Page 472 - Solid Waste Analysis and Minimization a Systems Approach

450 TRANSPORTATION, LOGISTICAL, AND WAREHOUSING APPLICATIONS

shredded in order to fit through the feeder grates of the furnaces. One drawback is the
presence of steel belts in many tires, which can build up over time and block the feeder
chutes.
In order to meet strict environmental guidelines, many landfills must provide a safe
covering over each day’s deliveries. Instead of using a layer of fill dirt, some landfill
operations are now using a layer of shredded recycled tires as a daily cover. Instead of
piling whole discarded tires in a hazardous tire pile, landfill operators can receive shred-
ded recycled tires from a local recycling center or invest in their own tire-shredding
machinery.
Recycled tires are also used as a cushioning material in playgrounds and other public
areas popular with children. Sometimes, the shredded recycled tires are spread over
the area like mulch, which can cushion the fall of a child or reduce the impact of play-
ground equipment. Recently, the rubber from recycled tires has been combined with
other binders and foam to produce a solid safety mat for playgrounds and schoolyards.
Even certain clothing manufacturers have discovered the benefits of using recycled
tires. Material composed of recycled tires is now used to form the rubber sole of some
athletic shoes and work boots. Recycled tires may one day be turned into other rubber-
based clothing and accessories, such as raincoats, boots, umbrellas, and hats.
One recent use of recycled tires may become a trend in larger cities. Traditional
concrete sidewalks can now be replaced with similar-sized panels constructed from
recycled tires and other materials. Proponents of these new sidewalk panels claim they
are more resistant to the damage caused by tree roots, and they provide more stability
for pedestrians. While the current cost per panel is higher than traditional concrete
forms, the new rubberized panels should require far less maintenance throughout their
lifespan.
Since recycled tires contain oil and carbon black, two very useful substances, sci-
entists are still seeking ways to retrieve these materials from discarded or recycled
tires. If these researchers are successful in their quest, the huge piles of scrap tires we
see today will ultimately become nothing more than a memory. Recycled tires may
provide enough reclaimed oil to make them worth salvaging, instead of merely
discarding.

35.6 Case Study

In 1999, The University of Toledo Solid Waste Minimization Team conducted a solid
waste audit at a large worldwide shipping company located in Northwest Ohio. In
1998, the company’s corporate revenues exceeded $2.3 billion dollars. The facility
moved between 4 and 5 millions pounds of freight across its dock every day. This
facility was a break-bulk facility with 205 dock doors. The terminal received all freight
collected from 20 regional satellite terminals.
The waste assessment team has identified nine major waste streams produced by the
dock operations at the facility. Of these nine streams, six of the streams are potentially
recyclable. By separating the potentially recyclable material from the waste stream,