Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated Beds
Autor(a) principal: | |
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Data de Publicação: | 2012 |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10400.6/1962 |
Resumo: | The evaluation of the dispersion in vegetated beds may allow indentifying mechanisms that affect the transport and reaction of solutes, namely organic and nitrogen compounds. A set of non-reactive tracer experiments (slag injection) was performed in a vegetated bed (a mesocosm with a LECA-based substratum and colonized with Phragmites australis) used for the removal of organic and nitrogen pollutant loads. Loads of approximately 300 mg COD/L and 30 mg NH4-N/L and a hydraulic loading rate of 3.5 cm/d were used. The results showed a delay in all the residence time distribution (RTD) curves and a variation in the dimensionless residence time (mu((m,theta))) of the E(theta) curves, which means that the mass centre of the impulse was late relatively to the expected one. A strong dispersion and tracer retention (due to the presence of stagnated areas and internal recirculation) was observed, especially in the first 33 cm of the bed, which seems to have been related to the presence of complex clusters of roots, solid material, biofilm and LECA particles. An analytical solution of the Multiple-Tanks-in-Series (MTS) model well represents the RTD curves obtained in the tracer experiments. The detected dispersion and dead volume ratios (7% to 12%) did not affect the performance of the bed, which presented mean removal efficiencies of 85% and 60.4% for COD and NH4-N, respectively. |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated BedsWetlandsMacrófitasDifusionDead volumesHidrodinamicaHydrodinamicsDispersionDispersãoTracer experimentsEnsaios de traçagemvegetated bedsFlow constructed wetlandsNutrient removalRemoção de azotoThe evaluation of the dispersion in vegetated beds may allow indentifying mechanisms that affect the transport and reaction of solutes, namely organic and nitrogen compounds. A set of non-reactive tracer experiments (slag injection) was performed in a vegetated bed (a mesocosm with a LECA-based substratum and colonized with Phragmites australis) used for the removal of organic and nitrogen pollutant loads. Loads of approximately 300 mg COD/L and 30 mg NH4-N/L and a hydraulic loading rate of 3.5 cm/d were used. The results showed a delay in all the residence time distribution (RTD) curves and a variation in the dimensionless residence time (mu((m,theta))) of the E(theta) curves, which means that the mass centre of the impulse was late relatively to the expected one. A strong dispersion and tracer retention (due to the presence of stagnated areas and internal recirculation) was observed, especially in the first 33 cm of the bed, which seems to have been related to the presence of complex clusters of roots, solid material, biofilm and LECA particles. An analytical solution of the Multiple-Tanks-in-Series (MTS) model well represents the RTD curves obtained in the tracer experiments. The detected dispersion and dead volume ratios (7% to 12%) did not affect the performance of the bed, which presented mean removal efficiencies of 85% and 60.4% for COD and NH4-N, respectively.TRANS TECH PUBLICATIONS LTDuBibliorumAlbuquerque, Antonio2014-06-30T17:59:00Z20122012-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10400.6/1962eng1012-0386info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-01-16T11:39:31ZPortal AgregadorONG |
dc.title.none.fl_str_mv |
Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated Beds |
title |
Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated Beds |
spellingShingle |
Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated Beds Albuquerque, Antonio Wetlands Macrófitas Difusion Dead volumes Hidrodinamica Hydrodinamics Dispersion Dispersão Tracer experiments Ensaios de traçagem vegetated beds Flow constructed wetlands Nutrient removal Remoção de azoto |
title_short |
Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated Beds |
title_full |
Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated Beds |
title_fullStr |
Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated Beds |
title_full_unstemmed |
Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated Beds |
title_sort |
Spatial Variation of Longitudinal Dispersion in LECA-Based Vegetated Beds |
author |
Albuquerque, Antonio |
author_facet |
Albuquerque, Antonio |
author_role |
author |
dc.contributor.none.fl_str_mv |
uBibliorum |
dc.contributor.author.fl_str_mv |
Albuquerque, Antonio |
dc.subject.por.fl_str_mv |
Wetlands Macrófitas Difusion Dead volumes Hidrodinamica Hydrodinamics Dispersion Dispersão Tracer experiments Ensaios de traçagem vegetated beds Flow constructed wetlands Nutrient removal Remoção de azoto |
topic |
Wetlands Macrófitas Difusion Dead volumes Hidrodinamica Hydrodinamics Dispersion Dispersão Tracer experiments Ensaios de traçagem vegetated beds Flow constructed wetlands Nutrient removal Remoção de azoto |
description |
The evaluation of the dispersion in vegetated beds may allow indentifying mechanisms that affect the transport and reaction of solutes, namely organic and nitrogen compounds. A set of non-reactive tracer experiments (slag injection) was performed in a vegetated bed (a mesocosm with a LECA-based substratum and colonized with Phragmites australis) used for the removal of organic and nitrogen pollutant loads. Loads of approximately 300 mg COD/L and 30 mg NH4-N/L and a hydraulic loading rate of 3.5 cm/d were used. The results showed a delay in all the residence time distribution (RTD) curves and a variation in the dimensionless residence time (mu((m,theta))) of the E(theta) curves, which means that the mass centre of the impulse was late relatively to the expected one. A strong dispersion and tracer retention (due to the presence of stagnated areas and internal recirculation) was observed, especially in the first 33 cm of the bed, which seems to have been related to the presence of complex clusters of roots, solid material, biofilm and LECA particles. An analytical solution of the Multiple-Tanks-in-Series (MTS) model well represents the RTD curves obtained in the tracer experiments. The detected dispersion and dead volume ratios (7% to 12%) did not affect the performance of the bed, which presented mean removal efficiencies of 85% and 60.4% for COD and NH4-N, respectively. |
publishDate |
2012 |
dc.date.none.fl_str_mv |
2012 2012-01-01T00:00:00Z 2014-06-30T17:59:00Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10400.6/1962 |
url |
http://hdl.handle.net/10400.6/1962 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
1012-0386 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
TRANS TECH PUBLICATIONS LTD |
publisher.none.fl_str_mv |
TRANS TECH PUBLICATIONS LTD |
dc.source.none.fl_str_mv |
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
instname_str |
Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
instacron_str |
RCAAP |
institution |
RCAAP |
reponame_str |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
collection |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
repository.name.fl_str_mv |
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repository.mail.fl_str_mv |
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1777301764861591552 |