Nitrogen removal in a wastewater treatment plant through biofilters: nitrous oxide emissions during nitrification and denitrification.
In order to estimate N(2)O emissions from immersed biofilters during nitrogen removal in tertiary treatments at urban wastewater treatment plants (WWTPs), a fixed culture from the WWTP of "Seine Centre" (Paris conurbation) was subjected to lab-scale batch experiments under various conditions of oxygenation and a gradient of methanol addition. The results show that during nitrification, N(2)O emissions are positively related to oxygenation (R (2) = 0.99). However, compared to the rates of ammonium oxidation, the percentage of emitted N(2)O is greater when oxygenation is low (0.5-1 mgO(2) L(-1)), representing up to 1% of the oxidized ammonium (0.4% on average). During denitrification, the N(2)O emission reaches a significant peak when the quantity of methanol allows denitrification of between 66% and 88%. When methanol concentrations lead to a denitrification of close to 100%, the flows of N(2)O are much lower and represent on average 0.2% of the reduced nitrate. By considering these results, we can estimate, the emissions of N(2)O during nitrogen removal, at the "Seine Centre" WWTP, to approximately 38 kgN-N(2)O day(-1).
Tallec
Gaëlle
G
SIAAP/DRD, 82, Av. Kléber, 92700 Colombes, France. gaelle_tallec@yahoo.fr
Garnier
Josette
J
Gousailles
Michel
M
D019149:Bioreactors / Q000382:microbiology*; D007220:Industrial Waste / Q000517:prevention & control*; D009609:Nitrous Oxide / Q000302:isolation & purification / Q000494:pharmacology*; D012722:Sewage / Q000382:microbiology*; D014462:Ultrafiltration / Q000379:methods; D014874:Water Pollutants, Chemical / Q000302:isolation & purification / Q000493:pharmacokinetics*; D018508:Water Purification / Q000379:methods*
D007220:Industrial Waste; D012722:Sewage; D014874:Water Pollutants, Chemical; D009609:Nitrous Oxide