Recycling Mythbusters: Biodegradable vs. Compostable

February 25th, 2014 | Kyle Reed
If you throw a biodegradable item into the compost at home, it will break down into a more natural form – for instance, biodegradable paper will turn into tiny bits of paper. However it will not offer nutrients to the soil in a compost bin. This is why biodegradable products do not belong in compost bins. However, it is morally difficult to throw biodegradable items into the trash can because landfills typically do not offer the moisture- and sunshine-rich biome that biodegradable products need in order to break down into their smallest and most basic form.
For an item to be compostable, it must break down into organic materials that can offer nutrients to the soil and plants around it (the technical term is humus: any organic material that has reached a point of stability and can offer those healthy nutrients). Compostable items are usually food waste, such as apple cores, banana peels, orange rinds, etc. Very rarely do any other products qualify to be thrown into the compost bin. Although plenty of products are sold as biodegradable, plant-based, or bio-based, these are not compostable.
To be safe, your compost bin with all its delicate plants and bugs and worms should not have any products other than food waste in it. Keep the compost bin clear of any plant-based products, because although they can biodegrade, they cannot offer your plants anything but an obstacle to grow around.

By Mythbusters Rachel Tholl and Kyle Reed

Who are the Recycling Mythbusters?

We are Kyle “Reedcycler” Reed, Amanda “Jill of All Trades” Abbott and Rachel “Waste Watcher” Tholl. This term we will be introducing you to some recycling-based myths, and busting them so you don’t have to.

From left to right: Amanda Abbott, Rachel Tholl, and Kyle Reed.

From left to right: Amanda Abbott, Rachel Tholl, and Kyle Reed.

Together we are the Recycling Mythbusters.

We don’t just tell the myths, we put them to rest.

Myth: If something is biodegradable, it is also compostable.

When something is called biodegradable, it means that it will break down into smaller parts after being disposed of. However, being biodegradable does not mean that it is also compostable. The largest reason for this is that while a biodegradable item may break down into smaller bits, these components may not be able to provide any nutrients when used as compost.

Click on this image to watch a video about composting in the PRC.

Click on this image to watch a video about composting in the PRC.

For an item to be compostable, it must break down into organic materials that can offer nutrients to the soil and plants around it (the technical term is humus: any organic material that has reached a point of stability and can offer those healthy nutrients). And while some items may indeed do this, they must do so within the 90 day composting process to be accepted as compostable at the Pacific Region Compost (PRC) facility. Here, compostable items are subjected to high temperatures, which assists in breaking them down.

Compost made at the PRC is sold to local businesses, farmers, gardeners, and landscapers around Corvallis and the surrounding areas.

Want to learn more about composting in your department? Click here.

Want to learn more about composting in your department? Click here.

Compostable items sent to the PRC include: food waste (such as apple cores, banana peels, orange rinds, etc.), paper towels and napkins, tea bags and coffee grounds, 100% paper plates, and compostable servingware. Although plenty of products are sold as biodegradable, plant-based, or bio-based, these are not necessarily compostable, and only servingware specifically labelled as compostable should be put into a compost or yard debris bin.

If you are the owner of your own compost, or are using a department composting worm bin, you’d best leave out large items like compostable servingware, as they will take much longer to break down than food waste or fibrous paper.

If you’d like to learn more about composting on campus, click here.

This post is part of our “Recycling Mythbusters” blog series, where we focus on busting common misconceptions about recycling. Tune in every week to learn more.


2 Responses to “Recycling Mythbusters: Biodegradable vs. Compostable”

  1. Kyle Reed says:

    Jennifer, it’s great to hear that you are putting together a presentation about this!

    First, I want to highlight some of the key differences between degradable and biodegradable. For something to be biodegradable, it must experience a complete breakdown. This breakdown is usually facilitated with heat, and results in the biodegradable object being turned into humus. Objects which are simply degradable, on the other hand, only break down into smaller parts, and may still contain some or many of the chemical properties of the original product. Unfortunately, many products are falsely labelled as biodegradable when they are only degradable, due to the fact that being green has been a hot marketing tool as of late.

    This leads me to the differences between home composting and composting at the PRC. As noted in this blog, items are only considered compostable at the PRC if they can be completely broken down during the ~90 day process. You can watch a video with more information about the PRC by clicking on one of the photos above. One of the key things to note, however, is that the composting materials at the PRC regularly reach temperatures of around 130-150 degrees Fahrenheit, which helps break down many biodegradable items. If a truly biodegradable product were put into the compost at home, then it would take much longer for it to undergo a breakdown, unless optimal conditions were created.

    I will send you an email with some additional resources for the topics discussed above. Hope this helps!

  2. Jennifer Le Pine says:

    Hello. I am preparing a presentation regarding the importance of recycling which includes information about the differences between recyclable plastics and degradable plastics. I want to be able to help people understand the differences between what can go in the recycling bin at home, what needs to be saved up and dropped off at a larger facility that accepts what home pick up does not, and what items need to be kept out of the recycling bin in order to prevent contamination of recyclable material with degradable material. However, I cannot find a source of actual labels for degradable material! I did see your list of plastic recycling symbols; thank you for sharing that. Can you point me in the right direction? Also, it would be helpful to know what can be done with degradable material, seeing as how some of it can be composted but not necessarily in home compost.
    Thank you!

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