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Ch. 22 Water Pollution

Ch. 22 Water Pollution. 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.

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Ch. 22 Water Pollution

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  1. Ch. 22 Water Pollution

  2. 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

  3. Solutions: Preventing and Reducing Surface Water Pollution Nonpoint Sources Point Sources • Reduce runoff • Clean Water Act • Buffer zone vegetation • Water Quality Act • Reduce soil erosion

  4. StepsinWaterPurification • Water comes from the stream • Settling pond - Al2(SO4)3 - ALUM – added, pulls clay particles downward • Filtration - passing it through porous material (sand) • Adsorption - use of Carbon to remove organic pollutants • Biological oxidation - use of bacteria & microbes - oxygen helps the organisms grow & eliminate colloidal particles • Disinfection - addition of Chlorine, Ozone, or UV to eliminate harmful pathogens • Voluntary fluoride treatment & storage in water tower for drinking water

  5. Technological Approach: Septic Systems Septic tank Nonperforated pipe Manhole (for cleanout) Household wastewater Drain field Gravel or crushed stone Perforated pipe Distribution box (optional) Vent pipe • Require suitable soils and maintenance Fig. 19.14, p. 494

  6. Technological Approach: Sewage Treatment Secondary Primary Grit chamber Chlorine disinfection tank Bar screen Settling tank Aeration tank Settling tank To river, lake, or ocean Raw sewage from sewers (kills bacteria) Sludge Activated sludge Air pump Sludge digester Sludge drying bed Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland Fig. 19.15, p. 494 • Mechanical and biological treatment

  7. Waste Water Treatment Primary mechanical Secondary biological

  8. StepsinWastewaterTreatment • Wastewater - sanitary sewer pipes • Pre-treatment - bar screen removes debris • Primary • 1. settling tank- (removes grit) • 2: clarifier- (lets sludge settle while oil removed by skimmer)

  9. Primary Treatment - Clarifier

  10. PrimaryTreatment (OilSkimmer)

  11. StepsinWastewaterTreatment • Secondary – • 1: aeration tank – • colloids & organics removed by hungry bacteria -aeration increases bacterial growth • activated sludge • 2: clarifier- • lets activated sludge settle – • some reused in aeration tank • rest goes to anaerobic digester • 3: disinfection- by Chlorine, Ozone, or sunlight in Wetland

  12. Secondary Treatment - Biological Oxidation (Aeration Tank)

  13. Technological Approach: Advanced Sewage Treatment Specialized compound removal (DDT, etc.) Effluent from Secondary treatment Alum flocculation plus sediments Desalination (electrodialysis or reverse osmosis) Activated carbon Nitrate removal 98% of suspended solids 90% of phosphates To rivers, lakes, streams, oceans, reservoirs, or industries 98% of dissolved organics Most of dissolved salts Recycled to land for irrigation and fertilization • Removes specific pollutants Fig. 19.16, p. 495

  14. WastewaterTreatment Tertiary • Removal of chemicals (P, N, etc) - not required! • Anaerobic digester – • sludge from primary/secondary treatment • breaks down waste further • disposed in a landfill/treated/used as fertilizer • Water returned to the stream

  15. After Anaerobic Digestion of Sludge & Activated Sludge - Uses Biogas – produced during anaerobic digestion - used as fuel Co-composting – combined post-consumer waste paper w/treated sludge decomposed by bacteria - use as fertilizer animal crops only Pasteurization – drying sludge in ovens kill pathogens pellets - sold as fertilizer

  16. Technological Approach: Using Wetlands to Treat Sewage (1)Raw sewage drains by gravity into the first pool and flows through a long perforated PVC pipe into a bed of limestone gravel. (3) Wastewater flows through another perforated pipe into a second pool, where the same process is repeated. Sewage Treated water Wetland type plants Wetland type plants 45 centimeter layer of limestone gravel coated with decomposing bacteria First concrete pool Second concrete pool (2) Microbes in the limestone gravel break down the sewage into chemicals, that can be absorbed by the plant roots, and the gravel absorbs phosphorus. (4) Treated water flowing from the second pool is nearly free of bacteria and plant nutrients. Treated water can be recycled for irrigation and flushing toilets. Fig. 19.17, p. 497

  17. Wetland Functions • Disperses volume of flow • moderates flow of water - less storm damage • Recharge groundwater from surface water • Removes sediment • Removes excess organic nutrients - microbial decomposition • Increased availability - limiting nutrients • Creates ecosystem -habitat for animals

  18. Emergent Wetlands dominated by perennial plants cattails, sedges & cordgrass – which are rooted in bottom sediments “emerge” above the surface of the water

  19. Federal LAWS Protecting Wetlands Rivers & Harbors Act of 1899- establishes a program to regulate activities affecting navigation in US waters Duck Stamp Act of 1934 - allocates funds for the acquisition of land for migratory birds Clean Water Act (Section 404)- establishes a program to regulate the discharge of dredged and fill material into water of the US Food Securities Act of 1985 - establishes rules for farmers concerning use of wetlands prior or since 1985 for farming.

  20. N. A. Wetlands Conservation Act - provides for voluntary action to create wetlands under a grant program Coastal Wetlands Planning, Protection, & Restoration Act - to grant funds to coastal states to carry out coastal wetlands conservation projects. There are a number of regulations that give various agencies such as the EPA, the Army Corps of Engineers, and the US Department of Agriculture the power to oversee and implement regulations provided for by these Acts. Having several government agencies oversee different parts of these regulations creates friction and leaves gaps in the implementation of these regulations.

  21. Wetland Mitigation If a construction project allows the destruction of a wetland (allowable by a permit from the Army Corps of Engineers) then another area of equal or larger size, has to be created as a new wetland. The lands are usually sold by private owners to corporations, that act as mitigators, for the purpose of restoring what was once a wetland or to create a new wetland.

  22. Drinking Water Quality Contaminated Probability 10 to 20 percent Greater than 20 percent Not tested • Bottled water • Safe Drinking Water Act • Maximum contaminant levels Fig. 19.10, p. 488

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