World Wetlands Day is celebrated every February 2nd to raise awareness of wetlands. This day also marks the anniversary of the Wetlands Convention, adopted as an international treaty in 1971. Its enactment is because nearly 90% of the world's wetlands have been degraded since 1700, decimated three times faster than the forests. However, they are essential ecosystems that contribute to biodiversity, climate mitigation and adaptation, freshwater availability, world economies, and much more.
Motivated by this moment of awareness and celebration, we present the characteristics and advantages of the effluent treatment system known as artificial or constructed wetlands. As the name implies, this method simulates the aforementioned natural environments, which are permanently or seasonally flooded — swamps, mangroves — and which, through a natural process, clean and filter the water.
Consisting of lakes or shallow artificial channels that house aquatic plants, constructed wetlands were initially used in Germany by Käthe Seidel, from the Max Planck Institute, in the mid-1950s, for removing phenol and reducing the organic load of dairy effluents. Today, more than 70 years later, the scope of the system includes the treatment of domestic and industrial effluents, gray water or stormwater runoff. In addition, they can be designed for land recovery after mining or as a mitigation step for natural areas suppressed by land use. In general terms, wetlands act as a biofilter, removing a series of pollutants such as organic matter, pathogens or heavy metals.
