constructed wetland

1. CONSTRUCTED WETLAND
MANAGEMENT
RISHABH RATHOR
B110229CE
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2. CONTENTS
• What is a wetland?
• Economic benefits
• Types of wetlands
• Components of wetlands
• Working mechanism
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3. WHAT IS A WETLAND?
• A wetland is an area that is regularly saturated
by surface water or groundwater and is
characterized by a prevalence of vegetation
that is adapted for life in saturated soil
conditions (e.g., swamps, bogs, fens, marshes
and estuaries).”
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4. CONSTRUCTED WETLAND
• Natural wastewater treatment systems
• Used for secondary or tertiary treatment
• Treatment processes
– Filtration
– Sedimentation
– Biological degradation
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5. BENEFITS
• Improvement of drinking water quality
• Flood control
• Cleaning the water
• Fisheries
• Recreation
• Wildlife habitat
• Other benifits
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6. TYPES OF WETLANDS
• Surface flow or free water surface constructed
wetland
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7. TYPES OF WETLANDS
• Subsurface horizontal flow constructed
wetland
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8. TYPES OF WETLANDS
• Vertical flow constructed wetland
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9. COMPONENTS OF WETLAND
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10. COMPONENTS OF WETLAND
• Waterproof basin
– To avoid groundwater and soil contamination
– To prevent infiltration of groundwater into the
wetland bed
– Layer of compacted clay
– Plastic liners
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11. COMPONENTS OF WETLAND
• Filter media
– Gravel (12-20mm)
– 20-40mm at ends
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12. COMPONENTS OF WETLAND
Wetland plants
• Helicona • Common reed
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13. COMPONETS OF WETLAND
• Inlet and outlet structures
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14. WORKING MECHANISM
• Organic matter
– Aerobic microbial degradation
– Anaerobic microbial degradation
• Suspended solids
– Sedimentation
– filtration
• Pathogens
– Sedimentation
– Filtration
– Natural die-off
– Predation
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15. WORKING MECHANISM
• Nitrogen
– Ammonification followed by microbial
nitrification (Nitrosomonas and Nitrobacter)
– Denitrification(anaerobic bacteria)
– Plant uptake
– Matrix adsorption
• Phosphorus
– Matrix sorption
– Plant uptake
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16. WORKING MECHANISM
• Removal efficiency
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Wastewater constituent Removal efficiency
Organic matter 80-90% (high)
Suspended solids 80-90% (high)
Phosphorus Approx 20% (low)
Nitrogen 20-40% (low)
Coliforms 1-3 log units (medium)
Helminth eggs Upto 3 log units (high)

17. CONSTRUCTION
• Site selection
– Position and topography of land
– Hydrograph preparation and data interpretation
– Sub-grade soil properties
– Plantation in the given area
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18. CONSTRUCTION
• Land survey
– Elevation survey
– Contour survey (1’ accuracy)
– Potential area with most acreage of shallow water
– Depth of water should be less than 3 feet
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19. CONSTRUCTION
• Levee construction
– To impound and manipulate water
– Compaction tests should be done
– Height < 4 -5 feet
– Freeboard – 1-2 feet
– Side slope- 3:1 to 10:1
– Highest points near water control structures
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20. CONSTRUCTION
• Water sources
– Rainfall runoff
– Wells
– Pumps
– Upstream storage lakes
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21. CONSTRUCTION
• Water control devices
– To regulate water impounded by leeves
– Not flood control fixures
– Types
• Flashboard risers
• Screw gates
• Flap gates
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22. CONSTRUCTION
• Flashboard risers
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23. CONSTRUCTION
• Screw gates
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24. CONSTRUCTION
• Flap gates
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25. THANK YOU
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