How many types of constructed wetlands?
The primary architectural elements of different types of constructed wetlands vary, as do the procedures used to remove pollution.
The classification of constructed wetlands is based on three factors: the kind of vegetation (emergent, submerged, floating, and free-floating); hydrology (free water surface and subsurface flow); and subsurface flow wetlands can be further classified based on the direction of the flow (vertical or horizontal). Hybrid systems made up of different types of constructed wetlands, could also improve treatment performance, particularly for nitrogen.
Let’s look at the types of constructed wetlands!
· Free Water Surface Constructed Wetlands
A typical FWS CW with emergent macrophytes is a shallow sealed basin or series of basins, with a water depth of 20–40 cm and 20–30 cm of rooting soil. FWS CWs are efficient at eliminating organic materials thanks to microbial decomposition, and colloidal particle settling. By settling and filtering through the thick vegetation, suspended particles are successfully eliminated.
Nitrification (in the water column) and denitrification (following, in the litter layer) are the main processes employed to remove nitrogen, as well as ammonia volatilization at higher pH levels brought on by algal photosynthesis. Due to the less water contact with soil particles that adsorb or precipitate phosphorus, phosphorus retention is typically poor.
· Constructed Wetlands with Horizontal Subsurface Flow
Gravel or rock beds sealed by an impermeable layer and covered with wetland flora, make up the horizontal flow constructed wetlands. The wastewater is fed at the inlet and travels in a more-or-less horizontal path, through the porous medium beneath the surface of the bed until it reaches the outlet zone, where it is gathered and released.
In a network of aerobic, anoxic, and anaerobic zones in the filtration beds, pollution is eliminated through microbial degradation as well as chemical and physical processes, with aerobic zones being limited to the regions next to roots, where oxygen escapes to the substrate.
The provision of substrate (via roots and rhizomes) for the growth of associated bacteria, radial oxygen loss (oxygen diffusion from roots to the rhizosphere), nutrient uptake, and insulation of the bed surface in cold and temperate locations, are the most crucial functions of plants in HF CWs.
· Constructed Wetlands with Vertical Subsurface Flow
Vertical flow constructed wetlands (VF CWs) are used to oxygenate anaerobic septic tank effluents. Large batches of water are injected, and after that, the liquid diffuses through the sand medium.
Only after all the water has filtered through and the bed is dry is the new batch fed. This makes it possible for oxygen from the air to diffuse into the bed. As a result, VF CWs are significantly more aerobic than HF CWs, and offer favourable nitrification conditions.
Vertical flow constructed wetlands are frequently used to treat domestic and municipal wastewater, particularly when ammonia-nitrogen discharge limitations are in place. The use of VF CWS for various types of wastewater, such as refinery effluent, composting leachate, airport runoff, dairy or cheese production effluent, has, however, been the subject of numerous publications, published in the literature.
· Hybrid Constructed Wetlands
Combining constructed wetlands with the benefits of each distinct system, would increase the treatment effect. In most hybrid constructed wetlands, VF and HF stages are combined.
Currently, hybrid constructed wetlands are used in many nations across the world, particularly when removal of total and ammonia-N is necessary. Other than treating sewage, these have also been used to treat landfill leachate, compost leaching, shrimp and fish aquaculture, and winery wastewater.
What do we offer?
Constructed wetlands in wastewater treatment may be the greatest option for your industry! To assist you with constructed wetland manufacture, operation and service, we provide various customizations and other solutions on an affordable price.
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