1 / 30

Treatment Wetlands: The Role of Emergent Vegetation

Treatment Wetlands: The Role of Emergent Vegetation. Treatment Wetlands :. The Role of Emergent Vegetation. Constructed Wetland. Simulates and uses the same treatment mechanisms as the natural environment Engineered to control substrate, vegetation, hydrology and configuration.

barnard
Télécharger la présentation

Treatment Wetlands: The Role of Emergent Vegetation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Treatment Wetlands: The Role of Emergent Vegetation

  2. Treatment Wetlands : The Role of Emergent Vegetation

  3. Constructed Wetland • Simulates and uses the same treatment mechanisms as the natural environment • Engineered to control substrate, vegetation, hydrology and configuration

  4. Treatment Mechanisms • Filtration and sedimentation • Adsorption by soil colloids and O.M. • Transformation and storage of nutrients and metals • Decomposition • Denitrification • Plant uptake • Antibiotics

  5. Uses for Wetland Treatment Systems • Domestic (On-site systems) • Municipal • Mine leachates • Landfill leachates • Industrial • Agricultural • Non-point source • Urban storm-water runoff

  6. Non-Point Source Pollutants • Sediments • Nutrients (N,P) • Pathogens • Pesticides • Metals • Organic Matter (BOD)

  7. Wetland Ecosystem Functions • Sources • Sinks • Transformers

  8. Treatment of Contaminants • Uptake • Degradation • Transformations

  9. Types of Treatment Wetlands • Surface flow • FWS (Free Water Surface) • Subsurface flow • VSB (Vegetated Submerged Beds) • Vertical flow

  10. Treatment Effectiveness • Loading rate • Detention time • Capacity of the vegetation, microorganisms and substrate to transform pollutants

  11. Components of Wetland Treatment Systems • Water column • Plants • Substrate • Microbial population (aerobic and anaerobic)

  12. The Role of the Soil • A surface area for microbial attachment • A substrate for plant growth • Removal of suspended solids, pathogenic bacteria and viruses by filtration • Precipitation of phosphate by iron, aluminum and calcium

  13. The Role of Microorganisms • Degradation of organic matter (in the oxidized and reduced zones) • Nitrification • Ammonium is oxidized to nitrate in the oxidized zones (rhizosphere) • Denitrification • Nitrate is converted to nitrogen gas in anoxic zones

  14. The Role of Vegetation • Surface stabilization • Attachment surfaces for microorganisms • Filter (increases sedimentation) • Produces organic carbon that supports denitrifiers • Oxygen transport to the rhizosphere

  15. Direct uptake and storage of nutrients • Light attenuation • Insulation • Wildlife habitat • Aesthetics • Soil hydraulic conductivity • Antibiotic exudates

  16. Factors Affecting Vegetation • Hydrology - flooding depth and duration • Substrate and water chemistry • Competition

  17. Selection of Plant Species • Treatment effectiveness • Management characteristics • Ancillary benefits

  18. Frequently Used Genera • Phragmites (Reed) • Typha (Cattail) • Scirpus (Bulrush) • Juncus (Rush) • Carex (Sedge)

  19. Desirable Characteristics for Plants Used in Wetland Treatment Systems • Local ecotype adapted to hydrologic conditions of the CWWT design • Economical to propagate and manage with an available supply of propagules of local origin • Tolerant of high concentrations of nutrients and pollutants

  20. Oxygen transport capability • Ability to assimilate pollutants • Tolerance to adverse climatic conditions • Resistance to pests and diseases • Secretion of microbiocidal exudates • Plants with economic or aesthetic value • Large surface area of roots, stems and leaves

  21. Constructed Wetlands for Treatment of Swine-Lagoon Effluent

  22. Experimental Design3 x 3 factorial Plants Lagoon Effluent Concentration (%) No plants 50 Juncus effusus 75 Scirpus validus 100

  23. Objectives • Determine the effects of swine-lagoon effluent on growth of Juncus effusus and Scirpus validus • Compare evapotranspiration and nutrient removal/storage capacity of vegetated and unvegetated wetland cells

  24. Conclusions • Evapotranspiration from cells with vigorously growing wetland plants is as much as 5 times greater than evaporation from unvegetated cells. • Scirpus validus was more effective than Juncus effusus for wastewater treatment.

  25. Conclusions • Growth of plants was better in 75% strength effluent than in 50% and 100%. • Emergent macrophytes do provide important functional values in treatment wetlands.

  26. Orlando’s 480 hectare Wilderness Park.

  27. Juncuseffusus

  28. Total Evapotranspiration(24 weeks)

  29. Total NH4-N Removal/Storage (lbs/ac)(24 weeks)

  30. Total PO4-P Removal/Storage (lbs/ac)(24 weeks)

More Related