Constructed Wetlands as a Water Treatment System: Arcata, California

1
Constructed Wetlands as aWater Treatment
SystemArcata, California

• Ricky Ebersohl
• SSC 570-601
• Fall 2008

2
Background2,5

• Wetlands serve to reduce and remove toxins from
  the environment
• Wetlands provide a buffer for flood control and
  draught
• Absorb and hold excesswater during rainy seasons
• Slowly release waterduring drier times
• Wetlands provide aunique habitat fororganisms
  of all kinds

Source North Queensland Area Consultative
Committee
3
Background1,2,5,6,7

• Aquatic plants that help to remove contaminants
• Broad-leafed arrowhead (Sagittaria latifolia)
• Lotus (Nelumbo lutea)
• Elodea (Elodea canadensis)
• Pickerelweed(Pontederia cordata)
• Wild rice (Zizania aquatica)
• Mosquito fern (Azolla mexicana)
• Wild celery(Vallisneria americana)
• Big duckweed(Spirodela polyrhiza)
• Lesser duckweed (Lemna minor)

Source http//www.okpond.com/
4
Background1

• Organic nitrogen
• Aerobic/anaerobic (ammonification)
• Affects oxygen levels inthe wetlands
• Removal mineralization intoinorganic forms
• Ammonia/ammonium/nitrates
• Toxicity to fish
• Nitrates can decrease the bloodsability to
  transport oxygen
• Removal in soils, nitrification (aerobic) and
  denitrification (primarily anaerobic) and taken
  up by plants

Source http//www.sciencedaily.com/
5
Background1

• Phosphorus
• Plants
• Stored during the growing season
• Released when the plants die
• Soils
• Stored in sediments(phosphorus sink)
• Redox potential wetlandsoils can reduce iron
  andrelease bound phosphorus
• Dependent largely onoxygen concentrations

Source USGS Water Resources
6
Overview2,5

• Purpose
• Storm water control andmanagement
• Municipal wastewatertreatment
• Agricultural wastewatertreatment
• Landfill leachate management
• Runoff control
• Components
• Soil and drainage construction
• Water
• Aquatic plants
• Micro-organisms

Source Colorado State University
7
Overview2,5

• Advantages over conventional wetlands
• Generally independent of groundwater channels
• Purpose-specific design (efficient)
• Develop and mature quickly
• Size remains constant

Source United Nations Environment Programme
8
How It Works
Source City of Arcata
9
How It Works3

• Primary treatment
• Uses multiple steps to removelarger solid
  objects
• Generates and then removesbulky sludge
• Aerobic and anaerobic digesters are used to
  stabilize sludge for removal
• Sludge is dried and removed

Source City of Arcata
Source United Nations Environment Programme
10
How It Works3

• Secondary treatment
• Uses oxidation ponds andtreatment wetlands
• Oxidation ponds
• Utilizes bacteria to break downorganic material
• Utilizes algae to provide oxygen
• Treatments wetlands
• Utilizes a marsh setup
• Cattails and other marshplants help remove
  ammonia,nitrogen, and phosphorus
• Reduces total and fecal coliform and settles
  remaining waste residue

Source City of Arcata
Source City of Arcata
11
How It Works3,7

• Tertiary treatment
• Enhancement marshes
• Final stage, in most cases
• Provides habitat
• Provides recreational facilities
• Lowers nutrient content
• Reduces BOD (measures organic matter content)
• Reduces effluent in a final step
• Resulting water can be directly released into the
  environment

Source City of Arcata
Source City of Arcata
12
How It Works3,6

• Disinfection
• Chlorination
• Used to destroy pathogens
• Removes ammonia
• Reduces sludge buildup
• Dechlorination
• Sulfur dioxide is used toremove chlorine from
  thesterilized water
• Resulting water is safe forrelease into
  theenvironment, outside ofthe wetlands

Source City of Arcata
Source City of Arcata
13
Water Quality Results4

• Average for total dissolved solids
• Average for chlorine and sulfates
• Average for specific conductance
• Zero positive for coliform
• Zero positive forfecal bacteria
• Zero positive for e.coli
• Negative for lead
• Negative for copper

Source http//www.thebacteriabusters.com/
14
References

1. Australian Natural Resource Management. Wetland
   ecosystem condition nutrients (phosphorus and
   nitrogen). http//www.nrm.gov.au/publications/fac
   tsheets/me-indicators/inland-aquatic/wetland-condi
   tion-nutrients.html. Accessed October 26, 2008.
2. Campbell, Craig S. and Michael H. Ogden.
   Constructed Wetlands in the Sustainable
   Landscape. John Wiley Sons, Inc. New York,
   p.270. 1999.
3. City of Arcata Arcata Marsh Wildlife
   Sanctuary. http//www.cityofarcata.org/index.php?o
   ptioncom_contenttaskviewid20Itemid47.
   Accessed October 25, 2008.
4. City of Arcata Drinking Water 2007 Water
   Quality Report. http//www.cityofarcata.org/images
   /stories/city_of_arcata_consumer_confidence_report
   _2007.pdf. Accessed October 26, 2008.
5. DeBusk, William F. Wastewater Treatment
   Wetlands Applications and Treatment Efficiency.
   University of Florida, Institute of Food and
   Agricultural Sciences (UF/IFAS). May 1999.
6. Hawkins, Julie. Constructed Treatment Wetlands.
   USDA-NRCS. USDA-NRCS. April 1, 2008.
7. Kadlec, Knight, Robert H., Robert L. Treatment
   Wetlands. CRC Press LLC, 1996.