Environmental Engineering Reference
In-Depth Information
and disposal systems, waste packaging is collected along with other residues and then partially
recycled, deposited in landfills, or incinerated. However, in places were collection of solid
waste is not a priority, packaging ends up as litter in open fields, the sides of roads, freshwater
bodies, and oceans. Littering practices added to the light weight of plastic containers promote
the dispersion of empty packages, so it is not just esthetically unappealing but a hazard for
local and regional ecosystems as well.
Organized collection and disposal of waste packaging as part of the municipal solid waste,
however, comes at a cost. For starters, curbside collection and transportation to local transfer/
sorting stations is conducted with trucks that burn fossil fuels. From there, solid waste is trans-
ported with larger trucks to landfills, which are generally located far from urban areas thus
requiring more fossil fuels. And then landfills—the final disposal site—require the use of
land, petroleum-derived materials (e.g., geomembranes), and fossil fuels to operate machinery
(see Chapter 10).
Incineration on the other hand, when combined with energy recovery, may produce a
positive outcome because of the energy generated. However, it comes at the cost of releasing
carbon dioxide and toxic compounds (especially from plastics) into the atmosphere.
REDUCING THE IMPACT OF PACKAGING
From the environmental point of view, the ideal packaging would be one capable of being
recycled efficiently an infinite number of times or returned to the ground as nutrients after
composting. The “recycling loop” in Figure 12.4 represents the circulation of renewable or
nonrenewable materials in a closed loop with zero waste. Materials capable of infinite
recycling are reused used over and over again without undergoing degradation. The “com-
posting” loop cycles biodegradable materials made from renewable resources made from
biomass.
The cradle-to-cradle concept is a brilliant philosophical principle that would eliminate the
use of nonrenewable resources to produce materials that after use get accumulated in landfills.
Unfortunately, such materials are not available yet on a large scale. PLA is the closest resin
that could be used in a cradle-to-cradle cycle, but because mostly nonrenewable energy is used
in its production, it is not a completely sustainable cycle.
Aluminum and steel can be recycled indefinitely without loss of quality. However, it is not
a zero-loop cycle. When aluminum is melted in a gas- or oil-fired reverberatory furnace, losses
due to oxidation can reach 5 to 8 percent. In electric furnaces, losses are lower, but still
between 0.5 and 3 percent (Choate, 2007). Steel has even higher losses.
Package
manufacture
Consumption
Food supply chain
Raw material
processing
Recovery/
separation
Zero-loss recycling loop
Composting, nutrients return
and growth of new resources
Figure 12.4
Cradle-to-cradle cycle for food packaging.
Adapted from Newcorn, 2003.
