constructed wetlands by dave lomeli. why use a constructed wetland constructed wetlands can treat...

Download Constructed Wetlands By Dave Lomeli. Why use a Constructed Wetland Constructed wetlands can treat wastewater from a variety of sources. One of the more

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  • Slide 1
  • Constructed Wetlands By Dave Lomeli
  • Slide 2
  • Why use a Constructed Wetland Constructed wetlands can treat wastewater from a variety of sources. One of the more common uses is to provide additional or advanced treatment of wastewater from homes, businesses and even communities. Wetlands treat wastewater that has already had most of the solid materials removed from it through some type of primary or secondary treatment. Constructed wetlands can treat wastewater from a variety of sources. One of the more common uses is to provide additional or advanced treatment of wastewater from homes, businesses and even communities. Wetlands treat wastewater that has already had most of the solid materials removed from it through some type of primary or secondary treatment. Homes, businesses, farms, schools, highways and other individual wastewater sources in rural areas sometimes can add a constructed wetland to a septic system or other onsite system to replace or assist a soil absorption field. Homes, businesses, farms, schools, highways and other individual wastewater sources in rural areas sometimes can add a constructed wetland to a septic system or other onsite system to replace or assist a soil absorption field. Some onsite systems can be specifically designed from the start to use a constructed wetland in addition to a soil absorption field on properties with site constraints, such as tight or saturated soils. Some onsite systems can be specifically designed from the start to use a constructed wetland in addition to a soil absorption field on properties with site constraints, such as tight or saturated soils. Wetlands are good at handling intermittent periods of both light and heavy wastewater flows. Therefore, they often work well with wastewater treatment systems that serve hotels, campsites, resorts and recreational areas. Wetlands are good at handling intermittent periods of both light and heavy wastewater flows. Therefore, they often work well with wastewater treatment systems that serve hotels, campsites, resorts and recreational areas.
  • Slide 3
  • Types Constructed wetlands built to mimic natural wetlands, not part of natural systems Constructed wetlands built to mimic natural wetlands, not part of natural systems Surface-flow Surface-flow Subsurface-flow Subsurface-flow Vertical Flow Systems Vertical Flow Systems New design systems used to overcome oxygen depletion problems in wetlands New design systems used to overcome oxygen depletion problems in wetlands
  • Slide 4
  • Wet Land Design factors Basic questions: - Geographic - Economic - Economic - Vegetation - Vegetation - Substrate/soils - Chemical input/output - Substrate/soils - Chemical input/output - Compartments/cells - Compartments/cells - Maintenance - Maintenance - Unexpected events - Unexpected events - Outlet considerations - Outlet considerations
  • Slide 5
  • Design Factors One of the most important factors affecting treatment is temperature. Biological treatment processes tend to speed up in warm weather and slow down in cold weather. In cold climates, systems must be large enough to accommodate the longer hydraulic residence times needed for treatment. Plants help treatment processes in several ways. The wetland plants filter wastes, regulate flow and provide surface area for bacterial and treatment. Floating plants, such as water lilies and emergent plants, such as cattails, shade the water surface and control algae growth. Even in winter when plants are dormant, they often are contributing to treatment Plants also contribute to treatment by taking up nutrients, metals, and other substances and retaining them. Many of these substances can accumulate again in the wetland when the plants die and decompose. Therefore harvesting vegetation is a good idea.
  • Slide 6
  • Design types
  • Slide 7
  • Surface Flow Surface-Flow Treatment Wetlands Surface-Flow Treatment Wetlands As soon as wastewater enters a surface flow wetland cell, natural processes immediately begin to break down and remove the waste materials in the water. Before the wastewater has moved very far in the wetland small suspended waste materials are physically strained out be submerged plants, plant stems, and plant litter in the wetland. The roots, stems, leaves, and litter of wetland plants also provide a multitude of small surfaces where wastes can become trapped and waste-consuming bacterial can attach themselves. As soon as wastewater enters a surface flow wetland cell, natural processes immediately begin to break down and remove the waste materials in the water. Before the wastewater has moved very far in the wetland small suspended waste materials are physically strained out be submerged plants, plant stems, and plant litter in the wetland. The roots, stems, leaves, and litter of wetland plants also provide a multitude of small surfaces where wastes can become trapped and waste-consuming bacterial can attach themselves.
  • Slide 8
  • Slide 9
  • Operation & Maintenance Surface Flow Wetland Surface flow wetlands have few operation and maintenance requirements, but maintenance must be performed properly to ensure system performance. Surface flow wetlands have few operation and maintenance requirements, but maintenance must be performed properly to ensure system performance. Operation may entail alternating cells or adjusting water levels and harvesting vegetation. Operation may entail alternating cells or adjusting water levels and harvesting vegetation. Some systems may have banks and berms that need to be maintained, and inlet and outlet structures that should b cleaned periodically. Some systems may have banks and berms that need to be maintained, and inlet and outlet structures that should b cleaned periodically. Mosquitoes and burrowing animals present problems in some systems. Different control methods are available, including natural solutions, such as trapping and relocating animals, introducing fish that eat insect larvae, and building bat houses. Mosquitoes and burrowing animals present problems in some systems. Different control methods are available, including natural solutions, such as trapping and relocating animals, introducing fish that eat insect larvae, and building bat houses.
  • Slide 10
  • Subsurface Flow In SSF wetlands the polluted substrate is transported through material (depends on what they want to use) where bacteria in the substrate and on the plants come in contact with the contaminated water and effectively degrade or bind the pollutant. Four basic parameters are considered when finalizing the layout and design of SSF wetlands: (1) Inlet distribution system, (2) Basin configuration, (3) Bed media, and (4) Outlet control system (Kadlec et al, 1996).
  • Slide 11
  • Slide 12
  • Surface flow wetlands have few operation and maintenance requirements, but maintenance must be performed properly to ensure system performance. Surface flow wetlands have few operation and maintenance requirements, but maintenance must be performed properly to ensure system performance. Operation may entail alternating cells or adjusting water levels and harvesting vegetation. Some systems may have banks and berms that need to be maintained, and inlet and outlet structures that should be cleaned periodically Operation may entail alternating cells or adjusting water levels and harvesting vegetation. Some systems may have banks and berms that need to be maintained, and inlet and outlet structures that should be cleaned periodically Operation & Maintenance Subsurface Flow Wetland
  • Slide 13
  • Advantages Constructed wetlands are typically inexpensive to build and maintain. Constructed wetlands are typically inexpensive to build and maintain. They require little or no energy to operate. They require little or no energy to operate. They can provide effective tertiary treatment. They can provide effective tertiary treatment. They can provide additional wildlife habitat. They can provide additional wildlife habitat. They can be aesthetically pleasing additions to homes and neighborhoods. They can be aesthetically pleasing additions to homes and neighborhoods. They are viewed as an environmentally friendly technology and are generally well received by the public. They are viewed as an environmentally friendly technology and are generally well received by the public.
  • Slide 14
  • Disadvantages Constructed wetlands require more land area than many other treatment options. Constructed wetlands require more land area than many other treatment options. Surface flow wetlands can attract mosquitoes and other pests. Surface flow wetlands can attract mosquitoes and other pests. Wetlands are not appropriate for treating some wastewater with high concentrations of certain pollutants. Wetlands are not appropriate for treating some wastewater with high concentrations of certain pollutants. The performance of wetlands may vary based on usage and climatic conditions. The performance of wetlands may vary based on usage and climatic conditions. There may be a prolonged initial start-up period before vegetation is adequately established. There may be a prolonged initial start-up period before vegetation is adequately established.
  • Slide 15
  • Examples of Constructed Wetlands Mai Po Marshes, Honk Kong Putrajaya Lake and constructed wetlands, Malaysia
  • Slide 16
  • In : (1) Mai Po Marshes, Honk Kong
  • Slide 17
  • Mia Po Marshes 1976 - the Mia Po Marshes were recognized as a protected area 1976 - the Mia P

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