Environmental Engineering Reference
In-Depth Information
2
SOURCES AND COMPOSITION OF MUNICIPAL SOLID
WA S T E
Municipal solid waste (MSW) is a diverse classification that includes residential,
commercial, and institutional waste. Residential facilities are single and multi-
family dwellings, as well as high-rise apartments and dormitory-style housing.
Residential waste typically includes paper, aluminum cans, ferrous materials,
glass, wood, and yard waste. Commercial waste is produced from stores, office
buildings, restaurants, and other businesses. These commercial facilities can
produce waste that includes paper, cardboard, glass, metals, and food waste.
Institutional waste includes waste generated from schools, hospitals, and other
public offices. The waste material from these sources would resemble the waste
from commercial facilities. The waste generated from residential, commercial,
and institutional sites are similar, with the biggest differences being in the per-
centages of each type of waste (Tchobanoglous et al. 1993) (see Table 5.1).
Table 5.1 shows the municipal solid waste generated in the United States from
1960 to 2006. The amount of MSW generated in United States has increased
about 285 percent from 1960 to 2006. However, most of the increases, from
88 to 238 million tons, which is about 270 percent, occurred between 1960
and 2000. Because of the environmental concerns and intensive waste reduc-
tion and recycling effort, the increase between 2000 and 2006 is about 5.5
percent, from 238 to 251 million tons. If the U.S. population increase is taken
into account, most of the increase occurred between 1960 and 1990 and the per
capita solid waste generation since 1990 is between 4.1 to 4.6 pounds per day. In
2006, U.S. residents, businesses, and institutions produced more than 251 million
tons of MSW, which is approximately 4.5 pounds of waste per person per day
(U.S. EPA 2007). Residential waste (including waste from apartment houses)
is estimated to be 55 to 65 percent of the total municipal solid waste genera-
tion, while waste from schools and commercial locations, such as hospitals and
businesses, amounted to 35 to 45 percent.
Table 5.2 shows the typical composition of MSW generated in the United
States from 2000 to 2006 based on Table 5.1. The total MSW generation in 2006
was 251 million tons. Organic materials continue to be the largest component of
MSW. Figure 5.1 illustrates the composition of MSW in 2006. Paper and paper-
board products account for 33.9 percent. Yard trimmings are the second-largest
component at 12.9 percent, followed by the food waste of 12.4 percent. Plastics
are 11.7 percent, metals make up 7.6 percent, and glass accounts for 5.3 percent.
The rest of 16.1 percent comes from wood, textiles, rubber, leather, and other
miscellaneous waste. Figure 5.2 shows the trend of generation and composition
of MSW from 1960 to 2006. Although paper and paperboard products have been
the largest component of the MSW, the amount became steady and does not
show any increase since year 2000. However, the amount of plastics continues
to increase over the years, from less than 1 percent in 1960 to 11.7 percent
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