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Nitrous oxide production under varied C/N-ratio and DO in an SBR treating digester supernatant

Stenström, Fredrik LU ; Baresel, Christian and la Cour Jansen, Jes LU (2013) 13th Nordic Wastewater Treatment Conference (NORDIWA2013)
Abstract (Swedish)
Nitrous oxide (N2O) is a greenhouse gas formed during biological wastewater treatment under aerobic and anoxic conditions. Two reasons for high N2O emissions are low oxygen concentration during nitrification and low carbon/nitrogen-ratio during denitrification. In this full-scale study of N2O emissions from a sequencing batch reactor for treating digester supernatant, the oxygen concentration was reduced stepwise and the carbon/nitrogen-ratio was varied to investigate how N2O emissions were influenced. N2O concentrations were measured online in water and off-gas. A distinct relationship was found between low oxygen concentrations and high N2O emissions. N2O was formed in water during both nitrification and denitrification. Decreased oxygen... (More)
Nitrous oxide (N2O) is a greenhouse gas formed during biological wastewater treatment under aerobic and anoxic conditions. Two reasons for high N2O emissions are low oxygen concentration during nitrification and low carbon/nitrogen-ratio during denitrification. In this full-scale study of N2O emissions from a sequencing batch reactor for treating digester supernatant, the oxygen concentration was reduced stepwise and the carbon/nitrogen-ratio was varied to investigate how N2O emissions were influenced. N2O concentrations were measured online in water and off-gas. A distinct relationship was found between low oxygen concentrations and high N2O emissions. N2O was formed in water during both nitrification and denitrification. Decreased oxygen concentration during nitrification led to increased nitrite concentration, which in turn led to increased N2O concentration in the subsequent denitrification phase. When nitrification resumed, accumulated N2O was stripped off to the atmosphere. A too low carbon/nitrogen-ratio resulted in increased N2O emissions in off-gas under longer-term conditions and increased risk of separate peak emissions. Very high N2O concentrations, over 76,000 ppm, were measured in the off-gas. Furthermore, the maximum N2O emitted during one cycle represented 217.9% of the total nitrogen load (36.2% of total nitrogen present in the bulk liquid at cycle start), among the highest emission levels measured from a full-scale municipal plant treating digester supernatant. (Less)
Abstract
Nitrous oxide (N2O) is a greenhouse gas formed during biological wastewater treatment under aerobic and anoxic conditions. Two reasons for high N2O emissions are low oxygen concentration during nitrification and low carbon/nitrogen-ratio during denitrification. In this full-scale study of N2O emissions from a sequencing batch reactor for treating digester supernatant, the oxygen concentration was reduced stepwise and the carbon/nitrogen-ratio was varied to investigate how N2O emissions were influenced. N2O concentrations were measured online in water and off-gas. A distinct relationship was found between low oxygen concentrations and high N2O emissions. N2O was formed in water during both nitrification and denitrification. Decreased oxygen... (More)
Nitrous oxide (N2O) is a greenhouse gas formed during biological wastewater treatment under aerobic and anoxic conditions. Two reasons for high N2O emissions are low oxygen concentration during nitrification and low carbon/nitrogen-ratio during denitrification. In this full-scale study of N2O emissions from a sequencing batch reactor for treating digester supernatant, the oxygen concentration was reduced stepwise and the carbon/nitrogen-ratio was varied to investigate how N2O emissions were influenced. N2O concentrations were measured online in water and off-gas. A distinct relationship was found between low oxygen concentrations and high N2O emissions. N2O was formed in water during both nitrification and denitrification. Decreased oxygen concentration during nitrification led to increased nitrite concentration, which in turn led to increased N2O concentration in the subsequent denitrification phase. When nitrification resumed, accumulated N2O was stripped off to the atmosphere. A too low carbon/nitrogen-ratio resulted in increased N2O emissions in off-gas under longer-term conditions and increased risk of separate peak emissions. Very high N2O concentrations, over 76,000 ppm, were measured in the off-gas. Furthermore, the maximum N2O emitted during one cycle represented 217.9% of the total nitrogen load (36.2% of total nitrogen present in the bulk liquid at cycle start), among the highest emission levels measured from a full-scale municipal plant treating digester supernatant. (Less)
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author
organization
publishing date
type
Contribution to conference
publication status
published
subject
keywords
Biological wastewater treatment, Digester supernatant, Nitrous oxide, C/N-ratio, Sequencing batch reactor
pages
8 pages
conference name
13th Nordic Wastewater Treatment Conference (NORDIWA2013)
language
English
LU publication?
yes
id
32d38a59-aafd-4a57-be63-d8413790bf3a
date added to LUP
2017-09-25 10:31:15
date last changed
2018-05-29 11:08:08
@misc{32d38a59-aafd-4a57-be63-d8413790bf3a,
  abstract     = {Nitrous oxide (N2O) is a greenhouse gas formed during biological wastewater treatment under aerobic and anoxic conditions. Two reasons for high N2O emissions are low oxygen concentration during nitrification and low carbon/nitrogen-ratio during denitrification. In this full-scale study of N2O emissions from a sequencing batch reactor for treating digester supernatant, the oxygen concentration was reduced stepwise and the carbon/nitrogen-ratio was varied to investigate how N2O emissions were influenced. N2O concentrations were measured online in water and off-gas. A distinct relationship was found between low oxygen concentrations and high N2O emissions. N2O was formed in water during both nitrification and denitrification. Decreased oxygen concentration during nitrification led to increased nitrite concentration, which in turn led to increased N2O concentration in the subsequent denitrification phase. When nitrification resumed, accumulated N2O was stripped off to the atmosphere. A too low carbon/nitrogen-ratio resulted in increased N2O emissions in off-gas under longer-term conditions and increased risk of separate peak emissions. Very high N2O concentrations, over 76,000 ppm, were measured in the off-gas. Furthermore, the maximum N2O emitted during one cycle represented 217.9% of the total nitrogen load (36.2% of total nitrogen present in the bulk liquid at cycle start), among the highest emission levels measured from a full-scale municipal plant treating digester supernatant.},
  author       = {Stenström, Fredrik and Baresel, Christian and la Cour Jansen, Jes},
  keyword      = {Biological wastewater treatment,Digester supernatant,Nitrous oxide,C/N-ratio,Sequencing batch reactor},
  language     = {eng},
  pages        = {8},
  title        = {Nitrous oxide production under varied C/N-ratio and DO in an SBR treating digester supernatant},
  year         = {2013},
}