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Environmental Science: Toward a Sustainable Future Richard T. Wright

Environmental Science: Toward a Sustainable Future Richard T. Wright. Chapters 17 . Water Pollution and Its Prevention. Water Pollution and Its Prevention. Water pollution Eutrophication Sewage management and treatment Public policy. Pollution.

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Environmental Science: Toward a Sustainable Future Richard T. Wright

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  1. Environmental Science: Toward a Sustainable FutureRichard T. Wright Chapters 17 Water Pollution and Its Prevention

  2. Water Pollution and Its Prevention • Water pollution • Eutrophication • Sewage management and treatment • Public policy

  3. Pollution • Pollution: “the presence of a substance in the environment that because of its chemical composition or quantity prevents the functioning of natural processes and produces undesirable environmental and health effects.”

  4. Water Pollution • Pollution essentials • Water pollution: sources, types, criteria

  5. Pollution Categories • Either water or land: • Nutrient oversupply • Solid wastes • Toxic chemicals • Pesticides/herbicides • Nuclear waste

  6. Water Pollution Source

  7. Water Pollution Types • Pathogens • Organic Wastes • Chemicals • Sediments • Nutrients- (N&P)

  8. Dissolved oxygen (DO) in the water is depleted during decomposition of organic wastes. Water quality test Biochemical oxygen demand (BOD): measure of the amount of organic material. Organic Wastes

  9. Testing Water for Sewage Fecal Coliform Test

  10. Different kinds of aquatic plants The impact of nutrient enrichment Combating eutrophication Eutrophication

  11. The Impacts of Nutrient Enrichment • Oligotrophic: nutrient-poor water • Eutrophic: nutrient-rich water What kind of plants would dominate in oligotrophic vs. eutrophic conditions?

  12. (Submerged aquatic vegetation)

  13. Eutrophication • As nutrients are added from pollution, an oligotrophic condition rapidly becomes eutrophic. Oligotrophic Eutrophic

  14. Eutrophic or Oligotrophic? • High dissolved O2 • Deep light penetration • High phytoplankton

  15. Eutrophic or Oligotrophic? • Turbid waters • High species diversity • Good recreational qualities • High detritus decomposition

  16. Eutrophic or Oligotrophic? • Low bacteria decomposition • Benthic plants • Warm water • High nutrient concentration • BOD • High sediments

  17. Natural and Cultural Eutrophication • Natural eutrophication • aquatic succession • occurs over several hundreds of years • Cultural eutrophication • driven by human activities • occurs rapidly

  18. Controlling Point Sources • Ban phosphate detergents • Sewage-treatment improvements

  19. Controlling Nonpoint Sources • Difficult to address runoff pollutants • Urban • Agricultural fields- fertilizer, N, P • Deforested woodlands- sediment • Overgrazed pastures-sediment

  20. Collecting Pond for Dairy-Barn Washings

  21. Sewage Management and Treatment • Development of sewage collection and treatment systems • The pollutants in raw sewage • Removing the pollutants from sewage • Treatment of sludge • Alternative treatment systems

  22. Development of Sewage Collection and Treatment Systems • Storm drains for collecting runoff from precipitation • Sanitary sewers to receive all the wastewater from sinks, tubs, and toilets

  23. Development of Sewage Collection and Treatment Systems • Through the 1970s sewage was discharged directly into waterways • Clean Water Act of 1972

  24. Pollutants in Raw Sewage • 99.9% water to 0.1% waste • Pollutants in sewage are: • Debris and grit • Particulate organic material • Colloidal and dissolved organic material • Dissolved inorganic material

  25. Removing Pollutants from Sewage: Match Technology with Function

  26. Trickling Filters for Secondary Treatment

  27. Trickling Filters for Secondary Treatment

  28. Biological Nutrient Removal • Activated sludge: 3 zones • Conversion of NH4 to NO3 • NO3 converted to N gas and released • PO4 taken up by bacteria and released with excess sludge

  29. Sludge Treatment • Anaerobic digestion • Composting • Pasteurization

  30. Treatment of Sludge Methane Humus

  31. Alternative Treatment Systems • Individual septic systems • Wastewater effluent irrigation • Reconstructed wetland systems • Beaumont, TX • The waterless toilet

  32. Septic Tank Treatment • Aerobic digestion of solids in septic tank • Flow of liquids into drain field for evaporation, infiltration, or irrigation

  33. What you need to know for Chapter 17:Pollution: point vs non-point sourcesTypes of pollutants: organic, sediment, nutrients, pathogensOligotrophic vs eutrophicEutrophication: what are the main nutrients? What grows best? What happens when they grow?Sewage treatment: What’s removed in primary and secondary treatment?What is BOD? What is sludge? What’s it good for?

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