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Vertical Flow Constructed Wetland

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sys1=[[Single Pit System |1]]|

sys2=[[Blackwater Treatment System with Infiltration|56]]|sys3=[[Blackwater Treatment System with SewerageEffluent Transport|67]]|sys4=[[Blackwater Transport to (Semi-) Centralized Treatment System |78]]|sys5=[[Sewerage System with Urine Diversion |89]]|

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pic=Vertical_flow_constructed_wetland.png|

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Input1=Blackwater|Input2=Greywater |Input3= Brownwater | Input4= Effluent |Input5=|Output1= Effluent | Output2= Biomass | Output3= | Output4= | Output5=|english_link=Vertical_Flow_Constructed_Wetland|french_link=Filtre_planté_à_écoulement_vertical|spanish_link=Humedal_Artificial_de_Flujo_Vertical

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'''A Vertical Flow Constructed Wetland is a filter bed that is planted with aquatic plants. Wastewater is poured or dosed onto the wetland surface from above using a mechanical dosing system. The water flows vertically down through the filter matrix. The important difference between a vertical and horizontal wetland is not simply the direction of the flow path, but rather the aerobic conditions.'''

By dosing the '''A vertical flow constructed wetland intermittently (four to ten times is a day), planted filter bed that is drained at the bottom. Wastewater is poured or dosed onto the filter goes through stages of being saturated and unsaturated, and accordingly, different phases of aerobic and anaerobic conditionssurface from above using a mechanical dosing system. The frequency of dosing should be timed such that the previous dose of wastewater has time to percolate water flows vertically down through the filter bed so that oxygen has time matrix to diffuse through the media bottom of the basin where it is collected in a drainage pipe. The important difference between a vertical and fill horizontal wetland is not simply the void spacesdirection of the flow path, but rather the aerobic conditions.'''

The Vertical Flow Constructed Wetland can be designed as <br>By intermittently dosing the wetland (4 to 10 times a shallow excavation or as an above ground construction. Each day), the filter should have an impermeable liner goes through stages of being saturated and unsaturated, and, accordingly, different phases of aerobic and an effluent collection systemanaerobic conditions. Vertical Flow Constructed Wetlands are most commonly designed to treat During a flush phase, the wastewater that has undergone primary treatmentpercolates down through the unsaturated bed. StructurallyAs the bed drains, there air is a layer of gravel for drainage (a minimum of 20cm), followed by layers of either sand drawn into it and gravel (for settled effluent) or sand and fine gravel (for raw wastewater)the oxygen has time to diffuse through the porous media. The filter media acts as both a filter for removing solids, a fixed surface upon which bacteria can attach and a base for the vegetation. The top layer is planted and the vegetation is allowed to develop deep, wide roots , which permeate the filter media. The vegetation transfers a small amount of oxygen to the root zone so that aerobic bacteria can colonize the area and degrade organics. However, the primary role of vegetation is to maintain permeability in the filter and provide habitat for microorganisms. Nutrients and organic material are absorbed and degraded by the dense microbial populations. By forcing the organisms into a starvation phase between dosing phases, excessive biomass growth can be decreased and porosity increased.

===Design Considerations=== The vertical flow constructed wetland can be designed as a shallow excavation or as an above ground construction. Clogging is a common problem. Therefore, the influent should be well settled in a primary treatment stage before flowing into the wetland. The design and size of the wetland is dependent on hydraulic and organic loads. Generally, a surface area of about 1 to 3 m2 per person equivalent is required. Each filter should have an impermeable liner and an effluent collection system. A ventilation pipe connected to the drainage system can contribute to aerobic conditions in the filter. Structurally, there is a layer of gravel for drainage (a minimum of 20 cm), followed by layers of sand and gravel. Depending on the climate, Phragmites australis(reed), Typha sp. (cattails ) or Echinochloa Pyramidalis pyramidalis are common plant options. The vegetation transfers a small amount of oxygen Testing may be required to determine the root zone so that aerobic bacteria can colonize the area and degrade organics. However, the primary role suitability of vegetation is to maintain permeability in locally available plants with the filter and provide habitat for microorganismsspecific wastewater.

During a flush phaseDue to good oxygen transfer, vertical flow wetlands have the wastewater percolates down through the unsaturated bed and ability to nitrify, but denitrification is filtered by the sand/gravel matrixlimited. Nutrients and organic material are absorbed and degraded by the dense microbial populations attached In order to the surface of the filter media and the roots. By forcing the organisms into create a starvation phase between dosing phasesnitrification-denitrification treatment train, excessive biomass growth this technology can be decreased and porosity increased. A drainage network at the base collects the effluentcombined with a [[Free-Water Surface Constructed Wetland|Free-Water Surface]] or [[Horizontal Subsurface Flow Constructed Wetland|Horizontal Flow Wetland]] (T. The design and size of the wetland is dependent on hydraulic 7 and organic loadsT. Pathogen removal is accomplished by natural decay, predation by higher organisms, and sedimentation8).

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{{procontable | pro=

- High reduction of BOD, suspended solids and pathogens <br>- Ability to nitrify due to good oxygen transfer <br>- Does not have the mosquito problems of the [[Free-Water Surface Constructed Wetland|Free-Water Surface Constructed Wetland]]. <br> - Less clogging than in a [[Horizontal Subsurface Flow Constructed Wetland|Horizontal Subsurface Flow Constructed Wetland]]. <br> - Requires less space than a Free-Water Surface Constructed or Horizontal Flow Wetland. <br> - High reduction in BODLow operating costs | con=- Requires expert design and construction, particularly, suspended solids and pathogens. the dosing system <br> - Construction can provide short-term employment to local labourers. | con=Requires more frequent maintenance than a Horizontal Subsurface Flow Constructed Wetland <br>- Constant A constant source of electrical energy may be required. <br> - Long startup time to work at full capacity <br>- Not all parts and materials may be locally available locally. <br> - Requires expert design and supervision. <br> - Moderate capital cost depending on land, liner, etc.; low operating costs. <br> - Pre-treatment is required to prevent clogging. <br> - Dosing system requires more complex engineering.

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<br>===AdequacyAppropriateness=== Clogging is a common problem. Therefore, the influent should be well settled with primary treatment before flowing into the The vertical flow constructed wetland. This technology is not appropriate for untreated domestic wastewater (i.e. blackwater). This is a good treatment for communities that have primary treatment (e.g. , [[Septic Tank|Septic Tanks]] or [[Waste Stabilization Pond|WSPs]] , S.9), but are looking to achieve a higher quality effluent. This is a good option where land is cheap and available, although the wetland will require maintenance for the duration of its life. There are many complex processes at work, and accordingly, there is a significant reduction in BOD, solids and pathogens. In many cases, the effluent will be adequate for discharge without further treatment. Because of the mechanical dosing system, this technology is most appropriate for communities with where trained maintenance staff, constant power supply, and spare partsare available. Since vertical flow constructed wetlands are able to nitrify, they can be an appropriate technology in the treatment process for wastewater with high ammonium concentrations. Vertical Flow Constructed Wetlands flow constructed wetlands are best suited to warm climates , but can be designed to tolerate some freezing and periods of low biological activity. ===Health Aspects/Acceptance=== The risk of mosquito breeding is low since there is no standing water. The system is generally aesthetic and can be integrated into wild areas or parklands. Care should be taken to ensure that people do not come in contact with the influent because of the risk of infection.

===MaintenanceHealth Aspects/Acceptance===Pathogen removal is accomplished by natural decay, predation by higher organisms, and filtration. The risk of mosquito breeding is low since there is no standing water. The system is generally aesthetic and can be integrated into wild areas or parklands. Care should be taken to ensure that people do not come in contact with the influent because of the risk of infection.

===Operation & Maintenance=== During the first growing season, it is important to remove weeds that can compete with the planted wetland vegetation. Distribution pipes should be cleaned once a year to remove sludge and biofilm that might block the holes. With time, the gravel will become clogged with by accumulated solids and bacterial film. The Resting intervals may restore the hydraulic conductivity of the bed. If this does not help, the accumulated material may have has to be removed and clogged parts of the filter material replaced every 8 to 15 or more years. Maintenance activities should focus on ensuring that primary treatment effectively lowers organics and is effective at reducing the concentration of solids concentrations in the wastewater before entering it enters the wetland. Testing may be required to determine Maintenanceshould also ensure that trees do not grow in the area as the suitability of locally available plants with roots can harm the specific wastewater. The vertical system requires more maintenance and technical expertise than other wetland technologiesliner.

===References===

* CritesBrix, RH. and TchobanoglousArias, GC. A. (19982005). [http://books.googleocfpathplanning.com/booksorg/aboutgraywater/Small_and_decentralized_wastewater_managBrixDanishGWguidelines.html?id=yx9SAAAAMAAJ Small and Decentralized pdf The Use of Vertical Flow Constructed Wetlands for on-Site Treatment of Domestic Wastewater Management Systems: New Danish Guidelines]. WCB and McGrawEcological Engineering 25 (5): 491-Hill, New York, USA. pp 599–609. Comprehensive summary chapter including solved problems500.

* MaraCrites, DDR. and Tchobanoglous, G. (20031998). [http://wwwSmall and Decentralized Wastewater Management Systems.pseau.orgWCB/outils/ouvrages/earthscan_ltd_domestic_wastewater_treatment_in_developing_countries_2003.pdf Domestic wastewater treatment in developing countries]. LondonMcGraw- Hill, EarthscanNew York, US. pp 85–187.599-609. (Book; Comprehensive summary chapter including solved problems)

* Poh-EngKadlec, LR. H. and PolprasertWallace, CS. D. (19982009). [httphttps://bookssswm.google.cominfo/sites/default/booksfiles/aboutreference_attachments/Constructed_Wetland_for_Wastewater_TreatKADLEC%20WALLACE%202009%20Treatment%20Wetlands%202nd%20Edition_0.html?id=uo5vNAAACAAJ Constructed pdf Treatment Wetlands for Wastewater Treatment and Resource Recovery, 2nd Ed]. Environmental Sanitation Information CenterCRC Press, AITTaylor & Francis Group, BangkokBoca Raton, ThailandUS.

* Polprasert, CUN-HABITAT (2008)., et al[https://unhabitat. (2001)org/constructed-wetlands-manual Constructed Wetlands Manual]. Wastewater Treatment II, Natural Systems UN-HABITAT Water for Wastewater Management. Lecture NotesAsian Cities Programme. IHE DelftKathmandu, The Netherlands. Chapter 6NP.

* Reed, SCU.S. EPA (19932000). [httphttps://watercfpub.epa.gov/type/wetlands/restore/uploadsi/2003_07_01_wetlands_pdf_subsi_public_record_report.pdf Subsurface Flow cfm?dirEntryId=64144&Lab=NRMRL Constructed Wetlands For Wastewater Treatment, A Technology Assessmentof Municipal Wastewaters]. United States [http:EPA/625/R-99/www010. U.epaS.gov Environmental Protection Agency], USAWashington, D.C. Comprehensive design manual, US.

===Acknowledgements===

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