1. Water Pollution & Cleanup 11 June 2010Water-Pollution.ppt1

2. Water pollution Classes of pollution, pollutants – Pathogens, parasites – Oxygen-demanding wastes – Inorganic chemicals – Inorganic plant nutrients – Organic chemicals – Sediments – Radioactive material – Heat (thermal pollution) 11 June 2010Water-Pollution.ppt2

3. 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) 11 June 2010Water-Pollution.ppt3

4. 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 11 June 2010Water-Pollution.ppt4

5. 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) 11 June 2010Water-Pollution.ppt5

6. 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 11 June 2010Water-Pollution.ppt6

7. 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 11 June 2010Water-Pollution.ppt7

8. 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) 11 June 2010Water-Pollution.ppt8

9. 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 11 June 2010Water-Pollution.ppt9

10. 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 11 June 2010Water-Pollution.ppt10

11. Water pollution Non-point and Point sources 11 June 2010Water-Pollution.ppt11

12. Ground water pollution Pollution of aquifers Non-point and Point sources – Pollutants slow to break down in cold & dark 11 June 2010Water-Pollution.ppt12

13. Water pollution In lakes, reservoirs – Low flow rate, long residence time – Deep, stratification – Pollutants can accumulate, concentrate 11 June 2010Water-Pollution.ppt13

14. 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 11 June 2010Water-Pollution.ppt14

15. Water pollution Prevention – Better to NOT pollute than to clean up later Clean up is expensive Clean up is never complete 11 June 2010Water-Pollution.ppt15

16. Sewage Treatment Primary – Screens and settling tanks remove grit & suspended organic matter. Secondary – Sewage aerated; aerobic bacteria consume organic matter – Leave dissolved inorganics, NO 3, PO 4, etc. Tertiary – Filters most dissolved inorganics and remaining dissolved organic compounds 11 June 2010Water-Pollution.ppt16

17. Sewage Treatment Primary – Screens and settling tanks remove grit & suspended organic matter. 11 June 2010Water-Pollution.ppt17

18. Sewage Treatment Secondary – Sewage aerated; aerobic bacteria consume organic matter – Leave dissolved inorganics, NO 3, PO 4, etc. 11 June 2010Water-Pollution.ppt18

19. Sewage Treatment Tertiary – Filters most dissolved inorganics and remaining dissolved organic compounds – Can be done biologically in wetlands Natural Artificial 11 June 2010Water-Pollution.ppt19

20. 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 11 June 2010Water-Pollution.ppt20