Membrane-aerated biofilm reactors (MABRs) are an emerging technology for nutrient removal; however, a trade-off remains between their removal rate and oxygen transfer efficiency. This study compares nitrifying flow-through MABRs operated under continuous and intermittent aeration modes at mainstream wastewater ammonia levels. The intermittently-aerated MABRs maintained maximal nitrification rates, including under conditions allowing the oxygen partial pressure on the gas side of the membrane to considerably drop during the no-aeration period. Nitrous oxide emissions of all reactors were comparable and amounted to approximately 20 % of the converted ammonia. Intermittent aeration increased the transformation rate constant of atenolol, yet did not affect the removal of sulfamethoxazole. Seven additional trace organic chemicals were not biodegraded by any of the reactors. The ammonia-oxidizing bacteria in the intermittently-aerated MABRs were dominated by Nitrosospira, previously shown to be abundant at low oxygen concentrations and provide reactor stability under changing conditions. Our findings indicate that intermittently-aerated flow-through MABRs can achieve high nitrification rates and oxygen transfer efficiencies, highlighting the possible implications of air supply discontinuity on nitrous oxide emissions and trace organic chemical biotransformation.
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http://dx.doi.org/10.1016/j.scitotenv.2023.164329 | DOI Listing |
Bioresour Technol
January 2025
School of Environment and Climate, Guangdong Engineering Research Center of Water Treatment Processes and Materials, and Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519000, China.
Efficient nitrogen removal after organic capture is challenging through conventional nitrification-denitrification process. Two biofilm-based anoxic/oxic reactors, with a single intermittent zone (R1) or dual intermittent zones (R2), were compared in treating carbon-limited wastewater. Intermittent aeration integrated partial nitrification-anammox (PNA), partial denitrification-anammox (PDA), and denitrification, with anammox-related pathways contributing over 75% nitrogen removal in both reactors.
View Article and Find Full Text PDFBioresour Technol
January 2025
Water Research Centre and Department of Civil and Environmental Engineering, University of Auckland, Auckland 1142, New Zealand. Electronic address:
Dynamic oxygen fluctuations in activated sludge were investigated to enhance valuable biochemical production during wastewater treatment. Batch experiments compared constant aeration with rapid cycling between oxygen-rich and oxygen-poor states. Fluctuating oxygen concentrations (0-2 mg/L) significantly increased production of valuable biochemicals compared to constant oxygen concentration (2 mg/L).
View Article and Find Full Text PDFEnviron Sci Pollut Res Int
January 2025
Department of Civil Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam, 781039, India.
The current research assessed the effectiveness of four hybrid constructed wetland (HCW) systems for the remediation of synthetic dye wastewater with Reactive Black 5 (RB5) azo dye. All HCW systems had identical configurations, consisting of a horizontal CW followed by a vertical CW, and operated under diverse conditions such as the presence of plants (Typha angustifolia), feeding modes (batch and continuous) and intermittent aeration (4 h day). Anaerobic-aerobic conditions simulated within the HCW systems were crucial in removing the pollutants from synthetic dye wastewater.
View Article and Find Full Text PDFJ Hazard Mater
December 2024
Department of Environmental Science, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China; The Key Laboratory of Water and Sediment Sciences (Peking University), Ministry of Education, Beijing 100871, PR China. Electronic address:
The reactive substance consisting manganese oxides (MnOx) and solid carbon have been reported to be effective in polishing secondary wastewater; however, the treatment characteristics and mechanism remains limited. In this study, MnOx/carbon (Mn-C) composites were applied in biofilters to evaluate simultaneous removal of nitrate and sulfamethoxazole (SMX), with the single carbon composites as control. Results showed that the effluent concentrations of NO-N and SMX were below 2.
View Article and Find Full Text PDFChemosphere
February 2025
Federal University of Tecnhology - Paraná (UTFPR) - Civil Construction Academic Department, Deputado Heitor de Alencar Furtado St., 5000, Ecoville, 81280-340, Curitiba, Paraná, Brazil. Electronic address:
Operational strategies have been applied in constructed wetlands to optimize the removal of nutrients and hormones that are still a concern in wastewater treatment. The strategy of intensifying intermittent aeration was investigated in two microcosm-scale vertical-flow constructed wetlands (VFCWs) planted with Eichhornia crassipes onto autoclaved aerated concrete (AC) in the removal of nutrients, estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2). CW-1 (2.
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