Increased Duration of Drying–Rewetting Cycles Increases Nitrate Removal in Woodchip Bioreactors

A previously reported experiment showed weekly drying–rewetting (DRW) cycles increase nitrate removal rates in woodchip-based denitrifying bioreactors. A follow-up experiment determined the effect of duration of unsaturated conditions on nitrate removal after rewetting. Three different levels of DRW...

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Main Authors: Bryan M. Maxwell, François Birgand, Louis A. Schipper, Laura E. Christianson, Shiying Tian, Matthew J. Helmers, David J. Williams, George M. Chescheir, Mohamed A. Youssef
Format: Article
Language:English
Published: Wiley 2019-09-01
Series:Agricultural & Environmental Letters
Online Access:https://dl.sciencesocieties.org/publications/ael/articles/4/1/190028
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author Bryan M. Maxwell
François Birgand
Louis A. Schipper
Laura E. Christianson
Shiying Tian
Matthew J. Helmers
David J. Williams
George M. Chescheir
Mohamed A. Youssef
author_facet Bryan M. Maxwell
François Birgand
Louis A. Schipper
Laura E. Christianson
Shiying Tian
Matthew J. Helmers
David J. Williams
George M. Chescheir
Mohamed A. Youssef
author_sort Bryan M. Maxwell
collection DOAJ
description A previously reported experiment showed weekly drying–rewetting (DRW) cycles increase nitrate removal rates in woodchip-based denitrifying bioreactors. A follow-up experiment determined the effect of duration of unsaturated conditions on nitrate removal after rewetting. Three different levels of DRW duration were tested in a 105-d column experiment ( = 2), with woodchips left unsaturated once a week for either 2 h, 8 h, or 24 h. Increasing duration of unsaturated conditions significantly increased nitrate removal rates. The longest DRW duration of 24 h resulted in the greatest increase in nitrate removal rates, relative to constantly saturated woodchips, with mean rate increases reaching 172% by the end of the experiment. Results suggest nitrate removal in denitrifying bioreactors is carbon limited, with labile carbon made available during aerobic periods of DRW cycles the most likely cause of observed rate increases. Both studies show DRW cycles dramatically increase the nitrate removal efficiency of denitrifying bioreactors.
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spelling doaj.art-46c561f33def43058b7cfd6833f78ac12022-12-21T23:46:24ZengWileyAgricultural & Environmental Letters2471-96252019-09-014110.2134/ael2019.07.0028Increased Duration of Drying–Rewetting Cycles Increases Nitrate Removal in Woodchip BioreactorsBryan M. MaxwellFrançois BirgandLouis A. SchipperLaura E. ChristiansonShiying TianMatthew J. HelmersDavid J. WilliamsGeorge M. ChescheirMohamed A. YoussefA previously reported experiment showed weekly drying–rewetting (DRW) cycles increase nitrate removal rates in woodchip-based denitrifying bioreactors. A follow-up experiment determined the effect of duration of unsaturated conditions on nitrate removal after rewetting. Three different levels of DRW duration were tested in a 105-d column experiment ( = 2), with woodchips left unsaturated once a week for either 2 h, 8 h, or 24 h. Increasing duration of unsaturated conditions significantly increased nitrate removal rates. The longest DRW duration of 24 h resulted in the greatest increase in nitrate removal rates, relative to constantly saturated woodchips, with mean rate increases reaching 172% by the end of the experiment. Results suggest nitrate removal in denitrifying bioreactors is carbon limited, with labile carbon made available during aerobic periods of DRW cycles the most likely cause of observed rate increases. Both studies show DRW cycles dramatically increase the nitrate removal efficiency of denitrifying bioreactors.https://dl.sciencesocieties.org/publications/ael/articles/4/1/190028
spellingShingle Bryan M. Maxwell
François Birgand
Louis A. Schipper
Laura E. Christianson
Shiying Tian
Matthew J. Helmers
David J. Williams
George M. Chescheir
Mohamed A. Youssef
Increased Duration of Drying–Rewetting Cycles Increases Nitrate Removal in Woodchip Bioreactors
Agricultural & Environmental Letters
title Increased Duration of Drying–Rewetting Cycles Increases Nitrate Removal in Woodchip Bioreactors
title_full Increased Duration of Drying–Rewetting Cycles Increases Nitrate Removal in Woodchip Bioreactors
title_fullStr Increased Duration of Drying–Rewetting Cycles Increases Nitrate Removal in Woodchip Bioreactors
title_full_unstemmed Increased Duration of Drying–Rewetting Cycles Increases Nitrate Removal in Woodchip Bioreactors
title_short Increased Duration of Drying–Rewetting Cycles Increases Nitrate Removal in Woodchip Bioreactors
title_sort increased duration of drying rewetting cycles increases nitrate removal in woodchip bioreactors
url https://dl.sciencesocieties.org/publications/ael/articles/4/1/190028
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