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.”

5. Water Pollution Source

6. Water Pollution Types Pathogens Organic Wastes Chemical Sediments
Nutrients

7. 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

9. Organic Wastes
Usually from fertilizers or waste
Dissolved oxygen (DO) in the water is depleted during decomposition of organic wastes.
Water quality test
Biochemical oxygen demand (BOD): the amount of dissolved oxygen required to break down the organic material in a given volume of water through aerobic activity;

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

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

13. Harmful changes in water caused by too much fertilizer or nutrients.
EUTROPHICATION
Harmful changes in water caused by too much fertilizer or nutrients.

14. STEPS OF EUTROPHICATION
Fertilizer flows into water
causing….
2. Increased plant growth on the surface of
water, causing…..
3. Decreased light in lower levels of water,
causing…
4. Plants in lower levels of water
to die, causing….
6. Death of fish and other animals.
5. Decay using up O2 and increasing
CO2,causing…...

15. These fish died due to eutrophication removing the oxygen.

16. Three Causes of Eutrophication:
Fertilizer or manure runoff from farmland.
Improper disposal of sewage.
Chemical and industrial waste.

19. Compare the water upstream from the dam to downstream, what differences do you see?

20. Compare these 2 ponds, the bottom one experiencing eutrophication.

23. Increased moss growth along this shoreline due to eutrophication

24. Eutrophication speeds up succession.
What role does eutrophication play on pond succession?
It speeds it up causing the pond to fill in faster.
Eutrophication speeds up succession.

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

26. Different Kinds of Aquatic Plants
Benthic plants (water plants)
Emergent vegetation: emerges!
Submerged aquatic vegetation (SAV)
Phytoplankton
Green filamentous and single cell
Blue-green single cell
Diatoms single cell

28. The Impacts of Nutrient Enrichment
Oligotrophic: nutrient-poor water
Eutrophic: nutrient-rich water

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

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

32. Eutrophic or Oligotrophic?
Turbid waters
High species diversity
Good recreational qualities
High detritus decomposition
Low bacteria decomposition
Benthic plants
Warm water
High nutrient concentration
High sediments

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

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

35. Combating Eutrophication
B. Getting at root cause
Controlling point sources
Controlling nonpoint sources

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

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

38. Collecting Pond for Dairy-Barn Washings

39. 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

40. Development of Sewage Collection and Treatment Systems
Through the 1970s sewage was discharged directly into waterways
Clean Water Act of 1972
Storm drains for collecting runoff from precipitation
Sanitary sewers to receive all the wastewater from sinks, tubs, and toilets

41. 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

43. Trickling Filters for Secondary Treatment

44. Trickling Filters for Secondary Treatment

45. 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

47. Sludge Treatment
Anaerobic digestion
Composting
Pasteurization

48. Treatment of Sludge
Methane
Humus

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

50. Dewatering Treated Sludge

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