Environmental Engineering Reference
In-Depth Information
traditional plastic bottles take many hundreds of years to degrade in a
landfi ll, its bottles can biodegrade within eighty days in a commercial
composting operation. The bottles are safe on store shelves because they
degrade only when they have been emptied and placed in composting
conditions, where high heat and humidity, as well as microorganisms,
eat them. Unfortunately, Biota declared bankruptcy in 2007 for reasons
unrelated to its eco-friendly bottle.
Tires
Another seemingly indestructible product used by almost every adult
in the United States is the automobile tire. Worldwide, about 1 billion
tires are sold annually, and eventually all are discarded. However, forty-
four states will not accept them in landfi lls because they have large
volumes but 75 percent void space. In addition, their concavity traps
methane gas generated by other garbage, and when they catch fi re they
burn uncontrollably, spewing black pollutants. In August 1998, a grass
fi re ignited 7 million tires in the San Joaquin Valley of California,
sending a plume of soot and noxious gas thousands of feet into the air
and burning for two and a half years. Cleanup took years and cost
$19 million.
Every year Americans discard 300 million tires whose 0.2 inch of
tread has worn off—about one tire for every man, woman, and child
in the country. About 45 million tires are used to make 25 million
retreads. Thirty percent of scrap tires are recycled for commercial pur-
poses, such as construction materials in roads and sidewalks, insulation,
and fuel for power plants and cement kilns. About half of the reclaimed
tires in the United States are burned for fuel. But burning a tire yields
only one-sixth of the energy used to make it, and 85 percent of a tire
is carbon, making tires a signifi cant source of carbon dioxide emissions.
They can be burned at temperatures high enough to destroy most organic
pollutants.
Environmental Benefi ts
Recycling has environmental benefi ts at every stage in the life cycle of
the products we use. Any time you make new stuff out of old stuff,
less energy, fewer chemicals, and less water are used. Recycling also
does more than reduce greenhouse gas emissions; it reduces air and
water pollution associated with making new products from raw materi-
als. Recycling trash leads to better health for all Americans, as well as
generating a more sustainable economy.
