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Waste Disposal

Waste Disposal. Chapter 16. Photo from Sandia National Laboratory, U.S. Department of Energy. Solid Wastes. Major source of solid waste in U.S. are: Agriculture (crops and animals): more than 50% Mineral industry (spoils, tailings, slag, and other rock and mineral wastes)

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Waste Disposal

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  1. Waste Disposal Chapter 16 Photo from Sandia National Laboratory, U.S. Department of Energy

  2. Solid Wastes • Major source of solid waste in U.S. are: • Agriculture (crops and animals): more than 50% • Mineral industry (spoils, tailings, slag, and other rock and mineral wastes) • Municipalities (small amount of municipal waste) • Industry (highly toxic)

  3. Municipal Waste Disposal • Open Dumps – unsightly, unsanitary, and smelly • Sanitary Landfills – alternate layers of compacted trash and a covering material • In U.S. open dumps no longer tolerated • Landfill design is important • Barriers need to lock in toxins and chemicals; must reduce leakage into the environment • Important to control the migration of leachate out of the landfill • Sites for sanitary landfills often controversial • NIMBY, NIMFY, NIMEY, and NOPE laws apply

  4. Sanitary landfills

  5. Landfill and Leachate

  6. “bathtub effect”

  7. Remaining landfill capacity

  8. Incineration • Partial solution to space problems faced by landfills • Burning waste produces abundant carbon dioxide plus other toxic substances • Recent technology have improved incinerators to burn hotter that breakdown complex toxic substances to less dangerous ones • Expensive to operate and still produce a residual waste; often toxic and require proper storage • The considerable heat generated by an incinerator can be recovered and used

  9. Proportions of municipal waste

  10. Waste-to-energy incineration facility

  11. Ocean Dumping • Ship board incineration, over the open ocean, and dumping residual waste into the ocean • Similar to land-based incineration but at sea • Incineration not 100% effective, residual toxic materials and chemicals dumped into the ocean will still pollute the ocean • Ocean dumping without incineration still popular in many places around the world • Very disastrous to local oceans where practiced • A dumping site for one very high-volume waste product: dredge spoils

  12. Dumping sediments with pollutants

  13. Reduce Waste Volume • Less volume means less landfill space and slower filling of available sites • Handling (Nontoxic) Organic Matter • Treated nontoxic organic waste can be fed to swine or composted • Recycling – any reuse of waste reduces volume at landfills • Recover recyclable waste by source separation; separate waste into useful categories (wood, paper, plastics, various metals, …) at the user’s site • Deposits on reusable material (glass, cans, containers, …) often attractive incentive • Many applications to this idea yet unexplored

  14. Solid wastes and paper recycle

  15. Recycling Symbols

  16. Recycling

  17. Reduce Waste Volume • Another options • Recycle crushed pavement as new roadbed material • Recycle steel into other useful objects • Re-use bricks as footpaths • Innovation has no limit here

  18. Municipal waste disposal

  19. Main generators of hazardous wastes

  20. Liquid-Waste Disposal • Sewage and by-products of industrial processes • Strategies: • Dilute and disperse • Concentrate and contain • Neither strategy is safe in long term • Secure Landfills– is it possible? • Placing liquid-waste into sealed drums, and covering with impermeable lining material; idea is to assure that the leachate will not migrate • Deep wells – inject deep into the crust • Leachate not contained • May act to lubricate faults • Expensive and unsafe

  21. Careless toxic-waste disposal leads to pollution

  22. A secure landfill design for toxic-waste disposal

  23. Deep-well disposal for liquid wastes

  24. Other Strategies • Incineration – produces carbon dioxide • Treatment by chemicals to breakdown or neutralized liquid waste is a possibility • Generate a less toxic liquid or residue • Would still require proper storage

  25. Sewage Treatment • Septic Systems: individual user-level treatment • Settling tank: solids separated and bacterial breakdown begins • Leach field or absorption field: liquid with remaining dissolved organic matter seeps out of porous pipes • Soil microorganisms and oxygen complete the breakdown of the organic matter • Soil permeability and field size are controlling factors

  26. Septic tank system

  27. Sewage Treatment • Municipal Sewage Treatment • Primary treatment: removal of solids from organic liquid waste • Secondary treatment: bacteria and fungi act to dissolve and breakdown the organic matter • Tertiary or advanced treatment: filtration, chlorination, and other chemical treatment may occur

  28. Primary, secondary, and tertiary stages of municipal treatment

  29. Ghosts of Toxins Past:Superfund • Disposal of identifiable toxic wastes in U.S. is currently controlled • Congress has mandated and provided billions of dollars to control and clean-up toxic spills from the past • Expensive • Political dynamite

  30. The first 951 toxic-waste dump sites Completed removals of Superfund, 1980-1990

  31. Radioactive Wastes • Radioactive Decay – unstable nuclei decay and produce energy • Radioisotopes each have their own rate of decay measured in a half-life • Half-lives of different radioisotopes vary from microseconds to billions of years • The decay of a radioisotope can not be accelerated or delayed • Energetic radioisotopes must be contained out of the environment for ‘ever’

  32. Effects of Radiation • Alpha, beta, and gamma rays are types of ionized radiation given off by the decay of various radioisotopes • Cancer, tumors, tissue burns, and genetic mutation can result due to exposure of high doses of radiation • Large doses result in death • Accidents have occurred: • Chernobyl and Three Mile Island

  33. Nature of Radioactive Wastes • Radioisotopes with half-lives of a few years to hundreds of years present the most risk • Radioactive enough to cause harm • Persistent in the environment long enough to require management • Some are toxic chemical poisons • Levels of radioactive waste: • Low-level: do not require extraordinary disposal precautions • High-level: require extraordinary precautions; must be isolated from the biosphere with confidence for a long time

  34. Historical Suggestions for Storage • Space • Antarctic Ice • Plate Tectonic Subduction Zones • Seabed Disposal • Bedrock Caverns for Liquid Waste • Bedrock Disposal of Solid High-Level Wastes • Multiple barrier concept

  35. Waste Isolation Pilot Plant (WIPP) • Southeast New Mexico site for storage of transuranic wastes • Opened March 26, 1999 • WIPP is located in bedded salt underlain by evaporites and overlain by mudstone • Located 2150 feet below the surface in a dry and stable tectonic region • Tectonic stable for over 200 million years

  36. Yucca Mountain • Established by Nuclear Waste Policy Act of 1982 – establish a high-level disposal site in the west • Yucca Mountain Attractive Characteristics: • Rhyolitic tuff host rock • Arid climate • Low population density (but Las Vegas is 60 miles to the southeast) • Low regional water table • Apparent geologic stability • Geological studies were detailed and revealing

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