For Publishers
DiscoveryMetadataPeer reviewHostingPublishing
For Researchers
JoinPublishReviewCollect
Register
Blog
About
Search
Advanced search
My ScienceOpen
Search
For Publishers
For Researchers
Blog
About
7
views
58
references
 Top references
cited by
2
    
0 reviews
 Review
0
comments
 Comment
0
recommends
+1 Recommend
0 collections
    0
    shares
      126
      similar
       All similar
      • Record: found
      • Abstract: found
      • Article: not found

      A consilience model to describe N2O production during biological N removal

      Read this article at

      ScienceOpenPublisher
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          A mathematical model congruent with the current understanding of the biological processes occurring during wastewater treatment operations is proposed.

          Abstract

          Nitrous oxide (N 2O), a potent greenhouse gas, is produced during biological nitrogen conversion in wastewater treatment operations. Complex mechanisms underlie N 2O production by autotrophic and heterotrophic organisms, which continue to be unravelled. Mathematical models that describe nitric oxide (NO) and N 2O dynamics have been proposed. Here, a first comprehensive model that considers all relevant NO and N 2O production and consumption mechanisms is proposed. The model describes autotrophic NO production by ammonia oxidizing bacteria associated with ammonia oxidation and with nitrite reduction, followed by NO reduction to N 2O. It also considers NO and N 2O as intermediates in heterotrophic denitrification in a 4-step model. Three biological NO and N 2O production pathways are accounted for, improving the capabilities of existing models while not increasing their complexity. Abiotic contributions from NH 2OH and HNO 2 reactions are also included. The consilient model structure can theoretically predict NO and N 2O emissions under a wide range of operating conditions and will help develop mitigation strategies.

          Related collections

          Most cited references58

          • Record: found
          • Abstract: found
          • Article: not found

          Bioreactor scale-up and oxygen transfer rate in microbial processes: an overview.

          Felix Garcia-Ochoa, Emilio Gomez (2009)
          In aerobic bioprocesses, oxygen is a key substrate; due to its low solubility in broths (aqueous solutions), a continuous supply is needed. The oxygen transfer rate (OTR) must be known, and if possible predicted to achieve an optimum design operation and scale-up of bioreactors. Many studies have been conducted to enhance the efficiency of oxygen transfer. The dissolved oxygen concentration in a suspension of aerobic microorganisms depends on the rate of oxygen transfer from the gas phase to the liquid, on the rate at which oxygen is transported into the cells (where it is consumed), and on the oxygen uptake rate (OUR) by the microorganism for growth, maintenance and production. The gas-liquid mass transfer in a bioprocess is strongly influenced by the hydrodynamic conditions in the bioreactors. These conditions are known to be a function of energy dissipation that depends on the operational conditions, the physicochemical properties of the culture, the geometrical parameters of the bioreactor and also on the presence of oxygen consuming cells. Stirred tank and bubble column (of various types) bioreactors are widely used in a large variety of bioprocesses (such as aerobic fermentation and biological wastewater treatments, among others). Stirred tanks bioreactors provide high values of mass and heat transfer rates and excellent mixing. In these systems, a high number of variables affect the mass transfer and mixing, but the most important among them are stirrer speed, type and number of stirrers and gas flow rate used. In bubble columns and airlifts, the low-shear environment compared to the stirred tanks has enabled successful cultivation of shear sensitive and filamentous cells. Oxygen transfer is often the rate-limiting step in the aerobic bioprocess due to the low solubility of oxygen in the medium. The correct measurement and/or prediction of the volumetric mass transfer coefficient, (k(L)a), is a crucial step in the design, operation and scale-up of bioreactors. The present work is aimed at the reviewing of the oxygen transfer rate (OTR) in bioprocesses to provide a better knowledge about the selection, design, scale-up and development of bioreactors. First, the most used measuring methods are revised; then the main empirical equations, including those using dimensionless numbers, are considered. The possible increasing on OTR due to the oxygen consumption by the cells is taken into account through the use of the biological enhancement factor. Theoretical predictions of both the volumetric mass transfer coefficient and the enhancement factor that have been recently proposed are described; finally, different criteria for bioreactor scale-up are considered in the light of the influence of OTR and OUR affecting the dissolved oxygen concentration in real bioprocess.
          Article 0 comments Cited 186 times – based on 0 reviews     Review now
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Unexpected nondenitrifier nitrous oxide reductase gene diversity and abundance in soils.

            Daniel C. Sanford, Frank Löffler, Qingzhong Wu … (2012)
            Agricultural and industrial practices more than doubled the intrinsic rate of terrestrial N fixation over the past century with drastic consequences, including increased atmospheric nitrous oxide (N(2)O) concentrations. N(2)O is a potent greenhouse gas and contributor to ozone layer destruction, and its release from fixed N is almost entirely controlled by microbial activities. Mitigation of N(2)O emissions to the atmosphere has been attributed exclusively to denitrifiers possessing NosZ, the enzyme system catalyzing N(2)O to N(2) reduction. We demonstrate that diverse microbial taxa possess divergent nos clusters with genes that are related yet evolutionarily distinct from the typical nos genes of denitirifers. nos clusters with atypical nosZ occur in Bacteria and Archaea that denitrify (44% of genomes), do not possess other denitrification genes (56%), or perform dissimilatory nitrate reduction to ammonium (DNRA; (31%). Experiments with the DNRA soil bacterium Anaeromyxobacter dehalogenans demonstrated that the atypical NosZ is an effective N(2)O reductase, and PCR-based surveys suggested that atypical nosZ are abundant in terrestrial environments. Bioinformatic analyses revealed that atypical nos clusters possess distinctive regulatory and functional components (e.g., Sec vs. Tat secretion pathway in typical nos), and that previous nosZ-targeted PCR primers do not capture the atypical nosZ diversity. Collectively, our results suggest that nondenitrifying populations with a broad range of metabolisms and habitats are potentially significant contributors to N(2)O consumption. Apparently, a large, previously unrecognized group of environmental nosZ has not been accounted for, and characterizing their contributions to N(2)O consumption will advance understanding of the ecological controls on N(2)O emissions and lead to refined greenhouse gas flux models.
            Article 0 comments Cited 177 times – based on 0 reviews     Review now
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Ammonia oxidation pathways and nitrifier denitrification are significant sources of N2O and NO under low oxygen availability.

              Xia ZHU, Martin Burger, Timothy Doane … (2013)
              The continuous increase of nitrous oxide (N2O) abundance in the atmosphere is a global concern. Multiple pathways of N2O production occur in soil, but their significance and dependence on oxygen (O2) availability and nitrogen (N) fertilizer source are poorly understood. We examined N2O and nitric oxide (NO) production under 21%, 3%, 1%, 0.5%, and 0% (vol/vol) O2 concentrations following urea or ammonium sulfate [(NH4)2SO4] additions in loam, clay loam, and sandy loam soils that also contained ample nitrate. The contribution of the ammonia (NH3) oxidation pathways (nitrifier nitrification, nitrifier denitrification, and nitrification-coupled denitrification) and heterotrophic denitrification (HD) to N2O production was determined in 36-h incubations in microcosms by (15)N-(18)O isotope and NH3 oxidation inhibition (by 0.01% acetylene) methods. Nitrous oxide and NO production via NH3 oxidation pathways increased as O2 concentrations decreased from 21% to 0.5%. At low (0.5% and 3%) O2 concentrations, nitrifier denitrification contributed between 34% and 66%, and HD between 34% and 50% of total N2O production. Heterotrophic denitrification was responsible for all N2O production at 0% O2. Nitrifier denitrification was the main source of N2O production from ammonical fertilizer under low O2 concentrations with urea producing more N2O than (NH4)2SO4 additions. These findings challenge established thought attributing N2O emissions from soils with high water content to HD due to presumably low O2 availability. Our results imply that management practices that increase soil aeration, e.g., reducing compaction and enhancing soil structure, together with careful selection of fertilizer sources and/or nitrification inhibitors, could decrease N2O production in agricultural soils.
              Article 0 comments Cited 145 times – based on 0 reviews     Review now
                Bookmark
                All references

                Author and article information

                Journal
                Journal ID (publisher-id): ESWRAR
                Title: Environmental Science: Water Research & Technology
                Abbreviated Title: Environ. Sci.: Water Res. Technol.
                Publisher: Royal Society of Chemistry (RSC)
                ISSN (Print): 2053-1400
                ISSN (Electronic): 2053-1419
                Publication date Created: 2016
                Publication date (Print): 2016
                Volume: 2
                Issue: 6
                Pages: 923-930
                Article
                DOI: 10.1039/C6EW00179C
                SO-VID: d8a4e9a2-26d2-4ff3-be95-a9fc301417dd
                Copyright © © 2016
                History

                Data availability:

                Comments

                Comment on this article

                scite_

                Similar content126

                See all similar

                Cited by2

                See all cited by

                Most referenced authors506

                See all reference authors