Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography
Clogging constitutes a major operational issue for treatment wetlands. The rest period is a key feature of French Vertical Flow (VF) treatment wetlands and serves to mitigate clogging. An ex-situ drying experiment was performed to mimic the rest period and record structural changes in the porous med...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-02-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/13/3/389 |
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| author | German Dario Martinez-Carvajal Laurent Oxarango Jérôme Adrien Pascal Molle Nicolas Forquet |
| author_facet | German Dario Martinez-Carvajal Laurent Oxarango Jérôme Adrien Pascal Molle Nicolas Forquet |
| author_sort | German Dario Martinez-Carvajal |
| collection | DOAJ |
| description | Clogging constitutes a major operational issue for treatment wetlands. The rest period is a key feature of French Vertical Flow (VF) treatment wetlands and serves to mitigate clogging. An ex-situ drying experiment was performed to mimic the rest period and record structural changes in the porous media using X-ray Computed Tomography (CT). Samples containing the deposit and gravel layers of a first stage French VF treatment wetland were extracted and left to dry in a control environment. Based on CT scans, three phases were identified (voids, biosolids, and gravels). The impact of the rest period was assessed by means of different pore-scale variables. Ultimately, the volume of biosolids had reduced to 58% of its initial value, the deposit layer thickness dropped to 68% of its initial value, and the void/biosolid specific surface area ratio increased from a minimum value of 1.1 to a maximum of 4.2. Cracks greater than 3 mm developed at the uppermost part of the deposit layer, while, in the gravel layer, the rise in void volume corresponds to pores smaller than 2 mm in diameter. Lastly, the air-filled microporosity is estimated to have increased by 0.11 <i>v</i>/<i>v</i>. |
| first_indexed | 2024-03-09T06:00:27Z |
| format | Article |
| id | doaj.art-b2fab756608a43ddb41bd36fe71a99bc |
| institution | Directory Open Access Journal |
| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-09T06:00:27Z |
| publishDate | 2021-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Water |
| spelling | doaj.art-b2fab756608a43ddb41bd36fe71a99bc2023-12-03T12:09:56ZengMDPI AGWater2073-44412021-02-0113338910.3390/w13030389Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray TomographyGerman Dario Martinez-Carvajal0Laurent Oxarango1Jérôme Adrien2Pascal Molle3Nicolas Forquet4Institut Blaise Pascal, 4 Avenue Blaise Pascal TSA 60026/CS 60026, CEDEX, 63178 Aubière, FranceCNRS, IRD, Grenoble INP, IGE, Université Grenoble Alpes, 38000 Grenoble, FranceINSA-Lyon, MATEIS Laboratory, University of Lyon, UMR CNRS 5510, 20 Avenue Albert Einstein, CEDEX, 69621 Villeurbanne, FranceUR REVERSAAL, INRAE 5 rue de la Doua-CS70077, 69626 Villeurbanne, FranceUR REVERSAAL, INRAE 5 rue de la Doua-CS70077, 69626 Villeurbanne, FranceClogging constitutes a major operational issue for treatment wetlands. The rest period is a key feature of French Vertical Flow (VF) treatment wetlands and serves to mitigate clogging. An ex-situ drying experiment was performed to mimic the rest period and record structural changes in the porous media using X-ray Computed Tomography (CT). Samples containing the deposit and gravel layers of a first stage French VF treatment wetland were extracted and left to dry in a control environment. Based on CT scans, three phases were identified (voids, biosolids, and gravels). The impact of the rest period was assessed by means of different pore-scale variables. Ultimately, the volume of biosolids had reduced to 58% of its initial value, the deposit layer thickness dropped to 68% of its initial value, and the void/biosolid specific surface area ratio increased from a minimum value of 1.1 to a maximum of 4.2. Cracks greater than 3 mm developed at the uppermost part of the deposit layer, while, in the gravel layer, the rise in void volume corresponds to pores smaller than 2 mm in diameter. Lastly, the air-filled microporosity is estimated to have increased by 0.11 <i>v</i>/<i>v</i>.https://www.mdpi.com/2073-4441/13/3/389constructed wetlandsdrying3D-phase distributionclogging |
| spellingShingle | German Dario Martinez-Carvajal Laurent Oxarango Jérôme Adrien Pascal Molle Nicolas Forquet Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography Water constructed wetlands drying 3D-phase distribution clogging |
| title | Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography |
| title_full | Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography |
| title_fullStr | Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography |
| title_full_unstemmed | Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography |
| title_short | Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography |
| title_sort | structural changes in french vf treatment wetland porous media during the rest period an ex situ study using x ray tomography |
| topic | constructed wetlands drying 3D-phase distribution clogging |
| url | https://www.mdpi.com/2073-4441/13/3/389 |
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