title: Comparison of sulfate-reducing and conventional Anammox upflow anaerobic sludge blanket reactors.
abstract: Autotrophic NH4(+) removal has been extensively researched, but few studies have investigated alternative electron acceptors (for example, SO4(2-)) in NH4(+) oxidation. In this study, sulfate-reducing anaerobic ammonium oxidation (SRAO) and conventional Anammox were started up in upflow anaerobic sludge blanket reactors (UASBRs) at 36 (±0.5)°C and 20 (±0.5)°C respectively, using reject water as a source of NH4(+). SO4(2-) or NO2(-), respectively, were applied as electron acceptors. It was assumed that higher temperature could promote the SRAO, partly compensating its thermodynamic disadvantage comparing with the conventional Anammox to achieve comparable total nitrogen (TN) removal rate. Average volumetric NH4(+)-N removal rate in the sulfate-reducing UASBR1 was however 5-6 times less (0.03 kg-N/(m(3) day)) than in the UASBR2 performing conventional nitrite-dependent autotrophic nitrogen removal (0.17 kg-N/(m(3) day)). However, the stoichiometric ratio of NH4(+) removal in UASBR1 was significantly higher than could be expected from the extent of SO4(2-) reduction, possibly due to interactions between the N- and S-compounds and organic matter of the reject water. Injections of N2H4 and NH2OH accelerated the SRAO. Similar effect was observed in batch tests with anthraquinone-2,6-disulfonate (AQDS). For detection of key microorganisms PCR-DGGE was used. From both UASBRs, uncultured bacterium clone ATB-KS-1929 belonging to the order Verrucomicrobiales, Anammox bacteria (uncultured Planctomycete clone Pla_PO55-9) and aerobic ammonium-oxidizing bacteria (uncultured sludge bacterium clone ASB08 "Nitrosomonas") were detected. Nevertheless the SRAO process was shown to be less effective for the treatment of reject water, compared to the conventional Anammox.
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila St., 50411 Tartu, Estonia. Electronic address: ergo.rikmann@ut.ee.
authors.forename: Ergo
authors.initials: E
authors.lastname: Rikmann
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila St., 50411 Tartu, Estonia.
authors.forename: Ivar
authors.initials: I
authors.lastname: Zekker
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila St., 50411 Tartu, Estonia.
authors.forename: Martin
authors.initials: M
authors.lastname: Tomingas
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila St., 50411 Tartu, Estonia.
authors.forename: Priit
authors.initials: P
authors.lastname: Vabamäe
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila St., 50411 Tartu, Estonia.
authors.forename: Kristel
authors.initials: K
authors.lastname: Kroon
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila St., 50411 Tartu, Estonia.
authors.forename: Alar
authors.initials: A
authors.lastname: Saluste
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila St., 50411 Tartu, Estonia.
authors.forename: Taavo
authors.initials: T
authors.lastname: Tenno
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila St., 50411 Tartu, Estonia.
authors.forename: Anne
authors.initials: A
authors.lastname: Menert
authors.affiliation: Tallinn University of Technology, 5 Ehitajate St., 19086 Tallinn, Estonia.
authors.forename: Liis
authors.initials: L
authors.lastname: Loorits
authors.affiliation: Centro Nacional de Investigaciones Biotecnologicas, CNIB, Calle Alcides Arguedas 429, Cala Cala, Cochabamba, Bolivia.
authors.forename: Sergio S C dC
authors.initials: SS
authors.lastname: Rubin
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila St., 50411 Tartu, Estonia.
authors.forename: Toomas
authors.initials: T
authors.lastname: Tenno
mesh_terms: D000641:Ammonia / Q000737:chemistry* / Q000378:metabolism; D000693:Anaerobiosis; D000880:Anthraquinones / Q000378:metabolism; D019149:Bioreactors; D002689:Chlamydia / Q000378:metabolism*; D009573:Nitrites / Q000737:chemistry* / Q000378:metabolism; D009584:Nitrogen / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D012722:Sewage / Q000382:microbiology*; D013431:Sulfates / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D000880:Anthraquinones; D009573:Nitrites; D012722:Sewage; D013431:Sulfates; C408124:anthraquinone-2,6-disulfonate; D000641:Ammonia; D009584:Nitrogen
keywords: Anammox intermediates; Autotrophic  removal; Humic matter; Sulfate-reducing ammonium oxidation; Upflow anaerobic sludge blanket reactor