open access publication

Article, 2023

Nitrous oxide emissions from two full-scale membrane-aerated biofilm reactors

The Science of The Total Environment, ISSN 1879-1026, 0048-9697, Volume 908, Page 168030, 10.1016/j.scitotenv.2023.168030

Contributors

Uri-Carreño, Nerea (Corresponding author) [1] [2] Nielsen, Per Henrik [3] Gernaey, Krist Victor Bernard 0000-0002-0364-1773 [2] Domingo-Félez, Carlos 0000-0003-3677-8597 [2] Flores-Alsina, Xavier 0000-0002-9310-0240 [2]

Affiliations

  1. [1] Vandcenter Syd A/S, Vandværksvej 7, Odense 5000, Denmark; Process and Systems Engineering Center (PROSYS), Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads 228A, Kgs. Lyngby 2800, Denmark. Electronic address: nur@vandcenter.dk.
    2. [NORA names: Denmark; Europe, EU; Nordic; OECD];
  2. [2] Technical University of Denmark
    3. [NORA names: DTU Technical University of Denmark; University; Denmark; Europe, EU; Nordic; OECD];
  3. [3] Vandcenter Syd A/S, Vandværksvej 7, Odense 5000, Denmark.
    4. [NORA names: Denmark; Europe, EU; Nordic; OECD]

Abstract

The upcoming change of legislation in some European countries where wastewater treatment facilities will start to be taxed based on direct greenhouse gas (GHG) emissions will force water utilities to take a closer look at nitrous oxide (N2O) production. In this study, we report for the first time N2O emissions from two full-scale size membrane aerated biofilm reactors (MABR) (R1, R2) from two different manufacturers treating municipal wastewater. N2O was monitored continuously for 12 months in both the MABR exhaust gas and liquid phase. Multivariate analysis was used to assess process performance. Results show that emission factors (EFN2O) for both R1 and R2 (0.88 ± 1.28 and 0.82 ± 0.86 %) were very similar to each other and below the standard value from the Intergovernmental Panel on Climate Change (IPCC) 2019 (1.6 %). More specifically, N2O was predominantly emitted in the MABR exhaust gas (NTRexh) and was strongly correlated to the ammonia/um load (NHx,load). Nevertheless, the implemented Oxidation Reduction Potential (ORP) control strategy increased the bulk contribution (NTRbulk), impacting the overall EFN2O. A thorough analysis of dynamic data reveals that the changes in the external aeration (EA)/loading rate patterns suggested by ORP control substantially impacted N2O mass transfer and biological production processes. It also suggests that NTRexh is mainly caused by ammonia-oxidizing organisms (AOO) activity, while ordinary heterotrophic organisms (OHO) are responsible for NTRbulk. Different methods for calculating EFN2O were compared, and results showed EFN2O would range from 0.6 to 5.5 depending on the assumptions made. Based on existing literature, a strong correlation between EFN2O and nitrogen loading rate (R2 = 0.73) was found for different technologies. Overall, an average EFN2O of 0.86 % N2O-N per N load was found with a nitrogen loading rate >200 g N m-3 d-1, which supports the hypothesis that MABR technology can achieve intensified biological nutrient removal without increasing N2O emissions.

Keywords

European countries, IPCC, Intergovernmental, Intergovernmental Panel, NTR, O emissions, OHO, R1, activity, ammonia-oxidizing organisms, analysis, analysis of dynamic data, assess process performance, assumptions, biofilm reactor, biological nutrient removal, biological production processes, changes, climate, climate change, control, control strategy, correlation, countries, data, different technologies, dynamic data, emission, emission factors, exhaust gas, facilities, factors, force water utilities, gas, greenhouse, greenhouse gases, gt;200, heterotrophic organisms, hypothesis, increase N<sub>2</sub>O emissions, legislation, liquid phase, literature, load, loading rate, manufacturing, membrane aerated biofilm reactor, membrane-aerated biofilm reactor, method, months, multivariate analysis, municipal wastewater, nitrogen, nitrogen loading rate, nitrous oxide, nitrous oxide emissions, nutrient removal, organization, oxidation, oxidation reduction potential, oxide emissions, panel, patterns, performance, phase, potential, process, process performance, production, production process, rate, rate patterns, reactor, reduction potential, removal, results, standard values, strategies, study, technology, treatment facilities, utilization, values, wastewater, wastewater treatment facilities, water utilities

Funders

  • Innovation Fund Denmark
  • Danida Fellowship Centre

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