406 CHAPTER 16 Solid and Hazardous Waste
consumer demand. In addition to a slow increase in paper
recycling in the United States, there is a growing demand
for U.S. waste paper in other countries. China, Mexico,
Taiwan, and Korea import large quantities of waste paper
and cardboard from the United States.Recycling Glass The United States currently recycles
about 33 percent of its glass containers. Recycled glass
costs less than glass made from virgin materials. Glass food
and beverage containers are crushed to form cullet, which
glass manufacturers can use to make new products. Cullet
is more valuable when glass containers of different colors
are separated before being crushed (Figure 16.9b).Recycling Metals The recycling of aluminum is
one of the best success stories in U.S. recycling, largely
because of economic factors (Figure 16.9c). Making a
new aluminum can from a recycled one requires a frac-
tion of the energy it would take to make a new can from
raw metal (Figure 16.9d). According to the EPA, in
2010, about 49 percent of discarded aluminum beverage
cans were recycled.
Other recyclable metals include lead, gold, iron and
steel, silver, and zinc. For example, according to the Insti-
tute of Scrap Recycling Industries, new steel products
contain an average of 56 percent recycled scrap steel.
One of the obstacles to recycling metal products dis-
carded in municipal solid waste is that their metallic com-
positions are often unknown. It is also difficult to extract
metal from products such as stoves that contain materials
besides metal (plastic, rubber, or glass, for instance).Recycling Plastic About 12 percent of plastic con-
tainers and packaging in the United States is recycled.
Depending on the economic situation, it is sometimes less
expensive to make plastic from raw materials (petroleum
and natural gas) than to recycle it. Some local and state
governments support or require the recycling of plastic.
According to the EPA, 37 percent of soft drink and water
bottles are recycled annually to make such diverse prod-
ucts as carpet, automobile parts, tennis ball felt, and poly-
ester cloth. One of the challenges associated with recycling
plastic is that there are many different kinds. Forty-six dif-
ferent plastics are common in consumer products, and
many products contain multiple kinds of plastic that must
be separated or sorted before they can be recycled.Recycling Tires Recycled tires are used for only a few
products: retread tires; playground equipment; trash cans,have environmental costs: Like all other human activities,
it uses energy and generates pollution. For example, the
de-inking process in paper recycling requires energy and
produces a toxic sludge that contains heavy metals.
The many different materials in municipal solid
waste must be separated before recycling. The separation
of materials in items with complex compositions is dif-
ficult. Some food containers are composed of thin layers
of metal foil, plastic, and paper, and trying to separate
these layers is a daunting prospect.
The number of communities with recycling programs
increased remarkably during the 1990s but leveled off
somewhat in the early 2000s. Recycling programs include
curbside collection, drop-off centers, buy-back programs,
and deposit systems. In 2010 the annual recycling rate of
aluminum and steel cans, plastic bottles, glass containers,
newspapers, and cardboard was 248 kg (557 lb) per person.
Recyclables are usually sent to a materials recovery
facility, where they are sorted and prepared for remanu-
facturing. Currently, the United States recycles about 34
percent of its municipal solid waste, including composting
of yard trimmings; this percentage is higher than in most
other highly developed nations (Figure 16.9a). (Recall,
however, that the United States also generates more
municipal solid waste than any other country.)
Most people think recycling involves merely separating
certain materials from the solid waste stream, but that is
only the first step. For recycling to work, there must be a
market for the recycled goods, and the recycled products
must be used in preference to virgin products. Prices paid
by processors for recyclable materials vary significantly from
one year to the next, depending largely on the demand for
recycled products. In some places, recycling—particularly
curbside collection—is not economically feasible.
Greater recycling generally occurs when the econ-
omy is strong, and the amount of recycling nationwide
varies from year to year. Thus, although the amount of
municipal solid waste generated is fairly constant, the
amount of recycling varies.
Recycling Paper The United States currently recycles
about 72 percent of its paper and paperboard. Many highly
developed countries have higher recycling rates. Den-
mark, for example, recycles 97 percent of its paper. Part of
the reason paper is not recycled more in the United States
is that many older paper mills are not equipped to process
waste paper. The number of mills that can process waste
paper has increased in recent years, in part because of