title: Point-of-Use Removal of Cryptosporidium parvum from Water: Independent Effects of Disinfection by Silver Nanoparticles and Silver Ions and by Physical Filtration in Ceramic Porous Media.
abstract: Ceramic water filters (CWFs) impregnated with silver nanoparticles are a means of household-level water treatment. CWFs remove/deactivate microbial pathogens by employing two mechanisms: metallic disinfection and physical filtration. Herein we report on the independent effects of silver salt and nanoparticles on Cryptosporidium parvum and the removal of C. parvum by physical filtration in porous ceramic filter media. Using a murine (mouse) model, we observed that treatment of oocysts with silver nitrate and proteinate-capped silver nanoparticles resulted in decreased infection relative to untreated oocysts. Microscopy and excystation experiments were conducted to support the disinfection investigation. Heat and proteinate-capped silver-nanoparticle treatment of oocysts resulted in morphological modifications and decreased excystation rates of sporozoites. Subsequently, disk-shaped ceramic filters were produced to investigate the transport of C. parvum. Two factors were varied: sawdust size and clay-to-sawdust ratio. Five disks were prepared with combinations of 10, 16, and 20 mesh sawdust and sawdust percentage that ranged from 9 to 11%. C. parvum removal efficiencies ranged from 1.5 log (96.4%) to 2.1 log (99.2%). The 16-mesh/10% sawdust had the greatest mean reduction of 2.1-log (99.2%), though there was no statistically significant difference in removal efficiency. Based on our findings, physical filtration and silver nanoparticle disinfection likely contribute to treatment of C. parvum for silver impregnated ceramic water filters, although the contribution of physical filtration is likely greater than silver disinfection.
authors.affiliation: Environmental Sciences and Engineering Department, University of North Carolina Chapel Hill, North Carolina 27599-7400, United States.
authors.forename: Lydia S
authors.initials: LS
authors.lastname: Abebe
authors.affiliation: Department of Electrical and Computer Engineering, University of Virginia , P.O. Box 400743 Charlottesville, Virginia 22904-4742, United States.
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Su
authors.affiliation: Department of Medicine, University of Virginia , P.O. Box 801379 Charlottesville, Virginia 22904-4742, United States.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Guerrant
authors.affiliation: Department of Electrical and Computer Engineering, University of Virginia , P.O. Box 400743 Charlottesville, Virginia 22904-4742, United States.
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Swami
authors.affiliation: University of Virginia , Department of Civil and Environmental Engineering, Charlottesville, Virginia 22904-4742, United States.
authors.forename: James A
authors.initials: JA
authors.lastname: Smith
mesh_terms: D000818:Animals; D001835:Body Weight; D002516:Ceramics / Q000494:pharmacology*; D016785:Cryptosporidium parvum / Q000187:drug effects / Q000302:isolation & purification*; D004203:Disinfection / Q000379:methods*; D005260:Female; D005374:Filtration / Q000379:methods*; D021621:Imaging, Three-Dimensional; D007477:Ions; D053768:Metal Nanoparticles / Q000737:chemistry*; D008810:Mice, Inbred C57BL; D033661:Oocysts / Q000166:cytology; D016062:Porosity; D012834:Silver / Q000494:pharmacology*; D012835:Silver Nitrate / Q000494:pharmacology; D014867:Water / Q000469:parasitology*; D018508:Water Purification
chemical_list: D007477:Ions; D014867:Water; D012834:Silver; D012835:Silver Nitrate