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SolidWaste Ch. 22 Second Half
Solutions: Reducing Solid Waste
• Refuse: to buy items that we really don’t need.• Reduce: consume less and live a simpler and
less stressful life by practicing simplicity.• Reuse: rely more on items that can be used
over and over.• Repurpose: use something for another purpose
instead of throwing it away.• Recycle: paper, glass, cans, plastics…and buy
items made from recycled materials.
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).
Electronic Waste: A Growing Problem
• E-waste consists of toxic and hazardous waste such as PVC, lead, mercury, and cadmium.
• The U.S. produces almost half of the world's e-waste but only recycles about 10% of it.
Figure 22-4
Problem
• If e-waste is not treated properly, it is a major source of toxins and carcinogens.
• Electronic waste represents 2 percent of America's trash in landfills, but it equals 70 percent of overall toxic waste.
• Up to thirty-eight separate chemical elements are incorporated into electronic waste items.
Fig. 22-15, p. 534
What Harmful Chemicals Are in Your Home?
• Glues and cements
• Dry-cell batteries (mercury and cadmium)
• Rust inhibitor and rust remover
• Brake and transmission fluid
General
Cleaning
• Battery acid
• Wood preservatives
• Stains, varnishes, and lacquers
Automotive
• Gasoline• Used motor oil
Paint• Latex and oil-based paints• Paint thinners, solvents, and strippers
Gardening
• Pesticides• Weed killers• Ant and rodent
killers
• Antifreeze
• Flea powders
• Disinfectants
• Septic tank cleaners• Spot removers
• Drain, toilet, and window cleaners
• Artist paints and inks
• Solvents
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)
• Cradle-to-the-grave system to keep track waste.
– Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
• Commonly known as Superfund program.
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.– Trust fund is now broke.– $20 million per site– $1.7 trillion eventually
How Would You Vote?
• Should the U.S. Congress reinstate the polluter-pays principle by using taxes from chemical, oil, mining, and smelting companies to reestablish a fund for cleaning up existing and new Superfund sites?– a. No. All taxpayers, not certain industries, should pay for cleaning up
sites polluted in the past.– b. Yes. Funding for Superfund is needed and waste-generating
industries rather than ordinary citizens should fund it.
DEALING WITH HAZARDOUS WASTE
• We can produce less hazardous waste and recycle, reuse, detoxify, burn, and bury what we continue to produce.
Figure 22-16
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.
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.
PhytostabilizationPlants such as willow trees and poplars can absorb chemicals and keep them from reaching groundwater or nearby surface water.
RhizofiltrationRoots 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.
PhytoextractionRoots 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.
PhytodegradationPlants such as poplarscan absorb toxic organic chemicals and break them down into less harmful compounds which they store or release slowly into the air.
Inorganicmetal contaminants
Organiccontaminants
Radioactivecontaminants
Brake fernPoplar treeIndian mustardWillow treeSunflower
Oilspill
Landfill
GroundwaterSoil
PollutedleachateDecontaminated
water out
Pollutedgroundwater in
GroundwaterSoil
Fig. 22-18, p. 538
Inexpensive
Low energy use
Easy to establish
Trade-Offs
Phytoremediation
Advantages Disadvantages
Some plants can become toxic to animals
Some toxic organic chemicals may evaporate from plant leaves
Produces little air pollution compared to incineration
Can reduce material dumped into landfills
Slow (can take several growing seasons)
Effective only at depth plant roots can reach
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.
Fig. 22-19, p. 538
Advantages
Trade-Offs
Plasma Arc
Small High cost
Produces no toxic ash
Can vaporize and release toxic metals and radioactive elements
Can release particulates and chlorine gas
Mobile. Easy to move to different sites
Produces CO2 and CO
Disadvantages
Long-Term Storage of Hazardous Waste
• Hazardous waste can be disposed of on or underneath the earth’s 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. (64% in US)
– Surface impoundments: excavated depressions such as ponds, pits, or lagoons into which liners are placed and liquid hazardous wastes are stored.
Fig. 22-20, p. 539
Safe method ifsites are chosencarefully
Trade-Offs
Deep Underground Wells
Advantages Disadvantages
Encourageswaste production
Existing fracturesor earthquakescan allow wastesto escape intogroundwater
Leaks fromcorrosion of wellcasing
Leaks or spills atsurface
Low cost
Easy to do
Wastes can beretrieved ifproblemsdevelop
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.
Secure Hazardous Waste Landfill• In the U.S. there are
only 23 commercial hazardous waste landfills.
Figure 22-22
How Would You Vote?
• Do the advantages of storing hazardous wastes in surface impoundments outweigh the disadvantages? – a. No. The environment should not be openly
exposed to liquid hazardous wastes.– b. Yes. Surface impoundments are inexpensive
solutions for at least the temporary storage of liquid wastes.
Fig. 22-23, p. 540
What Can You Do?
• 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.
Hazardous Waste
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.
Figure 22-26
Fig. 22-25, p. 542
BIOMAGNIFICATION IN FOOD CHAIN
SEDIMENT
PRECIPITATIONPRECIPITATION WINDSWINDS
AIR
WATER
Inorganic mercury and acids
(Hg2+)
Inorganic mercury and acids (Hg2+)
Organicmercury (CH3Hg+)
Inorganicmercury (Hg2+)
Hg2+ and acids
Runoff of Hg2+ and acids
Large fish
Small fish
ZooplanktonPhytoplankton
Hg and SO2Hg2+ and acids
Human sources
Incinerator
Coal-burning plant
Elemental mercury
vapor (Hg)
Photo-chemical
OxidationElemental
mercury liquid (Hg)
Deposition
Dep
ositi
on
Bacteria
Bacteria and acids
Settles out Settles
out Settles out
Vaporization
Dep
ositi
on
Deposition
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.
Global Outlook: International Action to Reduce Hazardous Waste
• An international treaty calls for phasing out the use of harmful persistent organic pollutants (POPs).– POPs are insoluble in water and soluble in fat.– Nearly every person on earth has detectable levels of
POPs in their blood.– The U.S has not ratified this treaty.
Animation: Economic Types
PLAYANIMATION