1. Environmental Science: Toward a Sustainable Future Richard T. Wright
Chapter 17
Water Pollution and Its Prevention
PPT by Clark E. Adams

2. Water Pollution and Its Prevention
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 Air Particulates Acid-forming compounds
Photochemical smog
CO2
CFCs

6. Pollution Categories Water and land Nutrient oversupply Solid wastes
Toxic chemicals
Pesticides/herbicides
Nuclear waste

7. Water Pollution Types Pathogens Organic Wastes Chemical Sediments
Nutrients

8. Pathogens Carried by Sewage
Disease-causing agents (Table 17.1)
Safety measures
Purification of public water supply
Sanitary collection/treatment of sewage
Sanitary practices when processing food

10. Organic Wastes
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.

11. Testing Water for Sewage
Fecal Coliform Test

12. Chemical Pollutants Inorganic chemicals
Heavy metals, acids, road salts
Organic chemicals
Petroleum, pesticides, detergents

13. Effect of Sediments on Stream Ecology
Loss of hiding/resting places for small fish
Attached aquatic organisms scoured from the rocks and sand
Poor light penetration

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

15. Different Kinds of Aquatic Plants
Benthic plants
Emergent vegetation
Submerged aquatic vegetation (SAV)

16. Different Kinds of Aquatic Plants
Phytoplankton
Green filamentous and single cell
Blue-green single cell
Diatoms single cell

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

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

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

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

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

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

23. Combating Eutrophication
Attack the symptoms
Chemical treatment
Aeration
Harvesting aquatic weeds
Drawing water down

24. Combating Eutrophication
Getting at root cause
Controlling point sources
Controlling nonpoint sources

25. Controlling Point Sources
Ban phosphate detergents
Sewage-treatment improvements

26. Controlling Nonpoint Sources
Difficult to address runoff pollutants
Urban
Agricultural fields
Deforested woodlands
Overgrazed pastures

27. Controlling Nonpoint Sources
Best Management Practices (BMP): Table 17-2
Agriculture
Construction
Urban

28. 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

29. 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

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

31. 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

32. Removing Pollutants from Sewage: Match Technology with Function
Bar Screen
Particulate organics
Grit Screen
Dissolved organics
Primary Treatment
Dissolved inorganics
Secondary Treatment
Large or small debris

33. Trickling Filters for Secondary Treatment

34. Trickling Filters for Secondary Treatment

35. 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

36. Sludge Treatment
Anaerobic digestion
Composting
Pasteurization

37. Treatment of Sludge
Methane
Humus

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

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

40. Public Policy
What was the legislative milestone in protecting natural waters and water supplies for each of the acts listed in Table 17-3?

41. End of Chapter 17