Environmental Engineering Reference
In-Depth Information
a. Material economy: extending the useful service life of the material by
reuse and recycling
b. Full utilization of the non-renewable resource: recovery of either the
energy and/or feedstock resources from waste destined for storage (in
landfills) or destruction (burning).
Reducing the use of plastics where it makes economic, functional, and
environmental sense to do so also conserves the resource and is captured
within the first goal. Where reduction is by using alternative materials, it is
important to base the decision on an appropriate life cycle analysis (LCA)
to make sure that the alternative (usually paper, wood, metal, or glass)
in fact has a lower environmental footprint compared to plastics. There is
no justification for adopting the extreme position that plastics as a class
are undesirable and should be therefore avoided wherever possible in all
applications. Multiple use (reuse) of a plastic product prior to its disposal is
clearly a superior means of extending its useful life compared to recycling it
after a single use. This helps conservation as recycling invariably has some
energy and externalities “costs” associated with it.
Recovery of plastics from MSW can be as a material resource (by material
recycling), a feedstock (by thermal or chemical degradation), or as energy
(by incineration or biological treatment). Different technical methods are
available for each of these recovery options.
Estimates for recovery given in
Figure 9.4
are average values for the United
States; the numbers can be very different at the state level where the choice
of disposal is dictated by economic considerations. While states such as MS,
OK, or MT with relatively undeveloped recycling programs for materials
landfill almost all wastes, others such as CA and OR recycle greater than
10% of the plastics. CT, MA, ME, NJ, and HI rely more on incineration as
a means of waste disposal and therefore recover significantly more energy
from plastic wastes.
Table 9.2
shows the recovery effort for different classes
of plastics, based on USEPA data for 2011. The recovery rates for the United
States summarized in the table are quite unimpressive compared to those
for Western Europe or Japan. Consumer education, incentives, and
improved recycling infrastructure can increase these rates significantly.
