at Oaxaca and to establish a functioning local network to self-sustain the manufacture and distribution of this technology in future.
Summary/Accomplishments (Outputs/Outcomes):
Phase I was designed to survey and document water quality and water use practices in three selected communities at Oaxaca. Relationship with community members has been developed by this effort and community engagement has begun via educational and outreach activities. A facile nano-enabled CWF has been designed and prepared with local Oaxacan materials, and disinfection and hardness removal has been demonstrated at the laboratory-scale. Engineering designs of community-appropriate prototypes to deploy these POU devices have been prepared in collaboration with Oaxacan academic institutions.
Household surveys and water quality analyses in more than 60 households at the select communities in rural Oaxaca was completed in partnership with Oaxacan partners. Communities were selected based on their respective water sources. Information in regard to expenditure on water, water sources and use, perception of water quality, and willingness to purchase new treatment solutions were collected. This case study in Oaxaca demonstrates the complexity in water use and water quality between communities and highlights the need for appropriate community-specific engineering of POU treatment solutions. The overarching similarities between communities included prevalence of gastrointestinal illnesses, collection of water from nearby natural sources and storage in a variety of containers, use of costly bottled water, and strong desire to minimize cost by accessing an alternative and effective treatment technology.
The perception on water quality was also different between communities (p-value 0.007) as was the true biological quality of water (p-value 0.001). The water in one community had high hardness (mean of 407 mg/L as CaCO3) with a high frequency of fecal coliform contamination (80% tested positive for fecal coliform presence). The other two communities are both located in close proximity to each other, where water hardness was found to be lower (average just over 50 mg/L as CaCO3) and only a few households (10% n=40) tested positive for fecal coliform presence.
Sustainability of the designed treatment option will likely be achieved via community engagement from the beginning and by the use of local materials to develop the treatment solution. AgNP-enabled CWFs prepared with locally collected clay and agave fiber materials showed effective pathogen inactivation (98.2% removal efficiency of E. coli). The locally collected zeolites showed effective removal of high hardness with breakthrough occurring after 1000 pore volumes. The laboratory studies also documented the effect of hardness on silver release, the performance of AgNP-enabled cartridges for bacterial inactivation, and the lifetime of the zeolites to remove hardness. Release of ionic silver increased with the increase in hardness. Use of zeolites is thus essential for pretreatment of the water (to remove hardness), which will increase longevity of the AgNP-enabled cartridges.
Based on a series of design considerations, two CWF device prototypes were designed and developed to target specific modes of water use in the communities. The device design also considered local water storage and water use practices and also followed methodology taught and practiced in a hands-on-educational workshop. Though water collection and storage methods varied greatly between houses and between the communities, survey results indicated that a majority of households either used or could easily gain access to garrafones and Rotoplas storage tanks with a standard faucet. A cost comparison showed that Oaxacan communities can achieve notable savings by implementing the developed technology in Phase I, when compared to their expenses to purchase bottled water for drinking.
Conclusions:
Phase I successfully met its proposed objectives. The UT team in collaboration with the Oaxacan academic institutions studied the local water issues, produced a solution with local materials, effectively completed laboratory-scale disinfection and hardness removal tests, and designed community-appropriate prototypes. The primary lesson learned in Phase I is that significant differences exist in water source and water use between the target communities. Such differences generate a need to customize the design for a specific community for achieving successful and long-term implementation of the developed solution. The customization though utilizes the same fundamental science, but is engineered as per the need of a community. Therefore, a modified engineering approach has been taken in order to design an appropriate water treatment solution for each of the targeted community. The flexibility in device design and engineering also will allow for implementation of the developed technology to other communities at Oaxaca or in regions elsewhere in the globe.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 1 publications | 1 publications in selected types | All 1 journal articles |
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Rowells L, Alcalde R, Bogolasky F, Kum S, Diaz-Arriaga F, Ayres C, Mikelonis A, Toledo-FLores L, Alonso-Gutierrez M, Perez-Flores M, Lawler D, Ward M, Lopez-Cruz J, Saleh N. Perceived versus actual water quality: Community studies in rural Oaxaca, Mexico. SCIENCE OF THE TOTAL ENVIRONMENT 2018;622-623:626-634 |
SU836762 (Final) |
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Supplemental Keywords:
ceramic water filters, nanotechnology, silver nanoparticles, zeolites, water purification, water filtration, drinking water, water treatment, water disinfection, nitrate removal, pathogen removal, environmental educationRelevant Websites:
http://bit.ly/oaxacaH2O Exit Exit
http://www.caee.utexas.edu/prof/saleh/index.html Exit
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.