Water Pollution

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Water Pollution Cleanup
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Water pollution

• Classes of pollution, pollutants
• Pathogens, parasites
• Oxygen-demanding wastes
• Inorganic chemicals
• Inorganic plant nutrients
• Organic chemicals
• Sediments
• Radioactive material
• Heat (thermal pollution)

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Water pollution

• Pathogens, parasites
• Usually from sewage, feedlots, slaughterhouses
• Viruses
• Bacteria (cholera, ...)
• Coliform bacteria usually not pathogenic,
• Used as indicators of pollution
• Protozoan parasites (Giardia, Cryptosporidium)

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Water pollution

• Oxygen-demanding wastes
• Organic materials from sewage, slaughterhouses,
  etc.
• Decomposed by bacteria
• Bacteria require, consume dissolved oxygen
• Biological Oxygen Demand (BOD)
• Measure of water quality
• Low in pristine water

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Water pollution

• Inorganic chemicals
• Mostly from industry
• Heavy metals
• Lead, arsenic, mercury, copper ions, etc.
• Ammonia
• Acids
• Sulfuric acid, nitric acid from acid deposition
• Also from industry
• Bases (caustic alkalines)

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Water pollution

• Inorganic plant nutrients (fertilizers)
• From agriculture, lawns gardens
• Leaching into groundwater
• Run-off into surface waters
• Stimulate growth of algae (algal blooms),
  eutrophication
• Algae die, sink, become oxygen-demanding waste

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Water pollution

• Inorganic plant nutrients (fertilizers)
• From agriculture, lawns gardens
• Eutrophication
• Natural process
• Accelerated by excess nutrient input
• Algae die, sink, become oxygen-demanding waste

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Water pollution

• Organic chemicals
• from industry, restaurants, cars, households,
  farms
• Gasoline, oil
• Engine coolant (ethylene glycol)
• Solvents
• Detergents
• Pesticides
• insecticides, herbicides, fungicides
• Polychlorinated Biphenyls (PCBs)

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Water pollution

• Sediments
• Erosion from construction sites, streets roads,
  farms, sewage
• Dense sediments sink, accumulate
• Sedimentation in reservoirs
• Less dense sediments may stay in water
• Reduce clarity (increase turbidity)
• Reduce light penetration photosynthesis

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Water pollution

• Radioactive material
• From spills, waste from atomic weapons production
• Hanford, Washington
• Savannah River Plant, South Carolina
• From nuclear power plants (minor)
• Closely regulated
• Heat (thermal pollution)
• Heated water from cooling of electrical
  generating equipment
• Alters ecosystem of river, lake

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Water pollution

• Non-point and Point sources

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Ground water pollution

• Pollution of aquifers
• Non-point and Point sources
• Pollutants slow to break down in cold dark

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Water pollution

• In lakes, reservoirs
• Low flow rate, long residence time
• Deep, stratification
• Pollutants can accumulate, concentrate

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Water pollution

• In streams, rivers
• Higher flow rate, dilution effect
• Turbulent
• Well mixed
• Well oxygenated
• Long riverbanks, contact with land
• Subject to non-point source pollutants
• Often flow near cities

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Water pollution

• Prevention
• Better to NOT pollute than to clean up later
• Clean up is expensive
• Clean up is never complete

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Sewage Treatment

• Primary
• Screens and settling tanks remove grit
  suspended organic matter.
• Secondary
• Sewage aerated aerobic bacteria consume organic
  matter
• Leave dissolved inorganics, NO3, PO4, etc.
• Tertiary
• Filters most dissolved inorganics and remaining
  dissolved organic compounds

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Sewage Treatment

• Primary
• Screens and settling tanks remove grit
  suspended organic matter.

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Sewage Treatment

• Secondary
• Sewage aerated aerobic bacteria consume organic
  matter
• Leave dissolved inorganics, NO3, PO4, etc.

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Sewage Treatment

• Tertiary
• Filters most dissolved inorganics and remaining
  dissolved organic compounds
• Can be done biologically in wetlands
• Natural
• Artificial

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Water Quality

• Improvement since 1970
• Surface waters no longer regarded as open sewers
• More and better sewage treatment systems
• Less dumping of industrial waste
• Clean Water Act of 1972, 1977
• Make all U.S. surface waters fishable and
  swimmable,
• Goal not fully met