Effect of Plant Species on the Performance and Bacteria Density Profile in Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment in a Tropical Climate
Bacteria are frequently studied due to their involvement in pollutants transformation processes during wastewater treatment. In this study, the treatment efficiency, bacteria densities and their vertical profile were investigated in pilot-scale vertical flow constructed wetlands (VFCW) planted with...
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MDPI AG
2021-12-01
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| Online Access: | https://www.mdpi.com/2073-4441/13/24/3485 |
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| author | Franck Michaël Zahui Jean-Marie Pétémanagnan Ouattara Mahamadou Kamagaté Lacina Coulibaly Alexandros I. Stefanakis |
| author_facet | Franck Michaël Zahui Jean-Marie Pétémanagnan Ouattara Mahamadou Kamagaté Lacina Coulibaly Alexandros I. Stefanakis |
| author_sort | Franck Michaël Zahui |
| collection | DOAJ |
| description | Bacteria are frequently studied due to their involvement in pollutants transformation processes during wastewater treatment. In this study, the treatment efficiency, bacteria densities and their vertical profile were investigated in pilot-scale vertical flow constructed wetlands (VFCW) planted with different plant species under a tropical climate in west Africa. Five beds were planted with local plant species, i.e., <i>Andropogon gayanus</i>, <i>Chrysopogon zizanioides</i>, <i>Echinochloa pyramidalis</i>, <i>Pennisetum purpureum</i> and <i>Tripsacum laxum</i>, while one bed remained unplanted. These species have been rarely used in CWs while some (e.g., <i>T. laxum</i>) are tested for the first time. After a 7-month trial, bacteria densities were measured in substrate samples separated into six layers along the bed depth. Plants presence enhanced the bacterial density and VFCW efficiency; the removal rates of organic matter (90.9–95.9%; COD and 95.2–98.5%; BOD<sub>5</sub>), nitrogen (74.3–84%; TN and 76–84%; NH<sub>4</sub>-N) and phosphorus (77.4–96.9%; PO<sub>4</sub>-P) were higher by 5.9–24.1% compared to the control bed, providing an overall excellent treatment performance for a single-stage VFCW system. Small numbers of anaerobic bacteria were obtained in the VFCWs, explaining the low-to-zero NO<sub>3</sub>-N removal, except for the VFCWs with <i>T. laxum</i> and <i>P. purpureum</i>. Aerobic bacteria decreased from the upper to bottom layers from 17.4 to 0.1 × 10<sup>6</sup> CFU/g in the planted beds, while anaerobic bacteria increased from 0.1 to 2.1 × 10<sup>6</sup> CFU/g. Anaerobic bacteria were more abundant in the unplanted than in the planted beds. The total bacteria count was dominated by aerobic bacteria, and decreased from the surface towards the bottom. Overall, the VFCW with <i>P. purpureum</i> demonstrated the highest efficiency, indicating that this design is an effective and sustainable nature-based solution for wastewater treatment in a tropical climate. |
| first_indexed | 2024-03-10T03:54:09Z |
| format | Article |
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| language | English |
| last_indexed | 2024-03-10T03:54:09Z |
| publishDate | 2021-12-01 |
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| spelling | doaj.art-64f5b2c3205b4aed8d0cd850067b43a92023-11-23T10:59:58ZengMDPI AGWater2073-44412021-12-011324348510.3390/w13243485Effect of Plant Species on the Performance and Bacteria Density Profile in Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment in a Tropical ClimateFranck Michaël Zahui0Jean-Marie Pétémanagnan Ouattara1Mahamadou Kamagaté2Lacina Coulibaly3Alexandros I. Stefanakis4Laboratory of Environment and Aquatic Biology, Department of Sciences and Environment Management, Nangui Abrogoua University, 02 BP 801 Abidjan 02, Côte d’IvoireLaboratory of Environment and Aquatic Biology, Department of Sciences and Environment Management, Nangui Abrogoua University, 02 BP 801 Abidjan 02, Côte d’IvoireDepartment of Agronomic, Forestry and Environmental Engineering, University of Man, BP 20 Man, Côte d’IvoireLaboratory of Environment and Aquatic Biology, Department of Sciences and Environment Management, Nangui Abrogoua University, 02 BP 801 Abidjan 02, Côte d’IvoireLaboratory of Environmental Engineering & Management, School of Chemical and Environmental Engineering, Technical University of Crete, 73100 Chania, GreeceBacteria are frequently studied due to their involvement in pollutants transformation processes during wastewater treatment. In this study, the treatment efficiency, bacteria densities and their vertical profile were investigated in pilot-scale vertical flow constructed wetlands (VFCW) planted with different plant species under a tropical climate in west Africa. Five beds were planted with local plant species, i.e., <i>Andropogon gayanus</i>, <i>Chrysopogon zizanioides</i>, <i>Echinochloa pyramidalis</i>, <i>Pennisetum purpureum</i> and <i>Tripsacum laxum</i>, while one bed remained unplanted. These species have been rarely used in CWs while some (e.g., <i>T. laxum</i>) are tested for the first time. After a 7-month trial, bacteria densities were measured in substrate samples separated into six layers along the bed depth. Plants presence enhanced the bacterial density and VFCW efficiency; the removal rates of organic matter (90.9–95.9%; COD and 95.2–98.5%; BOD<sub>5</sub>), nitrogen (74.3–84%; TN and 76–84%; NH<sub>4</sub>-N) and phosphorus (77.4–96.9%; PO<sub>4</sub>-P) were higher by 5.9–24.1% compared to the control bed, providing an overall excellent treatment performance for a single-stage VFCW system. Small numbers of anaerobic bacteria were obtained in the VFCWs, explaining the low-to-zero NO<sub>3</sub>-N removal, except for the VFCWs with <i>T. laxum</i> and <i>P. purpureum</i>. Aerobic bacteria decreased from the upper to bottom layers from 17.4 to 0.1 × 10<sup>6</sup> CFU/g in the planted beds, while anaerobic bacteria increased from 0.1 to 2.1 × 10<sup>6</sup> CFU/g. Anaerobic bacteria were more abundant in the unplanted than in the planted beds. The total bacteria count was dominated by aerobic bacteria, and decreased from the surface towards the bottom. Overall, the VFCW with <i>P. purpureum</i> demonstrated the highest efficiency, indicating that this design is an effective and sustainable nature-based solution for wastewater treatment in a tropical climate.https://www.mdpi.com/2073-4441/13/24/3485constructed wetlandsvertical flowdomestic wastewaterplant speciesbacterial densityaerobic bacteria |
| spellingShingle | Franck Michaël Zahui Jean-Marie Pétémanagnan Ouattara Mahamadou Kamagaté Lacina Coulibaly Alexandros I. Stefanakis Effect of Plant Species on the Performance and Bacteria Density Profile in Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment in a Tropical Climate Water constructed wetlands vertical flow domestic wastewater plant species bacterial density aerobic bacteria |
| title | Effect of Plant Species on the Performance and Bacteria Density Profile in Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment in a Tropical Climate |
| title_full | Effect of Plant Species on the Performance and Bacteria Density Profile in Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment in a Tropical Climate |
| title_fullStr | Effect of Plant Species on the Performance and Bacteria Density Profile in Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment in a Tropical Climate |
| title_full_unstemmed | Effect of Plant Species on the Performance and Bacteria Density Profile in Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment in a Tropical Climate |
| title_short | Effect of Plant Species on the Performance and Bacteria Density Profile in Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment in a Tropical Climate |
| title_sort | effect of plant species on the performance and bacteria density profile in vertical flow constructed wetlands for domestic wastewater treatment in a tropical climate |
| topic | constructed wetlands vertical flow domestic wastewater plant species bacterial density aerobic bacteria |
| url | https://www.mdpi.com/2073-4441/13/24/3485 |
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