title: Influence of flocculation conditions in the performance of an experimental domestic sewage treatment plant consisting of an anaerobic expanded bed reactor followed by dissolved air flotation.
abstract: This paper presents the results of a study performed with an experimental domestic sewage treatment plant (240 m3 x d(-1) flow) consisting of expanded bed anaerobic reactor (EBAR) followed by dissolved air flotation (DAF) unit. For the flotation step, the anaerobic reactor effluent was previously coagulated with 50 mgFeCl3 x l(-1) and flocculated under different conditions (mean velocity gradient, Gf, and flocculation time, Tf). The Gf values were from 60 to 100 s(-1) associated with 13 and 20 min Tf values. During the tests, the following operational conditions of the flotation unit were maintained: chemical addition (50 mgFeCl3 x l(-1)), 18% recirculation rate associated with a pressure of 450 +/- 10 kPa in the saturation chamber and overflow rate of 180 m3 x m(-2) x d(-1). Temperature ranged from 23.8 degrees C to 30.0 degrees C. Best results were achieved for Gf = 80 s(-1) and Tf = 20 min. For these conditions, the DAF unit removal efficiencies were: 94.4% for chemical oxygen demand (with 53 mg x l(-1) COD residual), 87% for phosphorus (with 0.80 mgP x l(-1) residual), 96.7% for total suspended solids (with 9 mg x l(-1) TSS residual) and 96.4% for turbidity (with 12.9 NTU residual), when the anaerobic reactor effluents have worst quality during the whole day.
authors.affiliation: Department of Hydraulic and Sanitary Engineering, São Carlos School of Engineering, University of São Paulo (SHS-EESC-USP), Av. Trabalhador São-carlense, 400, São Carlos, SP, Brasil 13560-250. penetra@otv.com.br
authors.forename: R G
authors.initials: RG
authors.lastname: Penetra
authors.forename: M A P
authors.initials: MA
authors.lastname: Reali
authors.forename: J R
authors.initials: JR
authors.lastname: Campos
mesh_terms: D000388:Air; D001421:Bacteria, Anaerobic / Q000502:physiology*; D019149:Bioreactors; D005427:Flocculation; D010758:Phosphorus / Q000302:isolation & purification; D012722:Sewage / Q000382:microbiology*; D012995:Solubility; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D012722:Sewage; D010758:Phosphorus