title: Granular biomass capable of partial nitritation and anammox.
abstract: A novel and efficient way of removing nitrogen from wastewater poor in biodegradable organic carbon, is the combination of partial nitritation and anoxic ammonium oxidation (anammox), as in the one-stage oxygen-limited autotrophic nitrification/denitrification (OLAND) process. Since anoxic ammonium-oxidizing bacteria grow very slowly, maximum biomass retention in the reactor is required. In this study, a lab-scale sequencing batch reactor (SBR) was used to develop granular, rapidly settling biomass. With SBR cycles of one hour and a minimum biomass settling velocity of 0.7 m/h, OLAND granules were formed in 1.5 months and the nitrogen removal rate increased from 50 to 450 mg N L(-1) d(-1) in 2 months. The granules had a mean diameter of 1.8 mm and their aerobic and anoxic ammonium-oxidizing activities were well equilibrated to perform the OLAND reaction. Fluorescent in-situ hybridization (FISH) demonstrated the presence of both beta-proteobacterial aerobic ammonium oxidizers and planctomycetes (among which anoxic ammonium oxidizers) in the granules. The presented results show the applicability of rapidly settling granular biomass for one-stage partial nitritation and anammox.
authors.affiliation: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, Ghent 9000, Belgium. siegfried.vlaeminck@ugent.be
authors.forename: S E
authors.initials: SE
authors.lastname: Vlaeminck
authors.forename: L F F
authors.initials: LF
authors.lastname: Cloetens
authors.forename: M
authors.initials: M
authors.lastname: Carballa
authors.forename: N
authors.initials: N
authors.lastname: Boon
authors.forename: W
authors.initials: W
authors.lastname: Verstraete
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D009584:Nitrogen / Q000378:metabolism*; D014871:Water Microbiology; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods
chemical_list: D000641:Ammonia; D009584:Nitrogen