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Heterotrophs are key contributors to nitrous oxide production in activated sludge under low C‐to‐N ratios during nitrification—Batch experiments and modeling
Author(s) -
DomingoFélez Carlos,
PellicerNàcher Carles,
Petersen Morten S.,
Jensen Marlene M.,
Plósz Benedek G.,
Smets Barth F.
Publication year - 2017
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.26062
Subject(s) - activated sludge model , autotroph , heterotroph , denitrifying bacteria , nitrification , denitrification , nitrous oxide , chemistry , activated sludge , environmental chemistry , nitrogen , sewage treatment , environmental engineering , biology , bacteria , environmental science , organic chemistry , genetics
Nitrous oxide (N 2 O), a by‐product of biological nitrogen removal during wastewater treatment, is produced by ammonia‐oxidizing bacteria (AOB) and heterotrophic denitrifying bacteria (HB). Mathematical models are used to predict N 2 O emissions, often including AOB as the main N 2 O producer. Several model structures have been proposed without consensus calibration procedures. Here, we present a new experimental design that was used to calibrate AOB‐driven N 2 O dynamics of a mixed culture. Even though AOB activity was favoured with respect to HB, oxygen uptake rates indicated HB activity. Hence, rigorous experimental design for calibration of autotrophic N 2 O production from mixed cultures is essential. The proposed N 2 O production pathways were examined using five alternative process models confronted with experimental data inferred. Individually, the autotrophic and heterotrophic denitrification pathway could describe the observed data. In the best‐fit model, which combined two denitrification pathways, the heterotrophic was stronger than the autotrophic contribution to N 2 O production. Importantly, the individual contribution of autotrophic and heterotrophic to the total N 2 O pool could not be unambiguously elucidated solely based on bulk N 2 O measurements. Data on NO would increase the practical identifiability of N 2 O production pathways. Biotechnol. Bioeng. 2017;114: 132–140. © 2016 Wiley Periodicals, Inc.