Integrating Navajo Pottery Techniques To Improve Silver Nanoparticle-Enabled Ceramic Water Filters for Disinfection

Abstract

Point-of-use treatment technologies can increase access to safe drinking water in rural areas. Sustained use of these technologies is uncommon due to oversight of community needs, user-perceived risks, long-term maintenance, and conflict with traditional practices. Nanosilver-enabled ceramic water filters are unique due to the use of locally sourced materials available at or near the target community; however, technical limitations persist (e.g., nanosilver's uncontrolled release and passivation from sulfide or chloride). This work aims to overcome these limitations by impregnating nanosilver onto ceramics with a Navajo pottery rosin, collected from pinyon trees with a third-generation artisan. Here, we investigate this sustainable and novel material for drinking water treatment; the study ranges from a proof of concept to testing under realistic conditions. Results show that when embedded in a thin film, the biopolymer controlled ionic silver dissolution and prevented silver passivation from sulfide and chloride. When applied to ceramic filters, the biopolymer effectively immobilized nanosilver in a range of waters. Over a 25 day study to emulate household-use conditions, this coating method sustained disinfection of a coculture of Gram-positive and Gram-negative bacteria while controlling biofouling. Overall, the use of this Navajo pottery material can facilitate adoption while providing the needed technological advancement to these widely used treatment devices.

Assessing the relative sustainability of point-of-use water disinfection technologies for off-grid communities

“…The CWF is coated with AgNPs such that the ceramic matrix filters for a combination of physical (through filtering) and chemical (through AgNPs) disinfection. [10][11][12]27 As shown in Figure S3, the setup has the ceramic coated with AgNP placed over a plastic bucket that holds the filtered and treated water. Materials used to make the setup (sawdust, clay, wood for the filters and polyethylene for the plastic container) were incorporated to account for their costs and environmental impacts.…”

“…Specifically, more frequent recoating is expected for higher turbidity and hardness because these constituents have been reported to remove more AgNPs. 10,11 In this analysis, a turbidity >10 NTU and/or hardness >60 mg CaCO3⋅L -1 were used as the thresholds for more frequent recoating of AgNPs.…”

“…31 Both waters have 1,500 -2,500 CFU⋅100 mL -1 of E. coli. 11 A characteristic groundwater had a turbidity of 1 -10 NTU and hardness of 60 -120 mg⋅L -1 as CaCO3, and characteristic surface water had a turbidity of 10 -30 NTU and hardness of 0 -60 mg⋅L -1 as CaCO3. 31…”

“…Demographic (household size), water quality (E. coli, turbidity, hardness), and energy (electricity cost and GWP characterization factor) data were collected from ten different communities. These communities include two from Africa (Kampala, Uganda; 36,37 Limpopo, South Africa 38 ), two from Asia (Gunungkidul, Indonesia; 39 Panobolon Island, Philippines 40 ), four from North America (Colonias, United States; 41,42 Navajo Nation, United States; 11 Les Anglais, Haiti 43 ; Oaxaca, Mexico 44 ), and two from South America (Santa Cruz, Bolivia 45 ; Antioquia, https://doi.org/10.26434/chemrxiv-2024-drv50 ORCID: https://orcid.org/0000-0002-3489-9179 Content not peer-reviewed by ChemRxiv. License: CC BY 4.0 Colombia 46 ).…”

“…9 Ceramic water filters are another POU technology that can be produced with local materials and provide dual mechanisms to remove bacteria, i.e., the porous physical ceramic matrix filtration and silver nanoparticle antimicrobial coating. 10,11 A randomized controlled field trial in Bolivia demonstrated the effectiveness of ceramic filters in meeting World Health Organization (WHO) drinking-water standards. While results obtained proved valuable in achieving compliance when faced with turbid challenge waters, additional research is needed.…”