title: Enhanced long-term nitrogen removal and its quantitative molecular mechanism in tidal flow constructed wetlands.
abstract: Tidal flow constructed wetlands (TF CWs) have recently been studied as a sustainable technology to achieve enhanced nitrogen removal; however, the underlying mechanisms responsible for removing ammonium (NH4(+)) and nitrate (NO3(-)) have not been compared and quantified at the molecular level (genes) in controlled TF CWs. In this study, two TF CWs T1 (treating NH4(+) wastewater) and T2 (treating NO3(-) wastewater) achieved high removal efficiencies for chemical oxygen demand (COD, 92 ± 2.7% and 95 ± 2.4%, respectively), NH4(+)/NO3(-) (76 ± 3.9% and 97 ± 2.2%, respectively), and total nitrogen (TN, 81 ± 3.5% and 93 ± 2.3%, respectively). Combined analyses revealed that the presence of simultaneous nitrification, anammox, and denitrification processes and the coupling of dissimilatory nitrate reduction to ammonium, ammonia oxidation, and anammox were the primary reason accounted for the robust treatment performance in T1 and T2, respectively. Results from stepwise regression analysis suggested that the NH4(+) removal rate in T1 was collectively controlled by amoA, nxrA, and anammox, while the NO3(-) removal rate in T2 was governed by nxrA and narG gene.
authors.affiliation: †Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing, 100871, China.|‡John and Willie Leone Department of Energy and Mineral Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhi
authors.affiliation: †Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing, 100871, China.
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.affiliation: †Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing, 100871, China.
authors.forename: Guodong
authors.initials: G
authors.lastname: Ji
authors.affiliation: §State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Northeast Normal University, Changchun, 130024, China.
authors.forename: Chunguang
authors.initials: C
authors.lastname: He
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism; D001419:Bacteria / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000032:analysis*; D053833:Wetlands
chemical_list: D064751:Ammonium Compounds; D001426:Bacterial Proteins; D009566:Nitrates; D009584:Nitrogen; D062065:Wastewater