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.

Performance and Acceptance of Novel Silver-Impregnated Ceramic Cubes for Drinking Water Treatment in Two Field Sites: Limpopo Province, South Africa and Dodoma Region, Tanzania

“…Additionally, the ceramic technology was distributed with locally available 22 L plastic buckets that had lids and spigots to reduce the risk of recontamination during retrieval of water. The cubes were produced at a facility at the University of Virginia according to the method described by Ehdaie et al [33]. To disinfect 5-15 L of water, the ceramic cubes were placed in a bucket of water for at least eight hours.…”

Adopting a Preparatory Strategy to Respond to Water Security Issues Arising from Geo-Hazards

“…In follow-up studies conducted in communities where CWFs were distributed, it was found that in one Sri Lankan tsunami response community, 23% of people were using the ceramic filter three months after distribution, in the Dominican Republic, 48.7% of households were correctly operating filters 16 months after distribution with 54% of water samples from operating filters (26.1% of total) free of thermo-tolerant coliform [29,30]. Ehdaie [31], reported that 63% ceramic water filter-treated samples had < 1 CFU/100mL of E-coli after 1 year. Average percent reduction of E-coli among ceramic water filter households declined to 60% after 52 weeks, which is lower than what has previously been seen in long-term ceramic water filter studies.…”

The Use of Ceramic Water Filters in Improving the Microbial Quality of Drinking Water

“…These anti-microbial agents are able to add value of improving the killing efficacy of the ceramic water filter [4]. A study by van der Laan et al [13] showed that there was no difference in removing pathogens in ceramic water filters with silver and without silver nanoparticles.…”

“…In rural areas due to lack of awareness and maintenance, most of the families carry out the routine activities such as clothes washing, utensil washing, bathing cattle's, washing near to the ground and river water sources which is one of the reasons for contamination [3]. Close to 2 billion people over the world lack access to safe drinking water and estimated 2 million fatalities are linked to water borne infections [4]. Safe drinking water is very important in controlling and preventing many diseases.…”