title: Post-treatment of anaerobic effluents in an overland flow system.
abstract: This research aimed at the investigation of an overland flow system applied to the post-treatment of anaerobic effluents. The system treated domestic sewage in Itabira City (Brazil), being composed by an anaerobic reactor and an overland flow system, the latter working as a post-treatment unit. A portion of the reactor's effluent was directed to a group of three overland flow slopes (demonstration scale), that were operated with different application rates. During Phase 1 of the research the overland flow system was fed under a permanent hydraulic regime (constant flows), having as inflow the effluent from an UASB reactor (full-scale, volume of 477 m3). During Phase 2, the overland system was fed under a hydraulic transient pattern (variable flows with hourly variations), having as inflow the effluent from a partitioned UASB reactor (demonstration-scale, volume of 9 m3). In general, the performance of the overland flow system as a polishing step was very good, mainly because of the low solids and organic matter concentration in the final effluent (average values of BOD from 48 to 62 mg/L; COD from 98 to 119 mg/L and SS from 17 to 57 mg/L). Regarding nutrients and coliforms, the system also reached satisfactory efficiency levels. Based on the experience obtained with this study, it is suggested that overland flow systems, working as post-treatment step of UASB reactors, can work with application rates in the range of 0.4 to 0.5 m3/m.h, which are higher than those normally applied.
authors.affiliation: Federal University of Minas Gerais-Department of Sanitary and Environmental Engineering, Av. Contorno 842/701-30110-060, Belo Horizonte, Brazil. calemos@desa.ufmg.br
authors.forename: C A
authors.initials: CA
authors.lastname: Chernicharo
authors.forename: R S
authors.initials: RS
authors.lastname: Cota
authors.forename: A M
authors.initials: AM
authors.lastname: Zerbini
authors.forename: M
authors.initials: M
authors.lastname: von Sperling
authors.forename: L H
authors.initials: LH
authors.lastname: Brito
mesh_terms: D001421:Bacteria, Anaerobic / Q000502:physiology*; D019149:Bioreactors; D010100:Oxygen / Q000378:metabolism; D011312:Pressure; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements; D018508:Water Purification / Q000379:methods*
chemical_list: D012722:Sewage; D010100:Oxygen