Sequestration and Transformation in Chemically Enhanced Treatment Wetlands: DOC, DBPPs, and Nutrients

AbstractThis paper examines the effectiveness of chemically enhanced treatment wetlands (CETWs), wetlands that received water treated with coagulants, to remove dissolved organic carbon (DOC), disinfection byproduct precursors (DBPPs), nutrients, and metals from agricultural drain water. Wetlands co...

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Bibliographic Details
Published in:Journal of environmental engineering (New York, N.Y.) N.Y.), 2019-08, Vol.145 (8)
Main Authors: Bachand, Philip A. M, Bachand, Sandra M, Kraus, Tamara E. C, Stern, Dylan, Liang, Yan Ling, Horwath, William R
Format: Article
Language:English
Subjects:
Coagulants
Coagulation
Disinfection
Dissolved organic carbon
Dissolved organic nitrogen
Dosage
Ferric sulfate
Hydraulic retention time
Iron sulfates
Low temperature
Metals
Nutrients
Organic chemistry
Organic nitrogen
Plug flow
Plug flow chemical reactors
Retention time
Sulfates
Technical Papers
Temperature dependence
Temperature effects
Water treatment
Wetland agriculture
Wetlands
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Summary:AbstractThis paper examines the effectiveness of chemically enhanced treatment wetlands (CETWs), wetlands that received water treated with coagulants, to remove dissolved organic carbon (DOC), disinfection byproduct precursors (DBPPs), nutrients, and metals from agricultural drain water. Wetlands consisted of controls with no coagulant addition, ferric sulfate dosed, and polyaluminum chloride dosed treatments. CETWs were more effective in removing DOC, DBPPs, phosphate, dissolved organic nitrogen, and metals than control wetlands. Coagulation-treated wetlands removed 245–349  g/m2/year DOC, whereas control wetlands produced 51  g/m2/year. Wetland passage released DOC in the controls and dosed treatments; this release was directly correlated to temperature, suggesting thermally dependent mechanism(s) were partly responsible. A first-order plug flow reactor kinetic model that considered hydraulic retention time (HRT), temperature, and DOC concentration was tested for wetland DOC processing. Models indicate that operating CETWs at high coagulant dosing and low temperature can result in the lowest DOC release. Operating at the lowest HRT to meet discharge targets helps overcome wetland processes that increase DOC release and provide the smallest footprint needed for treatment.
ISSN:0733-9372
1943-7870
DOI:10.1061/(ASCE)EE.1943-7870.0001536