Decomposition and Landfill Gases
Emanuel Gutierrez
December 6, 2007
Every time I take a trip to the landfill with my dad I always wonder if
there is anything that all that trash can be used for. I read an article online
about a new power plant in east Texas that is going to use gases from
decomposed garbage to produce energy. I wondered what types of landfill
materials would produce the most gases during the decomposition process. I
researched decomposition gases in landfills to find out more about this idea.
In America today people produce four pounds of trash per day per
person. That’s 210 million tons of garbage each year! Some of the trash is
recycled or burned, but most of the trash is buried in landfills.
Most of the trash buried in landfills is paper (32.2%), yard waste
(13.7%), and plastics (11.8%). Woods, metals, food wastes, glass, and other
products are also placed in landfills.
A landfill is a carefully designed structure in or on top of the ground.
The most important thing about a landfill is that it must keep wastes from
the water supply.
When trash is put into a landfill it is covered with soil. There is very
little moisture and very little oxygen. Over time the wastes break down
because of decomposing organisms called bacteria. The bacteria breaks
down chemicals in the trash and converts them into other substances.
Some of the substances produced are gases. The main gases given off
by decomposing garbage are carbon dioxide, hydrogen, methane, nitrogen,
and oxygen. After time, most of the landfill gas is methane (50%) and
carbon dioxide. Methane gas can explode or burn, so the gas must be vented
or burned. Recently it has been recognized that methane gas is a usable
energy source. The gas can be collected and used as a fuel.
In my science project I will test what landfill materials will produce
the most gases during the decomposing process. Knowing this information
could help energy companies decide what products it would allow into its
landfills.
Bibliography
Cooney, Dr. Timothy: Scott Foresman Science for Texas. USA: Addison-Wesley Educational Publishers, Inc., 2000.
“Gases and Decay”. World Book’s Young Scientist. 1990 ed.
“How Landfills Work”. Online posting. How Stuff Works. December 2, 2007.
“Fun Facts About Fungi”. Online posting. December 2, 2007. usu.edu/fungi/FunFacts/Decay.htm
“SRP Makes Methane Magic Using Gas Produced at Landfill”. Energy Services Bulletin. Online posting. December 4, 2007.
Glossary
Bacteria—organisms having only one cell, each visible only through a microscope—can be helpful (enriching the soil and ripening cheeses) or harmful (cause serious diseases)
Carbon Dioxide—an odorless, colorless, gaseous compound of carbon and oxygen
Decompose—to decay or rot, to break down into its basic parts or elements
Hydrogen—the lightest of the elements, a colorless, odorless, highly flammable gas, found mainly in combination with oxygen as water
Landfill—a carefully designed structure in or on top of the ground used to hold garbage
Methane—a colorless, odorless gas that burns easily and is a main part of the gas used for cooking, formed by decaying matter
Nitrogen—an odorless, colorless, gaseous element that makes up nearly four-fifths of the earth’s atmosphere, forms many useful compounds and is a necessary element in all living things