Details
| Original language | English |
|---|---|
| Article number | 2389 |
| Journal | Water |
| Volume | 15 |
| Issue number | 13 |
| Publication status | Published - 28 Jun 2023 |
Abstract
The reduction in N 2O emissions is an important task in the control of wastewater treatment plants. Since local operating conditions, especially inside biofilms, are usually not known, models are an important tool in the development and implementation of control strategies. For a pilot-scale nitrifying biofilm reactor and an SBR, different operational strategies to reduce autotrophic nitrous oxide (N 2O) formation were developed and tested by applying a combination of modeling and measurement. Both approaches highlighted the relevance of addressing the actual AOB activity as a sensitive control variable. The investigated strategies, therefore, focused on decreasing the AOB-related NH 4 conversion rate, as autotrophic N 2O formation is directly linked to AOB activity. The results showed that the biofilm system was more advantageous compared with suspended sludge systems. A higher AOB content resulted in a decrease in AOB activity, leading to fewer N 2O emissions at the same reactor performance. The highest reduction in autotrophic N 2O formation (SBR: 25%; Biofilm: 27%) was obtained by maximizing the aerated time per day and minimizing the number of aeration cycles (the suppression of nitrite-oxidizing bacteria still needed to be ensured). A higher biofilm thickness or a higher sludge mass in the SBR, however, did not have a noteworthy positive effect since no additional biomass could be kept in the system in the long term due to limited substrate availability. Besides nitritation, denitrification was also identified as a relevant source of N 2O in both systems (biofilm: main source) due to the inhibition of N 2O reduction by nitrous acid (elevated nitrite concentrations in combination with pH values < 7).
Keywords
- aeration strategies, biofilm, extended ASM model, greenhouse gas emissions, process control
ASJC Scopus subject areas
- Environmental Science(all)
- Water Science and Technology
- Social Sciences(all)
- Geography, Planning and Development
- Agricultural and Biological Sciences(all)
- Aquatic Science
- Biochemistry, Genetics and Molecular Biology(all)
- Biochemistry
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In: Water, Vol. 15, No. 13, 2389, 28.06.2023.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Activity of Ammonium-Oxidizing Bacteria—An Essential Parameter for Model-Based N2O Mitigation Control Strategies for Biofilms
AU - Freyschmidt, Arne
AU - Beier, Maike
N1 - This work was carried out as part of the MiNzE project (‘Minimization of the CO2 footprint by adapted process development in process water treatment—testing of the MiNzE process in an immersed fixed bed’, FKZ: 02WQ1482B). We thank the German Federal Ministry of Education and Research for financial support.
PY - 2023/6/28
Y1 - 2023/6/28
N2 - The reduction in N 2O emissions is an important task in the control of wastewater treatment plants. Since local operating conditions, especially inside biofilms, are usually not known, models are an important tool in the development and implementation of control strategies. For a pilot-scale nitrifying biofilm reactor and an SBR, different operational strategies to reduce autotrophic nitrous oxide (N 2O) formation were developed and tested by applying a combination of modeling and measurement. Both approaches highlighted the relevance of addressing the actual AOB activity as a sensitive control variable. The investigated strategies, therefore, focused on decreasing the AOB-related NH 4 conversion rate, as autotrophic N 2O formation is directly linked to AOB activity. The results showed that the biofilm system was more advantageous compared with suspended sludge systems. A higher AOB content resulted in a decrease in AOB activity, leading to fewer N 2O emissions at the same reactor performance. The highest reduction in autotrophic N 2O formation (SBR: 25%; Biofilm: 27%) was obtained by maximizing the aerated time per day and minimizing the number of aeration cycles (the suppression of nitrite-oxidizing bacteria still needed to be ensured). A higher biofilm thickness or a higher sludge mass in the SBR, however, did not have a noteworthy positive effect since no additional biomass could be kept in the system in the long term due to limited substrate availability. Besides nitritation, denitrification was also identified as a relevant source of N 2O in both systems (biofilm: main source) due to the inhibition of N 2O reduction by nitrous acid (elevated nitrite concentrations in combination with pH values < 7).
AB - The reduction in N 2O emissions is an important task in the control of wastewater treatment plants. Since local operating conditions, especially inside biofilms, are usually not known, models are an important tool in the development and implementation of control strategies. For a pilot-scale nitrifying biofilm reactor and an SBR, different operational strategies to reduce autotrophic nitrous oxide (N 2O) formation were developed and tested by applying a combination of modeling and measurement. Both approaches highlighted the relevance of addressing the actual AOB activity as a sensitive control variable. The investigated strategies, therefore, focused on decreasing the AOB-related NH 4 conversion rate, as autotrophic N 2O formation is directly linked to AOB activity. The results showed that the biofilm system was more advantageous compared with suspended sludge systems. A higher AOB content resulted in a decrease in AOB activity, leading to fewer N 2O emissions at the same reactor performance. The highest reduction in autotrophic N 2O formation (SBR: 25%; Biofilm: 27%) was obtained by maximizing the aerated time per day and minimizing the number of aeration cycles (the suppression of nitrite-oxidizing bacteria still needed to be ensured). A higher biofilm thickness or a higher sludge mass in the SBR, however, did not have a noteworthy positive effect since no additional biomass could be kept in the system in the long term due to limited substrate availability. Besides nitritation, denitrification was also identified as a relevant source of N 2O in both systems (biofilm: main source) due to the inhibition of N 2O reduction by nitrous acid (elevated nitrite concentrations in combination with pH values < 7).
KW - aeration strategies
KW - biofilm
KW - extended ASM model
KW - greenhouse gas emissions
KW - process control
UR - http://www.scopus.com/inward/record.url?scp=85164779594&partnerID=8YFLogxK
U2 - 10.3390/w15132389
DO - 10.3390/w15132389
M3 - Article
VL - 15
JO - Water
JF - Water
SN - 2073-4441
IS - 13
M1 - 2389
ER -