title: Temperature dependence of nitrogen removal activity by anammox bacteria enriched at low temperatures.
abstract: The anaerobic ammonium oxidation (anammox) process, which is applicable at ambient temperature, is necessary to develop more versatile nitrogen removal technologies. In this study, two anammox reactors, Low-R1 and Low-R2 inoculated with activated sludge respectively in Kumamoto and Hokkaido, Japan, achieved nitrogen removal rates (NRRs) of 1.5 kg-N/m3/day at 20°C. The specific anammox activity (SAA) of the Low-R1 and Low-R2 sludge samples had peaks, respectively, of 2.8±0.3 mg-N/g-VSS/h at 25°C and 4.2±0.3 mg-N/g-VSS/h at 30°C and dropped over the optimum temperature. Moreover, the SAA values of the Low-R1 and Low-R2 were higher at 10-25°C and 10-35°C, respectively, than that of an anammox reactor inoculated with activated sludge in Kumamoto operated at 35°C (Mod-R). The apparent activation energy for anammox of Low-R1, Low-R2, and Mod-R were 108 kJ/mol (10-25°C), 73 kJ/mol (10-30°C), and 89 kJ/mol (10-35°C), respectively. Candidatus Kuenenia stuttgartiensis dominated in the Mod-R sludge. The Low-R1 sludge was comprised of Ca. K. stuttgartiensis, Ca. Brocadia caroliniensis and Ca. B. fulgida and uncultured anammox-like or planctomycete-like bacteria. The Low-R2 sludge was comprised of various uncultured anammox-like or planctomycete-like bacteria. As Low-R2 was constructed, enrichment of freshwater anammox bacteria at low temperature with seed sludge collected from cold regions is expected to be an effective strategy for anammox applications under a wide temperature range.
authors.affiliation: Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Giri
authors.initials: G
authors.lastname: Park
authors.affiliation: Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan; Department of Civil and Environmental Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Takekawa
authors.affiliation: Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Soda
authors.affiliation: Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan. Electronic address: ike@see.eng.osaka-u.ac.jp.
authors.forename: Michihiko
authors.initials: M
authors.lastname: Ike
authors.affiliation: Department of Civil and Environmental Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Furukawa
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism*; D000693:Anaerobiosis; D001419:Bacteria / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D003080:Cold Temperature; D058440:Denitrification; D005618:Fresh Water / Q000382:microbiology; D007564:Japan; D009584:Nitrogen / Q000302:isolation & purification* / Q000378:metabolism; D010084:Oxidation-Reduction; D012722:Sewage / Q000382:microbiology; D013696:Temperature
chemical_list: D064751:Ammonium Compounds; D012722:Sewage; D009584:Nitrogen
keywords: Ambient temperature; Anaerobic ammonium oxidation; Apparent activation energy; Phylogenetic analysis; Temperature dependence