Environmental Engineering Reference
In-Depth Information
Solano et al. (2002a, 2002b) developed a comprehensive life-cycle-based
model for solid waste management. The model can be used to identify
solid waste management alternatives with the consideration of cost, energy
consumption, and environmental emissions.
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ENVIRONMENTAL IMPACT OF MSW AND LIFE-CYCLE
ASSESSMENT
The public and private sectors in the United States have come to realize the
importance of addressing the long-term consequences of solid waste management.
Providing our society with goods and services generates MSW and the associated
environmental impacts. For example, anaerobic processes in a landfill generate
leachate and gases, including carbon dioxide (CO 2 ) and methane (CH 4 ). The
leachate can cause water contamination, and both gases cause global warming.
Although the U.S. EPA estimated that roughly 60-90 percent of the methane
emitted from the landfill can be captured by a landfill gas extraction project,
only less than 20 percent of the landfills in the United States have actually
implemented the extraction project (U.S. EPA 2008). Incineration, by contrast,
causes air pollution and the disposal problems of the fly ash and bottom ash that
may contain toxic metals. Sustainable development requires methods and tools to
measure and compare these environmental impacts. Life-cycle assessment (LCA)
has been used in the past as a tool for examining the environmental impacts of
specific products. The purpose of life-cycle assessments (LCA) is to provide an
understanding of the environmental impacts associated with a product, process,
or activity. Life-cycle assessment is made up in four stages, which are used to
calculate the environmental impacts for newsprint, office paper, and paperboard.
The four major stages of the LCA are the goal definition, inventory, impact
assessment, and valuation assessment (Craighill and Powell 1996).
The use of LCA in solid waste management has resulted in evaluating and
comparing alternative disposal systems in regards to minimizing the environ-
mental impacts associated with disposal techniques. Arena et al. (2003) adopted
a life-cycle inventory aimed at identifying and quantifying the environmental
burdens or impacts. The results indicate that recycling of solid waste is always
environmentally preferable and that energy recovery from the processed materials
is possible. Mendes et al. (2003) employed LCA and assessed the environmental
impact of landfilling, composting, and biological treatment for the biodegradable
fraction of MSW.
LCA was employed for the evaluation of technology such as recycling as an
alternative to existing landfilling practices. Craighill and Powell (1996) indicated
that landfilling contributed to greater global warming of greenhouse gas emissions
than recycling. Nakamura (1999) observed that recycling is an effective way of
achieving a reduction in the amount of waste and emissions. Recycling reduces
the CO 2 emissions even when the efficiency of collection of waste is low, which
 
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