Environmental Engineering Reference
In-Depth Information
over the years, the average landfill size has increased. At the national level,
the total landfill capacity does not appear to be a problem, although regional
shortages may sometimes occur.
Since 1990, the total volume of MSW going to landfills dropped by 4 million
tons, from 142.3 million to 138.2 million tons in 2006. The net per capita discard
rate (after recycling, composting, and combustion for energy recovery) was 2.53
pounds per person per day, down from 3.12 pounds per person per day in 1990
and the 2.63 pounds per person per day in 2000, and similar to the 2.55 per capita
rate in 2004. The percentage of MSW that was landfilled increased slightly from
2005 to 2006. Over the long term, the tonnage of MSW landfilled in 1990 was
142.3 million tons, but decreased to 134.8 million tons in 2000. The tonnage
declined to 133.3 million tons in 2005, then increased to 135.5 million tons
in 2004.
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SUMMARY OF HISTORICAL MSW MANAGEMENT
As already discussed, MSW generation has grown steadily from 88 million tons
in 1960 to 251 million tons in 2006. Figure 5.5 shows the generation and recovery
trend for the MSW management. Up to 1980, most of the MSW were landfilled,
with a small percentage of recovery from recycling. After 1980, the significant
effort in recycling and combustion with energy recovery reduced the amount
of MSW disposal at landfills. In the meantime, recovery by composting also
increased, although by a relatively smaller amount. If the population is taken into
account, the per capita trend is shown in Figure 5.6. The per capita generation
rate of MSW increased steadily from 1960 to 1990. The generation rate stabilized
and remained at 4.5 lbs per capita per day from 1990 to 2006. The discard rate
increased from 1960 to 1980 and started a decreasing trend after that because
of the increased recycling rate. However, the recovery rate increase slowed and
stabilized around 1.9 lbs per capita per day, and the discard rates stabilized around
2.6 lbs per capita per day. In 2006, 55 percent of the MSW is discarded, 45 percent
was recovered. However, this recovery included 12.5 percent combustion with
energy recovery. Thus, the recovery by recycling and composting was only 32.5
percent of the generated MSW.
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MSW MANAGEMENT IN OTHER COUNTRIES
MSW generation rates depend on the level of economic development, environ-
mental awareness of the population, and cultural and social factors. The amount
of MSW generated is, in general, higher in the industrialized countries. It has
been reported that the MSW generation rate is in the order of 1.6 kg (3.5 lbs) per
person per day in the industrialized world and in the order of 0.8 kg (1.8 lbs) per
person per day in Third World countries (Fehr et al. 2000). This rates are consis-
tent with the data in the IPCC report (IPCC 2006) that list the MSW generation
 
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