title: Integrated horizontal-flow anaerobic and radial-flow aerobic reactors for the removal of organic matter and nitrogen from domestic sewage.
abstract: This paper presents the conception and discusses the results obtained from the operation of an integrated biological anaerobic/aerobic/anaerobic system composed of horizontal-flow anaerobic and radial-flow aerobic reactors for domestic sewage treatment. The performance of a horizontal-flow anaerobic immobilized biomass reactor, with five stages,followed by a radial-flow aerobic immobilized biomass reactor was evaluated along 22 weeks. After the 14th week, the last stage of the HAIB reactor was used as a denitrifying unit. Polyurethane foam cubic matrices with 1-cm sides were used as support for biomass immobilization in all the units. The influent domestic sewage presented mean chemical oxygen demand of 365 +/- 71 mg. 1(-1) and the temperature was 23 +/- 3degrees C. The integrated system achieved COD removal efficiency of 90% while the maximum ammonium removal efficiency was 97% in the aerobic post-treatment unit. The nitrification process was found to be better represented by first-order reactions in series model. The apparent first-order kinetic coefficient for nitrate formation was about 50 times higher than that estimated for the nitrite formation. The denitrification process was well represented by a Monod-type kinetic model. The maximum specific denitrifying rate and the half-saturation coefficient were 2.9 x 10(-4) mg NO(3)(-)-N mg(-1) VSS h(-1) and 19.4 mg NO(3)(-)-N 1(-1), respectively.
authors.affiliation: Laboratório de Processos Biológicos, Departamento de Hidráulica e Saneamento, Escola de Engenharia de São Carlos (EESC), Universidade de São Paulo (USP), Av. Trabalhador São-carlense, 400, 13566-590 São Carlos, SP, Brazil.
authors.forename: L G T
authors.initials: LG
authors.lastname: Vieira
authors.forename: A
authors.initials: A
authors.lastname: Fazolo
authors.forename: M
authors.initials: M
authors.lastname: Zaiat
authors.forename: E
authors.initials: E
authors.lastname: Foresti
mesh_terms: D001420:Bacteria, Aerobic; D001421:Bacteria, Anaerobic; D019149:Bioreactors; D007700:Kinetics; D009584:Nitrogen / Q000302:isolation & purification*; D010100:Oxygen; D011140:Polyurethanes; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements
chemical_list: D011140:Polyurethanes; D012722:Sewage; C028279:polyurethane foam; D009584:Nitrogen; D010100:Oxygen