title: Performance evaluation of a natural treatment system for small communities, composed of a UASB reactor, maturation ponds (baffled and unbaffled) and a granular rock filter in series.
abstract: Post-treatment of anaerobic reactor effluent with maturation ponds is a good option for small to medium-sized communities in tropical climates. The treatment line investigated, operating in Brazil, with an equivalent capacity to treat domestic sewage from 250 inhabitants, comprised a upflow anaerobic sludge blanket reactor followed by two shallow maturation ponds (unbaffled and baffled) and a granular rock filter (decreasing grain size) in series, requiring an area of only 1.5 m2inhabitant-1. With an overall hydraulic retention time of only 6.7 days, the performance was excellent for a natural treatment system. Based on over two years of continuous monitoring, median removal efficiencies were: biochemical oxygen demand = 93%, chemical oxygen demand = 79%, total suspended solids = 87%, ammonia = 43% and Escherichia coli = 6.1 log units. The final effluent complied with European discharge standards and WHO guidelines for some forms of irrigation, and appeared to be a suitable alternative for treating domestic sewage for small communities in warm areas, especially in developing countries.
authors.affiliation: a Department of Sanitary and Environmental Engineering , Federal University of Minas Gerais , Belo Horizonte , Brazil.
authors.forename: D F C
authors.initials: DFC
authors.lastname: Dias
authors.affiliation: a Department of Sanitary and Environmental Engineering , Federal University of Minas Gerais , Belo Horizonte , Brazil.
authors.forename: R G
authors.initials: RG
authors.lastname: Passos
authors.affiliation: a Department of Sanitary and Environmental Engineering , Federal University of Minas Gerais , Belo Horizonte , Brazil.
authors.forename: V A J
authors.initials: VAJ
authors.lastname: Rodrigues
authors.affiliation: a Department of Sanitary and Environmental Engineering , Federal University of Minas Gerais , Belo Horizonte , Brazil.
authors.forename: M P
authors.initials: MP
authors.lastname: de Matos
authors.affiliation: a Department of Sanitary and Environmental Engineering , Federal University of Minas Gerais , Belo Horizonte , Brazil.
authors.forename: C R S
authors.initials: CRS
authors.lastname: Santos
authors.affiliation: a Department of Sanitary and Environmental Engineering , Federal University of Minas Gerais , Belo Horizonte , Brazil.
authors.forename: M
authors.initials: M
authors.lastname: von Sperling
mesh_terms: D000641:Ammonia; D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D001938:Brazil; D005374:Filtration / Q000379:methods; D061005:Ponds; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D000641:Ammonia
keywords: Sewage; UASB reactor; baffled pond; granular rock filter; shallow maturation ponds