title: Nitrogen removal by granular nitritation-anammox in an upflow membrane-aerated biofilm reactor.
abstract: The nitritation-anammox process has been a promising nitrogen removal technology towards sustainable wastewater treatment, but its application in treating domestic wastewater with relatively low ammonium concentrations (mainstream) remains a great challenge. In this study, an innovative lab-scale upflow membrane-aerated biofilm reactor (UMABR) was employed to treat a synthetic wastewater containing 70 mg N L(-1) ammonium. With a DO level at 0.6 ± 0.1 mg O2 L(-1) and HRT of 32 h, the effluent ammonium concentration was 4.8 ± 2.0 mg N L(-1). Increasing the nitrogen loading rate from 52.4 to 104.8 g N m(-3) d(-1) with stepwise decreasing HRT from 32 to 16 h resulted in an average TN removal efficiency of 81% without nitrite accumulation. The average observed NO3(-)-N (residue)/NH4(+)-N (consumed) ratio of 8% was below the "theoretical ratio" of 13% and further reduction of nitrate residue needs to be addressed. Fluorescence in situ hybridization (FISH) and high-throughput sequencing analyses showed the coexistence of anammox bacteria and ammonium-oxidizing bacteria (AOB) in both biofilm and granular samples. Anammox bacteria accounted for up to 63.3% of the microbial community of the granules, with Candidatus Jettenia being the distinctly dominant anammox genus. In contrast, the biofilm contained abundant Nitrosomonadaceae (AOB, 33.1%). In addition, the brown-yellow granules exhibited a more balanced community structure with anammox bacteria and AOB accounting for 33.7% and 18.2%, respectively, which may contribute to the long-term operation of single-stage nitritation-anammox process. These results demonstrate that the nitritation-anammox UMABR could potentially be used for nitrogen removal from mainstream in some specific regions with relatively warm temperature.
authors.affiliation: Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
authors.forename: Xiaojin
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
authors.forename: Shan
authors.initials: S
authors.lastname: Sun
authors.affiliation: Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Badgley
authors.affiliation: College of Agriculture, Forestry, and Natural Resource Management, University of Hawaii at Hilo, Hilo, HI 96720, USA.
authors.forename: Shihwu
authors.initials: S
authors.lastname: Sung
authors.affiliation: Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
authors.forename: Husen
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA. Electronic address: zhenhe@vt.edu.
authors.forename: Zhen
authors.initials: Z
authors.lastname: He
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry*; D001419:Bacteria / Q000145:classification; D018441:Biofilms; D019149:Bioreactors / Q000382:microbiology; D004269:DNA, Bacterial / Q000302:isolation & purification; D008567:Membranes, Artificial; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D064751:Ammonium Compounds; D004269:DNA, Bacterial; D008567:Membranes, Artificial; D009566:Nitrates; D009584:Nitrogen; D062065:Wastewater
keywords: Biofilm; Granule; Low nitrogen strength; Membrane-aerated; Microbial community; Nitritation–anammox