Environmental Engineering Reference
In-Depth Information
into assuming that “recyclable” means that the stamped product will in
codes #3 to #7, for instance, are not even accepted for recycling in most
communities. Food trays, blister packs, yogurt cups, and bottles (other than
PET and HDPE) are not recycled because of insufficient demand for their
recyclate product.
Figure 9.13
Recycling symbols. PETE is polyester (PET), V is vinyl
plastics, and the “other” category covers all other resins.
Over 94% of the US population have access to PET and HDPE recycling
facilities. Therefore, in the United States, PET beverage bottles and HDPE
milk jugs enjoy 32.6 and 22.2% rate of recycling, respectively, compared to
thesingle-digitratesforotherclassesofplastics.Onlyasmallergroup(57%)
have access to facilities that can recover other plastics for recycling (Mouw
and Penner, 2013). By comparison, plastic films, especially post-consumer
to any significant extent. Despite recently reported encouraging increases
in US recycling rates for the general category of plastic films (that includes
industrial shrink wrap that is recovered at a high rate), only a few percent of
shopping bags are recycled (CalRecycle, 2009).
9.4.1 Recycling: A Sustainable Choice
The energy costs of using virgin resin to fabricate a product is {
E
P
+
E
F
+
E
D
}, where
E
P
, is the energy cost of virgin resin production,
E
F
, that
of product fabrication, and
E
D
, that of postuse disposal. The cost of using
recycled resin (that is subsequently disposed of) is (
E
C
+
E
R
+
E
F
+
E
D
),
where
E
C
, is the energy cost of collection of waste resin for recycling and
E
R
, the cost of recycling. Magnitude of
E
C
depends on the infrastructure
available for pickup (e.g., curbside collection or centers), the distance the
waste is transported. The value of
E
R
includes energy used in sorting,
cleaning, grinding, and pelletizing the recycled resin.
