What is constructed wetland system?
Constructed wetlands are treatment systems that use natural processes involving wetland vegetation, soils, and their associated microbial assemblages to improve water quality.
What are the three main types of constructed wetlands?
The three types of constructed wetlands discussed in this chapter are: 1) horizontal subsurface flow constructed wetlands, 2) horizontal free water surface flow constructed wetlands, and 3) vertical flow constructed wetlands. Constructed wetlands have been used to treat both centralized and on-site wastewater.
What does the term constructed wetlands normally refer to?
Constructed wetlands are designed and built similar to natural wetlands to treat wastewater. They consist of a shallow depression in the ground with a level bottom. The flow is controlled in constructed wetlands so the water is spread evenly among the wetland plants.
What is the concept behind integrated constructed wetlands?
The free surface flow Integrated Constructed Wetlands (ICW) concept explicitly combines the objectives of cleansing and managing water flow from farmyards with that of integrating the wetland infrastructure into the landscape and enhancing its biological diversity. This leads to system robustness and sustainability.
Why are constructed wetlands important?
Properly designed and operated, constructed wetlands for the treatment of wastewater can provide functions that include safe sanitation in decentralized settings, shelter for biodiversity, and cleansing of polluted sites.
What are the benefits of constructed wetlands?
Similar to natural wetland systems, the benefits of constructed wetlands include: wildlife habitat, flood control, and improved water quality. Wetlands are considered one of the most fertile and productive ecosystems next to rainforests and coral reefs (Ramsar, 1971).
How effective are constructed wetlands?
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.
When was constructed wetland invented?
1960s
Constructed Wetlands, Subsurface Flow The concept of both HSSF and VF CWs was developed in the 1960s by Käthe Seidel in Germany.
What are the limitations of constructed wetlands?
The major limitations are poor nutrient (nitrogen and phosphorus) removal, large land area requirements (referred in this document as footprint), and oxygen transfer limitation. The design of CWs depends on many factors such as required effluent quality, footprint, technology combinations, and use of energy.
Why do we need constructed wetlands?
Constructed wetlands are engineered ecosystems designed to treat wastewater including sewage, stormwater and agricultural runoff. Wetland water treatment systems use plants and naturally occurring microorganisms to reduce nutrients, pathogens and sediments which are present is wastewaters.
What are constructed wetlands made of?
The constructed wetland is a basin or cell containing microorganisms, media, and plants that provide treatment of incoming effluent. In subsurface flow wetlands, the cell is filled with graded gravel media or other porous material that is resistant to the corrosive and dissolving properties of wastewater.
How effective is constructed wetlands?
How are constructed wetlands used in developing countries?
Smaller, decentralized, wastewater management and treatment systems such as constructed wetlands can be a viable alternative for many urban areas in developing countries. Constructed wetlands are relatively inexpensive to build where land is aff ordable and can be easily operated and maintained even by the community.
How are natural wetlands used for wastewater treatment?
窶彜emi-natural treatment wetlands窶・(SNTWs) for wastewater treatment are natural wetland systems that have been modified for this purpose. Modifications made within these systems are usually based on increasing the volume of water reserved (i.e. dams) and constructing channels for targeting the influent and effluent.
What kind of plants are used in constructed wetlands?
Constructed wetlands are usually planted with emergent vegetation (non-woody plants that grow with their roots in the substrate and their stems and leaves emerging from the water surface). Common emergents used in constructed wetlands include bulrushes, cattails, reeds, and a number of broad-leaved species.
What should be the slope of a wetland?
No research has been done to determine an optimum slope, but a slope of 0.5 to 1% is recommended for ease of construction and proper draining. 5.8 Sealing of the bed. Subsurface fl ow wetlands providing secondary treatment should be lined to prevent direct contact between the wastewater and groundwater.