Page 66 - Solid Waste Analysis and Minimization a Systems Approach

44 BACKGROUND AND FUNDAMENTALS OF SOLID WASTE ANALYSIS AND MINIMIZATION

pesticides, solvents, and heavy metals may also be present. Modern landfill sites
require that the landfill leachate be collected and treated. Since there is no method to
ensure that rainwater cannot enter the landfill site, landfill sites must now have an
impermeable layer at the bottom. The landfill leachate that collects at the bottom must
be monitored and treated if required. This liquid can be treated in a similar manner to
sewage, and the treated water can then be safely released into the environment.
■ Global warming—One study reports that U.S. landfills are responsible for 3.8 percent
of the global warming damage from human sources in the United States. Municipal
solid waste landfills are the largest source of human-related methane emissions in
the United States, accounting for about 25 percent of these emissions in 2004
(www.epa.gov, 2005). This gas consists of about 50 percent methane (CH ), the
4
primary component of natural gas, about 50 percent carbon dioxide (CO ), and a
2
small amount of nonmethane organic compounds. In 2003, U.S. landfills generated
131.2 teragrams methane in terms of carbon dioxide equivalents (where 1 teragram
represents 1 million metric tons). Reducing the amounts of solid waste disposed
in landfills would reduce methane generation and subsequently reduce global
warming.
■ Consumption of natural resources—A large component of solid waste minimiza-
tion is recycling. Recycling reduces the consumption of virgin natural resources by
utilizing perceived waste materials. For example, production of recycled paper uses
80 percent less water and 65 percent less energy, and produces 95 percent less air
pollution than virgin paper production. If every American recycled their newspaper
just 1 day a week, the United States would save approximately 36 million trees a
year. For every 4-ft stack of paper recycled, one tree is saved and deforestation is
minimized. Recycling also reduced environmental impacts due to mining. For
example, by recycling aluminum, the need for the raw mineral bauxite is elimi-
nated, which in turn eliminates the need for bauxite mining and smelting.
■ Loss of habitat—Although it is difficult to accurately quantify habitat loss, many
animal species are displaced by the creation of landfills and the effects of defor-
estation. By minimizing solid waste levels and increasing recycling, available habi-
tats for animals will not be disrupted due to development or expansion of landfills
and the effects of deforestation to acquire virgin raw materials.

2.6 Industrial Ecology and

Solid Waste Exchanges

2.6.1 INTRODUCTION

Industrial ecology is the field of research that studies waste generation from a
macro level for all industries. From a solid waste standpoint, industrial ecology is
concerned with the conversion or reuse of undesirable materials into something
useful for another company or industry, in other words: waste exchanges and material