title: Bacteria and virus removal effectiveness of ceramic pot filters with different silver applications in a long term experiment.
abstract: In 2012 more than 4 million people used a ceramic pot filter (CPF) as household water treatment system for their daily drinking water needs. In the normal production protocol most low cost filters are impregnated with a silver solution to enhance the microbial removal efficiency. The aim of this study was to determine the role of silver during the filtration and subsequent storage. Twenty-two CPFs with three different silver applications (non, only outside and both sides) were compared in a long-term loading experiment with Escherichia coli (K12 and WR1) and MS2 bacteriophages in natural challenge water under highly controlled laboratory circumstances. No significant difference in Log Removal Values were found between the filters with different silver applications. The results show that the storage time in the receptacle is the dominant parameter to reach E. coli inactivation by silver, and not the contact time during the filtration phase. The hypothesis that the absence of silver would enhance the virus removal, due to biofilm formation on the ceramic filter element, could not be confirmed. The removal effectiveness for viruses is still of major concern for the CPF. This study suggests that the ceramic pot filter characteristics, such as burnt material content, do not determine E. coli removal efficacies, but rather the contact time with silver during storage is the dominant parameter to reach E. coli inactivation.
authors.affiliation: Delft University of Technology, Department of Water Management, 1, 2628 CN Delft, The Netherlands; Oasen Drinking Water Company, Post Box 122, 2800 AC Gouda, The Netherlands. Electronic address: harmen.van.der.laan@oasen.nl.
authors.forename: H
authors.initials: H
authors.lastname: van der Laan
authors.affiliation: Delft University of Technology, Department of Water Management, 1, 2628 CN Delft, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: van Halem
authors.affiliation: KWR Watercycle Research Institute, Groningenhaven 7, 3433 PE Nieuwegein, The Netherlands.
authors.forename: P W M H
authors.initials: PW
authors.lastname: Smeets
authors.affiliation: Aqua for All Foundation, Koningskade 40, 2596 AA The Hague, The Netherlands.
authors.forename: A I A
authors.initials: AI
authors.lastname: Soppe
authors.affiliation: Het Waterlaboratorium, J.W. Lucasweg 2, 2031 BE Haarlem, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Kroesbergen
authors.affiliation: Waterlaboratorium Noord, Rijksstraatweg 85, 9756 AD Glimmen, The Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: Wubbels
authors.affiliation: Practica Foundation, Oosteind 47, 3356 AB Papendrecht, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Nederstigt
authors.affiliation: Engineers Without Borders Australia, 99 Howard Street, North Melbourne, VIC, Australia; Downer EDI Works Ltd., 135A Main South Rd, Post Box 13-031, Green Island Dunedin, New Zealand.
authors.forename: I
authors.initials: I
authors.lastname: Gensburger
authors.affiliation: Delft University of Technology, Department of Water Management, 1, 2628 CN Delft, The Netherlands.
authors.forename: S G J
authors.initials: SG
authors.lastname: Heijman
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D004926:Escherichia coli / Q000187:drug effects / Q000302:isolation & purification; D005374:Filtration / Q000379:methods*; D017909:Levivirus / Q000187:drug effects / Q000302:isolation & purification; D008851:Micropore Filters; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology*; D013997:Time Factors; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods
chemical_list: D012834:Silver
keywords: Bacteria; Ceramic pot water filter; Point-of-use water treatment; Silver; Virus