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dc.contributor.authorWarneke, Sören
dc.contributor.authorSchipper, Louis A.
dc.contributor.authorBruesewitz, Denise A.
dc.contributor.authorBaisden, W. Troy
dc.coverage.spatialEnglanden_NZ
dc.date.accessioned2011-07-10T23:17:17Z
dc.date.available2011-07-10T23:17:17Z
dc.date.issued2011
dc.identifier.citationWarneke, S., Schipper, L.A., Bruesewitz, D.A. & Baisden, W.T. (2011). A comparison of different approaches for measuring denitrification rates in a nitrate removing bioreactor. Water Research, 45(4), 4141-4151.en_NZ
dc.identifier.urihttps://hdl.handle.net/10289/5464
dc.description.abstractDenitrifying woodchip bioreactors (denitrification beds) are increasingly used to remove excess nitrate (NO₃⁻) from point-sources such as wastewater effluent or subsurface drains from agricultural fields. NO₃⁻ removal in these beds is assumed to be due to microbial denitrification but direct measurements of denitrification are lacking. Our objective was to test four different approaches for measuring denitrification rates in a denitrification bed that treated effluent discharged from a glasshouse. We compared these denitrification rates with the rate of NO₃⁻ removal along the length of the bed. The NO₃⁻ removal rate was 8.73 ± 1.45 g m⁻³ d⁻¹. In vitro acetylene inhibition assays resulted in highly variable denitrification rates (DRAI) along the length of the bed and generally 5 times greater than the measured (NO₃⁻- N removal rate. An in situ push–pull test, where enriched ¹⁵N- NO₃⁻was injected into 2 locations along the bed, resulted in rates of 23.2 ± 1.43 g N m⁻³ d⁻¹ and 8.06 ± 1.64 g N m⁻³ d⁻¹. The denitrification rate calculated from the increase in dissolved N2 and N2O concentrations (DRN2) along the length of the denitrification bed was 6.7 ± 1.61 g N m⁻³ d⁻¹. Lastly, denitrification rates calculated from changes in natural abundance measurements of δ¹⁵N-N₂ and δ¹⁵N- NO₃⁻ along the length of the bed yielded a denitrification rate (DRNA) of 6.39 ± 2.07 g m⁻³ d⁻¹. Based on our experience, DRN2 measurements were the easiest and most efficient approach for determining the denitrification rate and N₂O production of a denitrification bed. However, the other approaches were useful for testing other hypotheses such as factors limiting denitrification or may be applied to determine denitrification rates in environmental systems different to our study site. DRN2 does require very careful sampling to avoid atmospheric N2 contamination but could be used to rapidly determine denitrification rates in a variety of aquatic systems with high N2 production and even water flows. These measurements demonstrated that the majority of NO₃⁻ removal was due to heterotrophic denitrification.en_NZ
dc.language.isoen
dc.publisherElsevieren_NZ
dc.relation.urihttp://www.sciencedirect.com/science/article/pii/S0043135411002909en_NZ
dc.subjectDenitrificationen_NZ
dc.subject¹⁵Nen_NZ
dc.subjectpush–pullen_NZ
dc.subjectstable isotopesen_NZ
dc.subjectacetylene blocken_NZ
dc.subjectnatural abundanceen_NZ
dc.titleA comparison of different approaches for measuring denitrification rates in a nitrate removing bioreactoren_NZ
dc.typeJournal Articleen_NZ
dc.identifier.doi10.1016/j.watres.2011.05.027en_NZ
dc.relation.isPartOfWater Researchen_NZ
pubs.begin-page4141en_NZ
pubs.elements-id36081
pubs.end-page4151en_NZ
pubs.issue14en_NZ
pubs.volume45en_NZ


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