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Sustainability of Municipal Solid Waste Management
• Quantity of foaming agent in the initial mixture: There is an inverse
proportional relationship between the density of the foam glass and
the quantity of coal in the initial mixture.
• Time and temperature of heat: There is a direct dependence of foam
glass formation and density on the time and temperature of heat.

5.8 Recycling of Aluminum and Tin Cans
Aluminum wastes are one of the most common items that can be recovered
through municipal solid waste because they provide higher revenues than
other recyclable materials. The recycling of aluminum cans uses 70–90%
less energy than producing them from virgin materials.
Steel food cans make up 80–90% of all food containers and are often
called tin cans because of the thin tin coating used to protect the containers
from corrosion. Some steel cans, such as tuna fish cans, are made with tin-
free steel, while others have an aluminum lid and a steel body and are com-
monly called bimetal cans. All these empty cans are completely recyclable
by the steel industry and should be included in any recycling program. The
collection vehicle discharges the solid wastes into a hopper bin, which dis-
charges to a conveyor belt shown in Figure 5.5 in the transfer station. The
conveyor transports the cans past an overhead magnetic separator where the
tin cans are removed. The belt continues past a pulley magnetic separator,
where any tin cans not removed with the overhead magnet are taken out.
The aluminum and tin cans, collected separately, are baled for shipment
through a hydraulic press located in the transfer station as shown in Figure 5.7.
At the aluminum foundry, aluminum scrap is melted in a smelting process.
Molten metal is formed into ingots that are transferred to manufacturing
plants and cut into disks, from which cans and other products are formed.
For more details, see Chapter 10 case studies.

5.9 Recycling of Textiles

Textile recycling has a long history, not for making new textile or returning
textile to its original fibers or other textile products but for making paper
(Dadd, 2004). Textile fiber can be classified into natural fibers such as cotton
and wool and synthetic fibers. By recycling cotton wastes, we not only con-
serve landfill space but also reduce the amount of land, water, energy, pesti-
cides, and human labor that goes into cotton production.
The textile recycling industry represents one of the most important
recycling activities from solid wastes in developing countries because it is a
labor intensive activity and can provide a lot of job opportunities as well as
the availability of textile waste everywhere. Most of the textile recycling
firms in developing countries are small, family-owned businesses with 5–20