38-54 Solid Waste Disposal

APES 2024

Solid waste

Solid waste

any discarded material that is not a liquid or gas

• Generated in domestic, industrial, business and agricultural sectors

• Most often disposed of in landfills

Solid waste

Landfills can lead to

groundwater contamination and release harmful
gases

Hazardous waste is a liquid, solid, or gas and is one of the following

• Ignitable

• Corrosive

• Reactive

• Toxic

Ignitable

easily catches fire (natural gas, alcohol)

Corrosive

corrodes metals in storage tanks or equipment

Reactive

chemically unstable and readily reacts with other
compounds, often explosively or by producing noxious fumes

Toxic

harms human health when inhaled, ingested, or
contact human skin

In the U.S., paper, yard debris, food scraps, and plastics are the

principal components of municipal solid waste

Most solid waste is

paper

In developing countries, food scraps are

the primary contributor to solid waste

Most municipal solid waste comes from

packaging and nondurable goods

U.S. citizens generate

1 ton/person each year

Sanitary municipal landfills have

• A bottom liner (plastic or clay)

• Storm water collection system

• A leachate collection system

• A cap

• A methane collection system

Sanitary landfills

waste buried in the ground or piled in large, engineered mounds to prevent contamination and health threats

Waste is partly decomposed by

bacteria and compresses under its own weight to make more space

Soil layers reduce

odor, speed decomposition, reduce infestation
by pets

Closed landfills must be

capped and maintained

Leachate

liquid from trash dissolved by rainwater
- collected and treated in landfills
- can escape if the liner is punctured

To protect against environmental contamination, landfills must be located

away from wetlands and earthquake-prone faults, and be 20 ft above the water table

Incineration

a controlled process that burns garbage at very high temperatures

In specially constructed faculties inicineration can be

an improvement over open-air burning of trash

Remaining ash from incineration must be disposed of in a

hazardous waste landfill

• Hazardous chemicals are created and released

Scrubbers

chemically treat the gases produced in combustion
• Remove hazardous parts and neutralize acidic gases

Waste-to-energy (WTE) facilities

use the heat produced by waste combustion to create electricity
• over 100 facilities are in use across the U.S.
• process nearly 100,000 tons of waste per day
• takes many years to become profitable
• reduces the volume of waste and can generate electricity

Bacteria decompose waste in a landfill’s

oxygen-deficient environment

Landfill gas

a mix of gases that consists of 50% methane
• Can be collected, processed, and used like natural gas

When not used commercially, landfill gas is burned
off to

reduce odors and greenhouse emissions

“Pay-as-you-throw” approach

uses financial incentives to influence consumer behavior

The less waste a house generates, the less it is

charged for trash collection

Bottle bills

consumers receive a refund for returning used bottles
• successful but beverage industries and groceries fight them

Electronic waste (“e-waste”)

waste involving electronic devices
• Ex. computers, printers, cell phones, TVs,
MP3 players

Americans discard how many decices per year?

400 million (67% are still in working order)

E-waste is put into landfills but

should be treated as hazardous waste

Resource Conservation and Recovery Act (RCRA)

states must manage hazardous waste

Large generators of hazardous waste must obtain permits

• Materials must be tracked “from cradle to grave”

• Intended to prevent illegal dumping

Comprehensive Environmental Response Compensation and Liability Act (CERCLA) (1980)

• Superfund is administered by the EPA

• Established a federal program to clean up U.S. sites polluted with hazardous waste

Brownfields are similar to Superfund sites because they both are

contaminated industrial or commercial sites that may require cleanup before they can be redeveloped or expanded
• Program created in 1995 for cleanup

Two events spurred creation of Superfund legislation

• Love Canal, Niagara Falls, New York

• Times Beach, Missouri

Love Canal, Niagara Falls, NY

1978–1980, families were evacuated after buried chemicals rose to the surface

Times Beach, Missouri

evacuated after contamination with dioxin from oil sprayed on roads

Waste Reduction methods

• Reduce, reuse, recycle

• Recycling

• Composting

Recycling

process by which certain solid waste materials are
processed and converted into new products
• Can be energy intensive and expensive

Composting

process of organic matter such as food scraps, paper and yard waste decomposing
• Product of decomposition can be used as fertilizer
• Drawbacks include odor and rodents

E-waste can be reduced by

recycling and reuse

E-waste may contain

hazardous chemicals including heavy metals such as lead and mercury

The heavy metals can

leach from landfills into the groundwater if not disposed of properly