1. Chapter 22 Water Pollution and Treatment

2. Water Pollution Primary water pollution problem (world) - lack of clean, disease-free drinking water. Major uses: –agriculture –industrial processes –domestic (household) supply Quality of water dependent on use. U.S. Environmental Protection Agency sets limits for some (not all) pollutants.

3. Biochemical Oxygen Demand The amount of oxygen required for biochemical decomposition process Dead organic matter; agricultural runoff and urban sewage 3 zones A pollution zone An active decomposition zone A recovery zone

5. Waterborne Disease Outbreaks –Fecal Coliform Bacteria (most common test) –Milwaukee, WI Cryptosporidium –Walkerton, ON E. coli Detected early!

6. Nutrients Eutrophication –The process by which a body of water develops a high concentration of nutrients –Nitrogen and phosphorus Cultural Eutrophication –When eutrophication is accelerated by human processes that add nutrients to a body of water

10. Oil Oil spills and normal shipping activities Exxon Valdez: Prince William Sound, Alaska Jessica: Galapagos Islands –currents and trade winds

11. Exxon Valdez March 24, 1989 250,000 barrels –14% collected Numerous fish, bird and marine mammal deaths 50% deposited on shoreline

12. Sediment Most abundant water pollutant (by weight) Fine to gravel sized pieces Results from erosion Exacerbated by human activity –Forest –Agriculture –Urban areas

13. Sediment Chokes streams Fills lakes, reservoirs, ponds, canals and harbors To minimize: –trap sediment –expose less land –tailor development to natural contours –protect exposed soil

14. Acid Mine Drainage Water with a high concentration of sulfuric acid that drains from mines Serious water pollution problem Damages aquatic ecosystems, pollutes bodies of water and degrades water quality

15. Surface Water Pollution Emitted from –Point Sources Distinct and confined sources such as pipes from industrial or sites –Nonpoint Sources Diffused and intermittent Ex) runoffs from streets

16. Surface Water Pollution Cuyahoga Rvr. (OH) –oil soaked wood caught fire Illinois River –municipal sewage and agricultural runoff –sewage treatment plant and TARP

17. Groundwater Pollution About ½ of all people in U.S. today depend on groundwater as source of drinking water Hazard presented by pollutant depends on: –concentration (toxicity) of the pollutant –degree of exposure of people or organisms to pollutant Difficult to treat because of large storage area and slow throughput rate

18. Groundwater Pollution Bioremediation: –a method of treating groundwater pollution problems that utilizes microorganisms in the ground to consume or break down pollutants Important points: –float or sink –multiple phases –treatment method must account for physical and chemical properties –emphasis needs to be on prevention vs. clean-up

21. Long Island, NY Two major groundwater problems: –salt-water intrusion intensive pumping subsurface outflow to ocean decreases allowing saltwater to migrate inland –shallow aquifer contamination (enter via surface) urban runoff septic tanks salt (de-icing) solid waste

23. Wastewater Treatment Septic Tank Disposal Systems Waste Treatment Plants –Primary Treatment –Secondary Treatment –Advanced Treatment –Chlorine Treatment

25. Wastewater Renovation and Conservation Cycle Steps: –1. Return of treated wastewater to crops –2. Renovation or natural purification by slow percolation of the wastewater into soil to eventually recharge the groundwater resource with clean water –3. Reuse of the treated water

28. Wastewater and Wetlands Can treat water quality problems from –municipal wastewater from primary or secondary treatment plants (BOD, pathogens, nutrients..) –stormwater runoff (metals, nitrate, BOD, oils..) –industrial wastewater (metals, acids, oils..) –agricultural wastewater and runoff (BOD, pesticides, suspended solids..) –mining waters (metals, acidic water..) –groundwater seeping from landfills (BOD, metals, oils..)

30. Water Reuse Inadvertent: –water is withdrawn, treated and returned to the environment Indirect: –Ex) the wastewater renovation and conservation cycle Direct: –The use of treated wastewater that is piped directly from a treatment plant to the next user

31. Water Pollution and Environmental Law Environmental Law –The branch of law dealing with conservation and use of natural resources and control of pollution –Laws address clean up and treatment of water as well as preventing pollutants from entering water –Clean Water Act (1972, amended 1977)