Diarrheal illnesses claim the lives of hundreds of thousands of children each year, most of whom live in rural and low-income communities. Ceramic Water Filters (CWF) are widely regarded as one water treatment technology with the potential to increase access to safe drinking water. While physical filtration mechanisms are a key contributor to improving the water safety, silver is commonly added to improve disinfection performance. Therefore, a thorough review of silver disinfection efficacy and disinfection mechanisms in relation to CWFs are critically important. This paper reviews filter mechanisms and efficacy for bacteria removal for cases with and without silver addition. Method of silver application (dipping, painting, or co-firing) is assessed. Silver release and retention is discussed. The findings from this paper illustrate that eluted silver contributes to filter bacterial disinfection. However, more research is needed on the impact of silver on preventing a "slime layer" on the filter surface and receptacle. Silver application method, water quality and particle characteristics were demonstrated to impact release. For instance, co-firing results in the most consistent elution over time but at lower concentrations than other methods. Finally, research into alternative metals to silver for enhanced disinfection present emerging opportunities within the CWF field.

The synergistic potential of silver and zinc oxide nanoparticles for water disinfection was investigated herein. By causing cell death through membrane interactions, oxidative killing, and DNA deactivation, metallic nanoparticles may be integrated with point-of-use water treatment systems for applications in rural and remote geographies. Disinfection efficacy was evaluated in batch-phase experiments under both synthetic and real water conditions, where synthetic water was varied by pH and dissolved oxygen levels. Ceramic pot filters with comparative nanoparticle concentrations were also investigated. In all cases, combinations of silver and zinc nanoparticles resulted in improved disinfection in comparison to either metal in isolation. In batch experiments, dissolved oxygen proved to be particularly impactful, with kinetic rates reducing approximately 45% when in low oxygen environment (<3 mg/L) versus high oxygen (>8 mg/L). Log removal values (LRVs) were further, on average, 31% lower in real water than synthetic water after 300 min, though silver–zinc combinations were still superior to either metal alone. In filters, those impregnated with 67% silver and 33% zinc achieved average LRVs of 2.7 and 2.9 after 60 min of filtration and 24 h of storage, respectively, while those with only silver achieved average LRVs of 2.0 and 3.1 at those same times.

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The current methodological paradigm for addressing water, sanitation, and hygiene (WaSH) inaccessibility in rural sub-Saharan Africa is achieving insufficient progress. This essay evaluates WaSH-related policy, programming, and discourse from 1918 to 2021 to identify how this paradigm evolved and how it may reform. I argue that political–economic environments have strongly influenced existing sectoral praxis, shaping both programmatic methods and means. Colonial occupations generated rural–urban material inequalities, which were maintained and exacerbated during postwar reconstruction (1950–1970) and the proliferation of neoliberalism (1970–1990s). Meanwhile, modernization theory, a fundamental feature of colonial thought, has persisted discursively and practically. That is, rural resource limitations led WaSH practitioners to promote lower-cost appropriate technologies in the 1980s. Then, with challenges regarding technological disuse and misuse, behavior change–oriented methodologies responsively emerged in the 2000s and continue today. Yet, much like colonial predecessors, this latter turn presupposes that its programmatic benefactors must adapt to access WaSH services. Behavior change programs thus fail to critically consider the role of technological inadequacies and associated risk exposures in perpetuating existing inequities. Investigation of utility-style service models, where WaSH services adapt to the lives of its benefactors and behavioral persuasion is substituted for nonuser technological management, is recommended.

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