title: Start-up of the Anammox process in a membrane bioreactor.
abstract: The start-up of an Anammox process was studied in a membrane sequencing batch reactor (MSBR) in which a submerged hollow fibre membrane module was used to retain the biomass. The reactor was seed with Anammox biomass and fed using the Van de Graaf medium. During a first operating stage, salt precipitation was observed and interfered with microbial activity and caused a decrease of the nitrogen removal rate of the reactor from 100 to only 10 mgl(-1) per day. Salt precipitation was avoided by diminishing adequately the Ca and P concentrations of the Van de Graaf medium during the last operating stage. This action increased quickly the activity of the system, and nitrogen removal rate reached up to 710 mgl(-1) per day with almost full nitrite removal. Sporadic flotation of the sludge was observed in the MSBR. The use of the membrane avoided biomass wash-out from the system. Moreover, a surprising fact was that Anammox biomass did not grow in flocs in the MSBR, but in granules. This fact showed that this kind of microorganisms have a trend to grow in aggregates. Results indicated that the use of the MSBR could be a suitable system for nitrogen removal by using the Anammox reaction.
authors.affiliation: Department of Chemical Engineering, Faculty of Engineering, University of Santiago de Compostela, Avda Lope Gómez de Marzoa, E-15782 Santiago de Compostela, Galicia, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Trigo
authors.forename: J L
authors.initials: JL
authors.lastname: Campos
authors.forename: J M
authors.initials: JM
authors.lastname: Garrido
authors.forename: R
authors.initials: R
authors.lastname: Méndez
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000378:metabolism; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D008566:Membranes; D008855:Microscopy, Electron, Scanning; D009573:Nitrites / Q000378:metabolism; D009584:Nitrogen / Q000302:isolation & purification* / Q000378:metabolism*; D010084:Oxidation-Reduction; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D009573:Nitrites; D000641:Ammonia; D009584:Nitrogen