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Constructed Wetlands Find this presentation and more on: Contents 1.Concept 2.How can Constructed Wetlands optimise SSWM 3.Design Principles 4.Treatment Efficiency 5.Operation and Maintenance 6.Applicability 7.Pros and Cons 8.References 3
Constructed Wetlands Find this presentation and more on: Introduction Treatment step of DEWATS systems Secondary treatment facilities for household (blackwater or greywater, brownwater) and/or municipal or biodegredable industrial wastewater. (HOFFMANN et al. 2010) Tertiary treatment system for polishing (e.g. activated sludge, trickling filter plants) before safety disposal or reuse. Outflow of CW: groundwater recharge, fertigation, aquaculture Types of constructed wetlands. They are classified according to the water flow regime as: ◦ Horizontal flow constructed wetlands ◦ Vertical flow constructed wetlands ◦ Free surface constructed wetlands Combined flow regimes are so called hybrid constructed wetlands and exploit the specific advantages of the different systems Concept
Constructed Wetlands Find this presentation and more on: Example 1: Onsite or Semi-centralised Treatment System 5 2. How can Constructed Wetlands Optimise SSWM Low-flush toilet, shower, kitchen sink, etc. Horizontal (picture), vertical, free surface or a combined hybrid filter Water for irrigation or aquaculture, etc. Groundwater recharge Source: UN-HABITAT (2008); STAUFFER (2012); MOREL & DIENER (2006); RUUESCH (2011); IPTRID (2008) Compost filter (above), septic tank, imhoff tank, anaerobic baffled reactor (below), etc.
Constructed Wetlands Find this presentation and more on: Example 2: Hybrid CW for a Community CW’s can also act as a treatment system for a community up to 3400 people (e.g. Bayawan City): Protecting coastal waters from pollution Protect the health of local residents Reuse of treated waste water for irrigation 6 2. How can Constructed Wetlands Optimise SSWM Source: LIPKOW and MUENCH (2010) Wastewater is collected in septic tanks and transferred through a small bore sewer system to the hybrid constructed wetland. The treated water can be reused (irrigation), one part is recirculated or it could be disposed (optional).
Constructed Wetlands Find this presentation and more on: Example 3: Greywater Treatment in Urban Areas (Norway) CW’s can be embedded nicely in urban areas that greywater can be reused for irrigation or recharge groundwater How can Constructed Wetlands Optimise SSWM Source: JENSSEN (n.y) The latest generation of constructed wetlands for cold climate with integrated aerobic biofilter in Norway.
Constructed Wetlands Find this presentation and more on: Example 3: Greywater Treatment in Urban Areas (Norway) 8 2. How can Constructed Wetlands Optimise SSWM Source: JENSSEN (n.y) Upper right: the wetland in the foreground the biofilter is underneath the playground behind the stonewall. Upper Left: flowforms. Lower left: the effluent is exposed in a shallow pond and can be discharged in a local stream (lower right).
Constructed Wetlands Find this presentation and more on: Example 4: Stormwater Wetlands (also called Wet Ponds or Retention Ponds) Adapted design for stormwater management Microbiological breakdown of pollutants Plant uptake (nutrients) Retention, settling and adsorption Flood control Aesthetic design for rural areas (e.g. city parks) 9 2. How can Constructed Wetlands Optimise SSWM Source: METROCOUNCIL (n.y.); COASTAL WATER WATCH (2010)
Constructed Wetlands Find this presentation and more on: Horizontal Flow (HF) Large gravel and sand-filled channel, planted with aquatic vegetation Wastewater flows horizontally through the channel Mainly anaerobic conditions The filter material filters out particles and microorganisms degrade organic matter Design Principals Source: MOREL and DIENER (2006)
Constructed Wetlands Find this presentation and more on: Vertical Flow (VF) Gravel and sand filter, aquatic vegetation Intermittent appliance (pump or syphon) of wastewater over the whole filter surface higher O 2 injection Wastewater drains vertically through the filter layers towards a drainage system at the bottom Design Principals Source: MOREL and DIENER (2006) Source: HOFFMANN et al. (2010)
Constructed Wetlands Find this presentation and more on: Free Water Surface Flow (FWS) Flooded and planted channels Imitate the naturally occurring processes of a natural wetland, marsh or swamp Water slowly flows through the wetland (on the surface), particles settle, pathogens are destroyed, and organisms and plants utilise the nutrients (TILLEY et al. 2008) Design Principals Source: TILLEY et al (2008)
Constructed Wetlands Find this presentation and more on: Hybrid Flow Design Principals Combined CWs, sequentially arranged (usually VF and HF) HF provide denitrification, VF nitrification Obviously the advantages of both systems can be combined Source: UPC (n.y.) Prototype of an integrated blackwater system (hybrid CW): UASB, followed by a vertical and then a horizontal flow wetland).
Constructed Wetlands Find this presentation and more on: Pollution Removal Treatment Efficiency Horizontal CWHigh reduction in BOD, suspended solids and pathogens. Provides mainly denitrification. (TILLEY et al. 2008) Vertical CWHigh reduction in BOD, suspended solids and pathogens. Provides mainly nitrification. Free-Surface CW High removals of suspended solids Moderate removal of pathogens, nutrients and other pollutants such as heavy metals (TILLEY et al. 2008) Hybrid CWIncreased performance due to a combination of different methods (e.g. VF HF)
Constructed Wetlands Find this presentation and more on: Health Aspect A CW system provides an adequate handling of wastewater and minimises health risks caused by pathogens and avoids contamination of the environment by untreated wastewater. High risk of infection if contact with the liquid filter influent or the settled sludge in the pre-treatment facility Low risk of mosquito breeding (could be a problem of free-surface CW due to open water surface) Settled sludge must be disposed safe and correctly Correct handling of treated water if used for irrigation Treatment Efficiency
Constructed Wetlands Find this presentation and more on: CWs constantly require basic maintenance throughout the duration of its life but its relatively simple (no high-tech appliances or chemical additives). (GAUSS 2008) It is important to ensure that primary treatment effectively lowers organics and solids concentrations. (TILLEY et al. 2008) The pre-treatment facility (e.g. septic tank) should be emptied periodically and sludge discharged in a safe way properly (see photo – ABR in Pune, India). Filter material has to be replaced every 8 to 15 years. (TILLEY et al. 2008) Operation and Maintenance Source: SPUHLER (2010)
Constructed Wetlands Find this presentation and more on: Secondary or tertiary treatment process for black, brown and greywater Adequate strategy if land is no limiting factor (space and costs) Constructed wetlands are natural systems and do not require electrical energy (unless for pumps) or chemicals Best suited for warm climates, but can be designed to tolerate freezing periods CW’s can be combined with many other techniques such as aquaculture, irrigation and several pre-treatment options Applicability
Constructed Wetlands Find this presentation and more on: 18 Advantages: Simple O&M due to high process stability No chemicals required Can be built and repaired with locally available materials Utilisation of natural processes Efficient removal of suspended and dissolved organic matter, nutrients and pathogens Disadvantages: Permanent land required Requires expert design and supervision Moderate capital cost depending on land, liner, fill, etc.; low operating costs Pre-treatment is required to prevent clogging Low tolerance to durable cold climates Electricity may be required 7. Pros’ and Cons’
Constructed Wetlands Find this presentation and more on: References COASTAL WATER WATCH (Editor) (2010): Rain Garden and Ponds. URL: [Accessed: ]http://www.coastalwaterwatch.com/product2121.htm GAUSS, M.; WSP (Editor) (2008): Constructed Wetlands: A Promising Wastewater Treatment system for Small Localities. Experiences from Latin America. Washington D.C.: The World Bank. URL: [Accessed: ]http://www.wsp.org/wsp/sites/wsp.org/files/publications/ConstructedWetlands.pdf HOFFMANN, H.; PLATZER, C.; WINKER, M.; MUENCH, E., v.; GTZ (Editor) (2011): Technology Review of Constructed Wetlands. Subsurface Flow Constructed Wetlands for Greywater and Domestic Wastewater Treatment. Eschborn: Deutsche Gesellschaft für Technische Zusammenarbeit GmbH (GTZ) Sustainable sanitation - ecosan program. URL: [Accessed: ]http://www.gtz.de/en/dokumente/giz2011-en-technology-review-constructed-wetlands.pdf IPTRID (Editor) (2008): Grid – IPTRID Network Magazine. February Rome: International Programme for Technology and Research in Irrigation and Drainage (IPTRID). URL: [Accessed: ]http://www.fao.org/landandwater/iptrid/docs/GRID28eng.pdf JENSSEN, P. (n.y.): Decentralized Urban Greywater Treatment at Klosterenga Oslo. In: Ecological Engineering-Bridging between Ecology and Civil Engineering, URL: [Accessed: ].http://www.umb.no/statisk/ecosan/publications/Klosterenga.pdf LIPKOW, U.; MUENCH, E. von (2010): Constructed Wetland for a Peri-urban Housing Area Bayawan City, Philippines. Eschborn: Sustainable Sanitation Alliance (SuSanA). URL: [Accessed: ]http://www.susana.org/docs_ccbk/susana_download/2-51-en-susana-cs-philippines-bayawan-constr-wetlands-2009.pdf METROCOUNCIL (n.y.): Constructed Wetlands: Stormwater Wetlands. Saint Paul: Metropolitan Council. URL: [Accessed: ] MOREL, A.; DIENER, S. (2006): Greywater Management in Low and Middle-Income Countries, Review of different treatment systems for households or neighbourhoods. Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL: [Accessed: ]http://www.eawag.ch/forschung/sandec/publikationen/ewm/dl/Morel_Diener_Greywater_2006.pdf TILLEY, E.; LUETHY, C.; MOREL, A.; ZURBRUEGG, C.; SCHERTENLEIB, R. (2008): Compendium of Sanitation Systems and Technologies. Duebendorf and Geneva: Swiss Federal Institute of Aquatic Science and Technology (EAWAG). URL: [Accessed: ]http://www.eawag.ch/forschung/sandec/publikationen/index UN-HABITAT (Editor) (2008): Constructed Wetlands Manual. Kathmandu: UN-HABITAT, Water for Asian Cities Program. URL: [Accessed: ] UPC (n.y.): Prototype of an Integrated Blackwater System. Barcelona: Universitat Politecnica de Catalunya. VYMAZAL, J. (2005): Horizontal Sub-Surface Flow and Hybrid Constructed Wetlands Systems for Wastewater Treatment. Durham: Duke University Wetland Center. URL: [Accessed: ]
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