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.
Highlights
Drinking water for approximately 1.8 billion people around the world is contaminated with fecal pathogenic microorganisms, and contributes to the 2 million deaths annually associated to diarrheal diseases [1]
At week 52, the ceramic water purification systems (CWF)+silver-embedded ceramic tablet when used alone (SCT) group had a higher number of CWF+SCTs providing 100% reduction in E. coli compared to the control group
The same trend was seen among the POUWTs when comparing geometric mean of E. coli and total coliform reductions, bacterial reduction was consistently high among CWF and CWF+SCT groups
Summary
Drinking water for approximately 1.8 billion people around the world is contaminated with fecal pathogenic microorganisms, and contributes to the 2 million deaths annually associated to diarrheal diseases [1]. Households may have access to public taps monitored by the municipal government, they often face water shortages and impaired municipal water systems leading to poor drinking water quality [3]. Point-of-use water treatment (PoUWT) methods have shown great promise in improving water quality at the point of consumption. There are multiple promising PoUWTs, including ceramic water filters [4,5,6], chlorine-based methods [7,8], biosand filters [9,10] and flocculent/disinfecting powders [11]. Proven effective in a laboratory setting, the performance of these PoUWT methods is dependent on external factors, such as user-compliance, ease of use of the technology, and existing poor sanitation and hygiene conditions, when used in households [12]. Long-term performance of PoUWT methods can decline when applied in field settings [15,16]
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