End of Life
The advantages and disadvantages of composting biobased materials depend on the material, the product, and the infrastructure.
When recycling systems exist and are successful, composting the product or package will lose the front-end inputs that were used in its extraction, refining and production although this must be weighed against the costs of transportation and recycling.
However, because bioplastics otherwise hold so much promise, research should be encouraged to develop and commercialize means to recycle rather than compost PLA to approximate the net value of PET. If that can be done and is corroborated by major recycling programs, pilot programs may be appropriate to validate such systems in a test. Based on what is presently commercialized in the market, however, there is much controversy about the introduction of bioplastic predicated upon composting at the end of the life for bottles where there is an existing and successful recycling system.
Potential PLA bottle manufacturers are urged to develop systems to successfully and economically recycle bioplastic bottles to overcome the challenges posed to the current recycling program before there is widespread production. This is in contrast to other applications such as cutlery, cups and utensils or which there is presently no flourishing recycling infrastructure.
In most recycling facilities, it is difficult to separate biobased PLA (polylactic acid) from PET (polyethylene terephthalate), which is the most widely used plastic in plastic bottles. PLA contamination degrades the ability to recycle PET. While technology exists to separate PLA from PET, it is costly and not commonly used.
Bottles made from PET are extremely valuable for current recycling programs. That high value would be completely lost if there were significant PLA contamination, given current recycling technologies.
Many recyclers therefore oppose the use of PLA until the recycling technology is capable of weeding out products made with PLA. Even after technologies to detect and sort PLA are in widespread use, recyclers would still incur additional sorting costs to remove the PLA contaminant.
Currently, all biodegradable/compostable bags available on the market contain a large percentage of fossil-fuel-based plastics. They also present similar challenges to existing plastic recycling systems as do bottles. Unless appropriate infrastructure is in place for collecting compostable materials, biodegradable bags for retail applications should be avoided(as should other single-use fossil-fuel based bags).
One excellent application for biodegradable bags is to collect foodwaste for composting. Indeed, food scrap composting programs and use of compostable bags are expanding, most notably in the San Francisco Bay Area and some other key cities.
While much traditional plastic film is technically recyclable and demand for this material is high, only a tiny portion is actually being recycled (less than 1% nationally). One reason is that traditional plastic film is not economically recyclable or compostable in household curbside collection programs.
When this material is mixed with recyclables or organics at curbside, it becomes a major contaminant in recycling and composting programs. As curbside organics collection programs expand to include many types of compostable materials, compostable bags and film products have the potential to reach higher recovery levels than their petroleum-based counterparts.