title: Process stability and the recovery control associated with inhibition factors in a UASB-anammox reactor with a long-term operation.
abstract: A UASB-anammox reactor was operated for 900 days to study its process stability. The negative effects of free ammonia (FA) and free nitrous acid (FNA) were investigated over three separate inhibitions and recoveries. The IC10, IC50 and IC90 (inhibitory concentration/a 10%, 50% and 90% activity loss) of FNA and FA responding to the NH4(+)-N, NO2(-)-N and TN removal efficiency were evaluated. In the 1st inhibition, the average FNA-IC10 observed was 0.67 μg L(-1) and the FA-IC10 for TN removal was 4.85 mg L(-1). In the 2nd inhibition, an FNA-IC10 of 0.44μ g L(-1) and an FA-IC10 of 3.56 were found. In the 3rd inhibition, however, both the FNA-IC10 and FA-IC10 were found to have increased, with values of 0.50 μg L(-1) and 4.42 mg L(-1), respectively. A clear control region was established for multiple inhibitions and the recoveries, which followed (pH 7.5-8.5, FA below 10mg/100mg NH4(+)-N and an FNA below 0.005 mg/100 mg NO2(-)-N) for the purpose of optimizing the operation conditions of the UASB-anammox reactor.
authors.affiliation: Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University: 6-6-06, Aramaki-aza-aoba, Sendai, Miyagi, 980-8579, Japan.
authors.forename: Qigui
authors.initials: Q
authors.lastname: Niu
authors.affiliation: Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University: 6-6-06, Aramaki-aza-aoba, Sendai, Miyagi, 980-8579, Japan; School of Environment and Spatial Informatics, China University of Mining & Technology, Xuzhou 221116, China.
authors.forename: Shilong
authors.initials: S
authors.lastname: He
authors.affiliation: Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University: 6-6-06, Aramaki-aza-aoba, Sendai, Miyagi, 980-8579, Japan.
authors.forename: Yanlong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University: 6-6-06, Aramaki-aza-aoba, Sendai, Miyagi, 980-8579, Japan.
authors.forename: Haiyuan
authors.initials: H
authors.lastname: Ma
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, 6-6-06 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University: 6-6-06, Aramaki-aza-aoba, Sendai, Miyagi, 980-8579, Japan; Graduate School of Environmental Studies, Tohoku University, 6-6-06 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan. Electronic address: yyli@epl1.civil.tohoku.ac.jp.
authors.forename: Yu-You
authors.initials: YY
authors.lastname: Li
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D019149:Bioreactors; D009584:Nitrogen / Q000302:isolation & purification*; D009608:Nitrous Acid / Q000378:metabolism*; D014876:Water Pollution / Q000517:prevention & control
chemical_list: D000641:Ammonia; D009584:Nitrogen; D009608:Nitrous Acid
keywords: Free ammonia; Free nitrous acid; Inhibition factors; Process recovery; UASB stability