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Session 3151
SOLID WASTE MANAGEMENT: COMPARISON OF METHODS
Bahador Ghahramani, Ph.D., P.E., CPE
Engineering Management Department
School of Engineering
University of Missouri - Rolla
Rolla, Missouri 65401-0249 (USA)
E-mail:ghahrama@shuttle.cc.umr.edu
Tel: (573) 341-6057
Fax: (573) 341-6567
ABSTRACT
This paper analyzes the adverse impact of solid waste disposal on the environment using
the relatively new “Tragedy of the Commons” paradigm. The “Tragedy of the Commons”
paradigm is rapidly becoming popular as scientists and environmentalists predict that natural
resources will soon become scarce. The tragedy of the commons is based on the assumption that
an environment that permits perfect and unrestricted freedom of action in activities that are
adversely impacted common well-fare, well-being and properties was eventually doomed to
failure. In addition, we are exponentially polluting the environment with tons of solid waste.
Solid waste disposal is destined to be one of the critical issues in the twenty-first century and will
soon be on the forefront of our global agenda. The environmental scientists and other concerned
groups are gaining strength and publicity -- they are becoming more vigilant in addressing this
highly sensitive issue. The issue at hand is the proper disposal of solid waste and the
maximization of recycling to reduce the consumption rate of the world’s natural resources.
INTRODUCTION
Municipal solid waste (MSW) is defined as waste from residential, commercial,
institutional, and some industrial sources. While our population continues to grow, so does the
total amount of MSW that we generate each year. In fact, the total MSW increased upwards of
250 percent in the past 35 years, from 88 million tons 1960 to over 210 million tons in 1995 that
is discussed in Figure 1.
P
age 3.499.1
230
s 230
s 205
205
180
180
155
155
130
130
Millions of TonMillions of Ton105
105
80
80
1960 1965 1970 1975 1980 1985 1990 1995 2000
1960 1965 1970 1975 1980 1985 1990 1995 2000
Years
Years
MSW Generated (Millions of tons)
MSW Generated (Millions of tons)
FIGURE 1, INCREASED IN MSW.
(Data by the US Environmental Protection Agency)
MSW generation rates are simply estimates, since population and economics are ever
changing. Nonetheless, natural population growth and sustained long-term growth in the
economy will likely increase MSW generation. The EPA projects increase in annual MSW
generation at about the rate of 1.2% annually through the year 2000; 223 million tons of MSW is
estimated for the year 2000.
All of these materials are at least partially recoverable by recycling, but in 1995, only about
21% were recycled, 15% were incinerated (a good portion with energy recovery), 3% composted,
and the remaining 61 % were disposed of in landfills and by other means. To reduce the effort
and expense required managing waste through recycling, incineration, composting, and disposal
in landfills, it is essential to limit waste generation at the source as much as possible -- using the
strategy known as “source reduction”.
BACKGROUND
As the quantity of MSW grows, concern for its safe and efficient management grows too.
Effective waste management requires what is known as an integrated approach -- the
consideration of a number of waste management methods that work compatibly. These waste
management methods include source reduction, recycling, composting, incineration, and sanitary
landfill. Together, these methods effectively manage our nation's waste, while, at the same time,
protecting human health and the environment. This paper examines the technical, social,
economical and environmental justification for an integrated waste management hierarchy. The
hierarchy of methods suggests that it is best to first reduce the generation of waste at the source, P
then to recycle and compost what cannot be reduced, and then incinerate or landfill the age 3.499.2
remainder. Managing waste according to the proposed hierarchy reduces costs and the
environmental impacts in the solid waste system.
BASIC METHODS
Sustainable development is defined as "Development that meets the needs of the present
without compromising the ability of future generations to meet their own needs." There are
numerous ways to interpret what that particular definition means. Therefore, a discussion of solid
waste management will show how controlling solid waste impacts the sustainable development
of the United States. Solid waste management is broken into four basic areas. They are,
landfilling, composting, incineration, and recycling. This paper addresses the four contributors to
solid waste management:
• Landfilling,
• Composting,
• Incineration, and
• Recycling.
There is an increasing concern with regards to the environmental impacts of landfills and a
tremendous amount of money is being spent to investigate alternate means of disposing of solid
waste. However, landfills still comprise the majority of waste disposal in the United States. It is
estimated that 80 percent of all municipal solid waste goes to landfills, 10 percent is recycled, 10
percent incinerated, and a small percent is composted.
LANDFILLS
The environmental concern with landfills is their potential to pollute the groundwater. The
pollutants in the waste can cause health and other environmental problems if allowed to migrate
into the groundwater because 70 percent of the nation's drinking water originates from
groundwater. The pollutants are caused by chemical reactions that make metals become soluble
and migrate when not properly contained in a landfill. Another problem is the production of an
odorless gas called methane. It is an explosive gas produced during the decomposition of organic
material contained in the landfill. This methane gas can kill local vegetation and cause erosion
problems for the containing berms and caps. Also, the gas can migrate to nearby structures
causing a threat of explosion. If there are so many problems, why do we still use landfills in the
United States? A discussion of how they are constructed, their advantages, and disadvantages
will bring to the surface this dilemma.
The only real advantage to landfills is that, in short term, they are very cost effective
relative to the other methods. The average cost per acre of landfill over its entire lifetime is about P
$200,000. This cost is distributed over the entire lifetime by only excavating and utilizing land age 3.499.3
that is needed at that particular time. One initiative is to increase the capacities of the landfills
and to reduce the cost of opening a new one. Table 1 shows that between 1986 to 1991, only
three states have expanded capacity and have more than ten years remaining in their landfills.
Most states have only five years or less remaining.
STATES IN 1986 STATES IN 1991
Less than 5 Years Remaining: Less than 5 Years Remaining:
• Connecticut • Connecticut
• Kentucky • Kentucky
• Massachusetts • New Jersey
• New Jersey • Virginia
• Ohio • West Virginia
• Pennsylvania
• Virginia
• West Virginia
5 to 10 Years Remaining: 5 to 10 Years Remaining:
• Colorado • Massachusetts
• Oklahoma • Ohio
More that 10 Years Remaining: More than 10 Years Remaining:
• Colorado
• Oklahoma
• Pennsylvania
TABLE 1, LANDFILL CAPACITY OF THE STATES.
(EPA Estimates)
There are three basic configurations for landfills:
• Area method,
• Ramp method, and
• Trench method.
The area method consists of reducing the amount and volume of waste in the landfill by
spreading it in layers and covering it. The waste is then compacted by heavy machines and
rollers. This process continues until there is ten to twelve feet of successive layers on top of each
other. At the conclusion of each day the waste is again covered either with soil or a synthetic
cover.
The ramp method is similar to the area method except that it is located on gently sloping P
ground. The ramp method also uses heavy machines and rollers to reduce and manage the waste. age 3.499.4
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