1. Silver research Vinka Oyanedel-Craver Assistant Professor University of Rhode Island Department of Civil and Environmental Engineering

2. Silver nanoparticles Disinfectant properties of silver can be used to add biocide properties to different materials and/or prevent biofilm growth

3. Goal of study Inputs Silver nanoparticles (nAg) and silver ions (Ag+) Amount of silver Water chemistry Materials (clay and burn-out) Outcomes Microbiological removal effectiveness Desorption of silver Biofilm development

4. Ceramic filters Clays: Indonesia, Tanzania,and Nicaragua Combustible material: sawdust, rice husk Silver: Colloidal silver (nAg) and silver nitrate (Ag+) Silver release Bacteria removal Biofilm formation Materials Methods

5. Experimental Setup a) A schematic diagram of the tracer, bacteria and virus transport experiments b) One-dimensional ceramic filter disc c) Permeameter chamber a) b) c)

6. Experimental Setup A schematic diagram of the tracer, bacteria transport experiments One-dimensional ceramic filter disc c)

7. Silver release EPA silver standard in drinking water 100 microgram/L

8. nAg Control range Control range Ag+ Silver impregnated disks have higher bacterial removal than controls Performance of nAg slightly superior than Ag+ Performance better at higher concentration Sig. difference between clays No difference in burn-out

9. Viable bacteria inside the ceramic materials as function of silver concentration and clay material Sig. difference between clays (Nicaragua) No difference in water chemistries

10. Recommendations Ag+ not used above 0.03 mg/g Health consequences Loss of silver Increase nAg used to 640 mg/filter If hard water is used, increase more

11. Future Research Investigate Chlorine effect on sorption of silver Various methods of application Alternative disinfectants