title: Study of slow sand filtration with backwash and the influence of the filter media on the filter recovery and cleaning.
abstract: Slow sand filters are considered as a great alternative for supplying drinking water in rural and/or isolated areas where raw water that is treatable with this technique is available. Some studies used backwashing as an alternative for cleaning the slow sand filter with the goal of applying the technology in small communities, since filters that supply water to a small number of people do not require much space. In this study the influence of the effective diameter on water quality in the filters and cleaning system was evaluated. A pilot system with six filters was built: three filters were conventionally cleaned by scraping and the other three were cleaned by backwashing, each with a different effective diameter of filter medium. Most filters had an average turbidity of less than 1.0 NTU, the turbidity required at the output of the filters by the Brazilian Ministry of Health Ordinance. In the study, the filters cleaned by scraping with smaller-diameter filter beds effectively filtered water better but had worse effective production. The opposite occurs in the case of backwashed filters.
authors.affiliation: a Departamento de Engenharia Sanitária e Ambiental , Universidade Federal de Santa Catarina , Florianópolis , Brazil.
authors.forename: Fernando Hymnô
authors.initials: FH
authors.lastname: de Souza
authors.affiliation: b Departamento de Ciências Agrárias e Ambientais , Universidade Federal de Santa Maria , Frederico Westphalen , Brazil.
authors.forename: Bruno Segalla
authors.initials: BS
authors.lastname: Pizzolatti
authors.affiliation: a Departamento de Engenharia Sanitária e Ambiental , Universidade Federal de Santa Catarina , Florianópolis , Brazil.
authors.forename: Juliana Marques
authors.initials: JM
authors.lastname: Schöntag
authors.affiliation: a Departamento de Engenharia Sanitária e Ambiental , Universidade Federal de Santa Catarina , Florianópolis , Brazil.
authors.forename: Maurício Luiz
authors.initials: ML
authors.lastname: Sens
mesh_terms: D001938:Brazil; D005374:Filtration / Q000379:methods*; D012822:Silicon Dioxide; D018508:Water Purification / Q000379:methods*; D060753:Water Quality; D014881:Water Supply
chemical_list: D012822:Silicon Dioxide
keywords: Slow sand filtration; backwashing; filter bed; filter cleaning; water treatment