COMPOSTABLE PLASTICS ANOTHER GREENWASHING TRICK?
For some time now, due to the emerging public awareness of the destruction caused by the disposal of plastic items, food and beverage outlets have been using expensive compostable take-out packaging. Embracing their inner eco-warrior, millennials can now drink their favorite coffee concoctions guilt-free thanks to this more planet-friendly solution to single-use plastic.
How compostable are these compostable plastics?
Compostable plastics come from plant materials and touted to break down through composting.
Instead of using plastic made from petrochemicals and fossil fuels, compostable plastics are derived from renewable materials like corn, potato, and tapioca starches, cellulose, soy protein, and lactic acid. Compostable plastics are non-toxic and decompose back into carbon dioxide, water, and biomass when composted. At least it is the message we hear from the PLA plastic producers and their fans. The exact nature of the biomass left over is usually left very vague.
However for this process to take place composting facilities need to control parameters such as temperature, carbon-to-nitrogen ratio, humidity and air supply, so that aerobic micro-organisms decay the organic materials without leaving any toxic material behind. Efficient composting processes can be completed within two to six months.
Alas, efficient composting of these PLAs does not happen as often as it is thought.
Composting issues.
Large-scale commercial composters are maintained at around 60°C, whereas small-scale home composting systems typically reach temperatures of lower than 40°C. Commercial composters also shred, mix and aerate the material, while home backyards composting is usually done in small piles, or rotating barrels where mixing is limited.
When compostable plastics are placed in open landfills where oxygen is available, they will eventually decompose with other biodegradable materials. However, it is an extremely slow process and may take decades or even centuries.
We can also note that commercial composting facilities use copious amounts of energy.
Infrastructure to handle PLA is lacking.
Few cities have the infrastructure to collect compostable food-service packaging. There are less than 200 proper composting facilities in the entire US. Even in areas where organic food waste is collected from restaurants, compost facilities tend to say no to food-service packaging.
Currently, most councils in the UK don’t accept compostable packaging in food or garden waste collections. The presence of PLA plastics with other regular plastics prevents their recycling. So these items cannot be thrown into the plastic recycle bin either.
So for PLA plastics to be properly treated, they need to be segragated from regular plastics AND food-stuff. This means one additional recycling bin in every homes, restaurants and offices.
After drinking your iced-coffee in the street and chucking your “compostable” cup in the trash, you can be certain that it will end up in a landfill and remain there for centuries.
In areas which do not have a comprehensive garbage disposal system in place, which is most of the world, these plastic cups and bags labeled “compostable” will simply contribute to our growing mountain of garbage. So for most users, families or institutions, compostable plastics are not the environmentally responsible solution it is supposed to be.
The only planet-friendly single-use plastic is NONE.