ABSTRACT
Constructed wetlands are engineered systems that have been designed and constructed to utilize natural processes for wastewater treatment. They are designed to take advantage of many of the same processes that occur in natural wetlands, but do so within a more controlled environment. There are many types of constructed wetlands that could be classified according to several criteria such as presence or absence of free water surface or direction of flow. This entry deals with constructed wetlands with horizontal and vertical subsurface flow and their combination, so-called hybrid systems. The entry contains the major characteristics of mentioned systems and their use for various types of wastewater.
