A wetland formed by the beach between the tidal zone and the low tide line. The Ramsar Convention on Wetlands extends the scope of wetlands to a depth of 6 meters below the low tide line.
Inland wetland
Wetlands developed on land outside the coastal zone.
Artificial wetland
Wetlands formed by human factors. Such as paddy fields, reservoirs, canals, salt fields and fish ponds.
Surface flow constructed wetland
Subsurface flow synthetic wetland
The core technology of constructed wetland is subsurface flow wetland. Generally, it consists of two-stage wetlands in series and parallel processing units. Wetlands are filled with different media according to different pollutants to be treated, and different kinds of purified plants are planted. Purification of water by physical, chemical and biological means such as substrate, plants and microorganisms has obvious removal effect on BOD, COD, TSS, TP, TN, algae and petroleum. In addition, the unique flow pattern and structure of the process form a good nitrification and denitrification functional zone, which is obviously superior to other treatment methods in removing TN, TP and petroleum. It mainly includes internal structure system, active enzyme medium system, plant cultivation and collocation system, water distribution and collection system, anti-blocking technology and winter operation technology. Subsurface constructed wetlands can be divided into vertical constructed wetlands and horizontal constructed wetlands. Purification of influent water by using different water flow characteristics of wetland. The river water purified by subsurface flow wetland can meet the Class III standard of surface water, and then it is discharged through the drainage system.
Vertical flow subsurface flow constructed wetland: In vertical subsurface flow system, sewage flows vertically from the surface to the bed bottom, and in the process of vertical flow, sewage passes through different patented media layers in turn to achieve the purpose of purification. Vertical subsurface flow wetland has a complete water distribution system and water collection system. Compared with other forms of wetland, it has the advantages of small floor space and high treatment efficiency. The whole system can be completely built underground, and green space can be built on the ground to cooperate with landscape planning.
Horizontal flow subsurface constructed wetland: it is another form of subsurface constructed wetland. In the process of horizontal flow from one end of the water inlet, sewage passes through sand, medium and plant roots in turn and flows to one end of the water outlet to achieve the purpose of purification.
Trench constructed wetland: Trench wetland bed includes plant system, substrate system and collection system. It mainly collects and treats non-point source pollution such as rainwater, and achieves the purpose of purifying rainwater and sewage by means of filtration, adsorption and biochemistry. It is an effective means of water quality control and protection in small watersheds.