1. 20-5 How Can We Best Deal with Water Pollution? Concept 20-5 Reducing water pollution requires we prevent it, work with nature to treat sewage, cut resource use and waste, reduce poverty, and slow population growth.

2. Reducing Surface Water Pollution from Nonpoint Sources There are a number of ways to reduce ___________ sources of water pollution…most of which come from agriculture Use soil ________________ methods to prevent erosion ______________ the amount of fertilizers used _________ - less pesticide use Plant buffer zones of _____________ between cultivated fields and nearby surface waters nonpoint conservation Reduce IPM vegetation

3. Reducing Surface Water Pollution from Nonpoint Sources Use _________________ farming techniques Deal with animal ____________ better….keep feedlots away from sloped land, surface water, etc… organic waste

4. Laws Can Help Reduce Water Pollution from Point Sources (1) Laws greatly help to reduce ___________ source pollution…which is easier to regulate First U.S. federal water pollution law was the… ______________________________________ Has gone through several amendments and has been strengthened by other acts 1977: U.S. Clean Water Act Sets standards for 100 key water pollutants and requires polluters to get ____________ that limit how much they can ______________ into aquatic systems point Federal Water Pollution Control Act permits discharge

5. Laws Can Help Reduce Water Pollution from Point Sources (2) 1987: Water Quality Act Requires ___________ to _____________ waters that do not meet water quality standards due to the discharge of toxic substances EPA: experimenting with a discharge ____________ _____________ that uses market forces So an industry could pollute at higher levels than its permit allows if it buys credits from permit holders who are below their allowed levels Also called _____________________ statesidentify trading policy cap-and-trade

6. Laws Can Help Reduce Water Pollution from Point Sources (3) Potential problems with discharge trading policy? Effectiveness depends on how low the cap on total pollution levels is ________ Buying credits could allow pollution levels to build to _________________ levels in certain areas set dangerous

7. Case Study: The U.S. Experience with Reducing Point-Source Pollution (1) U.S. water laws have lead to numerous improvements in water quality… % of Americans served by community water systems that met federal health standards increased from 79% to _____ % of U.S. stream lengths found to be fishable and swimmable increased from 36% to ______ The proportion of the U.S. population served by sewage treatment plants increased from 32% to ______ Annual wetland loss decreased by ______ 94% 60% 74% 80%

8. Case Study: The U.S. Experience with Reducing Point-Source Pollution (1) Much more work needs to be done though… 45% of our lakes and 40% of our streams are not safe for swimming or fishing Runoff of animal wastes from feedlots and meat processing plants pollutes ______ of every ______ U.S. rivers Treated wastewater can still contain nutrients that produce ______________ Many gasoline storage tanks found throughout 43 states are ______________ 710 algal blooms leaking

9. Case Study: The U.S. Experience with Reducing Point-Source Pollution (2) In 2005, studies showed that half of our industrial and wastewater facilities ______________ their allowed discharge at least once _____ in ________U.S. water treatment systems violated the Safe Drinking Water Act between 2003 and 2008 A U.S. Supreme Court decision created ______________ over which waterways are protected EPA has been ________ in enforcing water pollution permits and collecting fines exceeded 15 confusion lax

10. Case Study: The U.S. Experience with Reducing Point-Source Pollution (3) Should the Clean Water Act be strengthened? Shift focus of the law to pollution ______________ Mandatory fines Expand the rights of citizens to bring _____________ to ensure that water pollution laws are enforced Clarify that it covers _______ waterways Some states and officials argue that it is ________________ and too _________________ to test for all of the pollutants required by federal law prevention lawsuits all unnecessary expensive

11. Sewage Treatment Reduces Water Pollution In rural and suburban areas with suitable soil, sewage from each house is discharged into a _____________ ___________ that has a large drainage field septic tank

12. In the settling tank, grease and oil rise to the top and solids fall to the bottom and are ___________ by bacteria Wastewater is discharged into the drainage field where it _________________ downward decomposed percolates

13. The soil filters out some of the pollutants and soil __________________ decompose biodegradable materials bacteria

14. In urban areas in MDCs, most waterborne waste and storm runoff flows through a network of _________ __________ to wastewater or sewage treatment plants Sludge Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland Raw sewage from sewers Sludge digester Sludge drying bed (kills bacteria) To river, lake, or ocean Activated sludge Air pump Primary Grit chamberBar screenSettling tank Secondary Chlorine disinfection tank Aeration tankSettling tank sewer pipes

15. Primary sewage treatment is a ______________ process that uses screens and a grit tank to allow solids to ______________ out Sludge Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland Raw sewage from sewers Sludge digester Sludge drying bed (kills bacteria) To river, lake, or ocean Activated sludge Air pump Primary Grit chamberBar screenSettling tank Secondary Chlorine disinfection tank Aeration tankSettling tank physical settle

16. Primary sewage treatment removes about…. –______ of the suspended solids and __________of the oxygen-demanding organic wastes Does ________ remove… –Pathogens –Phosphates, nitrates, salts –Radioisotopes –Trace amounts of medications –pesticides 60% 30-40% not

17. Secondary sewage treatment is a _____________ process in which aerobic bacteria remove up to _____ of dissolved and biodegradable oxygen demanding organic waste Sludge Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland Raw sewage from sewers Sludge digester Sludge drying bed (kills bacteria) To river, lake, or ocean Activated sludge Air pump Primary Grit chamberBar screenSettling tank Secondary Chlorine disinfection tank Aeration tankSettling tank biological 90%

18. Secondary sewage treatment does ________ remove… –Pathogens –All persistent organic chemicals Advanced or Tertiary Sewage treatment uses a series of specialized _____________ and physical processes to remove specific pollutants still left in the water –Helpful for removing _________________ and _____________ from water –Not widely used due to __________ NOT chemical nitrates phosphates cost

19. Before discharge, water usually undergoes __________ to remove water coloration and _____________ to kill disease carrying bacteria and some viruses Sludge Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland Raw sewage from sewers Sludge digester Sludge drying bed (kills bacteria) To river, lake, or ocean Activated sludge Air pump Primary Grit chamberBar screenSettling tank Secondary Chlorine disinfection tank Aeration tankSettling tank bleaching disinfection

20. What is done with the remaining sludge? Sludge Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland Raw sewage from sewers Sludge digester Sludge drying bed (kills bacteria) To river, lake, or ocean Activated sludge Air pump Primary Grit chamberBar screenSettling tank Secondary Chlorine disinfection tank Aeration tankSettling tank

21. We Can Improve Conventional Sewage Treatment Peter Montague, an environmental scientist, calls for redesigning our sewage treatment systems… He suggests preventing toxic or hazard chemicals from ______________ sewage treatment plants Require industries to _________ toxic wastes before water goes to the municipal sewage treatment plants _________ or eliminate use and waste of toxic chemicals Use __________________ toilet systems Waterless, odorless, fecal matter converted to a fertilizer supplement (mimics natural _______________________) Already being used in a number of countries reaching remove Reduce composting chemical cycling

22. We Can Improve Conventional Sewage Treatment ________________-based sewage treatment systems Filters and cleanses water Organisms in the wetlands can… ____________________ waste Take up __________________ ________________ toxic metals Preserve or restore our wetlands Done in Arcata, California…__________________ festival wetland decompose nutrients Absorb “Flush with Pride”

23. Solutions: Ecological Wastewater Purification by a Living Machine, RI, U.S. Fig. 20-C, p. 553 John Todd: biologist Natural water purification system Sewer water flows into a _______________ where a ___________ of tanks containing different organisms are used to purify water greenhouse series

24. Solutions: Methods for Preventing and Reducing Water Pollution Fig. 20-21, p. 553

25. What Can You Do? Reducing Water Pollution Fig. 20-22, p. 554

26. Review Questions What would a water pollution discharge trading policy allow? Differentiate between primary and secondary sewage treatment levels. For industries to buy or sell (trade) pollution credits Physical “settling” Biological “decomposition”

27. Review Questions How can we redesign our sewage treatment systems? Prevent toxic chemicals from reaching treatment plants composting toilets Wetland-based