title: Stability of the ANAMMOX process in a gas-lift reactor and a SBR.
abstract: In the last years, the ANAerobic AMMonium OXidation (ANAMMOX) process has been put forward as a promising alternative to treat ammonium rich wastewaters. An ANAMMOX gas-lift reactor and a sequential batch reactor (SBR) were operated during around 200 days in this study, reaching nitrogen loading rates (NLRs) of 2.0 and 0.75 g l(-1) per day, respectively. The efficiency in the nitrite (limiting substrate) removal was 99%. The ammonium and nitrite influent concentrations were increased stepwise until biomass in the reactors started to float. These flotation events coincided with periods when the NLR exceeded the maximum specific ANAMMOX activity (MSAA) of the sludge. The MSAA, determined in batch experiments, was 0.9 and 0.44 g g(-1) per day for biomasses from the gas-lift reactor and the SBR, respectively. Flotation of the biomass occurred most likely due to a granule density decrease caused by dinitrogen gas accumulation inside the granules and an apparent breakage of the granules. Further research is needed to understand this phenomenon and to optimise the corresponding strategies to counteract the flotation.
authors.affiliation: Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, Avda. Lope Gómez de Marzoa s/n, E-15782 Santiago de Compostela, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Dapena-Mora
authors.forename: J L
authors.initials: JL
authors.lastname: Campos
authors.forename: A
authors.initials: A
authors.lastname: Mosquera-Corral
authors.forename: M S M
authors.initials: MS
authors.lastname: Jetten
authors.forename: R
authors.initials: R
authors.lastname: Méndez
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism*; D018533:Biomass; D019149:Bioreactors; D004867:Equipment Design; D005427:Flocculation; D009573:Nitrites / Q000032:analysis / Q000378:metabolism*; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D010084:Oxidation-Reduction; D000644:Quaternary Ammonium Compounds / Q000032:analysis / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
chemical_list: D009573:Nitrites; D000644:Quaternary Ammonium Compounds; D009584:Nitrogen