Chapter 16
Waste Generation and Waste
Disposal
Humans generate waste that other
Humans generate waste that
other organisms cannot use
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In 1900 in the U.S. virtually all metal, wood, and glass
materials were recycled.
After World War II, industrialization brought wealth to
may Americans, which made it possible for people to
purchase household conveniences that could be used and
thrown away.
Municipal Solid Waste (MSW)- refuse collected by
municipalities from households, small businesses, and
institutions such as schools, prisons, municipal buildings,
and hospitals.
Approaches to Waste Management
• Waste – any unwanted material or substances that
results from a human activity or process.
• Municipal Solid Waste – non-liguid waste that comes
from homes, institutions, and small businesses.
• Industrial Solid waste – includes waste from production
of consumer goods, mining, agriculture, and petroleum
extraction and refining.
• Hazardous Waste – refers to solid or liquid waste that is
toxic, chemically reactive, flammable, or corrosive.
(paint, household cleaners, medical waste, industrial
solvents)
Aims for Managing Waste
• Waste can degrade
– Water
– Soil
– Human health
– Environment
• Waste Stream – the flow of waste as it moves
from its sources toward disposal destinations.
Can be recycled, incinerated, placed in a solid
waste landfill or disposed of in another way.
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A large dump in Manila, Philippines. Throughout the
world, impoverished people scavenge dumps.
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MSW composition in the United States in 2008 by category.
E-Waste
• Electronic waste or e-waste, is one
component of MSW that is small by weight
but very important and rapidly increasing.
• E-waste includes televisions, computers,
portable music players, and cell phones.
• E-waste often has heavy metals such as lead,
mercury and cadmium.
• Lots of e-waste is being recycled and in doing
so, the people who are taking them apart are
at risk of working with hazardous substances
• Much of our e-waste gets shipped over-seas
and the disassembly is done by poor workers
with minimal safety regulations.
• “Environmental Justice Concern”
• The cathode ray tubes in TV’s and computers
represent the second largest source of lead in
landfills.
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E-waste being recycled in China. Much of the recycling is
done without protective gear and respirators that would
typically be used in the U.S.
Three Components of Waste
Management
• Minimizing the amount of waste we generate
• Recovering waste materials and finding ways
to recycle them
• Disposing of waste safely
The three Rs
Reduce, Reuse, Recycle
• Reduce- waste minimization or
prevention
• Reuse- reusing something like a
disposable cup more than once
• Recycle- materials are collected and
converted into raw materials and then
used to produce new objects
The three Rs
Reduce, Reuse, Recycle
• Closed-loop recycling is the recycling of
product into the same product. An example
is an aluminum can. This process is called
closed loop because in theory, it is possible to
keep making aluminum cans from only old
aluminum cans.
• Open –loop recycling is the recycling of one
product such as plastic soda bottles into
another product, such as a polar fleece jacket.
Minimizing
– Source reduction
– Manufactures could use materials more efficiently
– Consumers can buy fewer goods, less packaging
and use goods longer
– Reuse goods, buy used and donate used
Reducing Waste is a Better Option
• Reducing is the best way to avoid cost of
disposal and all the environmental issues that
go along with disposal.
• Source Reduction – preventing waste
generation
• Much of waste comes from package
– Buy unwrapped fruit and vegetables
– Buy in bulk
– Use recycled goods
– Use re-usable bags to shop with instead of plastic
Recovering Waste Materials
• Recovery – recycling and composting is viewed as
the next best strategy in management.
• Recycling – sending goods to facilities that extract
and reprocess raw materials to manufacture new
goods. (newspapers, white paper, cardboard,
glass, metal cans, appliances and some plastic
containers.
• Today about 30% of waste is recycled
• New technologies have been developed for
recycling.
Recycling Consists of Three Steps
• Recycling – consists of collecting materials that
can be broken down and reprocessed to
manufacture new items.
• Step 1 – collecting and processing the materials.
Materials are taken to a Materials Recovery
Facility (MRF’s)
• Step 2 – Sorting, cleaning and preparing for
reprocessing
• Step 3 – Manufacturing new goods and
purchasing by the public
Recycling
United States Recycling Rates
Recycling has grown rapidly and can
expand further
• Thousands of curbside recycling programs
exist today
• More then 500 MRF’s are in operation.
• In the United Sates recycling has risen from
6.4% to 23.8%.
Reuse is the major strategy for waste
reduction
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Substitute disposal goods for durable goods
Bring your own coffee mug
Bring your own shopping bags
Buy used cloths
By used cars
Canadian City Showcases Reduction
and Recycling
• Edmonton, Alberta has created one of the
worlds most advanced waste management
programs
• 85% of the city’s waste was being landfilled
and space was running out.
• Today, 35% goes to landfills, 50% is composted
and 15% is recycled.
• 81% of the cities citizens participate in
curbside recycling.
State of the Art Recycling and Refuse
Center
Composting
• Biological decomposition – the recovery of
organic waste. Organic material that has
decomposed under controlled conditions to
produce an organic-rich material
Composting
• Composting is the conversion of organic waste
into mulch or humus through natural
biological process of decomposition.
• Compost can be used to enrich soil.
• Compost can be in underground pits, pile or
constructed containers
• Things that can be composted – non meat
foods, coffee grounds, grass clippings, leaves
and many other items.
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Composting
Municipal composting facility. A typical facility collects
almost 100,000 metric tons of food scraps and paper per year
and turns it into usable compost.
Financial incentives can help address
waste
• Economic incentives to reduce such as “pay-asyou-throw” approach to garbage collection, uses
financial incentive to change consumer behavior.
• “Bottle bills” 11 states have these laws to allow
return for cash of bottles.
• Bottle bills – designed to cut down on litter.
• Challenges - (1) amendments to the bottle laws
needs to include newer type of containers. Such
as colored bottles (2) adjust refunds on bottles
for inflation
Waste Disposal Methods
• Burying waste in landfills
• Burning waste in incinerators
Currently, most solid waste is
buried in landfills or incinerated
• Sanitary landfills- engineered ground
facilities designed to hold MSW with as
little contamination of the surrounding
environment as possible.
• Leachate- the water that leaches through
the solid waste and removes various
chemical compounds with which it comes
into contact.
Municipal Solid Waste
• Municipal waste varies from place to place.
– In the United States, paper, yard debris food
scraps and plastics are components of municipal
solid waste (71%).
• Most solid waste comes from packaging and
nondurable goods.
• U.S leads the world in solid waste followed by
– Canada and the Netherlands.
Municipal Waste
Waste generations is rising in all
nations
• Waste generations has been increasing since
1960.
• Per capita waste has risen 69%.
• More and more developing nations are
increasing their solid waste.
• Over the past 3 decades, per capita waste
generation rates have more than doubled.
Open dumping of the past has given
way to improved disposal methods
• There use to be open dumping and burning of
waste. This still exists in some areas of the
world.
• Some people scavenge on dumps and then
sell trash to make money.
• Many nations have improved their methods of
waste disposal.
• Most industrial nations now bury waste in a
lined and covered landfill.
• Dump – is unlined
• Sanitary Landfill – are capped after they have
reached there permitted level.
Unlined Dump
Lined Landfill
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Modern Sanitary Landfill
Landfill constructed today has many features to keep
components of the solid waste from entering soil, water
table or nearby streams.
Sanitary landfills are regulated by
health and environmental guidelines
• Designed to prevent waste from contaminating
the environment and threatening public health.
• Landfills in the United States are regulated
locally and by the State but also must meet
national standards set by the U.S.
Environmental Protection Agency (EPA)
Modern Sanitary Landfill
• A municipality or private enterprise constructs a
landfill at a tremendous cost. These costs are
recovered by charging a fee, called a tipping fee.
• Tipping fees at solid waste landfills average $35 per
ton in the U.S., although in certain regions, such as
the Northeast, fees can be twice as much.
• These fees create an economic incentive to reduce
the amount of waste that goes to the landfill.
• The EPA regulates landfills under the Resource
Conservation and Recovery Act (RCRA).
• RCRA enacted in 1976 and amended in 1984.
How Landfills Work
• Waste is partially decomposed by bacteria and
compresses under its own weight.
• Waste is layered along with soil, this limits
odor
• Limiting infiltrations allows for biodegradation
by aerobic and anaerobic bacteria.
How Landfills Work
“Continued”
• Landfills are required to be located away from
wetlands and earth-quake-prone faults and 6
feet above the water table.
• Bottoms and sides must be lined with heavy
plastic and up to 4 ft of impermeable clay to
help prevent contaminants from seeping into
aquifers.
• A system of pipes are used to gather leachate
– liquid that results when substances from the
trash dissolves in water as rainwater
percolates down.
Landfill layers
Landfill Closure
• After a landfill is closed, it is capped with an
engineered cover that must be maintained.
• The cap is a hydraulic barrier of plastic that
prevents water from seeping down and from
gas seeping up.
• Methane gas is produced by the
decompositions that takes place in the landfill.
• This gas can be extracted and used as a source
of energy when burned.
Landfill Cap
Methane Collection System
Landfills can Produce Gas for Energy
• Anaerobic decomposition that takes in
landfills produces Methane as a by-product.
• This can be used collected, processed and
used the same way as natural gas.
Landfill Transformation After Closure
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Some get converted to public parks
Shea Stadium
Queens Museum of Art
New York Hall of Science
Queens Botanical Gardens
Playgrounds
Some Problems with Landfills
• Liners can be punctured and leachate collection
systems are not maintained.
• Problems with decomposition
• Finding suitable areas to locate landfills because
many communities do not want them (NIMBY).
• Disproportionate amount of landfills are located
in poor and minority communities.
• Landfills produce methane and it can be explosive
if not handled correctly
Incinerating Trash Reduces Pressure
on Landfills
• Incinerators are specially constructed facilities that may
be an improvement over open –air burning of trash.
• Incineration – is the combustion or burning waste
materials to reduce its volume and mass and
sometimes to generate electricity and heat
• Waste is sorted and metals are removed.
• Emissions from incineration can be a health threat.
• Scrubbers – chemically treat the gasses produced in
combustion to treat the hazardous components.
• Neutralize acidic gases such as sulfur dioxide and
hydrochloric acid turning them into water and salt.
Incineration basics
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Ash – is the residual nonorganic material that does not
combust during incineration.
Residue collected underneath the furnace is known as
bottom ash and residue collected beyond the furnace is
called fly ash.
Disposal of this ash is determined by its concentration of
toxic metals.
When heat generated by incineration is used rather than
released to the atmosphere, it is known as a waste-toenergy system.
How Scrubbers Work
• A liquid containing a solution to neutralize the
gases is sprayed or the gases are passed
through dry lime.
Trash to Steam Plant
Particulate Removal
• Particulate matter is physically removed from
incinerator emissions in a system of huge
filters known as a Baghouse.
• The particles called fly ash often contain some
of the worst dioxin and heavy metal
pollutants.
• Burning garbage at very high temperatures
can destroy pollutants such as PCB’s.
• However, you can not fully eliminate toxic
emissions.
Many incinerators burn waste to generate
energy.
Waste-to energy or Trash to Steam
- using the heat produced to boil water, creating
steam that drives electricity generation or that
fuels heating systems.
Some Problems with
Incineration
• Tipping fees for incinerating trash
• Releases air pollutants such as organic
compounds from incomplete combustion of
plastics and metals.
• Ash is often toxic and must be disposed of
properly.
• Incinerators may not completely burn all the
waste deposited in them.
Industrial Solid Waste
• Regulation and economics influence industrial
waste generation.
– 7.6 billion tons of industrial waste is generated
each year, 97% is wastewater
– Strategies for industrial waste are the same for
municipal
– Regulations vary greatly State by State
– Raising cost of disposal enhances the finacial
incentive to reduce.
Hazardous Waste
• Hazardous waste are diverse in their chemical
composition and may be liquid, solid, or gaseous
that are harmful to humans and ecosystems.
• EPA definition – Hazardous is waste that is one of
following:
– Ignitable – substances that easily catch fire
– Corrosive – substances that corrode metals in storage
tanks or equipment
– Reactive – substances that chemically unstable and
readily react with other compounds, often explosive or by
producing noxious fumes
– Toxic – substances that harm human health when they
are inhaled, are ingested, or contact human skin
Hazardous waste have diverse sources
• Industry, mining, household, small businesses,
agriculture, utilities, and building demolition all
create hazardous waste.
• Industry produces the largest amounts of
hazardous waste, but in most developed nations
industrial waste generation and disposal is highly
regulated.
• Organic compounds and heavy metals are the
two most hazardous groups of industrial
chemicals.
Organic Compounds and Heavy Metals
• We use a lot of synthetic organic compounds
and petroleum products.
• Plastic containers, rubber tires, pesticides,
solvents and wood preservatives resist
decomposition.
• Many synthetic compounds are toxic because
they can be absorbed through the skin.
• Many act as mutagens, carcinogens,
teratogens and endocrine disruptors.
Heavy Metals
• Lead, chromium, mercury, arsenic, cadmium,
tin and copper are widely used in industry
especially in electronics fabrication.
• Heavy metals enter the environment when
batteries, paints, electronic devices and other
materials are disposed of .
• Heavy metals are fat soluble, break down
slowly and can bioaccumulate in our food web
system.
Several Steps Precede the Disposal of
Hazardous Waste
• Under the Resource Conservation and Recovery
Act, the EPA sets standards for states to manage
hazardous waste.
• Large generators of hazardous waste to obtain
permits and mandates the hazardous materials
be tracked from “cradle to Grave”
• This means at each step of transportation and
disposal facility, a report must be sent to the EPA
listing the amount and type of material generated
• This is intended to stop illegal dumping
• Because of the cost to dump hazardous waste,
sometimes companies dump illegally.
• Good thing is the high cost of dumping has
mad more businesses to invest in reducing
their hazardous waste.
Three Disposal Methods for Hazardous Waste
• Landfills
• Surface Impoundments
• Injection Wells
• The three methods do not lesson the hazards
but it does isolate it from people.
• Landfills that take hazardous waste have much
stricter design and constructions standards
then regular landfills.
– Several impervious liners
– Leachate removal systems must be located far
from aquifers
• Liquid hazardous waste goes to surface
impoundment – shallow depressions lined
with plastic and impervious material such as
clay
Surface Impoundment
• Water containing dilute hazardous waste is put
into the ponds and then it evaporates, leaving the
residue of the solid hazardous waste on the
bottom.
• The dry material then get landfilled
• Deep-well injection – this is a well that is drilled
deep beneath the water table into porous rock,
and wastes are injected into it.
• The waste is supposed to stay deep underground
away from groundwater and human contact.
• Problem – wells corrode and leak waste into soil,
and then into aquifers.
Deep Injection Well
Radioactive Waste is Especially
Hazardous
• In New Mexico is the first underground
repository for nuclear waste
• The caverns are 655 meters below the surface
in a huge salt formation which is thought to be
geologically stable
Laws
• Resource Conservation and Recovery Act
(RCRA)- designed to reduce or eliminate
hazardous waste. Also known as “cradle-tograve” tracking.
• RCRA ensures that hazardous waste is
tracked and properly disposed of.
• In 1976, the RCRA’s main goal was to protect
human health and the environment by
reducing or eliminating the generation of
hazardous waste.
Laws
• Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA)- also
know as “Superfund”.
• Puts a tax on the chemical and petroleum
industries. This revenue is used to cleanup
abandoned and non-operating hazardous waste
sites where a responsible party cannot be found.
• Requires the federal government to respond
directly to the release of substance that may pose a
threat to human health or the environment.
Contaminated Site are Being Cleaned
Up slowly
• Thousands of former military and industrial
sites remain contaminated with hazardous
waste.
• Comprehensive Environmental Response
Compensation and Liability Act (CERCLA) –
1980. This was created to clean up sites
polluted with hazardous waste from past sites.
• EPA administers the clean program called
Superfund.
Superfund
• Under the EPA, sites are identified in order to
protect groundwater near these sites and
clean up pollution.
• EPA is also in charge of cleaning up
Brownfields – these are land whose reuse or
development are complicated by the presence
of hazardous materials.
Brownfields
• Contaminated industrial or commercial sites
that may require environmental cleanup
before they can be redeveloped or expanded.
• Many brownfields include old factories,
industrial areas and waterfronts, dry
cleaners, gas stations, landfills, and rail
yards.
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Laws
Map showing distribution of NPL (Superfund) sites in the
U.S. The EPA maintains the NPL of contaminated sites
that are eligible for cleanup funds.
National Priorities
List (NPL) has
more than 1,200
sites throughout
the U.S. Most well
known NPL site
could be Love
Canal, New York.
Two Publicized Cases Spurred the
Creation of Superfund
• Love Canal – a residential neighborhood in
Niagara Falls where toxic chemicals were
buried by a company decades before.
• Times Beach – In Missouri, was an area
contaminated with dioxin from buried waste
oil.
Love Canal Superfund Site
Integrated Waste
Management
• A method that seeks to develop as many
options as possible, to reduce environmental
harm and cost.
• Reduction, recycling, composting, landfills,
and incineration are some ways IWM is
utilized.
• The book Cradle to Cradle argues that it is first
necessary to assess existing practices in order
to minimize waste generation before, during,
and after manufacturing.