Co-Collection:
The act of picking up post-consumer plastic (or secondary)
materials or compostable materials simultaneously with garbage. (The
Recycler's Lexicon: A Glossary of Contemporary Terms and Acronyms, Resource
Recycling Inc., 1995).
Co-Combustion:
The simultaneous combustion of two or more fuel
types to provide useful energy. Generally, a primary fuel is combusted with
one or more supplemental fuels. Examples would include the co-combustion of
wood with coal, or processed combustible materials derived from residential,
commercial and industrial sources, which could include plastics-enhanced
pelletized fuel products, with coal as the primary fuel in industrial or
utility boilers. (Kenneth Smith, Vice President, wTe Corporation, Bedford,
Mass., 1996).
Coextrusion:
Involves a process where parts are blow-molded with
walls containing two or more layers of different material. Coextrusion
offers wide latitude for material selection and also allows the use of
recycled materials. A material with good barrier properties, for example,
can be used for the inside and outside surfaces of a blow molded bottle,
while recycled material can be used for the internal layer. (Modern Plastics
Encyclopedia 1995).
Cogeneration:
The simultaneous production of power and another
form of useful thermal energy from a single fuel-consuming process. The most
common cogeneration systems being constructed today utilize combustion or
co-combustion processes to produce electricity via a turbine as the
principal product and steam and/or hot water as by-products. The electricity
generally is sold to a utility or used for adjacent industrial processes and
the steam and hot water generally are exported to adjacent companies for
industrial process uses and for space heating. When combusting fuels in
typical boilers, cogeneration is significantly more energy efficient than
the generation of electricity alone. Approximately 75 percent of the energy
value in the fuel can be extracted in a cogeneration facility compared to
approximately 35 percent when electricity is produced solely. (Singer,
Joseph G., "Combustion Fossil Power," Fourth Edition, Combustion
Engineering, Inc., Windsor, Conn., 1991; Lund, Herbert F., "The
McGraw-Hill Recycling Handbook," McGraw-Hill, Inc., New York, 1993).
Combustion:
A chemical process in which oxygen rapidly combines
with the fuel and converts the fuel into gases, primarily water (H20) and
carbon dioxide (C02), and residues. The combustion process produces
significant thermal energy (heat) and light, and generally is self
sustaining-that is no external source of heat is required to maintain
combustion of fuel. In modern, state-of-the-art waste-to-energy facilities,
and in other modern energy production facilities, the combustion process is
carefully controlled to extract maximum energy value from the fuel source
and to reduce the generation of potentially harmful substances significantly
well below stringent regulatory levels. Industrial and post-consumer plastic
plastics that cannot be economically recycled are excellent fuel sources
that combust very well in such facilities. The energy value of these
plastics is comparable to oil and can be more than 50 percent greater than
coal. (Tchobanoglous, George, Hilary Theisen and Rolf Eliassen, "Solid
Wastes, Engineering Principles and Management Issues," McGraw-Hill,
Inc., New York, 1977; Lund, Herbert F., "The McGraw-Hill Recycling
Handbook," McGraw-Hill, Inc., New York, 1993).
Compatibilizers:
Additives that enable two or more materials to
exist in close and permanent association indefinitely. They may be used to
blend virgin and post-consumer plastic resins or different types of resins
to maintain the quality of the products. (Dr. Ronald Liesemer, Vice
President of Technology, APC, Washington, D.C., 1996).
Compounding:
The incorporation of additional ingredients needed
for processing in order to have optimal properties. These ingredients may
include Additives to improve a polymer's physical properties, stability or
processability. Compounding is usually required for recycled materials for
the following reasons:
- Recycled materials are typically ground from parts that produce
flakes. The compounding (palletizing) process turns them into pellets
that can be more easily handled by traditional plastics processing
equipment.
- It allows Additives to be compounded into the recycled material to
meet target application requirements.
- It allows virgin materials to be mixed with recycled materials to
meet material specifications for performance and recycled material
content targets.
- It provides a very important homogenization step. Recycled materials
are usually a mix of many different grades of the same basic material.
Even though the materials might be from the same family, differences in
molecular weight, copolymer ratios, etc. can lead to a mixed material
having poor homogeneity. The intensive physical mixing in a molten
polymer that is achieved during extrusion can homogenize different
grades of materials and even some types and amounts of foreign material
that might not have been removed during the recycling process. (Adapted
from Modern Plastics Encyclopedia 1995).
Cradle-To-Grave Analysis:
A methodology that quantifies energy
consumption and environmental emissions at each stage of a product's life
cycle, beginning at the point of raw material extraction and proceeding
through processing, manufacturing, consumer use, and final recycling, reuse
or disposal. (Resource and Environmental Profile Analysis of High Density
Polyethylene and Bleached Paperboard Gable Milk Containers, Franklin
Associates, Ltd., February 1991)
Curbside Collection:
A collection process where consumers place
designated recyclables at the roadside or curb, usually in a special
container or bag, for collection separate from non-recyclable material such
as garbage. (The Blueprint for Plastics Recycling, The Council for Solid
Waste Solutions, 1991).
