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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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