Page 187 - Materials Chemistry, Second Edition

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158 Waste Management Practices: Municipal, Hazardous, and Industrial

TABLE 6.9
Rubber and Leather in MSW and Recycled, 1999

Generation Recovery Recovery
Product (thousands (thousands (percent of
of tons) of tons) generation)
Durable goods
Rubber in tires a 2,980 7902 6.5
Other durables b 2,430 Neg. Neg.
Total rubber and leather in durable goods 5,410 790 14.6
Nondurable goods
Clothing and footwear 540 Neg. Neg.
Other nondurables 250 Neg. Neg.
Containers and packing 790 Neg. Neg.
Total rubber and leather 6,220 790 12.7
Neg. Less than 5000 tons or 0.05 %. Details may not add to totals due to rounding.
a Automobile and truck tires. Does not include other materials in tires.
b Includes carpets and rugs and other miscellaneous durables.
Adapted from U.S. EPA, EPA 530-R-01-014, 2001.

(Table 6.9) (U.S. EPA, 2002). This number does not include over 30 million tires that are retreaded
every year. Until recently, waste tires were simply stockpiled (Figure 6.17), landfilled, or burned.
Open, uncontrolled tire fires have resulted in the production of many noxious and hazardous air pol-
lutants and such fires are difficult to extinguish, in some cases lasting months or years. Tires also
serve as a breeding ground for insects such as mosquitoes and other pests.

6.14.1 DESIGN AND MANUFACTURE
Tires are constructed from one of two distinct designs, i.e., nonbelted and steel-belted. The latter
type dominates the tire market by virtue of its greatly improved lifespan as well as improved gas
mileage. A longer lifespan results in less tires ending up in landfills. Unfortunately, however, steel-
belted tires are more difficult to recycle, and comprise about 90% of all used tires in the waste
stream. Tables 6.10 and 6.11 list the typical types of materials used in tire manufacture.

6.14.2 DISPOSAL AND RECYCLING
Many states have targeted the tire dumping problem by restricting land disposal of tires, setting up
recycling programs, and assisting in the development of markets for collected scrap tires. Bans on
disposing scrap tires in landfills are in effect in 33 states, and over 30 states collect disposal fees on
tires to fund disposal and management and, in some cases, to support research and market devel-
opment for tire recycling (U.S. EPA, 2002). The fate of scrap tires is outlined in Figure 6.18. The
majority is land-disposed (landfilled and stockpiled).
Disposal of waste tires by sanitary landfilling causes problems for operators, such as tires ris-
ing to the surface due to their low density. Such rising may eventually damage the integrity of a
landfill liner. Some landfill operators cut tires to prevent such “floating” behavior. Others have
shredded tires for use as a daily landfill cell cover material. Landfill disposal of tires is generally
considered wasteful for the following reasons (Rhyner et al., 1995):
● Tires are relatively inert and may not necessarily need land disposal to limit any hazards.
● Tires have potential value as a recovered material.
● Tires have a potentially high economic value as a fuel.