title: Effect of Sand Bed Depth and Medium Age on Escherichia coli and Turbidity Removal in Biosand Filters.
abstract: The main objective of this study was to build several full-scale biosand filters (BSFs) and assess the long-term (9 month) efficacy for particulate and Escherichia coli removal under simulated real-world usage. Four replicates of three different filter designs were built: the traditional concrete BSF and two scaled-down versions that use a 5 or 2 gal bucket as the casing material. The smaller sand bed depths in the bucket-sized filters did not impact filter performance with respect to (i) turbidity and E. coli removal or (ii) effluent levels of turbidity and E. coli. All filters produced effluents with a mean turbidity of <0.6 nephelometric turbidity unit. In addition, 78, 74, and 72% of effluent samples for the concrete, 5 gal, and 2 gal filters, respectively, had E. coli concentrations of <1 colony-forming unit/100 mL. The bucket-sized filters were found to be a potential alternative to the concrete BSFs for the removal of E. coli and turbidity from drinking water. Because smaller BSFs must be filled more frequently than larger BSFs to produce comparable water volumes, the effect of shorter pause periods on BSF performance should be investigated.
authors.affiliation: Department of Civil and Environmental Engineering, Lehigh University , Bethlehem, Pennsylvania 18015, United States.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Napotnik
authors.affiliation: Centre for Affordable Water and Sanitation Technology , Calgary, Alberta T2E 8H6, Canada.
authors.forename: Derek
authors.initials: D
authors.lastname: Baker
authors.affiliation: Department of Civil and Environmental Engineering, Lehigh University , Bethlehem, Pennsylvania 18015, United States.
authors.forename: Kristen L
authors.identifier: 0000-0002-9915-0230
authors.initials: KL
authors.lastname: Jellison
mesh_terms: D004926:Escherichia coli; D005374:Filtration; D012822:Silicon Dioxide; D014871:Water Microbiology; D018508:Water Purification
chemical_list: D012822:Silicon Dioxide