Intermittent aeration to regulate microbial activities in membrane-aerated biofilm reactors: energy-efficient nitrogen removal and low nitrous oxide emission

Ma, Y., Piscedda, A., Veras, A. D. L. C., Domingo-Félez, C. and Smets, B. F. (2022) Intermittent aeration to regulate microbial activities in membrane-aerated biofilm reactors: energy-efficient nitrogen removal and low nitrous oxide emission. Chemical Engineering Journal, 433(Part 2), 133630. (doi: 10.1016/j.cej.2021.133630)

Abstract

autotrophic nitrogen removal, yet control of nitrogen turnover remains challenging in MABR counter-diffusion biofilms. In this study, we regulated microbial activities in two lab-scale MABRs by providing continuous versus intermittent aeration. Nitrogen consumption by different functional microbial groups was estimated from bulk measurements via a mass balance approach. Nitrite-oxidizing bacteria (NOB) proliferated under continuous aeration while they were significantly suppressed under intermittent aeration, and NOB suppression activated anaerobic ammonium oxidation. Nitritation performance in the MABR was studied through long-term bulk measurements and in situ biofilm microprofiles of dissolved oxygen (DO) and pH. During intermittent aeration pH effects rather than DO effects determined nitritation success, especially ammonia speciation, which serves as substrate and inhibitor in nitrification processes. Biofilm transition phases were monitored upon aeration switches. Canonical correspondence analysis suggested that the relative transition after anoxia and aeration intermittency were less decisive for biofilm performance than the relative aeration duration. Heterotrophic bacteria displayed minor denitrification rates with aeration control, but contributed to mitigation of nitrous oxide (N2O) emissions. N2O production hotspots were identified at the top of the anoxic biofilm zone under continuous aeration. Instead, under intermittent aeration an anoxic N2O reduction zone was established. Our observations support intermittent aeration control of MABRs as a simple strategy for energy-efficient nitrogen removal with low N2O emission.

• Item Type: Articles
• Additional Information: The authors would like to thank the China Scholarship Council (CSC) for financial support to Y.M. and the Danish Council for Independent Research Technology and Production Sciences (FTP) (Project N2Oman, File No. 1335-00100B) for additional financial support.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Domingo-Felez, Dr Carlos
• Authors: Ma, Y., Piscedda, A., Veras, A. D. L. C., Domingo-Félez, C., and Smets, B. F.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: Chemical Engineering Journal
• Publisher: Elsevier
• ISSN: 1385-8947
• ISSN (Online): 1873-3212
• Published Online: 18 November 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Chemical Engineering Journal 433(Part 2): 133630
• Publisher Policy: Reproduced under a Creative Commons License