title: Characterization of nitrifying granules produced in an aerobic upflow fluidized bed reactor.
abstract: Since nitrification is the rate-determining step in the biological nitrogen removal from wastewater, many research studies have been conducted on the immobilization of nitrifying bacteria. In this research, granulation of nitrifying bacteria in an aerobic upflow fluidized bed (AUFB) reactor in a nitrification process for inorganic wastewater containing 500 g/m(3) of NH(4)(+)-N was investigated. It was observed that spherical, pseudocubic and elliptical granules with a diameter of 346 microm were produced at the bottom of the reactor after 300 days. Denaturing gradient gel electrophoresis analysis revealed that Nitrosomonas-like bacteria were the dominant ammonia-oxidizing species in the granules. Many colonies of Nitrosomonas-like bacteria were found in the outer part of the granules based on the spatial distribution analysis by fluorescence in situ hybridization. By stepwise reduction of the hydraulic retention time, the ammonia removal rate of the AUFB reactor containing these nitrifying granules finally reached 1.5 kg-N/m(3)/day. Results suggested that the use of granules realizes the retention of a large amount of nitrifying bacteria in the reactor, which guarantees a highly efficient nitrification.
authors: Department of Chemical Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan. stsuneda@waseda.jp
authors: Satoshi
authors: S
authors: Tsuneda
authors: Tatsuo
authors: T
authors: Nagano
authors: Tatsuhiko
authors: T
authors: Hoshino
authors: Yoshihiro
authors: Y
authors: Ejiri
authors: Naohiro
authors: N
authors: Noda
authors: Akira
authors: A
authors: Hirata
mesh_terms: D000641:Ammonia / Q000032:analysis; D001420:Bacteria, Aerobic; D019149:Bioreactors; D017404:In Situ Hybridization, Fluorescence; D009584:Nitrogen / Q000378:metabolism*; D009606:Nitrosomonas / Q000502:physiology*; D010316:Particle Size; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements
chemical_list: D000641:Ammonia; D009584:Nitrogen