Environmental Engineering Reference
In-Depth Information
adverse ecological impacts of plastics debris now shift from the larger
fauna to smaller, less visible, genera including zooplanktons that are
vital to the marine food pyramid.
Urban litter is aesthetically unacceptable and enhanced photodegradable
plasticsdoaddresstheproblembutbyfragmentinglargerwasteintominute
fragments that are not easily discernible against the background. Littering,
however, is primarily a behavioral problem that will worsen with the
ongoing trend toward overpopulated urban centers. Degradable plastics
cannot be expected to address this impending problem in its entirety. There
is even the possibility that “degradability” label may in fact be
misinterpreted leading to more littering as the waste is expected to degrade!
Compostable plastics in products such as compost bags or food-contact
packaging are commercially available. Plastics, however, are not good
biomass does). They are in fact removed from municipal waste streams
intended for composting. Composting releases sequestered carbon in the
plastic back into the atmosphere, contributing to global warming. The
releasesofthiscarbonbackintothecarboncycleisoflittlemeritandisnota
persuasive argument in favor of composting or biodegrading, as the carbon
in plastics was not removed from the operational carbon cycle to start with.
It was sequestered for millions of years as fossil fuels.
Compostable plasticsmayhaveanicheroletoplaywhereitsusecontributes
to better compost quality by minimizing the plastic residue in the product
(GoldsteinandBlock,2000).Thiscanbetrue,forinstance,withplasticfood
packaging that is difficult or expensive to remove from the food residue and
is disposed of in a compost stream.
All plastic waste including litter is a material of value in terms of the
embedded energy and the nonrenewable materials that comprise it. It is
clearly a resource or a raw material that must ideally be recycled and its
material and/or energy resources extracted for reuse. Degradability and
compostability do not facilitate this key sustainability objective.
REFERENCES
Albertsson AC. Biodegradation of synthetic polymers. 2. Limited microbial
conversation of C-14 in polyethylene to (CO-2)-C-14 by some soil fungi. J
Appl Polym Sci 1978;22:3419-3433.
