NO emission in full-scale wastewater treatment: Proposing a refined monitoring strategy.

Nitrous oxide (NO) emissions from wastewater treatment contribute significantly to greenhouse gas emissions. They have been shown to exhibit a strong seasonal and daily profile in previously conducted monitoring campaigns. However, only two year-long online monitoring campaigns have been published to date.

Isotopic evidence for nitrous oxide production pathways in a partial nitritation-anammox reactor.

Nitrous oxide (N2O) production pathways in a single stage, continuously fed partial nitritation-anammox reactor were investigated using online isotopic analysis of offgas N2O with quantum cascade laser absorption spectroscopy (QCLAS). N2O emissions increased when reactor operating conditions were not optimal, for example, high dissolved oxygen concentration. SP measurements indicated that the increase in N2O was due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor.

Isotope signatures of N₂O in a mixed microbial population system: constraints on N₂O producing pathways in wastewater treatment.

We present measurements of site preference (SP) and bulk (15)N/(14)N ratios (δ(15)N(bulk)(N2O)) of nitrous oxide (N(2)O) by quantum cascade laser absorption spectroscopy (QCLAS) as a powerful tool to investigate N(2)O production pathways in biological wastewater treatment. QCLAS enables high-precision N(2)O isotopomer analysis in real time. This allowed us to trace short-term fluctuations in SP and δ(15)N(bulk)(N2O) and, hence, microbial transformation pathways during individual batch experiments with activated sludge from a pilot-scale facility treating municipal wastewater.

Nitric oxide and nitrous oxide turnover in natural and engineered microbial communities: biological pathways, chemical reactions, and novel technologies.

Nitrous oxide (N(2)O) is an environmentally important atmospheric trace gas because it is an effective greenhouse gas and it leads to ozone depletion through photo-chemical nitric oxide (NO) production in the stratosphere. Mitigating its steady increase in atmospheric concentration requires an understanding of the mechanisms that lead to its formation in natural and engineered microbial communities. N(2)O is formed biologically from the oxidation of hydroxylamine (NH(2)OH) or the reduction of nitrite (NO(-) (2)) to NO and further to N(2)O.

Nitrous oxide emissions from the oxidation tank of a pilot activated sludge plant.

This study discusses the results of the continuous monitoring of nitrous oxide emissions from the oxidation tank of a pilot conventional wastewater treatment plant. Nitrous oxide emissions from biological processes for nitrogen removal in wastewater treatment plants have drawn great attention over the last years, due to the high greenhouse effect. However, even if several studies have been carried out to quantify nitrous oxide emission rates from different types of treatment, quite wide ranges have been reported.

N2O emissions: modeling the effect of process configuration and diurnal loading patterns.

The objective of this research was to develop a mechanistic model for quantifying N2O emissions from activated sludge plants and demonstrate how this may be used to evaluate the effects of process configuration and diurnal loading patterns. The model describes the mechanistic link between the factors recognized to correlate positively with N2O emissions. The primary factors are the presence of ammonia and nitrite accumulation.

Mechanisms of N2O production in biological wastewater treatment under nitrifying and denitrifying conditions.

Nitrous oxide (N2O) is an important greenhouse gas and a major sink for stratospheric ozone. In biological wastewater treatment, microbial processes such as autotrophic nitrification and heterotrophic denitrification have been identified as major sources; however, the underlying pathways remain unclear. In this study, the mechanisms of N2O production were investigated in a laboratory batch-scale system with activated sludge for treating municipal wastewater.