13 results on '"Wunderlin, Pascal"'
Search Results
2. Nitrous oxide emissions from the oxidation tank of a pilot activated sludge plant
- Author
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Lotito, Adriana Maria, Wunderlin, Pascal, Joss, Adriano, Kipf, Marco, and Siegrist, Hansruedi
- Published
- 2012
- Full Text
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3. Mechanisms of N 2O production in biological wastewater treatment under nitrifying and denitrifying conditions
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Wunderlin, Pascal, Mohn, Joachim, Joss, Adriano, Emmenegger, Lukas, and Siegrist, Hansruedi
- Published
- 2012
- Full Text
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4. N 2 O Emissions: Modeling the Effect of Process Configuration and Diurnal Loading Patterns
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Houweling, Dwight, Wunderlin, Pascal, Dold, Peter, Bye, Chris, Joss, Adriano, and Siegrist, Hansruedi
- Published
- 2011
5. Nitric oxide and nitrous oxide turnover in natural and engineered microbial communities: biological pathways, chemical reactions, and novel technologies
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Schreiber, Frank, Wunderlin, Pascal, Udert, Kai M., and Wells, George F.
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Isotopic signature ,Microsensors ,Molecular tools ,Dinitrogen oxide ,Nitrogen monoxide ,Pathway identification ,Quantum cascade laser absorption spectrometry (QCLAS) ,Site preference ,Review Article ,isotopic signature ,site preference ,molecular tools ,nitrogen monoxide ,Microbiology ,dinitrogen oxide ,microsensors ,pathway identification ,quantum cascade laser absorption spectroscopy (QCLAS) - Abstract
Nitrous oxide (N_2O) 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_2O is formed biologically from the oxidation of hydroxylamine (NH_2OH) or the reduction of nitrite (NO^−_2) to NO and further to N_2O. Our review of the biological pathways for N_2O production shows that apparently all organisms and pathways known to be involved in the catabolic branch of microbial N-cycle have the potential to catalyze the reduction of NO^−_2 to NO and the further reduction of NO to N_2O, while N_2O formation from NH_2OH is only performed by ammonia oxidizing bacteria (AOB). In addition to biological pathways, we review important chemical reactions that can lead to NO and N_2O formation due to the reactivity of NO^−_2, NH_2OH, and nitroxyl (HNO). Moreover, biological N_2O formation is highly dynamic in response to N-imbalance imposed on a system. Thus, understanding NO formation and capturing the dynamics of NO and N_2O build-up are key to understand mechanisms of N_2O release. Here, we discuss novel technologies that allow experiments on NO and N_2O formation at high temporal resolution, namely NO and N_2O microelectrodes and the dynamic analysis of the isotopic signature of N_2O with quantum cascade laser absorption spectroscopy (QCLAS). In addition, we introduce other techniques that use the isotopic composition of N_2O to distinguish production pathways and findings that were made with emerging molecular techniques in complex environments. Finally, we discuss how a combination of the presented tools might help to address important open questions on pathways and controls of nitrogen flow through complex microbial communities that eventually lead to N_2O build-up., Frontiers in Microbiology, 3, ISSN:1664-302X
- Published
- 2012
6. Isotope Signatures of N2O in a Mixed Microbial Population System: Constraints on N2O Producing Pathways in Wastewater Treatment.
- Author
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Wunderlin, Pascal, Lehmann, Moritz F., Siegrist, Hansruedi, Tuzson, Béla, Joss, Adriano, Emmenegger, Lukas, and Mohn, Joachim
- Subjects
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NITROUS oxide , *ISOTOPIC signatures , *QUANTUM cascade lasers , *ABSORPTION spectra , *SPECTRUM analysis , *RESEARCH methodology , *BIOLOGICAL nutrient removal , *NITROGEN metabolism , *MICROBIOLOGICAL synthesis - Abstract
We present measurements of site preference (SP) and bulk 15N/14N ratios (δ15NbulkN2O) of nitrous oxide (N2O) by quantum cascade laser absorption spectroscopy (QCLAS) as a powerful tool to investigate N2O production pathways in biological wastewater treatment. QCLAS enables high-precision N2O isotopomer analysis in real time. This allowed us to trace short-term fluctuations in SP and δ15NbulkN2O and, hence, microbial transformation pathways during individual batch experiments with activated sludge from a pilot-scale facility treating municipal wastewater. On the basis of previous work with microbial pure cultures, we demonstrate that N2O emitted during ammonia (NH4+) oxidation with a SP of −5.8 to 5.6 ‰ derives mostly from nitrite (NO2-) reduction (e.g., nitrifier denitrification), with a minor contribution from hydroxylamine (NH2OH) oxidation at the beginning of the experiments. SP of N2O produced under anoxic conditions was always positive (1.2 to 26.1 ‰), and SP values at the high end of this spectrum (24.9 to 26.1 ‰) are indicative of N2O reductase activity. The measured δ15NbulkN2O at the initiation of the NH4+ oxidation experiments ranged between −42.3 and −57.6 ‰ (corresponding to a nitrogen isotope effect Δδ15N = δ15Nsubstrate - δ15NbulkN2O of 43.5 to 58.8 ‰), which is considerably higher than under denitrifying conditions (δ15NbulkN2O 2.4 to −17 ‰; Δδ15N = 0.1 to 19.5 ‰). During the course of all NH4+ oxidation and nitrate (NO3-) reduction experiments, δ15NbulkN2O increased significantly, indicating net 15N enrichment in the dissolved inorganic nitrogen substrates (NH4+, NO3-) and transfer into the N2O pool. The decrease in δ15NbulkN2O during NO2- and NH2OH oxidation experiments is best explained by inverse fractionation during the oxidation of NO2- to NO3-. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
7. Mechanisms of N2O production in biological wastewater treatment under nitrifying and denitrifying conditions
- Author
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Wunderlin, Pascal, Mohn, Joachim, Joss, Adriano, Emmenegger, Lukas, and Siegrist, Hansruedi
- Subjects
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NITROUS oxide , *WASTEWATER treatment , *BIOGAS , *DENITRIFICATION , *HYDROXYLAMINE oxidase , *BIOCONCENTRATION , *AMMONIA-oxidizing bacteria , *AQUATIC microbiology - Abstract
Abstract: 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. This relatively complex mixed population system is well representative for full-scale activated sludge treatment under nitrifying and denitrifying conditions. Under aerobic conditions, the addition of nitrite resulted in strongly nitrite-dependent N2O production, mainly by nitrifier denitrification of ammonia-oxidizing bacteria (AOB). Furthermore, N2O is produced via hydroxylamine oxidation, as has been shown by the addition of hydroxylamine. In both sets of experiments, N2O production was highest at the beginning of the experiment, then decreased continuously and ceased when the substrate (nitrite, hydroxylamine) had been completely consumed. In ammonia oxidation experiments, N2O peaked at the beginning of the experiment when the nitrite concentration was lowest. This indicates that N2O production via hydroxylamine oxidation is favored at high ammonia and low nitrite concentrations, and in combination with a high metabolic activity of ammonia-oxidizing bacteria (at 2 to 3 mgO2/l); the contribution of nitrifier denitrification by AOB increased at higher nitrite and lower ammonia concentrations towards the end of the experiment. Under anoxic conditions, nitrate reducing experiments confirmed that N2O emission is low under optimal growth conditions for heterotrophic denitrifiers (e.g. no oxygen input and no limitation of readily biodegradable organic carbon). However, N2O and nitric oxide (NO) production rates increased significantly in the presence of nitrite or low dissolved oxygen concentrations. [Copyright &y& Elsevier]
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- 2012
- Full Text
- View/download PDF
8. N2O Emissions: Modeling the Effect of Process Configuration and Diurnal Loading Patterns.
- Author
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Houweling, Dwight, Wunderlin, Pascal, Dold, Peter, Bye, Chris, Joss, Adriano, and Siegrist, Hansruedi
- Subjects
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NITROGEN oxides , *EMISSIONS (Air pollution) , *AMMONIA-oxidizing bacteria , *NITRATES , *SLUDGE management , *WATER quality management - Abstract
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. Low dissolved oxygen concentrations also may be implicated through differential impacts on ammonia-oxidizing bacteria (AOB) versus nitrite-oxidizing bacteria (NOB) activity. Factors promoting N2O emissions at treatment plants are discussed below. The model was applied to data from laboratory and pilot-scale systems. From a practical standpoint, plant configuration (e.g., plug-flow versus complete-mix), influent loading patterns (and peak load), and certain operating strategies (e.g., handling of return streams) are all important in determining N2O emissions. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
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9. In Response: What are the challenges and prospects? A governmental perspective.
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Wunderlin, Pascal, Dominguez, Damian, and Schärer, Michael
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POISONS & the environment , *EFFECT of water pollution on aquatic organisms , *WATER quality management , *WASTEWATER treatment , *MICROPOLLUTANTS , *CHEMICAL safety , *GOVERNMENT policy - Abstract
The article discusses the perspective of water industry focusing on poisonous chemicals affecting aquatic animals. Topics include the Water Framework Directive designed by the European Union (EU), the need for wastewater treatment, removing micropollutants from wastewater, and Great Britain's Chemicals Investigation Programme.
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- 2014
- Full Text
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10. Online N2O Measurement: The Next Standard for Controlling Biological Ammonia Oxidation?
- Author
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Wunderlin, Pascal, Hansruedi Siegrist, and Joss, Adriano
- Subjects
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NITROUS oxide , *OUTGASSING , *AMMONIA-oxidizing bacteria , *SEWAGE disposal plants , *WASTEWATER treatment - Abstract
The article focuses on a study on the implementation of online nitrous oxide off-gas analysis for the process control of full-scale nitritation-anammox treatment. Nitrous oxide production is driven by ammonia-oxidizing bacteria. Long-term continuous nitrous oxide off-gas analysis is needed for the accurate recording of emission dynamics and levels of conventional wastewater treatment plants.
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- 2013
- Full Text
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11. N2O emission in full-scale wastewater treatment: Proposing a refined monitoring strategy.
- Author
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Gruber, Wenzel, Villez, Kris, Kipf, Marco, Wunderlin, Pascal, Siegrist, Hansruedi, Vogt, Liliane, and Joss, Adriano
- Abstract
• Long-term N 2 O emission data set of three different activated sludge systems. • Significant spatial and temporal emission variation on all three treatment plants. • Guiding principles for monitoring on wastewater treatment plants with open tanks. • Separate reject water treatment can reduce overall N 2 O emissions. Nitrous oxide (N 2 O) 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. Based on three monitoring campaigns on three full-scale wastewater treatment plants (WWTPs) with different activated sludge configurations, each of which lasted at least one year, we propose a refined monitoring strategy for long-term emission monitoring with multiple flux chambers on open tanks. Our monitoring campaigns confirm that the N 2 O emissions exhibited a strong seasonal profile and were substantial on all three plants (1–2.4% of the total nitrogen load). These results confirm that N 2 O is the most important greenhouse gas emission from wastewater treatment. The temporal variation was more distinct than the spatial variation within aeration tanks. Nevertheless, multiple monitoring spots along a single lane are crucial to assess representative emission factors in flow-through systems. Sequencing batch reactor systems were shown to exhibit comparable emissions within one reactor but significant variation between parallel reactors. The results indicate that considerable emission differences between lanes are to be expected in cases of inhomogeneous loading and discontinuous feeding. For example, N 2 O emission could be shown to depend on the amount of treated reject water: lanes without emitted <1% of the influent load, while parallel lanes emitted around 3%. In case of inhomogeneous loading, monitoring of multiple lanes is required. Our study enables robust planning of monitoring campaigns on WWTPs with open tanks. Extensive full-scale emission monitoring campaigns are important as a basis for reliable decisions about reducing the climate impact of wastewater treatment. More specifically, such data sets help us to define general emission factors for wastewater treatment plants and to construct and critically evaluate N 2 O emission models. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
12. Isotope signatures of N₂O in a mixed microbial population system: constraints on N₂O producing pathways in wastewater treatment.
- Author
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Wunderlin P, Lehmann MF, Siegrist H, Tuzson B, Joss A, Emmenegger L, and Mohn J
- Subjects
- Batch Cell Culture Techniques, Denitrification, Heterotrophic Processes, Nitrites, Nitrogen Isotopes, Oxidation-Reduction, Quaternary Ammonium Compounds metabolism, Bacteria metabolism, Biosynthetic Pathways, Isotope Labeling, Nitrous Oxide analysis, Wastewater microbiology, Water Purification
- Abstract
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. On the basis of previous work with microbial pure cultures, we demonstrate that N(2)O emitted during ammonia (NH(4)(+)) oxidation with a SP of -5.8 to 5.6 ‰ derives mostly from nitrite (NO(2)(-)) reduction (e.g., nitrifier denitrification), with a minor contribution from hydroxylamine (NH(2)OH) oxidation at the beginning of the experiments. SP of N(2)O produced under anoxic conditions was always positive (1.2 to 26.1 ‰), and SP values at the high end of this spectrum (24.9 to 26.1 ‰) are indicative of N(2)O reductase activity. The measured δ(15)N(bulk)(N2O) at the initiation of the NH(4)(+) oxidation experiments ranged between -42.3 and -57.6 ‰ (corresponding to a nitrogen isotope effect Δδ(15)N = δ(15)N(substrate) - δ(15)N(bulk)(N2O) of 43.5 to 58.8 ‰), which is considerably higher than under denitrifying conditions (δ(15)N(bulk)(N2O) 2.4 to -17 ‰; Δδ(15)N = 0.1 to 19.5 ‰). During the course of all NH(4)(+) oxidation and nitrate (NO(3)(-)) reduction experiments, δ(15)N(bulk)(N2O) increased significantly, indicating net (15)N enrichment in the dissolved inorganic nitrogen substrates (NH(4)(+), NO(3)(-)) and transfer into the N(2)O pool. The decrease in δ(15)N(bulk)(N2O) during NO(2)(-) and NH(2)OH oxidation experiments is best explained by inverse fractionation during the oxidation of NO(2)(-) to NO(3)(-).
- Published
- 2013
- Full Text
- View/download PDF
13. N2O emissions: modeling the effect of process configuration and diurnal loading patterns.
- Author
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Houweling D, Wunderlin P, Dold P, Bye C, Joss A, and Siegrist H
- Subjects
- Calibration, Pilot Projects, Sewage, Solubility, Circadian Rhythm, Models, Theoretical, Nitrous Oxide analysis
- Abstract
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. Low dissolved oxygen concentrations also may be implicated through differential impacts on ammonia-oxidizing bacteria (AOB) versus nitrite-oxidizing bacteria (NOB) activity. Factors promoting N2O emissions at treatment plants are discussed below. The model was applied to data from laboratory and pilot-scale systems. From a practical standpoint, plant configuration (e.g., plug-flow versus complete-mix), influent loading patterns (and peak load), and certain operating strategies (e.g., handling of return streams) are all important in determining N2O emissions.
- Published
- 2011
- Full Text
- View/download PDF
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