Constructed wetland

A constructed wetland (CW) is an artificial wetland to treat municipal or industrial wastewater, greywater or stormwater runoff. It may also be designed for land reclamation after mining, or as a mitigation step for natural areas lost to land development.

Constructed wetlands are engineered systems that use natural functions vegetation, soil, and organisms to treat wastewater. Depending on the type of wastewater the design of the constructed wetland has to be adjusted accordingly. Constructed wetlands have been used to treat both centralized and on-site wastewater. Primary treatment is recommended when there is a large amount of suspended solids or soluble organic matter (measured as BOD and COD).[1]

Similarly to natural wetlands, constructed wetlands also act as a biofilter and/or can remove a range of pollutants (such as organic matter, nutrients, pathogens, heavy metals) from the water. Constructed wetlands are a sanitation technology that have not been designed specifically for pathogen removal, but instead, have been designed to remove other water quality constituents such as suspended solids, organic matter and nutrients (nitrogen and phosphorus).[1] All types of pathogens (i.e., bacteria, viruses, protozoan and helminths) are expected to be removed to some extent in a constructed wetland. Subsurface wetland provide greater pathogen removal than surface wetlands.[1]

There are two main types of constructed wetlands: subsurface flow and surface flow constructed wetlands. The planted vegetation plays an important role in contaminant removal. The filter bed, consisting usually of sand and gravel, has an equally important role to play.[2] Some constructed wetlands may also serve as a habitat for native and migratory wildlife, although that is not their main purpose. Subsurface flow constructed wetlands are designed to have either horizontal flow or vertical flow of water through the gravel and sand bed. Vertical flow systems have a smaller space requirement than horizontal flow systems.

Flintenbreite constructed wetland
Constructed wetland in an ecological settlement in Flintenbreite near Lübeck, Germany

Terminology

Many terms are used to denote constructed wetlands, such as reed beds, soil infiltration beds, treatment wetlands, engineered wetlands, man-made or artificial wetlands.[2] A biofilter has some similarities with a constructed wetland, but is usually without plants.

The term of constructed wetlands can also be used to describe restored and recultivated land that was destroyed in the past through draining and converting into farmland, or mining.

Overview

Hamburg-Allermöhe, effluent from constructed wetland (3252520051)
Effluent from a constructed wetland for greywater treatment at an ecological housing estate in Hamburg-Allermoehe, Germany
Constructed wetland Bayawan City (4113800865)
Constructed wetland for domestic wastewater treatment in Bayawan City, the Philippines

A constructed wetland is an engineered sequence of water bodies designed to filter and treat waterborne pollutants found in sewage, industrial effluent or storm water runoff. Constructed wetlands are used for wastewater treatment or for greywater treatment.[3] They can be used after a septic tank for primary treatment (or other types of systems) in order to separate the solids from the liquid effluent. Some constructed wetland designs however do not use upfront primary treatment.

Vegetation in a wetland provides a substrate (roots, stems, and leaves) upon which microorganisms can grow as they break down organic materials. This community of microorganisms is known as the periphyton. The periphyton and natural chemical processes are responsible for approximately 90 percent of pollutant removal and waste breakdown. The plants remove about seven to ten percent of pollutants, and act as a carbon source for the microbes when they decay. Different species of aquatic plants have different rates of heavy metal uptake, a consideration for plant selection in a constructed wetland used for water treatment. Constructed wetlands are of two basic types: subsurface flow and surface flow wetlands.

Constructed wetlands are one example of nature-based solutions and of phytoremediation.

Many regulatory agencies list treatment wetlands as one of their recommended "best management practices" for controlling urban runoff.[4]

Removal of contaminants

Physical, chemical, and biological processes combine in wetlands to remove contaminants from wastewater. An understanding of these processes is fundamental not only to designing wetland systems but to understanding the fate of chemicals once they enter the wetland. Theoretically, wastewater treatment within a constructed wetland occurs as it passes through the wetland medium and the plant rhizosphere. A thin film around each root hair is aerobic due to the leakage of oxygen from the rhizomes, roots, and rootlets.[5] Aerobic and anaerobic micro-organisms facilitate decomposition of organic matter. Microbial nitrification and subsequent denitrification releases nitrogen as gas to the atmosphere. Phosphorus is coprecipitated with iron, aluminium, and calcium compounds located in the root-bed medium.[5][6] Suspended solids filter out as they settle in the water column in surface flow wetlands or are physically filtered out by the medium within subsurface flow wetlands. Harmful bacteria and viruses are reduced by filtration and adsorption by biofilms on the gravel or sand media in subsurface flow and vertical flow systems.

Nitrogen removal

The dominant forms of nitrogen in wetlands that are of importance to wastewater treatment include organic nitrogen, ammonia, ammonium, nitrate and nitrite. Total nitrogen refers to all nitrogen species. Wastewater nitrogen removal is important because of ammonia’s toxicity to fish if discharged into watercourses. Excessive nitrates in drinking water is thought to cause methemoglobinemia in infants, which decreases the blood's oxygen transport ability. Moreover, excess input of N from point and non-point sources to surface water promotes eutrophication in rivers, lakes, estuaries, and coastal oceans which causes several problems in aquatic ecosystems e.g. toxic algal blooms, oxygen depletion in water, fish mortality, loss of aquatic biodiversity.[7]

Ammonia removal occurs in constructed wetlands – if they are designed to achieve biological nutrient removal – in a similar ways as in sewage treatment plants, except that no external, energy-intensive addition of air (oxygen) is needed.[3] It is a two-step process, consisting of nitrification followed by denitrification. The nitrogen cycle is completed as follows: ammonia in the wastewater is converted to ammonium ions; the aerobic bacterium Nitrosomonas sp. oxidizes ammonium to nitrite; the bacterium Nitrobacter sp. then converts nitrite to nitrate. Under anaerobic conditions, nitrate is reduced to relatively harmless nitrogen gas that enters the atmosphere.

Nitrification

Nitrification is the biological conversion of organic and inorganic nitrogenous compounds from a reduced state to a more oxidized state, based on the action of two different bacteria types.[8] Nitrification is strictly an aerobic process in which the end product is nitrate (NO
3
). The process of nitrification oxidizes ammonium (from the wastewater) to nitrite (NO
2
), and then nitrite is oxidized to nitrate (NO
3
).

Denitrification

Denitrification is the biochemical reduction of oxidized nitrogen anions, nitrate and nitrite to produce the gaseous products nitric oxide (NO), nitrous oxide (N
2
O
) and nitrogen gas (N
2
), with concomitant oxidation of organic matter.[8] The end product, N
2
, and to a lesser extent the intermediary by product, N
2
O
, are gases that re-enter the atmosphere.

Ammonia removal from mine water

Constructed wetlands have been used to remove ammonia and other nitrogenous compounds from contaminated mine water,[9] including cyanide and nitrate.

Phosphorus removal

Phosphorus occurs naturally in both organic and inorganic forms. The analytical measure of biologically available orthophosphates is referred to as soluble reactive phosphorus (SR-P). Dissolved organic phosphorus and insoluble forms of organic and inorganic phosphorus are generally not biologically available until transformed into soluble inorganic forms.[10]

In freshwater aquatic ecosystems phosphorus is typically the major limiting nutrient. Under undisturbed natural conditions, phosphorus is in short supply. The natural scarcity of phosphorus is demonstrated by the explosive growth of algae in water receiving heavy discharges of phosphorus-rich wastes. Because phosphorus does not have an atmospheric component, unlike nitrogen, the phosphorus cycle can be characterized as closed. The removal and storage of phosphorus from wastewater can only occur within the constructed wetland itself. Phosphorus may be sequestered within a wetland system by:

  1. The binding of phosphorus in organic matter as a result of incorporation into living biomass,
  2. Precipitation of insoluble phosphates with ferric iron, calcium, and aluminium found in wetland soils.[10]

Biomass plants incorporation

Aquatic vegetation may play an important role in phosphorus removal and, if harvested, extend the life of a system by postponing phosphorus saturation of the sediments.[11] Plants create a unique environment at the biofilm's attachment surface. Certain plants transport oxygen which is released at the biofilm/root interface, adding oxygen to the wetland system. Plants also increase soil or other root-bed medium hydraulic conductivity. As roots and rhizomes grow they are thought to disturb and loosen the medium, increasing its porosity, which may allow more effective fluid movement in the rhizosphere. When roots decay they leave behind ports and channels known as macropores which are effective in channeling water through the soil.

Metals removal

Constructed wetlands have been used extensively for the removal of dissolved metals and metalloids. Although these contaminants are prevalent in mine drainage, they are also found in stormwater, landfill leachate and other sources (e.g., leachate or FDG washwater at coal-fired power plants), for which treatment wetlands have been constructed for mines.[12]

Mine water—Acid drainage removal

Constructed wetlands can also be used for treatment of acid mine drainage from coal mines.[13]

Pathogen removal

Constructed wetlands are a sanitation technology that have not typically been designed for pathogen removal, but instead, have been designed to remove other water quality constituents such as suspended solids, organic matter (BOD/COD) and nutrients (nitrogen and phosphorus).[1]

All types of pathogens are expected to be removed in a constructed wetland; however, greater pathogen removal is expected to occur in a subsurface wetland. In a free water surface flow wetland one can expect 1 to 2 log10 reduction of pathogens; however, bacteria and virus removal may be less than 1 log10 reduction in systems that are heavily planted with vegetation.[1] This is because constructed wetlands typically include vegetation which assists in removing other pollutants such as nitrogen and phosphorus. Therefore, the importance of sunlight exposure in removing viruses and bacteria is minimized in these systems.[1]

Removal in a properly designed and operated free water surface flow wetland is reported to be less than 1 to 2 log10 for bacteria, less than 1 to 2 log10 for viruses, 1 to 2 log10 for protozoa:, and 1 to 2 log10 for helminths.[1] In subsurface flow wetlands, the expected removal of pathogens is reported to be 1 to 3 log10 for bacteria, 1 to 2 log10 for viruses, 2 log10 for protozoa, and 2 log10 for helminths.[1]

The log10 removal efficiencies reported here can also be understood in terms of the common way of reporting removal efficiencies as percentages: 1 log10 removal is equivalent to a removal efficiency of 90%; 2 log10 = 99%; 3 log10 = 99.9%; 4 log10 = 99.99% and so on.[3]

Types and design considerations

The main three broad types of constructed wetlands include:[14][3]

  • Subsurface flow constructed wetland - this wetland can be either with vertical flow (the effluent moves vertically, from the planted layer down through the substrate and out) or with horizontal flow (the effluent moves horizontally, parallel to the surface)
  • Surface flow constructed wetland (this wetland has horizontal flow)
  • Floating treatment wetland

The former types are placed in a basin with a substrate to provide a surface area upon which large amounts of waste degrading biofilms form, while the latter relies on a flooded treatment basin upon which aquatic plants are held in flotation till they develop a thick mat of roots and rhizomes upon which biofilms form. In most cases, the bottom is lined with either a polymer geomembrane, concrete or clay (when there is appropriate clay type) in order to protect the water table and surrounding grounds. The substrate can be either gravel—generally limestone or pumice/volcanic rock, depending on local availability, sand or a mixture of various sizes of media (for vertical flow constructed wetlands).

Subsurface flow

Tilley et al 2014 Schematic of the Vertical Flow Constructed Wetland
Schematic of a vertical subsurface flow constructed wetland: Effluent flows through pipes on the subsurface of the ground through the root zone to the ground.[15]
Tilley et al 2014 Schematic of the Horizontal Subsurface Flow Constructed Wetland
Schematic of the Horizontal Subsurface Flow Constructed Wetland: Effluent flows horizontally through the bed.[15]
Final tags
Vertical flow type of constructed wetlands (subsurface flow)

In subsurface flow constructed wetlands the flow of wastewater occurs between the roots of the plants and there is no water surfacing (it is kept below gravel). As a result, the system is more efficient, does not attract mosquitoes, is less odorous and less sensitive to winter conditions. Also, less area is needed to purify water. A downside to the system are the intakes, which can clog or bioclog easily, although some larger sized gravel will often solve this problem.

Subsurface flow wetlands can be further classified as horizontal flow or vertical flow constructed wetlands. In the vertical flow constructed wetland, the effluent moves vertically from the planted layer down through the substrate and out (requiring air pumps to aerate the bed).[16] In the horizontal flow constructed wetland the effluent moves horizontally via gravity, parallel to the surface, with no surface water thus avoiding mosquito breeding. Vertical flow constructed wetlands are considered to be more efficient with less area required compared to horizontal flow constructed wetlands. However, they need to be interval-loaded and their design requires more know-how while horizontal flow constructed wetlands can receive wastewater continuously and are easier to build.[2]

Due to the increased efficiency a vertical flow subsurface constructed wetland requires only about 3 square metres (32 sq ft) of space per person equivalent, down to 1.5 square metres in hot climates.[2]

The "French System" combines primary and secondary treatment of raw wastewater. The effluent passes various filter beds whose grain size is getting progressively smaller (from gravel to sand).[2]

Applications

Subsurface flow wetlands can treat a variety of different wastewaters, such as household wastewater, agricultural, paper mill wastewater, mining runoff, tannery or meat processing wastes, storm water.[3]

The quality of the effluent is determined by the design and should be customized for the intended reuse application (like irrigation or toilet flushing) or the disposal method.

Design considerations

Depending on the type of constructed wetlands, the wastewater passes through a gravel and more rarely sand medium on which plants are rooted.[3] A gravel medium (generally limestone or volcanic rock lavastone) can be used as well (the use of lavastone will allow for a surface reduction of about 20% over limestone) is mainly deployed in horizontal flow systems though it does not work as efficiently as sand (but sand will clog more readily).[2]

Constructed subsurface flow wetlands are meant as secondary treatment systems which means that the effluent needs to first pass a primary treatment which effectively removes solids. Such a primary treatment can consist of sand and grit removal, grease trap, compost filter, septic tank, Imhoff tank, anaerobic baffled reactor or upflow anaerobic sludge blanket (UASB) reactor.[2] The following treatment is based on different biological and physical processes like filtration, adsorption or nitrification. Most important is the biological filtration through a biofilm of aerobic or facultative bacteria. Coarse sand in the filter bed provides a surfaces for microbial growth and supports the adsorption and filtration processes. For those microorganisms the oxygen supply needs to be sufficient.

Especially in warm and dry climates the effects of evapotranspiration and precipitation are significant. In cases of water loss, a vertical flow constructed wetland is preferable to a horizontal because of an unsaturated upper layer and a shorter retention time, although vertical flow systems are more dependent on an external energy source. Evapotranspiration (as is rainfall) is taken into account in designing a horizontal flow system.[3]

The effluent can have a yellowish or brownish colour if domestic wastewater or blackwater is treated. Treated greywater usually does not tend to have a colour. Concerning pathogen levels, treated greywater meets the standards of pathogen levels for safe discharge to surface water.[1] Treated domestic wastewater might need a tertiary treatment, depending on the intended reuse application.[2]

Plantings of reedbeds are popular in European constructed subsurface flow wetlands, although at least twenty other plant species are usable. Many fast growing timer plants can be used, as well for example as Musa spp., Juncus spp., cattails (Typha spp.) and sedges.

Operation and maintenance

Overloading peaks should not cause performance problems while continuous overloading lead to a loss of treatment capacity through too much suspended solids, sludge or fats.

Subsurface flow wetlands require the following maintenance tasks: regular checking of the pretreatment process, of pumps when they are used, of influent loads and distribution on the filter bed.[2]

Comparisons with other types

Subsurface wetlands are less hospitable to mosquitoes compared to surface flow wetlands, as there is no water exposed to the surface. Mosquitos can be a problem in surface flow constructed wetlands. Subsurface flow systems have the advantage of requiring less land area for water treatment than surface flow. However, surface flow wetlands can be more suitable for wildlife habitat.

For urban applications the area requirement of a subsurface flow constructed wetland might be a limiting factor compared to conventional municipal wastewater treatment plants. High rate aerobic treatment processes like activated sludge plants, trickling filters, rotating discs, submerged aerated filters or membrane bioreactor plants require less space. The advantage of subsurface flow constructed wetlands compared to those technologies is their operational robustness which is particularly important in developing countries. The fact that constructed wetlands do not produce secondary sludge (sewage sludge) is another advantage as there is no need for sewage sludge treatment.[2] However, primary sludge from primary settling tanks does get produced and needs to be removed and treated.

Costs

The costs of subsurface flow constructed wetlands mainly depend on the costs of sand with which the bed has to be filled.[3] Another factor is the cost of land.

Surface flow

Schematic of the Free Water Surface Constructed Wetland
Schematic of a free-water surface constructed wetland: It aims to replicate the naturally occurring processes, where particles settle, pathogens are destroyed, and organisms and plants utilize the nutrients.

Surface flow wetlands, also known as free water surface constructed wetlands, can be used for tertiary treatment or polishing of effluent from wastewater treatment plants. They are also suitable to treat stormwater drainage.

Surface flow constructed wetlands always have horizontal flow of wastewater across the roots of the plants, rather than vertical flow. They require a relatively large area to purify water compared to subsurface flow constructed wetlands and may have increased smell and lower performance in winter.

Surface flow wetlands have a similar appearance to ponds for wastewater treatment (such as "waste stabilization ponds") but are in the technical literature not classified as ponds.[17]

Pathogens are destroyed by natural decay, predation from higher organisms, sedimentation and UV irradiation since the water is exposed to direct sunlight.[1] The soil layer below the water is anaerobic but the roots of the plants release oxygen around them, this allows complex biological and chemical reactions.

Surface flow wetlands can be supported by a wide variety of soil types including bay mud and other silty clays.

Plants such as Water Hyacinth (Eichhornia crassipes) and Pontederia spp. are used worldwide (although Typha and Phragmites are highly invasive).

However, surface flow constructed wetlands may encourage mosquito breeding. They may also have high algae production that lowers the effluent quality and due to open water surface mosquitos and odours, it is more difficult to integrate them in an urban neighbourhood.

Hybrid systems

A combination of different types of constructed wetlands is possible to use the specific advantages of each system.[2]

Newly planted constructed wetland
Newly planted constructed wetland
Mature Constructed Wetland
Same constructed wetland, two years later

Others

Integrated constructed wetland

An integrated constructed wetland (ICW) is an unlined free surface flow constructed wetland with emergent vegetated areas and local soil material. Its objectives is not only to treat wastewater from farmyards and other wastewater sources, but also to integrate the wetland infrastructure into the landscape and enhancing its biological diversity.[18]

Integrated constructed wetland facilitates may be more robust treatment systems compared to other constructed wetlands.[19][20][18] This is due to the greater biological complexity and generally relatively larger land area use and associated longer hydraulic residence time of integrated constructed wetland compared to conventional constructed wetlands.[21]

Integreated constructed wetlands are used in Ireland, the UK and the United States since about 2007. Farm constructed wetlands, which are a subtype of integrated constructed wetlands, are promoted by the Scottish Environment Protection Agency and the Northern Ireland Environment Agency since 2008.[21]

Plants and other organisms

Plants

Newly planted constructed wetland - details (3110372910)
Newly planted constructed wetland for blackwater treatment (Lima, Peru)
Constructed wetland (5547294390)
The large roots of this uprooted plant growing in a constructed wetlands indicate a healthy plant (Lima, Peru)

Typhas and Phragmites are the main species used in constructed wetland due to their effectiveness, even though they can be invasive outside their native range.

In North America, cattails (Typha latifolia) are common in constructed wetlands because of their widespread abundance, ability to grow at different water depths, ease of transport and transplantation, and broad tolerance of water composition (including pH, salinity, dissolved oxygen and contaminant concentrations). Elsewhere, Common Reed (Phragmites australis) are common (both in blackwater treatment but also in greywater treatment systems to purify wastewater).

Plants are usually indigenous in that location for ecological reasons and optimum workings.

Animals

Flowform
A hybrid system using Flowforms in a treatment pond, in Norway.

Locally grown non-predatory fish can be added to surface flow constructed wetlands to eliminate or reduce pests, such as mosquitos.

Stormwater wetlands provide habitat for amphibians but the pollutants they accumulate can affect the survival of larval stages, potentially making them function as "ecological traps".[22]

Costs

Since constructed wetlands are self-sustaining their lifetime costs are significantly lower than those of conventional treatment systems. Often their capital costs are also lower compared to conventional treatment systems.[23] They do take up significant space, and are therefore not preferred where real estate costs are high.

History

Subsurface flow constructed wetlands with sand filter bed have their origin in China and are now used in Asia. Subsurface flow constructed wetlands with a gravel bed are mainly found in small cities.[2]

Examples

Austria

The total number of constructed wetlands in Austria is 5,450 (in 2015).[24] Due to legal requirements (nitrification), only vertical flow constructed wetlands are implemented in Austria as they achieve better nitrification performance than horizontal flow constructed wetlands. Only about 100 of these constructed wetlands have a design size of 50 population equivalents or more. The remaining 5,350 treatment plants are smaller than that.[24]

United States of America

The Arcata Marsh in Arcata, California is a sewage treatment and wildlife protection marsh.

Australia

The Urrbrae Wetland in Australia was constructed for urban flood control and environmental education.

At the Ranger Uranium Mine, in Australia, ammonia is removed in "enhanced" natural wetlands (rather than fully engineered constructed wetlands), along with manganese, uranium and other metals.

See also

References

  1. ^ a b c d e f g h i j Maiga, Y., von Sperling, M., Mihelcic, J. 2017. Constructed Wetlands. In: J.B. Rose and B. Jiménez-Cisneros, (eds) Global Water Pathogens Project. (C. Haas, J.R. Mihelcic and M.E. Verbyla) (eds) Part 4 Management Of Risk from Excreta and Wastewater) Michigan State University, E. Lansing, MI, UNESCO. CC-BY-SA icon.svg Material was copied from this source, which is available under a Creative Commons Attribution-ShareAlike 3.0 Unported license.
  2. ^ a b c d e f g h i j k l Hoffmann, H., Platzer, C., von Münch, E., Winker, M. (2011): Technology review of constructed wetlands – Subsurface flow constructed wetlands for greywater and domestic wastewater treatment. Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
  3. ^ a b c d e f g h Dotro, G.; Langergraber, G.; Molle, P.; Nivala, J.; Puigagut Juárez, J.; Stein, O. R.; von Sperling, M. (2017). "Treatment wetlands". Volume 7. Biological Wastewater Treatment Series. London: IWA Publishing. ISBN 9781780408767. OCLC 984563578.
  4. ^ For example, see Urban Drainage and Flood Control District, Denver, CO. "Treatment BMP Fact Sheets:"
  5. ^ a b Brix, H., Schierup, H. (1989): Danish experience with sewage treatment in constructed wetlands. In: Hammer, D.A., ed. (1989): Constructed wetlands for wastewater treatment. Lewis publishers, Chelsea, Michigan, pp. 565–573
  6. ^ Davies, T.H., Hart, B.T. (1990): Use of aeration to promote nitrification in reed beds treating wastewater. Advanced Water Pollution Control 11: 77–84. doi:10.1016/b978-0-08-040784-5.50012-7. ISBN 9780080407845.
  7. ^ Carpenter, S.R., Caraco, N.F., Correll, D.L., Howarth, R.W., Sharpley, A.N. & Smith, V.H. (1998)Nonpoint pollution of surface waters with phosphorus and nitrogen.Ecological Applications, 8, 559–568.
  8. ^ a b Wetzel, R.G. (1983): Limnology. Orlando, Florida: Saunders college publishing.
  9. ^ Hallin, S., Hellman, M., Choudhury, M.I. & Ecke, F. (2015) Relative importance of plant uptake and plant associated denitrification for removal of nitrogen from mine drainage in sub-arctic wetlands. Water Research, 85, 377–383.
  10. ^ Guntensbergen, G.R., Stearns, F., Kadlec, J.A. (1989): Wetland vegetation. In Hammer, D.A., ed. (1989): Constructed wetlands for wastewater treatment. Lewis publishers, Chelsea, Michigan, pp. 73–88
  11. ^ "Wetlands for Treatment of Mine Drainage". Technology.infomine.com. Retrieved 2014-01-21.
  12. ^ Hedin, R.S., Nairn, R.W.; Kleinmann, R.L.P. (1994): Passive treatment of coal mine drainage. Information Circular (Pittsburgh, PA.: U.S. Bureau of Mines) (9389).
  13. ^ Stefanakis, Alexandros; Akratos, Christos; Tsihrintzis, Vassilios (5 August 2014). Vertical Flow Constructed Wetlands: Eco-engineering Systems for Wastewater and Sludge Treatment (1st ed.). Elsevier Science. p. 392. ISBN 978-0-12-404612-2.
  14. ^ a b Tilley, E., Ulrich, L., Lüthi, C., Reymond, Ph., Zurbrügg, C. (2014): Compendium of Sanitation Systems and Technologies – (2nd Revised Edition). Swiss Federal Institute of Aquatic Science and Technology (Eawag), Duebendorf, Switzerland. ISBN 978-3-906484-57-0.
  15. ^ Stefanakis, Alexandros; Akratos, Christos; Tsihrintzis, Vassilios (5 August 2014). Vertical Flow Constructed Wetlands: Eco-engineering Systems for Wastewater and Sludge Treatment (1st ed.). Amsterdam: Elsevier Science. p. 392. ISBN 9780124046122.
  16. ^ Tilley, Elizabeth; Ulrich, Lukas; Lüthi, Christoph; Reymond, Philippe; Zurbrügg, Chris (2014). Compendium of Sanitation Systems and Technologies (2nd ed.). Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag). ISBN 978-3-906484-57-0.
  17. ^ a b Scholz M., Sadowski A. J., Harrington R. and Carroll P. (2007b), Integrated Constructed Wetlands Assessment and Design for Phosphate Removal. Biosystems Engineering, 97 (3), 415–423.
  18. ^ Mustafa A., Scholz M., Harrington R. and Carrol P. (2009) Long-term Performance of a Representative Integrated Constructed Wetland Treating Farmyard Runoff. Ecological Engineering, 35 (5), 779–790.
  19. ^ Scholz M., Harrington R., Carroll P. and Mustafa A. (2007a), The Integrated Constructed Wetlands (ICW) Concept. Wetlands, 27 (2), 337–354.
  20. ^ a b Carty A., Scholz M., Heal K., Gouriveau F. and Mustafa A. (2008), The Universal Design, Operation and Maintenance Guidelines for Farm Constructed Wetlands (FCW) in Temperate Climates. Bioresource Technology, 99 (15), 6780–6792.
  21. ^ Sievers, Michael; Parris, Kirsten M.; Swearer, Stephen E.; Hale, Robin (June 2018). "Stormwater wetlands can function as ecological traps for urban frogs". Ecological Applications. 28 (4): 1106–1115. doi:10.1002/eap.1714. PMID 29495099.
  22. ^ Technical and Regulatory Guidance Document for Constructed Treatment Wetlands (PDF) (Report). Washington, D.C.: Interstate Technology & Regulatory Council. December 2003.
  23. ^ a b Langergraber, Guenter; Weissenbacher, Norbert (2017-05-25). "Survey on number and size distribution of treatment wetlands in Austria". Water Science and Technology. 75 (10): 2309–2315. doi:10.2166/wst.2017.112. ISSN 0273-1223. PMID 28541938.

Further reading

  • Harrington R. and Ryder C. (2002), The use of integrated constructed wetlands in the management of farmyard runoff and waste water. In: Proceedings of the National Hydrology Seminar on Water Resources Management Sustainable Supply and Demand. The Irish National Committees of the IHP (International Hydrological Programme) and ICID (International Commission on Irrigation and Drainage), Tullamore, Ireland.

External links

Acid mine drainage

Acid mine drainage, acid and metalliferous drainage (AMD), or acid rock drainage (ARD) is the outflow of acidic water from metal mines or coal mines.

Acid rock drainage occurs naturally within some environments as part of the rock weathering process but is exacerbated by large-scale earth disturbances characteristic of mining and other large construction activities, usually within rocks containing an abundance of sulfide minerals. Areas where the earth has been disturbed (e.g. construction sites, subdivisions, and transportation corridors) may create acid rock drainage. In many localities, the liquid that drains from coal stocks, coal handling facilities, coal washeries, and coal waste tips can be highly acidic, and in such cases it is treated as acid rock drainage. This liquid often contains toxic metals, such as copper or iron. These, combined with reduced pH, have a detrimental impact on the streams aquatic environments.

The same type of chemical reactions and processes may occur through the disturbance of acid sulfate soils formed under coastal or estuarine conditions after the last major sea level rise, and constitutes a similar environmental hazard.

Banping Lake Wetland Park

The Banping Lake Wetland Park (Chinese: 半屏湖濕地公園; pinyin: Bànpínghú Shīdì Gōngyuán) is a constructed wetland in Zuoying District, Kaohsiung, Taiwan.

Blackwater (waste)

Blackwater in a sanitation context denotes wastewater from toilets, which likely contains pathogens. Blackwater can contain feces, urine, water and toilet paper from flush toilets. Blackwater is distinguished from greywater, which comes from household use other than toilets. Greywater results from washing food, clothing, dishes, as well as from showering or bathing.Blackwater and greywater are separated in "ecological buildings", such as autonomous buildings. Recreational vehicles often have separate holding tanks for greywater from showers and sinks, and blackwater from the toilet.

Clark County Wetlands Park

The Clark County Wetlands Park is the largest park in the Clark County, Nevada park system. The park is on the east side of the Las Vegas valley and runs from the various water treatment plants near the natural beginning of the Las Vegas Wash to where the wash flows under Lake Las Vegas and later into Lake Mead.

One purpose of the park is to reduce the environmental impact of the waste water and stormwater runoff leaving the drainage basin area, by building a constructed wetland. This is being accomplished by installing a series of water flow control structures such as dams and weirs and by creating ponds that together slow down the flow of the water, catching silt, and reducing the undercutting of the dirt walls that form the wash. As of June, 2005 nine of these structures were operational.

The sides of the wash are being stabilized by installing native plants and large pieces of demolished construction debris. Some of the native plants, especially those in areas of standing water, also help purify the water by removing various pollutants as the slow moving water provides these plants with nourishment. This method of purification is also called natural water polishing.

The second purpose of the park is education. The displays within the park show visitors how the wash looked before major settlement occurred in the valley and the impact people have had on the environment.

The park has a nature center with displays about the park's plants and animals. There are miles of walking paths.

Fulton Creek (North Saskatchewan River)

Fulton Creek Is a minor tributary which flows into the North Saskatchewan River. Fulton Creek originates within The Meadows area of Edmonton, Alberta. As with other urban Edmonton waterways, with long stretches running through underground culverts, and water volume managed by other urban land uses and for erosion control, Fulton Creek has been labeled a lost creek.

Hydrus (software)

Hydrus is a suite of Windows-based modeling software that can be used for analysis of water flow, heat and solute transport in variably saturated porous media (e.g., soils). HYDRUS suite of software is supported by an interactive graphics-based interface for data-preprocessing, discretization of the soil profile, and graphic presentation of the results. While HYDRUS-1D simulates water flow, solute and heat transport in one-dimension, and is a public domain software, HYDRUS 2D/3D extends the simulation capabilities to the second and third dimensions, and is distributed commercially.

ICW

ICW may refer to:

Integrated constructed wetland

International Clan War

International Community of Women Living with HIV/AIDS

International Confederation of Wizards

International Council of Women

Internet call waiting, a technology that allows a telephone line to accept incoming calls while connected to a dialup connection

Intracoastal Waterway

Indonesia Corruption Watch

Island cricket warriors ( maldevies )

Phinizy Swamp Nature Park

Phinizy Swamp Nature Park is a 1,100-acre (450 ha) nature park in Augusta, Georgia. The park contains wetlands and woodlands and has a campus for water research and environmental education, which includes a visitor center. It has many bald cypresses draped in Spanish moss and forests of loblolly and longleaf pine trees. Birds commonly found at Phinizy Swamp include: red-shouldered hawks, great blue herons, sora, wood ducks and bald eagles. Sometimes the park yields rarities for Georgia, including black-bellied whistling ducks, and a cave swallow, in 2004. Other wildlife commonly found in the park include frogs and toads; snakes, including water moccasin, pigmy rattlesnake, and copperhead; beavers and muskrat; turtles; and dragonflies. Fishing and hunting are not permitted within the park. Phinizy Swamp Nature Park is managed by Phinizy Center for Water Sciences.

Phragmites

Phragmites is a genus of four species of large perennial grasses found in wetlands throughout temperate and tropical regions of the world. The World Checklist of Selected Plant Families, maintained by Kew Garden in London, accepts the following four species:

Phragmites australis (Cav.) Trin. ex Steud. – cosmopolitan

Phragmites japonicus Steud. – Japan, Korea, Ryukyu Islands, Russian Far East

Phragmites karka (Retz.) Trin. ex Steud. – tropical Africa, southern Asia, Australia, some Pacific Islands

Phragmites mauritianus Kunth – central + southern Africa, Madagascar, Mauritius

Reed (plant)

Reed is a common name for several tall, grass-like plants of wetlands.

San Joaquin Wildlife Sanctuary

The San Joaquin Wildlife Sanctuary is a 300 acres (120 ha; 0.47 sq mi) constructed wetland in Irvine, California, in the flood plain of San Diego Creek just above its outlet into the Upper Newport Bay.

The site is owned by the Irvine Ranch Water District; it was used for farmland in the 1950s and 1960s, and (prior to its reconstruction) as a duck hunting range. Restoration of the wetlands began in 1988 and was completed in 2000.

Now, the site serves a dual purpose of removing nitrates from the creek water and providing a bird habitat. The water district also operates an adjacent wastewater treatment facility but the treated wastewater does not enter the wildlife sanctuary.Within the sanctuary, water from the creek percolates through a system of ponds, constructed in 1997 and ringed with bulrushes; the ponds are periodically drained and re-seeded, and the surrounding land is covered with native plants. A small hill at one edge of the site serves as an arboretum for non-native trees, planted for Earth Day in 1990. The landscaping has been designed to attract birds, and nesting boxes for the birds have been provided. Monthly censuses have found over 120 species of birds including hawks, swallows, roadrunners, hummingbirds, herons, egrets, pelicans, sandpipers, ducks, geese, and kingfishers.The sanctuary is open to the public daily during the daytime, and has over 10 miles (16 km) of wheelchair-accessible hiking trails. The facilities also include free parking, restrooms, benches, and trail maps. The Duck Club, a building that was moved to the site in the 1940s and was until 1988 the base for two hunting clubs, serves as a free meeting facility for non-profit organizations. The Audubon Society maintains a chapter office in another building, the former bunkhouse of the Duck Club.

Sengkang Riverside Park

Sengkang Riverside Park is a riverine park located at Anchorvale Street abutting Sungei Punggol, Singapore. The park consist of three open-space land parcels and is also home to a constructed wetland. The Sengkang Sports Complex is located just adjacent to the riverine park, connected by a floating wetland.

The EcoCenter at Heron's Head Park

Designed to meet the needs of underserved Bayview-Hunters Point communities in southeast San Francisco, the EcoCenter at Heron's Head Park is a unique educational facility that combines environmental education, experience-based learning and habitat restoration. Located by the Bay in one of the last of San Francisco's wild landscapes, the EcoCenter is also a model for green building and sustainable resource use.

As a living classroom and drop-in visitor center, the EcoCenter demonstrates how environmental resources can be used to promote healthy people, vigorous ecosystems, and strong economies in local communities. To enhance community-building, the EcoCenter offers elementary school through college educational programming, internships for youth and young adults, tours, seminars, workshops, and other activities, all free of charge.

The EcoCenter's Science Saturdays program is a particularly popular series of weekly events appropriate for all ages. These hands-on activities range from park restoration and plastic debris cleanups, to climate change science experiments, to healthy cooking and eating demonstrations, and to citizen science field trips. Other ongoing activities include a unique opportunity for place-based green jobs training. Youth interns monitor onsite wastewater treatment, nurture a constructed wetland, participate in rainwater harvesting, and maintain renewable energy systems. Volunteers and guests are invited to join the staff for hands-on experiences with native plants, landscaping, and habitat restoration. By learning more about urban design that mimics natural processes, visitors better understand the connections between sustainability in the built environment and the local wetlands. They leave the EcoCenter inspired to pursue green resource use in their everyday lives.

Tzintzuntzan Municipality

Tzintzuntzan Municipality is one of the municipalities of Michoacán. The seat is Tzintzuntzan, Michoacán.

University of Waterloo Faculty of Environment

The Faculty of Environment is one of six faculties at the University of Waterloo in Waterloo, Ontario, Canada.

The faculty was established in 1969. During its 40th anniversary at the start of the Fall 2008 term, its name was changed from Faculty of Environmental Studies to the current name, Faculty of Environment. With the name change, the buildings formerly known as ES1 and ES2 have been renamed EV1 and EV2. Recently completed is a third building, appropriately named EV3. EV3 consists largely of the School of Environment, Enterprise and Development (SEED) and the School of Planning, as well as a lecture hall. The newly constructed building has obtained LEED Platinum status. As part of this certification, there are many green features that conserve energy and resources. From a two-story high living wall to a constructed wetland that deals with wastewater to solar panels and energy efficient technology, Environment 3 was built with sustainability in mind.

Veerplas

Veerplas (Dutch pronunciation: [ˌveːrˈplɑs] (listen)) is an artificial lake directly east of the Dutch city of Haarlem. It was dug in 1994, mainly for recreation purposes and forms part of the Spaarnwoude recreational area.

The lake measures 450 by 400 metres. The southern shore is formed by a constructed wetland used for water purification. Large numbers of waterfowl may be found here and along the swampy eastern shore during the winter season (e.g. greylag geese, wigeons, common goldeneyes). The local angling club has released carps into the lake. A sandy beach measuring some 300 m was created at the western shore. An area sufficiently shallow to accommodate safe swimming by inexperienced bathers is cordoned off. Furthermore, a grassy sunbathing area sporting a public toilet adjoins the lake, as well as a children's adventure playground. The lake is only a short walking distance from Haarlem Spaarnwoude railway station and relatively close to the A200 and A9 motorways. This favourable location has helped to make it a popular area for organising mid to large-scale events. Thus, 2006 saw the Circus Herman Renz pitch its tent alongside the lake.

Wetlands Construídos

Wetlands Construídos is a Brazilian startup company that specializes in the area of constructed wetland. Its business includes the consulting and implementation of natural systems for water treatment and wastewater - specifically constructed wetland systems. The company was officially founded in 2011 in Belo Horizonte, Minas Gerais by CEO André Baxter Barreto and was incubated in a business incubator known as INOVA UFMG - Incubadora de Empresas at the Federal University of Minas Gerais in 2015.

Wuluo River

The Wuluo River, also spelled Wulo River, (Chinese: 武洛溪; pinyin: Wǔluò Xī; Wade–Giles: Wu3-lo4 Hsi1) is a tributary of the Gaoping River in Pingtung County, Taiwan.The river has long been polluted by untreated domestic and partially treated pig farming wastewater. It is among the most polluted rivers in Taiwan and the most polluted tributary of the Gaoping River. As one mitigation measure, a constructed wetland was established in 2004.

Xinhai Constructed Wetland

The Xinhai Constructed Wetland (Chinese: 新海人工溼地; pinyin: Xīnhǎi Réngōng Shīdì) is a constructed wetland in Banqiao District, New Taipei, Taiwan.

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Classification systems
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Treatment / Containment
Flow control
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