title: Evaluation of a Silver-Embedded Ceramic Tablet as a Primary and Secondary Point-of-Use Water Purification Technology in Limpopo Province, S. Africa.
abstract: The World Health Organization (WHO) recognizes point-of-use water treatment (PoUWT) technologies as effective means to improve water quality. This paper investigates long-term performance and social acceptance of a novel PoUWT technology, a silver-infused ceramic tablet, in Limpopo Province, South Africa. When placed in a water storage container, the silver-embedded ceramic tablet releases silver ions into water, thereby disinfecting microbial pathogens and leaving the water safe for human consumption. As a result of its simplicity and efficiency, the silver-embedded ceramic tablet can serve as a stand-alone PoUWT method and as a secondary PoUWT to improve exisitng PoUWT methods, such as ceramic water filters. In this paper, three PoUWT interventions were conducted to evaluate the silver-embedded ceramic tablet: (1) the silver-embedded ceramic tablet as a stand-alone PoUWT method, (2) ceramic water filters stand-alone, and (3) a filter-tablet combination. The filter-tablet combination evaluates the silver-embedded ceramic tablet as a secondary PoUWT method when placed in the lower reservoir of the ceramic water filter system to provide residual disinfection post-filtration. Samples were collected from 79 households over one year and analyzed for turbidity, total silver levels and coliform bacteria. Results show that the silver-embedded ceramic tablet effectively reduced total coliform bacteria (TC) and E. coli when used as a stand-alone PoUWT method and when used in combination with ceramic water filters. The silver-embedded ceramic tablet's performance as a stand-alone PoUWT method was comparable to current inexpensive, single-use PoUWT methods, demonstrating 100% and 75% median reduction in E. coli and TC, respectively, after two months of use. Overall, the the filter-tablet combination performed the best of the three interventions, providing a 100% average percent reduction in E. coli over one year. User surveys were also conducted and indicated that the silver-embedded ceramic tablet was simple to use and culturally appropriate. Also, silver levels in all treated water samples remained below 20 μg/L, significantly lower than the drinking water standard of 100 μg/L, making it safe for consumption. Long-term data demonstrates that the silver-embedded ceramic tablet has beneficial effects even after one year of use. This study demonstrates that the silver-embedded ceramic tablet can effectively improve water quality when used alone, or with ceramic water filters, to reduce rates of recontamination. Therefore, the tablet has the potential to provide a low-cost means to purify water in resource-limited settings.
authors.affiliation: Department of Civil and Environmental Engineering, Unviersity of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Beeta
authors.initials: B
authors.lastname: Ehdaie
authors.affiliation: Department of Civil and Environmental Engineering, Unviersity of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Chloe T
authors.initials: CT
authors.lastname: Rento
authors.affiliation: Department of Civil and Environmental Engineering, Unviersity of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Veronica
authors.initials: V
authors.lastname: Son
authors.affiliation: Department of Civil and Environmental Engineering, Unviersity of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Sydney S
authors.initials: SS
authors.lastname: Turner
authors.affiliation: Department of Microbiology, University of Venda, Department of Chemistry, University of Venda, Thohoyandou, Limpopo Province, South Africa.
authors.forename: Amidou
authors.initials: A
authors.lastname: Samie
authors.affiliation: Department of Medicine, University of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Dillingham
authors.affiliation: Department of Civil and Environmental Engineering, Unviersity of Virginia, Charlottesville, Virginia, United States of America.
authors.forename: James A
authors.identifier: http://orcid.org/0000-0002-0338-0868
authors.initials: JA
authors.lastname: Smith
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D004202:Disinfectants / Q000737:chemistry*; D004203:Disinfection; D005374:Filtration; D006801:Humans; D012834:Silver / Q000737:chemistry*; D013019:South Africa; D013607:Tablets / Q000737:chemistry*; D014871:Water Microbiology; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods*; D060753:Water Quality
chemical_list: D004202:Disinfectants; D013607:Tablets; D012834:Silver