HAZARDOUS WASTE

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HAZARDOUS WASTE

• Hazardous waste is any discarded solid or liquid
  material that is toxic, ignitable, corrosive, or
  reactive enough to explode or release toxic
  fumes.
• The two largest classes of hazardous wastes are
  organic compounds (e.g. pesticides, PCBs,
  dioxins) and toxic heavy metals (e.g. lead,
  mercury, arsenic).

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What Harmful Chemicals Are in Your Home?
Cleaning
Gardening
Disinfectants
Pesticides
Drain, toilet, and window cleaners
Weed killers
Ant and rodent killers
Spot removers
Septic tank cleaners
Flea powders
Paint
Latex and oil-based paints
Paint thinners, solvents, and strippers
Automotive
Stains, varnishes, and lacquers
Gasoline
Used motor oil
Wood preservatives
Antifreeze
Artist paints and inks
Battery acid
General
Solvents
Dry-cell batteries (mercury and cadmium)
Brake and transmission fluid
Rust inhibitor and rust remover
Glues and cements
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Hazardous Waste Regulations in the United States

• Two major federal laws regulate the management
  and disposal of hazardous waste in the U.S.
• Resource Conservation and Recovery Act (RCRA)
  pronounced RICK-ra
• Cradle-to-the-grave system to keep track waste.
• Comprehensive Environmental Response,
  Compensation, and Liability Act (CERCLA)
• Commonly known as Superfund program.

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Hazardous Waste Regulations in the United States

• The Superfund law was designed to have polluters
  pay for cleaning up abandoned hazardous waste
  sites.
• Only 70 of the cleanup costs have come from the
  polluters, the rest comes from a trust fund
  financed until 1995 by taxes on chemical raw
  materials and oil.
• Note Congress did not renew this this tax, the
  Superfund is now broke, taxpayers (not the
  polluters!) are paying the bill and the pace of
  cleanup has slowed.
• National Priorities List (NPL) The worst sites
  that represent an immediate and severe threat to
  human health

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DEALING WITH HAZARDOUS WASTE

• We can produce less hazardous waste and recycle,
  reuse, detoxify, burn, and bury what we continue
  to produce.

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Conversion to Less Hazardous Substances

• Physical Methods using charcoal or resins to
  separate out harmful chemicals.
• Chemical Methods using chemical reactions that
  can convert hazardous chemicals to less harmful
  or harmless chemicals.

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Conversion to Less Hazardous Substances

• Biological Methods
• Bioremediation bacteria or enzymes help destroy
  toxic and hazardous waste or convert them to more
  benign substances.
• Phytoremediation involves using natural or
  genetically engineered plants to absorb, filter
  and remove contaminants from polluted soil and
  water.

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Inorganic metal contaminants
Organic contaminants
Radioactive contaminants
Poplar tree
Brake fern
Willow tree
Sunflower
Indian mustard
Landfill
Oil spill
Polluted groundwater in
Polluted leachate
Decontaminated water out
Soil
Soil
Groundwater
Groundwater
Phytostabilization Plants such as willow trees
and poplars can absorb chemicals and keep them
from reaching groundwater or nearby surface water.
Rhizofiltration Roots of plants such as
sunflowers with dangling roots on ponds or in
green- houses can absorb pollutants such as
radioactive strontium-90 and cesium-137 and
various organic chemicals.
Phytoextraction Roots of plants such as Indian
mustard and brake ferns can absorb toxic metals
such as lead, arsenic, and others and store
them in their leaves. Plants can then be
recycled or harvested and incinerated.
Phytodegradation Plants such as poplars can
absorb toxic organic chemicals and break them
down into less harmful compounds which they
store or release slowly into the air.
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Trade-Offs
Phytoremediation
Advantages
Disadvantages
Easy to establish
Slow (can take several growing seasons)
Inexpensive
Effective only at depth plant roots can reach
Can reduce material dumped into landfills
Some toxic organic chemicals may evaporate from
plant leaves
Produces little air pollution compared to
incineration
Some plants can become toxic to animals
Low energy use
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Conversion to Less Hazardous Substances

• Incineration heating many types of hazardous
  waste to high temperatures up to 2000 C in
  an incinerator can break them down and convert
  them to less harmful or harmless chemicals.

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Conversion to Less Hazardous Substances

• Plasma Torch passing electrical current through
  gas to generate an electric arc and very high
  temperatures can create plasma.
• The plasma process can be carried out in a torch
  which can decompose liquid or solid hazardous
  organic material.

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Trade-Offs
Plasma Arc
Advantages
Disadvantages
Small
High cost
Produces CO2 and CO
Mobile. Easy to move to different sites
Can release particulates and chlorine gas
Can vaporize and release toxic metals and
radioactive elements
Produces no toxic ash
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Long-Term Storage of Hazardous Waste

• Hazardous waste can be disposed of on or
  underneath the earths surface, but without
  proper design and care this can pollute the air
  and water.
• Deep-well disposal liquid hazardous wastes are
  pumped under pressure into dry porous rock far
  beneath aquifers.
• Surface impoundments excavated depressions such
  as ponds, pits, or lagoons into which liners are
  placed and liquid hazardous wastes are stored.

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Trade-Offs
Deep Underground Wells
Advantages
Disadvantages
Leaks or spills at surface
Safe method if sites are chosen carefully
Leaks from corrosion of well casing
Wastes can be retrieved if problems develop
Existing fractures or earthquakes can allow
wastes to escape into groundwater
Easy to do
Encourages waste production
Low cost
Fig. 22-20, p. 539
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Trade-Offs
Surface Impoundments
Advantages
Disadvantages
Groundwater contamination from leaking liners (or
no lining)
Low construction costs
Low operating costs
Air pollution from volatile organic compounds
Can be built quickly
Overflow from flooding
Wastes can be retrieved if necessary
Disruption and leakage from earthquakes
Can store wastes indefinitely with secure double
liners
Promotes waste production
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Long-Term Storage of Hazardous Waste

• Long-Term Retrievable Storage Some highly toxic
  materials cannot be detoxified or destroyed.
  Metal drums are used to stored them in areas that
  can be inspected and retrieved.
• Secure Landfills Sometimes hazardous waste are
  put into drums and buried in carefully designed
  and monitored sites.

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Secure Hazardous Waste Landfill

• In the U.S. there are only 23 commercial
  hazardous waste landfills.

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What Can You Do?
Hazardous Waste
Use pesticides in the smallest amount possible.
Use less harmful substances instead of
commercial chemicals for most household
cleaners. For example use liquid ammonia to clean
appliances and windows vinegar to polish metals,
clean surfaces, and remove stains and mildew
baking soda to clean household utensils,
deodorize, and remove stains borax to
remove stains and mildew.
Do not dispose of pesticides, paints,
solvents, oil, antifreeze, or other products
containing hazardous chemicals by flushing them
down the toilet, pouring them down the drain,
burying them, throwing them into the garbage, or
dumping them down storm drains.
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Case Study Lead

• Lead is especially harmful to children and is
  still used in leaded gasoline and household
  paints in about 100 countries.

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Case Study Mercury

• Mercury is released into the environment mostly
  by burning coal and incinerating wastes and can
  build to high levels in some types of fish.

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AIR
PRECIPITATION
PRECIPITATION
WINDS
WINDS
Hg2 and acids
Hg2 and acids
Hg and SO2
Photo- chemical
Elemental mercury vapor (Hg)
Inorganic mercury and acids (Hg2)
Human sources
Inorganic mercury and acids (Hg2)
Coal- burning plant
Incinerator
Deposition
Runoff of Hg2 and acids
Deposition
WATER
Large fish
Vaporization
BIOMAGNIFICATION IN FOOD CHAIN
Deposition
Small fish
Deposition
Zooplankton
Phytoplankton
Bacteria and acids
Oxidation
Organic mercury (CH3Hg)
Inorganic mercury (Hg2)
Elemental mercury liquid (Hg)
Bacteria
Settles out
Settles out
Settles out
SEDIMENT
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ACHIEVING A LOW-WASTE SOCIETY

• In the U.S., citizens have kept large numbers of
  incinerators, landfills, and hazardous waste
  treatment plants from being built in their local
  areas.
• Environmental justice means that everyone is
  entitled to protection from environmental hazards
  without discrimination.

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Making the Transition to a Low-Waste Society A
New Vision

• Everything is connected.
• There is no away for the wastes we produce.
• Dilution is not always the solution to pollution.
• The best and cheapest way to deal with wastes are
  reduction and pollution prevention.