<small-title />{|style="float: left;"<!|{{Language-box|english_link=Horizontal_Subsurface_Flow_Constructed_Wetland|french_link=Filtre_planté_à_écoulement_horizontal_sous- table at top of page with logo, picture, Application level, Management level, and input-output tables -->surface|spanish_link=Humedal_Artificial_de_Flujo_de_Horizontal_subsuperficial|hindi_link=coming soon|malayalam_link=coming soon|tamil_link=coming soon | korean_link=coming soon | chinese_link=Coming soon | indonesian_link=Coming soon | japanese_link=Coming soon}}|}
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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|9]]|
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pic=Horizontal_subsurface_flow_consructed_wetland.png|
ApplHousehold=X|
ManShared=XX|
ManPublic=XX|
Input1=Blackwater|Input2=Greywater |Input3= Brownwater | Input4= Effluent |Input5=|Output1= Effluent | Output2= Biomass | Output3= | Output4= | Output5=|english_link=Horizontal_Subsurface_Flow_Constructed_Wetland|french_link=Filtre_planté_à_écoulement_horizontal_sous-surface|spanish_link=Humedal_Artificial_de_Flujo_de_Horizontal_subsuperficial
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'''A Horizontal Subsurface Flow Constructed Wetland horizontal subsurface flow constructed wetland is a large gravel and sand-filled channel basin that is planted with aquatic wetland vegetation. As wastewater flows horizontally through the channelbasin, the filter material filters out particles and microorganisms degrade the organics.'''
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The water level in a Horizontal Subsurface Flow Constructed Wetland is maintained at 5 to 15cm below the surface to ensure subsurface flow. The bed should be wide and shallow so that the flow path of the water is maximized. A wide inlet zone should be used to evenly distribute the flow. Pre-treatment is essential to prevent clogging and ensure efficient treatment. The bed should be lined with an impermeable liner (clay or geotextile) to prevent leaching. Small, round, evenly sized gravel (3–32mm in diameter) is most commonly used to fill the bed to a depth of 0.5 to 1m. To limit clogging, the gravel should be clean and free of fines. Sand is also acceptable, but is more prone to clogging. In recent years, alternative filter materials such as PET have been successfully used. The removal efficiency of the wetland is a function of the surface area (length multiplied by width), while the cross-sectional area (width multiplied by depth) determines the maximum possible flow. A well-designed inlet that allows for even distribution is important to prevent short-circuiting. The outlet should be variable so that the water surface can be adjusted to optimize treatment performance. 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. Although facultative and anaerobic bacteria degrade most organics, the vegetation transfers a small amount of oxygen to the root zone so that aerobic bacteria can colonize the area and degrade organics as well. The plant roots play an important role in maintaining the permeability of the filter.
Any plant with deep===Design Considerations=== The design of a horizontal subsurface flow constructed wetland depends on the treatment target and the amount and quality of the influent. It includes decisions about the amount of parallel flow paths and compartmentation. The removal efficiency of the wetland is a function of the surface area (length multiplied by width), wide roots that can grow in while the cross-sectional area (width multiplied by depth) determines the wetmaximum possible flow. Generally, nutrienta surface area ofabout 5 to 10 m2 per person equivalent is required. Pre-rich environment and primary treatment is appropriateessential to prevent cloggingand ensure efficient treatment. Phragmites australis The influent can be aerated by an inlet cascade to support oxygen-dependentprocesses, such as BOD reduction and nitrification. The bed should be lined with an impermeable liner (reedclay or geotextile) to prevent leaching. It should be wide and shallow so that the flow path of the water in contact with vegetation roots is a common choice because it forms horizontal rhizomes maximized. A wide inlet zone should be used to evenly distribute the flow. A well-designed inlet that allows for even distribution is important to prevent short-circuiting. The outlet should be variable so that penetrate the entire filter depthwater surface can be adjusted to optimize treatment performance.
Pathogen removal Small, round, evenly sized gravel (3 to 32 mm in diameter) is most commonly used to fill the bed to a depth of 0.5 to 1 m. To limit clogging, the gravel should be clean and free of fines. Sand is also acceptable, but is more prone to clogging than gravel. In recent years, alternative filter materials, such as PET, have been successfully used. The water level in the wetland is accomplished by natural decaymaintained at 5 to 15 cm below the surface to ensure subsurface flow. Any native plant with deep, predation by higher organismswide roots that can grow in the wet, and sedimentationnutrient-rich environment is appropriate. Phragmites australis (reed) is a common choice because it forms horizontal rhizomes that penetrate the entire filter depth.
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{{procontable | pro=
- Requires less space than a Free-Water Surface Constructed Wetland. <br> - High reduction in of BOD, suspended solids and pathogens. <br> - Does not have the mosquito problems of the [[<br>- Free-Water Surface Constructed Wetland]]. <br> - Can be built and repaired with locally available materials. No electrical energy is required <br> - Construction can provide shortLow operating costs| con=-term employment to local labourers. Requires a large land area <br> - No electrical energy required. | con=- Requires expert design and supervision. Little nutrient removal <br> - Moderate capital cost Risk of clogging, depending on land, liner, fill, etc.; low operating costs. pre- and primary treatment <br>- PreLong startup time to work at full capacity <br>-treatment is required to prevent clogging.Requires expert design and construction
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===AdequacyAppropriateness===Clogging is a common problem and, therefore, the influent should be well settled with primary treatment before flowing into the wetland. This technology is not appropriate for untreated domestic wastewater (i.e. blackwater). It is a good treatment for communities that have primary treatment (e.g., [[Septic Tank|Septic Tanks]], S.9), but are looking to achieve a higher quality effluent.
Clogging The horizontal subsurface flow constructed wetland is a common problem good option where land is cheap and therefore available. Dependingon the influent should be well settled with primary treatment before flowing into volume of the water and the corresponding area requirement of the wetland. This technology is not , it can be appropriate for untreated domestic waste water (ismall sections of urban areas, as well as for peri-urban and rural communities.e. blackwater)It can also be designed for single households. This technology is a good treatment best suited for communities that have primary treatment (e.g. [[Septic Tank|Septic Tanks]] or [[Waste Stabilization Pond|WSPs]]) warm climates, but are looking it can be designed to achieve a higher quality tolerate some freezing and periods of low biological activity. If the effluent. This is to be reused, the losses due to high evapotranspiration rates could be a good option where land is cheap and availabledrawback of this technology, although the wetland will require maintenance for depending on the duration of its lifeclimate.
Depending on ===Health Aspects/Acceptance=== Significant pathogen removal is accomplished by natural decay, predation by higher organisms, and filtration. As the volume of water, and therefore flows below the sizesurface, this type any contact of wetland can be appropriate for small sections pathogenic organisms with humans and wildlife is minimized. The risk of urban areas, perimosquito breeding is reduced since there is no standing water compared to the risk associated with [[Free-Water Surface Constructed Wetland|Free-urban Water Surface Constructed Wetlands]] (T.7). The wetland is aesthetically pleasing and rural communities. They can also be designed for single householdsintegrated into wild areas or parklands.
Horizontal Subsurface Flow Constructed Wetlands are best suited for warm climates but they can be designed to tolerate some freezing and periods of low biological activity. ===Health Aspects/AcceptanceOperation & Maintenance=== The risk of mosquito breeding is reduced since there During the first growing season, it is no standing water compared important to remove weeds that can compete with the risk associated with [[Free-Water Surface Constructed Wetland|Free-Water Surface Constructed Wetlands]]. The planted wetland is aesthetically pleasing and can be integrated into wild areas or parklandsvegetation. ===Maintenance=== With time, the gravel will clog become clogged with accumulated solids and bacterial film. The filter material at the inlet zone will require replacement every 8 to 15 10 or more years. Maintenance activities should focus on ensuring that primary treatment is effective at reducing the concentration of solids in the wastewater before it enters the wetland. Maintenance should also ensure that trees do not grow in the area as the roots can harm the liner.
===References===
===References===* Crites, R. and Tchobanoglous, G. (1998). Small and Decentralized Wastewater Management Systems. WCB and /McGraw-Hill, New York, USAUS. pp 599–609. 599-609. (Book; Comprehensive summary chapter including solved problems.)
* MaraHoffmann, DDH., Platzer, C., Winker, M. and von Münch, E. (20032011). [https://www.susana.org/en/knowledge-hub/resources-and-publications/library/details/930 Technology Review of Constructed Wetlands. Subsurface Flow Constructed Wetlands for Greywater and Domestic wastewater treatment in developing countriesWastewater Treatment]. EarthscanGesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, London. pp 85–187Eschborn, DE.
* Poh-EngKadlec, LR. H. and PolprasertWallace, CS. D. (19982009). Constructed [https://sswm.info/sites/default/files/reference_attachments/KADLEC%20WALLACE%202009%20Treatment%20Wetlands%202nd%20Edition_0.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 ManagementAsian Cities Programme. Lectur Notes, 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 EPA/625/R-99/010. U.S. Environmental Protection Agency, USAWashington, D. Comprehensive design manualC., US.
===Acknowledgements===
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