Biodegradable vs. Compostable: Know The Difference

Compostable and biodegradable are not interchangeable, even though they sound similar. (This is not a bi-annual vs. semi-annual clothing sale kind of thing.)

Here's what you need to know.

Biodegradable

We see the word "biodegradable" today on everything from soaps and shampoos, to coffee cups and takeout containers.

But what does it mean? 

Biodegradable substances must break down quickly and safely into mostly harmless compounds. These include CO2 (carbon dioxide), H2O (water), methane, biomass (organic waste), and mineral salts, like calcium, phosphorus, magnesium, sodium, potassium and others.

Microorganisms in the environment, like bacteria, fungi, and algae, do the heavy lifting for us. They feed on waste materials and transform it into usable energy sources for future life.

The catch is, how quickly a “biodegradable” substance breaks down is not defined. Different materials break down at different rates, depending on the original material and how much it has been processed.

Technically speaking, this means anything is biodegradable...with enough time. Well, almost. 

Most plant-based, animal-based, or natural mineral-based products are biodegradable. They break down differently, depending on the environment, the material it’s made of, and how much it has been processed.

Plastics almost never degrade past a microplastic level, and most  styrofoams have a shelf life, sadly, of forever. 

If you’re interested to learn more about how long it takes things to biodegrade, you can check out this article from New Zealand’s Science Learning Hub.

Compostable

On the other hand "compostable" is rare on labels of products we buy.

Wait, are we talking about a garden now? 

Sort of. Compostable substances break down completely into natural elements. This leaves only carbon dioxide, water, other inorganic compounds (like salts), and biomass (like plant debris). Composting requires the right environment, a recipe that requires heat, water, and oxygen.

The American Society for Testing and Materials (ASTM) and the European Committee for Standardization (CEN) set strict standards for a material to be certified as “compostable.” Careful testing requires individual ingredients to be tested for biodegradability (consumed by microorganisms).

The finished product must fully disintegrate, or physically break down during composting. They must also be tested for plant toxicity and heavy metals. 

Effective composting does not produce methane, which contributes to global warming. Methane production occurs in the absence of oxygen. Combine organic material with moisture, air, and enough heat, and your byproduct should only be carbon dioxide.

Better still, many compost ecosystems contain microorganisms, plants, and algaes that recycle that CO2 so it’s not released either.

The byproducts of composting are valuable, nutrient-rich materials that support life, whether that's on the forest floor, our backyard garden, or in the ocean deep.

So what can I do?

Change starts small.

Many brands have started to move towards eco-safe packaging, and that’s a great place to begin. If you receive cardboard boxes filled with paper stuffing, that’s all recyclable or safe to introduce to a compost environment (minus the tape and labeling). 

Actively purchasing biodegradable products is a step in the right direction. But as we’ve discussed, biodegradable and even compostable ≠ safe.

Be a conscious consumer, and read into the companies and products you purchase. Reuse products, plastics, and other consumer goods whenever possible.

You can move onto transitioning your household products to those made with plant-based materials. Better still, you can clean with distilled white vinegar and lemon juice, wiping down with water.

If you’re interested in a more compostable lifestyle, research which products your local waste management company (who picks up your garbage) accepts and safely processes.

If they accept #7 bioplastics, look for products labeled with:

• Compostable (of course!)
• Certified by _____ (valid 3rd party name or logo)
• Meeting ASTM D6400 or 6868 (US) or Meeting CEN EN 13432:2000 (EU).

🌊🌊🌊🌊🌊 

Our hope is to inspire people to perform their own small-scale beach cleanups whenever they visit our beautiful oceans. Every bit helps, so we hope you join the community and share your stories.

Thanks, and we’ll see you on the next wave!

Enjoy what you're reading?

Sign up to join our community, The Wave, and get articles, ocean magic, and product updates as we have them.

Never email trash, just the good stuff.

              

Thank you for being you.