Innovations in constructed wetland design to improve wastewater treatment

Abstract

Constructed wetlands (CW) or treatment wetlands (TW) are eco-technologies that, with engineering design, imitate the physical, chemical and biological processes of a natural wetland to remove contaminants present in wastewater. However, thanks to multiple investigations, they can be given some characteristics such as low construction, operation and maintenance costs. Therefore, they become an excellent option for rural areas, where economic development is lower in relation to an urban area. According to the water flow, CW have been classified as surface or subsurface systems, the latter due to the entry of water into vertical or horizontal subsurfaces. These being the most used. Currently, to accelerate the removal processes, new designs have been tested that include adaptations for oxygen entry, water distribution, use of new species or combination of substrates, said adaptations convert these systems into intensified treatment wetlands (ITW). Since very little is known about these innovations and their application in Mexico is scarce, this chapter aimed to analyse the most studied components of HC and the technological advances in the design of ITW through documentary research techniques and bibliographic review. Where it was identified that the substrate, microorganisms and vegetation are the most studied components to make the purification of wastewater from different sources more efficient. In addition, six types of wetlands were analysed (surface wetland, vertical and horizontal subsurface wetland, aerated, vertical French-type and pulsed), with China being the country with the most research in each of them and France being the dominant country in the French-type vertical wetland, which was implemented for the first time in 2012, being the most recent innovation to date.