Aquatic Plants and the Environment SWES, ECOL, WFSc 474574

1
Aquatic Plants and the Environment (SWES, ECOL,
WFSc 474/574)

• Constructed Wetlands
• Dr. Kevin Fitzsimmons
• Professor University of Arizona

2
Terminology of constructed wetlands

• 1. Restored wetlands - those under
  rehabilitation. Put back into working order
  (fixed) hydrology of wetland either by dredging
  or by taking out a dike (common in small areas).
• 2. Constructed wetlands - built where none
  existed before (usually for water treatment).
  Usually well engineered.
• 3. Created wetlands - developed where none
  existed before (usually for wildlife habitat).
  Normally done with little engineering.

3
Reasons for constructed wetlands

• 1. Waste Treatment
• 2. Hydraulic modification - for flood control,
  water storage
• 3. Water quality changes
• 4. Erosion protection
• 5. Open spaces and aesthetics
• 6. Mitigation
• 7. Habitat for wildlife

4
1. Waste Treatment

• Municipal waste (sewage) secondary/tertiary
  treatment of wastewaters. To reduce the
  nitrogen, phosphorus, TSS (Total Suspended
  Solid), BOD (Biological Oxygen Demand), TFC
  (Total Fecal Coliforms).
• CAFO treatments (Concentrated Animal Feeding
  Operations) treat wastes from dairies, feedlots,
  hog sheds, chicken ranches, and fish farms.

5
1. Waste Treatment

• Acid Mine Drainage Absorb heavy metals and
  increase the pH.
• Highway Runoffs Effective for cleaning the water
  that runs off roads carrying oil, gas, dirt, etc.
  
• Specific Pollutants Wetlands put in to treat or
  absorb a heavy metal or organic. Often, the
  plants will accumulate chemicals inside the plant
  stem and leaves (concentrating the pollutants).
  The plant can then be disposed of.
• Storm Water Handle storm waters in developed
  areas where runoff is a problem. Cleans up
  runoff as well.

6
2. Hydraulic modification

• Flood control reduce flood waters and impacts
• Water storage reservoir
• Groundwater recharge

7
3. Specific water quality changes

• Reduce sediment loading
• Raise or lower extremes of pH
• Add or remove organics (remove in the case of
  paper mills, add in acid mine drainage).

8
4. Erosion and flood protection

• Bank or shoreline stabilization
• Dissipation of wave energy
• Dissipation of flood flows
• Alter flow patterns of stream or river

9
5. Open spaces and aesthetics

• Used by resorts or new developments to increase
  land value.
• Adds nature values
• Property owners will pay extra for sounds, smells
  and sights of wildlife and wetland plants

10
6. Mitigation

• Intended to replace the function of lost
  wetlands.
• In US, when developers destroy wetlands they must
  replace them by a 1 to 2 or 1 to 3 ratio.
• The developer is not only responsible for
  replacement, but the function as well.
• Usually replaced wetlands do not function as
  well. Lots of problems occur with how to build
  and maintain them.

11
7. Habitat as life support

• Habitat specifically for threatened and
  endangered species
• Habitat for other wildlife.

12
Design of constructed wetlands

•  A. Free water surface systems (FWS) have open
  water surfaces, water is exposed, covering the
  substrate, submerged and emergent plants.
•  B. Subsurface flow systems (SFS) water below
  surface level, the substrate is exposed to air
  at the surface. Only emergent plants        

13
Design of constructed wetlands

•  A. Free water surface systems (FWS) have open
  water surfaces, water is exposed, covering the
  substrate, submerged and emergent plants.
•  B. Subsurface flow systems (SFS) water below
  surface level, the substrate is exposed to air
  at the surface. Only emergent plants        

14
Typical construction for a small sub-surface
wetland
15
Constructed wetlands can be customized for the
task

• Select submerged flow or free surface
• Determine volume of anaerobic vs aerobic needed
• Select plants that will accomplish task - fast
  growing plants that scour nutrients
• - plants that bio-accumulate heavy metals
• - plants that accumulate or break down organics
• - plant community that drops leaves to add
  organics to water

16
Typical subsurface flow systems
Treating grey water from a house in Italy
Treating municipal waste in Virginia, USA
17
Typical free water surface flow
Farm animal waste treated In Pennsylvania, USA
Municipal waste treated In Florida, USA