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Because You Asked: Can I Compost Biodegradable Plastic?

By Recyclebank |
Here’s the scoop on biodegradable plastic, and why you should leave it out of your compost bin.

Dear Recyclebank: I received a product order in a plastic bag labeled “biodegradable film.” Does this mean I can put that film in the garden (like mulch), and it will decompose? –Susie C.

Dear Susie: The concept of biodegradable film, or bioplastic, sounds like a dream come true: if it biodegrades, I can simply toss it in the dirt, and it’ll naturally decompose into organic matter just like a banana peel, right?

Not quite, unfortunately. Firstly, it’s important to remember that everything biodegrades eventually, even if it takes a thousand years, so the term “biodegradable” is vague and a bit misleading. Part of the waste-problem equation is that petroleum-based plastics (the majority of plastics available) take so long to decompose that we don’t refer to them as biodegradable.

The term “bioplastics” refers to plastics made from materials found in biomass, such as vegetable oil or cornstarch. Products made of these materials can sometimes be identified by their greenish tint or by their label.

These “biodegradable” products may or may not be naturally biodegradable in the same way a banana peel is. Bioplastics from the company NatureWorks, for instance, need to be recycled at industrial composting facilities so that they can be exposed to the proper conditions that ensure decomposition. BioBags also require these sorts of conditions, although a handful of their products are home-compost certified, which means you really can let these decompose in your yard. However, if they’re not home-compost certified, putting bioplastics (which may nevertheless be labeled as “compostable” or “biodegradable”) in your pile will contaminate your at-home compost and won’t break down properly there, or in your garden.

What’s more, in the resin identification code table, these plastics would fall under #7(“Other”) plastics, and cannot be recycled with other plastic film as they would contaminate the recycling stream. The exception: Coca-Cola’s PlantBottle, which is partially made from plant-derived PET plastic and can be recycled with other plastic bottles.

Chances are your biodegradable film needs to be processed in an industrial composting facility in order to break down properly. This is because, despite the name, many bioplastics won’t simply biodegrade on their own; they need a specific, contained environment in order to decompose quickly enough, such as those created at industrial composting facilities. Your best bet is to seek out an industrial composter to see if they’re equipped to handle these types of plastics. If there’s not one available, sadly, you have no choice but to relegate it to the landfill (where, incidentally, it will NOT biodegrade since it will not be exposed to the oxygen needed for the degradation process).

Many of us wish for a substitute for fossil-fuel based plastics, (the production of which creates large amounts of harmful greenhouse gases), and it’s tempting to think bioplastics are the answer we’ve been waiting for.

However, when we look closely at the environmental impacts of producing and disposing of bioplastics, we see there can be detrimental effects from them as well. For instance, according to a research paper by Winrock International, corn production increases the amount of nitrous oxide in the environment, which is apparently over 300 times more potent for global warming than notorious CO2! An increase in bioplastics production would probably bring with it a steep increase in greenhouse gases. There really are no easy solutions. One thing we can do is make conscious efforts to reduce our use of all kinds of plastics, and if we can, to reuse the plastics we have so as not to encourage more production.
Do you think bioplastics are a good idea? Share your opinion in the comments below.
 
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  • Barbara W. 9 days ago
    What about the 'dirt' used in purchased nursery plants? It often appears to have polystyrene pieces in it...is it safe to add to compost? Does it contaminate topsoil?
  • Karen K. 1 month ago
    Jeez, farting cows and now corn? Next!
  • Cesselie J. 2 months ago
    No, because it gets confusing and if you make a mistake with your in home compost pile, it's ruined.
  • Vicky M. 2 months ago
    I think minimizing plastics all together is a better solution. I too have a green cone composter with compostable cups and utensils that haven't changed much since their composting in 2008. Why do people through away plastic utensils instead of washing and reusing like all other utensils?
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