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# Difference between revisions of "Constructed wetlands"

 See also the Constructed wetlands category. for subtopics, how-tos, project pages, designs, organization pages and more.

A constructed wetland is an artificial ecosystem growing in a shallow basin, with plants suited to a swampy environment (hydrophytic plants).

The purpose of the constructed wetland is to deal with a wastewater stream, such as partially treated sewage or contaminated runoff.

When used in the final stages of wastewater treatment, their role can be described as "polishing" (raising the water quality from fairly clean to very clean). In greywater reuse, a constructed wetland is sometimes used for treatment.

An overlapping term is reed beds, which might be considered a synonym, or a specific type of constructed wetland.[verification needed]

Mosquito control should be considered as part of the design. In a balanced ecosystem, there will be predators (such as certain types of fish) to eat the mosquito larvae.

Constituent Free-Water Surface Subsurface Flow
BOD 93% 93%
TSS 91% 72%
Nitrogen 88% 94%
Phosphorus 53% 65%

How to Size a Free Water Surface Wetland using Kadlec and Knight model

1. Determine the limiting effluent requirements for BOD, nitrogen, or pathogens.

2. Calculate the surface area for BOD, nitrogen, or pathogens using the following equation. The largest surface area will be the control.

[math]A = ((0.0365Q)/(k\lt sub\gt t\lt /sub\gt ))*ln((Ci-C*)/(Ce-C*))[/math]

A is the wetland area required (hectares)