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Constructed Wetlands as a Water Treatment System: Arcata, California

Constructed Wetlands as a Water Treatment System: Arcata, California. Ricky Ebersohl SSC 570-601 Fall 2008. Background 2,5. Wetlands serve to reduce and remove toxins from the environment Wetlands provide a buffer for flood control and draught

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Constructed Wetlands as a Water Treatment System: Arcata, California

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  1. Constructed Wetlands as aWater Treatment System:Arcata, 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 blood’sability 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 • Australian Natural Resource Management. “Wetland ecosystem condition: nutrients (phosphorus and nitrogen)”. http://www.nrm.gov.au/publications/factsheets/me-indicators/inland-aquatic/wetland-condition-nutrients.html. Accessed October 26, 2008. • Campbell, Craig S. and Michael H. Ogden. Constructed Wetlands in the Sustainable Landscape. John Wiley & Sons, Inc. New York, p.270. 1999. • City of Arcata – Arcata Marsh & Wildlife Sanctuary. http://www.cityofarcata.org/index.php?option=com_content&task=view&id=20&Itemid=47. Accessed October 25, 2008. • 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. • DeBusk, William F. “Wastewater Treatment Wetlands: Applications and Treatment Efficiency”. University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS). May 1999. • Hawkins, Julie. “Constructed Treatment Wetlands”. USDA-NRCS. USDA-NRCS. April 1, 2008. • Kadlec, Knight, Robert H., Robert L. Treatment Wetlands. CRC Press LLC, 1996.

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