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Waste Disposal
Chapter 16
Photo from Sandia National Laboratory, U.S. Department of Energy
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Solid Wastes
Major source of solid waste in U.S. are:
Agriculture (crops and animals): more than 50%
Mineral industry (spoils, tailings, slag, and otherrock and mineral wastes)
Municipalities (small amount of municipal waste)
Industry (highly toxic)
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Municipal Waste Disposal
Open Dumpsunsightly, unsanitary, and smelly
Sanitary Landfillsalternate layers ofcompacted 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; mustreduce leakage into the environment
Important to control the migration of leachateout ofthe landfill
Sites for sanitary landfills often controversial
NIMBY, NIMFY, NIMEY, and NOPE laws apply
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Sanitary landfills
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Landfill and Leachate
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Remaining landfill capacity
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Incineration
Partial solution to space problems faced bylandfills
Burning waste produces abundant carbon dioxide
plus other toxic substances Recent technology have improved incinerators to
burn hotter that breakdown complex toxicsubstances to less dangerous ones
Expensive to operate and still produce a residualwaste; often toxic and require proper storage
The considerable heat generated by anincinerator can be recovered and used
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Proportions of municipal waste
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Waste-to-energy incineration facility
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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 willstill pollute the ocean
Ocean dumping without incineration still popularin many places around the world
Very disastrous to local oceans where practiced
A dumping site for one very high-volume wasteproduct: dredge spoils
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Dumping sediments with pollutants
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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 orcomposted
Recyclingany reuse of waste reduces volumeat landfills
Recover recyclable waste by source separation;
separate waste into useful categories (wood, paper,plastics, various metals, ) at the users site
Deposits on reusable material (glass, cans, containers,) often attractive incentive
Many applications to this idea yet unexplored
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Solid wastes and paper recycle
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Recycling Symbols
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Recycling
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Reduce Waste Volume
Another options
Recycle crushed pavement as new roadbedmaterial
Recycle steel into other useful objects
Re-use bricks as footpaths
Innovation has no limit here
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Main generators of hazardous wastes
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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 Landfillsis it possible? Placing liquid-waste into sealed drums, and covering
with impermeable lining material; idea is to assurethat the leachate will not migrate
Deep wellsinject deep into the crust Leachate not contained
May act to lubricate faults
Expensive and unsafe
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Careless toxic-waste disposal leads to pollution
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A secure landfill design for toxic-waste disposal
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Deep-well disposal for
liquid wastes
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Other Strategies
Incinerationproduces carbon dioxide
Treatment by chemicals to breakdown orneutralized liquid waste is a possibility
Generate a less toxic liquid or residue
Would still require proper storage
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Sewage Treatment
Septic Systems: individual user-leveltreatment
Settling tank: solids separated and bacterialbreakdown begins
Leach field or absorption field: liquid withremaining dissolved organic matter seeps out ofporous pipes
Soil microorganisms and oxygen complete thebreakdown of the organic matter
Soil permeability and field size are controllingfactors
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Septic tank system
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Sewage Treatment
Municipal Sewage Treatment Primary treatment: removal of solids from
organic liquid waste
Secondary treatment: bacteria and fungi act todissolve and breakdown the organic matter
Tertiary or advanced treatment: filtration,chlorination, and other chemical treatmentmay occur
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Primary, secondary, and tertiary stages of
municipal treatment
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Ghosts of Toxins Past:Superfund
Disposal of identifiable toxic wastes in U.S.is currently controlled
Congress has mandated and providedbillions of dollars to control and clean-uptoxic spills from the past
Expensive
Political dynamite
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The first 951 toxic-wastedump sites
Completed removals ofSuperfund, 1980-1990
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Radioactive Wastes
Radioactive Decayunstable nuclei decay andproduce energy
Radioisotopes each have their own rate of decaymeasured in a half-life
Half-lives of different radioisotopes vary frommicroseconds 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
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Effects of Radiation
Alpha, beta, and gamma rays are types ofionized radiation given off by the decay ofvarious radioisotopes
Cancer, tumors, tissue burns, and geneticmutation can result due to exposure of highdoses of radiation
Large doses result in death
Accidents have occurred:
Chernobyl and Three Mile Island
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Nature of Radioactive Wastes
Radioisotopes with half-lives of a few years tohundreds 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 along time
l f
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Historical Suggestions forStorage
Space
Antarctic Ice
Plate Tectonic Subduction Zones Seabed Disposal
Bedrock Caverns for Liquid Waste
Bedrock Disposal of Solid High-Level Wastes Multiple barrier concept
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W I l i Pil Pl
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Waste Isolation Pilot Plant(WIPP)
Southeast New Mexico site for storage oftransuranic wastes
Opened March 26, 1999
WIPP is located in bedded salt underlainby 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
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Yucca Mountain
Established by Nuclear Waste Policy Act of 1982establish 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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