Environmental Engineering Reference
In-Depth Information
toxic compounds during production, and at the end of its life cycle would be completely com-
posted or recycled.
Design for compostability/biodegradability
This particular attribute implies that the packaging can be composted at the end of its useful
life. Compostable is not the same as biodegradable. Biodegradable means that eventually a
material will be transformed into carbon dioxide, methane, water, and inorganic compounds
by the action of microorganisms without specifying a time scale. Compostable materials, on
the other hand, are those capable of undergoing transformation into new biomass (compost),
carbon dioxide, and water in aerobic conditions with the additional generation of methane
under anaerobiosis (Avérous, 2004).
Composting needs to take place in a reasonable time length under specified conditions,
which are generally temperatures around 60°C and typical moisture levels used at commercial
composting facilities (Envirowise, 2008). Compostability is an inherent property to the pack-
age and the material that of which it is built. A package can be made from a material that is
biodegradable (e.g., wood and paper) but composting is not practical unless the material is
used in thin films (Envirowise, 2008).
As a disadvantage, the use of compostable or biodegradable packaging needs coordination
of consumers with downstream treatment of exhausted packages as follows:
Compostable packaging needs separation from regular trash by consumers.
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Cities need the added capability of compostable packaging collection and treatment.
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Consumers need training to prevent them from separating compostable packaging with
recyclable ones, such as PET, based on their similar looks.
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Design for recyclability
Most packaging in use today has functionality as the main attribute. For packaging that is
intended to be recycled, recycling needs consideration at the design stage instead of as an
afterthought after the design is finished. One of the best examples of recyclability is the alu-
minum can. The body of the can is made with the alloy 3004 (1% Mn and 1% Mg), whereas
the lid and opening tab is made of the alloy 5182 (1% Mn and 4% Mg). However, all the
components of the can are recycled together. Plastic or glass bottles in general are straightfor-
ward to recycle once the caps are removed, which are normally nonrecyclable.
As a general rule, simplicity increases recyclability, and as the packaging becomes
more complex, the recyclability decreases. The use of multiple components such as alumi-
nized paperboard for sides, metal or plastic for bottoms and lids, or cartons used in aseptic
packaging of liquid foods, makes recycling increasingly difficult. Traditional Tetra Pack
®
type containers are made of about 75 percent paperboard laminated with polyethylene and
aluminum foil. There are technologies that allow the recovery of cellulose fibers from
cartons that then can be used in other applications such as printing paper, corrugated
boxes, and tissue paper. Moreover, applications have been developed to capture the poly-
ethylene and aluminum leftovers after the paper is recovered (Tetra Pack, 2010). However,
separation of materials requires more steps than when packaging is made from a single
material.
Design for disassembly
Design for disassembly is mostly applied to durable products. It is about creating products that
are easy to take apart at the end of their useful life so the individual parts, which are made of
different materials, can be recycled.
