Water pollution


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Water pollution

  1. 1. Water Pollution The pollution saga of the nectar of life…
  2. 2. The Blue Marble or the Blue Sapphire! “Our liquid planet glows like a soft blue sapphire in the hard- edged darkness of space. There is nothing else like it in the solar system. It is because of water.” - John Todd
  3. 3. Water and Water issues • Water is an essential thing for life. • Without water life is impossible • How much water is required per person per day? • As per universal standards(Average) * For drinking 5 litres * sanitation 20 litres * Bathing 15 litres * Food preparation 10 litres
  4. 4. Some facts on water  Only 2.5 % of the total water on earth is fresh water  About 80 countries or 40% of the world’s population suffering from water shortages  By 2025, 66% of the world population may suffer from serious water problems  Still, 1 billion people lack access to safe drinking water and 2.4 billion lack access to proper sanitation  Agriculture accounts for more than 70% of the fresh water • Fewer than 35% of the cities in the developing world treat their waste water • Many countries lack adequate legislation and policies for efficient water management
  5. 5. Water management problems • There is sufficient water in the world. • It is not managed well • Water security was a subject to all the world countries during the World summit, 2002 • Water policy is required by all the nations
  6. 6. What is water pollution? Any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired usage.
  7. 7. What is water pollution? Infectious Agents: bacteria and viruses often from animal wastes Inorganic Chemicals: Acids and toxic chemicals often from runoff, industries and household cleaners
  8. 8. What is water pollution? Organic Chemicals: oil, gasoline, plastics, detergents often from surface runoff, industries and cleaners Plant Nutrients: water soluble nitrates, ammonia and phosphates often from sewage, agriculture and urban fertilizers Sediment: soils and silts from land erosion can disrupt photosynthesis, destroy spawning grounds, clog rivers and streams Pollution and Radioactivity: mostly from powerplants
  9. 9. Impact of water pollution As per WHO: • 3.4 million premature deaths each year from waterborne diseases • 1.9 million die from diarrhea
  10. 10. Types, Effects and Sources of Water Pollution Point sources Nonpoint sources Water quality
  11. 11. Point and Nonpoint Sources NONPOINT SOURCES Urban streets Suburban development Wastewater treatment plant Rural homes Cropland Factory Animal feedlot POINT SOURCES
  12. 12. Major Sources of Water Pollution Agriculture: by far the leader • Sediment, fertilizers, bacteria from livestock, food processing, salt from soil irrigation Industrial: factories and powerplants Mining: surface mining toxics, acids, sediment
  13. 13. Freshwater Stream Pollution Flowing streams can recover from moderate level of degradable water pollution if their flows are not reduced. • Natural biodegradation process • Does not work if overloaded or stream flow reduced • Does not work against non biodegradable pollutants
  14. 14. Pollution of Streams  Oxygen sag curve Factors influencing recovery What factors will influence this oxygen sag curve?
  15. 15. Two Worlds Developed Countries U.S. and other developed countries sharply reduced point sources even with population and economic growth • Nonpoint still a problem • Toxic chemicals still problem • Success Thames River
  16. 16. Two Worlds Developing Countries: Serious and growing problem • Half of world’s 500 major rivers heavily polluted • Sewage treatment minimal $$$ • Law enforcement difficult • 10% of sewage in China treated • Economic growth with little $$$ to clean up
  17. 17. India’s Ganges River • Holy River (1 million take daily holy dip) • 350 million (1/3rd of pop) live in watershed • Little sewage treatment • Used for bathing, drinking etc. • Bodies (cremated or not) thrown in river • Good news is the Indian government is beginning to work on problem
  18. 18. Pollution of Lakes Eutrophication
  19. 19. Eutrophication of Lakes Eutrophication: nutrient enrichment of lakes mostly from runoff of plant nutrients (nitrates and phosphates) • During hot dry weather can lead to algae blooms • Decrease of photosynthesis • Fishes killed, bad odour
  20. 20. Eutrophication in Lakes Solutions: • Advanced sewage treatment (N, P) • Household detergents • Soil conservation • Remove excess weed build up • Pump in oxygen or freshwater
  21. 21. Case Study: The Great Lakes •Pollution levels dropped, but long way to go •95% of U.S. freshwater •30% Canadian pop, 14% U.S. •38 million drink •1% flow out St. Lawrence •Toxic fish
  22. 22. Section 4: Groundwater • Why is groundwater pollution a serious problem? • What is the extent of the problem? • What are the solutions?
  23. 23. Groundwater Groundwater can become contaminated • No way to cleanse itself • Little dilution and dispersion • Out of sight pollution • Prime source for irrigation and drinking • REMOVAL of pollutant difficult
  24. 24. Groundwater Pollution: Causes  Low flow rates  Few bacteria  Cold temperatures Coal strip mine runoff Pumping well Waste lagoon Accidental spills Groundwater flow Confined aquifer Discharge Leakage from faulty casing Hazardous waste injection well Pesticides Gasoline station Buried gasoline and solvent tank Sewer Cesspool septic tank De-icing road salt Unconfined freshwater aquifer Confined freshwater aquifer Water pumping well Landfill  Low oxygen Fig. 22-9 p. 502
  25. 25. Groundwater • Pollution moves in plumes • Soil, rocks, etc. act like sponge • Cleansing does not work (low O, low flow, cold) • Nondegradables may be permanent
  26. 26. Prevention is the most effective and cheapest
  27. 27. Groundwater Pollution Prevention  Monitor aquifers  Leak detection systems  Strictly regulating hazardous waste disposal  Store hazardous materials above ground  Find less hazardous substitutes
  28. 28. Ocean Pollution • How much pollution can the oceans tolerate? • Coastal zones: How does pollution affect coastal zones? • What are major sources of ocean pollution and what is being done? • Oils spills
  29. 29. Ocean Pollution Oceans can disperse and break down large quantities of degradable pollution if they are not overloaded. • Pollution worst near heavily populated coastal zones • Wetlands, estuaries, coral reefs, mangrove swamps • 40% of world’s pop. Live within 62 miles of coast
  30. 30. Mangrove Swamp
  31. 31. Estuaries
  32. 32. Ocean Pollution • Large amounts of untreated raw sewage (viruses) • Leaking septic tanks • Runoff • Algae blooms from nutrients • Dead zones NO DO • Airborne toxins • Oil spills
  33. 33. Ocean Pollution Fig. 22-11 p. 504
  34. 34. Case Study: Chesapeake Bay  Largest US estuary  Relatively shallow  Slow “flushing” action to Atlantic  Major problems with dissolved O2 Fig. 22-13 p. 506
  35. 35. Preventing and reducing the flow of pollution from land and from streams emptying into the ocean is key to protecting oceans
  36. 36. Oil Spills  Sources: offshore wells, tankers, pipelines and storage tanks  Effects: death of organisms, loss of animal insulation and buoyancy, smothering  Significant economic impacts  Mechanical cleanup methods: skimmers and blotters  Chemical cleanup methods: coagulants and dispersing agents
  37. 37. Oil Spills
  38. 38. Prevention and Reduction • How can we reduce surface water pollution: point and also nonpoint. • How do sewage treatment plants work? • How successful has the U.S. been at reducing water pollution? Clean Water Act
  39. 39. Solutions: Preventing and Reducing Surface Water Pollution Nonpoint Sources Point Sources Reduce runoff Buffer zone vegetation Reduce soil erosion Clean Water Act Water Quality Act  Only apply pesticides and fertilizers as needed
  40. 40. Nonpoint Sources Reduce runoff
  41. 41. Nonpoint Sources Buffer Zones Near Streams
  42. 42. Nonpoint Prevent soil erosion and only apply needed pesticides and fertilizers
  43. 43. Point Sources Most developed countries use laws to set water pollution standards. • Regulates navigable waterways..streams, wetlands, rivers, lake
  44. 44. Clean Water Act • Sets standards for key pollutants • Requires permits for discharge • Requires sewage treatment • Require permits for wetland destruction • Does not deal with nonpoint sources well • Goal All Waterways fishable and swimable
  45. 45. Technological Approach: Septic Systems Require suitable soils and maintenance Fig. 22-15 p. 510 •¼ of all U.S. homes have Septic tanks •Can be used in parking lots, business parks, etc.
  46. 46. Combined sewer overflow is a problem in many older towns •EPA: 1.8 M to 3.85 M sick from swimming in water contaminated by sewer overflows •EPA: $100 billion to fix
  47. 47. Technological Approach: Sewage Treatment Physical and biological treatment Fig. 22-16 p. 511
  48. 48. Primary: removes 60% of solids and 30-40% oxygen demanding wastes (physically) Secondary: uses biological processes to remove up to 90% of biodegradables Tertiary: advanced techniques only used in 5% of U.S. $$$$ Disinfection: chlorine, ozone, UV What is not taken out???
  49. 49. Technological Approach: Advanced (Tertiary) Sewage Treatment Uses physical and chemical processes Removes nitrate and phosphate Expensive Not widely used
  50. 50. Sludge disposal…using as fertilizer
  51. 51. Technological Approach: Using Wetlands to Treat Sewage Fig. 22-18 p. 513
  52. 52. Rain Water HarvestingRain Water Harvesting • Rain Water Harvesting RWH- process of collecting, conveying & storing water from rainfall in an area – for beneficial use. • Storage – in tanks, reservoirs, underground storage- groundwater • Hydrological Cycle
  53. 53. Appropriate Technology Water conservation and groundwater recharge techniques Water harvesting cum supplementary irrigation techniques
  54. 54. The Good News Largely thanks to CWA: • Between 1972 – 2002 fishable and swimmable streams 36% to 60% • 74% served by sewage treatment • Wetlands loss dropped by 80% • Topsoil losses dropped by 1 billion tons annually
  55. 55. The Bad News • 45% of Lakes, 40% streams still not fishable and swimmable • Nonpoint sources still huge problem • Livestock and Ag. Runoff • Fish with toxins
  56. 56. Drinking Water • How is drinking water purified? High tech way. • How can we purify drinking water in developing nations? • What is the Safe Drinking Water Act? • Is bottled water a good answer or an expensive rip-off?
  57. 57. Drinking Water Quality  Safe Drinking Water Act  Maximum contaminant levels (MCLs)  Purification of urban drinking water  Bottled water  Protection from terrorism  Purification of rural drinking water
  58. 58. Purification of urban drinking water Surface Water: • Removed to reservoir to improve clarity • Pumped to a treatment plant to meet drinking water standards Groundwater: often does not need much treatment
  59. 59. Purification of rural drinking water There can be simple ways to purify water: • Exposing to heat and UV rays • Fine cloths to filter water • Add small amounts of chlorine
  60. 60. Safe Drinking Water Act • 54 countries have drinking water laws SDWA passed 1974 requires EPA to set drinking water standards Maximum Contaminating Levels (MCLs)
  61. 61. Safe Drinking Water Act • Privately owned wells exempt from SDWA SDWA requires public notification of failing to meet standards and fine. MCLs often stated in parts per million or parts per billion
  62. 62. Bottle Water U.S. has the world’s safest tap water due to billions of $$$ of investment Bottle water 240 to 10,000 times more expensive than tap water 25% of bottle water is tap water
  63. 63. Bottle Water 1.4 million metric tons of bottle thrown away each year Toxic fumes released during bottling Bottles made from oil based plastics Water does not need to meet SDWA