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4 Characterization of Solid Waste

4.1 INTRODUCTION
In order for a community to formulate an integrated solid waste management program, accurate and
reliable data on waste composition and quantities are essential. Such data will encourage well -
organized and smoothly functioning recycling programs; foster the optimal design and operation of
materials recovery facilities and municipal incinerators; and, ultimately, reduce the amount of waste
generated and keep the overall waste management costs low.
Knowledge of the chemical composition of MSW will guide engineers and scientists of its util-
ity as a fuel and will also help in predicting the makeup of gaseous emissions after incineration as
well as of possible hazardous substances occurring in the ash. Waste composition will provide infor-
mation on the utility of the material for composting or for biological conversion into biogas fuel. In
addition, given that the majority of U.S. municipal solid waste (MSW) is disposed of in landfills,
knowledge of chemical composition will help in predicting leachate composition and necessary
treatment options. The physical properties of MSW will indicate ease of transport, processing
requirements, combustion characteristics, and a rough prediction of landfill lifetime.

4.2 SAMPLING PROTOCOLS FOR MSW

MSW consists of a wide range of materials that vary depending on the community and its consumers’
income and lifestyles, its degree of industrialization, institutionalism, and commercialism. Given these
variables, several protocols can be followed to estimate the MSW composition for an area.
In order to compile accurate data, several issues must be addressed (Rhyner et al., 1995):

● How to obtain representative samples of the MSW?
● What is the desired sample size?
● How many samples are needed to achieve a desired level of accuracy?

4.2.1 DIRECT SAMPLING
Direct sampling is useful on a small scale for obtaining information about MSW composition. The
direct sampling method involves physically sampling and sorting MSW at the source of generation.
Although MSW can be extremely heterogeneous, direct sampling is one of the more accurate char-
acterization methods. In order to make accurate judgments as to composition, sorting and analysis
should be conducted in several randomly selected locations within the community. Waste sampling
from single- and multi-family homes, commercial establishments (restaurants and businesses), and
institutions (schools, hospitals) is encouraged, as these inputs create local variations.
Another direct sampling approach is to sample the waste after it has arrived at a centralized col-
lection point or a tipping (i.e., unloading) area. This may include a transfer station or disposal facility.
ASTM Method D5231-92 (ASTM, 1998) calls for a sample size of 91 to 136 kg (200 to 300 lb) to
be manually sorted at the disposal facility. Whether at the source or a disposal facility, the degree
of sorting is a function of the number of product categories desired. For example, if a composting
program is to be instituted, a sorting scheme might include organic and inorganic materials only.
Alternatively, food and yard wastes, the highest quality compost feedstock, can be separated from

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