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

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

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

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

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)

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

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

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

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

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

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