title: Mechanisms and microbial structure of partial denitrification with high nitrite accumulation.
abstract: Nitrite (NO2 (-)-N) accumulation in denitrification can provide the substrate for anammox, an efficient and cost-saving process for nitrogen removal from wastewater. This batch-mode study aimed at achieving high NO2 (-)-N accumulation over long-term operation with the acetate as sole organic carbon source and elucidating the mechanisms of NO2 (-)-N accumulation. The results showed that the specific nitrate (NO3 (-)-N) reduction rate (59.61 mg N VSS(-1) h(-1) at NO3 (-)-N of 20 mg/L) was much higher than specific NO2 (-)-N reduction rate (7.30 mg N VSS(-1) h(-1) at NO3 (-)-N of 20 mg/L), and the NO2 (-)-N accumulation proceeded well at the NO3 (-)-N to NO2 (-)-N transformation ratio (NTR) as high as 90 %. NO2 (-)-N accumulation was barely affected by the ratio of chemical oxygen demand (COD) to NO3 (-)-N concentration (C/N). With the addition of NO3 (-)-N, NO2 (-)-N accumulation occurred and the specific NO2 (-)-N reduction rate declined to a much lower level compared with the value in the absence of NO3 (-)-N. This indicated that the denitrifying bacteria in the system preferred to use NO3 (-)-N as electron acceptor rather than use NO2 (-)-N. In addition, the Illumina high-throughput sequencing analysis revealed that the genus of Thauera bacteria was dominant in the denitrifying community with high NO2 (-)-N accumulation and account for 67.25 % of total microorganism. This bacterium might be functional for high NO2 (-)-N accumulation in the presence of NO3 (-)-N.
authors.affiliation: Engineering Research Center of Beijing, Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Pingleyuan 100, Chaoyang District, Beijing, 100124, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Du
authors.affiliation: Engineering Research Center of Beijing, Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Pingleyuan 100, Chaoyang District, Beijing, 100124, People's Republic of China. pyz@bjut.edu.cn.
authors.forename: Yongzhen
authors.initials: Y
authors.lastname: Peng
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.
authors.forename: Shenbin
authors.initials: S
authors.lastname: Cao
authors.affiliation: Engineering Research Center of Beijing, Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Pingleyuan 100, Chaoyang District, Beijing, 100124, People's Republic of China.
authors.forename: Baikun
authors.initials: B
authors.lastname: Li
authors.affiliation: Engineering Research Center of Beijing, Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Pingleyuan 100, Chaoyang District, Beijing, 100124, People's Republic of China.
authors.forename: Shuying
authors.initials: S
authors.lastname: Wang
authors.affiliation: Engineering Research Center of Beijing, Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Pingleyuan 100, Chaoyang District, Beijing, 100124, People's Republic of China.
authors.forename: Meng
authors.initials: M
authors.lastname: Niu
mesh_terms: D000085:Acetates / Q000378:metabolism; D058448:Biota; D002244:Carbon / Q000378:metabolism; D058440:Denitrification; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D020628:Thauera / Q000302:isolation & purification / Q000378:metabolism; D062065:Wastewater / Q000382:microbiology*; D014873:Water Pollutants / Q000378:metabolism*
chemical_list: D000085:Acetates; D002244:Carbon; D009566:Nitrates; D009573:Nitrites; D062065:Wastewater; D014873:Water Pollutants
keywords: Anammox; Microbial community; Nitrate-to-nitrite transformation ratio; Nitrite accumulation; Partial denitrification