Artificial wetlands are natural treatment systems formed by lagoons or shallow channels, filled with gravel and sand, where aquatic vegetation is planted. In these systems, decontamination procedures take place through the interaction that occurs between water, filtering fillers, microorganisms and vegetation.
In wetlands with subsurface flow, there is groundwater circulation through a granular medium in contact with the roots and rhizomes of the plants. The depth of the sheet of water is usually between 0.3 and 0.9 m. The biofilm that grows adhered to the granular medium and to the roots and rhizomes of the plants plays a fundamental role in the processes of water decontamination.
Subsurface wetlands are classified, based on the direction of water
circulation, in horizontal or vertical wetlands.
SUBSURFACE HORIZONTAL FLOW WETLAND
In this type of systems the water circulates horizontally through the granular medium and the rhizomes and roots of the plants. The depth of the water is between 0.3 and 0.9 m. They are characterized by functioning permanently flooded (water is found between 0.05 and 0.1m below the surface) and with loads of around 6 g BOD/m2/day.
SUBSURFACE VERTICAL FLOW WETLAND
This type of wetland was developed as an alternative to horizontal wetlands in order to produce nitrified effluents. Generally vertical systems are combined with horizontal systems so that the nitrification and denitrification processes take place progressively, thus eliminating nitrogen. Water circulation is of vertical type and takes place by pulses, so that the granular medium is not permanently flooded. The depth of the granular medium is between 0.5 and 0.8 and they operate with loads of around 20 g BOD/m2 per day.
Vertical systems have a greater capacity of treatment than the horizontal ones (they require less surface to treat a certain organic load). On the other hand, they are more susceptible to aggradation.
Subsurface Wetlands are ecological
wastewater treatment systems.
Applications for this type
of wastewater treatment plants:
BIDATEK offers engineering services for the
design of treatment plants equipped with both:
implemented in gabions
Installation of HDPE sheet
Wetland vessel implemented in concrete
and use of draining plastic cells.
Treatment of industrial water.