MUNICIPAL SOLID WASTE MANAGEMENT AND DISPOSAL - Environmentally Conscious Materials Handling - page 147

4.9 Glass

Glass is found in MSW primarily in the form of containers but also in durable
goods such as furniture, appliances, and consumer electronics. In the container
category, glass is found in beer and soft drink bottles, wine and liquor bottles,
and bottles and jars for food, cosmetics, and other products. Most recovered glass
containers (bottles) are used to make new glass containers, but a portion goes
to other uses such as fiberglass insulation, aggregate, and glasphalt for highway
construction. In 2006, 13.2 million tons of glass were generated in MSW. Out of
these, 2.88 million tons, or 21.8 percent, were recovered and 10.3 million tons
were discarded. Almost all the recovered glass tonnages were glass containers.
In general, most of the glass recovered was due to local government collec-
tion efforts. Although large quantities of glass were generated from commercial
sources, quantities recovered from nonresidential locations were far below 10
percent of the total glass recovered. Most (more than half) of the glass waste
can be characterized as flint (clear), followed by amber (brown). Less than 10
percent is green. Generally, the production of green glass is decreasing in the
United States.
Glass containers marketers are classified into primary and secondary end users.
Primary end users reuse the glass cullet (broken/crushed glass) to manufacture
glass containers. Secondary end users use the glass for different purposes other
than making glass containers. The glass container industry is the largest consumer
for glass cullet in the United States.
Contamination is a major concern in glass recycling. The Institute of Scrap
Recycling Industries specifications prohibit materials such as ferrous and non-
ferrous metals, ceramics, and other glass and other materials (bricks, rocks, etc.)
from being present in glass cullet. Flint cullet must have no more than 5 percent
nonflint cullet. Amber can withstand up to 10 percent nonamber cullet in the mix,
and green can withstand up to 30 percent nongreen cullet. Many factors rather
than economic factors affect supply and demand. The first and most important
is public education. To meet high standards of glass is expensive and results in
a low price paid for glass by the processor which makes it less profitable for
generators. Transportation for long distances further increases the cost of glass
recycling (NCDENR 1998).

5 MSW COLLECTION

Collection and transportation of solid waste is considered to be one of the most
important stages of solid waste management because the cost of collection and
transportation can reach as mush as 80 percent of all costs associated with solid
waste removal. Thus, the optimization of waste collection and transportation ser-
vices can yield large savings. As a result short term planning of vehicle routing
and scheduling is valuable after the completion of long-term regional planning
in a solid waste management system. Studies in this area concentrated in finding