N2O and NO emissions during wastewater denitrification step: Influence of temperature on the biological process

Abstract

The denitrification process occurring in wastewater treatment plants (WWTPs) is responsible for nitrous oxide (N 2 O) and nitric oxide (NO) emissions. These compounds indirectly lead to the global warming. In this study, we investigated the impact of the temperature on N 2 O and NO emissions. Experiments were achieved at PH 7 in a batch reactor with acetate as the carbon source. The nitrogen source was nitrates (NO 3 À ) and the COD/N ratio was set to three. Results showed that NO and N 2 O emissions increased when the temperature decreased. NO emissions appeared only at 10 8C and 5 8C, with respectively 8% and 18% of the total denitrified nitrogen. N 2 O emissions increased from 13 to 40 then 82% of the total denitrified nitrogen, respectively at 20, 10 and 5 8C. Several hypotheses were suggested to explain these results: a general enzymatic slow down, enzymatic inhibitions, electron donor competition between the different enzymes and metabolic pathway alterations.

Nitrous oxide emissions in a membrane bioreactor treating saline wastewater contaminated by hydrocarbons

“…The other pathway is represented by the incomplete oxidation of hydroxylamine (NH 2 OH) to NO 2 (Kampschreur et al, 2009;Chandran et al, 2011;Law et al, 2012a). AOB denitrification is the predominant pathway in N 2 O production especially under O 2 stress condition, which has been identified as the major factor leading to nitrous oxide emission (Kampschreur et al, 2009;Adouani et al, 2015). Specifically, when operating with low dissolved oxygen (DO) concentrations, Tallec et al (2006) found that the 83% of the total nitrous oxide production could be ascribed to this pathway.…”

Kinetic characteristics and N2O production of a heterotrophic nitrifying bacterium Pseudomonas putida YH capable of tolerating adverse environmental conditions

“…Meanwhile, the N 2 O releasing factor under different temperatures was 0.02‰, 0.03‰, 0.07‰ and 0.08‰, respectively, indicating that temperature had negligible impacts on N 2 O generation of strain YH. It was noted that conventional biological nitrogen removal was vulnerable to extreme temperature, resulting in massive N 2 O emission on account of enzymatic inhibition and metabolic pathway alteration . By contrast, strain YH showed excellent adaptability to temperature variation in N 2 O emission control, confirming its promise as a candidate in practical applications.…”

“…It was noted that conventional biological nitrogen removal was vulnerable to extreme temperature, resulting in massive N 2 O emission on account of enzymatic inhibition and metabolic pathway alteration. 38 By contrast, strain YH showed excellent adaptability to temperature variation in N 2 O emission control, confirming its promise as a candidate in practical applications.…”

Effect of seasonal variation on nitrogen transformations in aquaponics of northern China

“…Seasonal variation of temperature and NO 3 − -N concentration affected denitrification process. Optimal temperature for denitrification process was around 30 • C, and denitrification rate decreased linearly as temperature decreased (Adouani et al, 2015). In summer, temperature was so suitable that denitrification can occur smoothly, while in autumn, as the temperature dropped, denitrification rate slowed down and sometimes even stopped at night (temperature below freezing).…”