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Compostable Definition 

If you’ve done your zero waste research, you’ll know that composting is one of the main activities zero wasters can and are encouraged to do. In fact, compostable materials play a big role in one of the five R’s in zero waste: to rot used goods.

For the uninitiated, composting is recycling organic matter. Anything that can break down well is compostable. Compost is just a managed pile where you’re speeding up the process of decaying and breaking down all these organic matter.

Food scraps, dry leaves and twigs, paper, and other organic matter (except feline waste!) are turned into decomposed matter, which looks like rich, fertile soil.

Composting is a doable, scalable way to reduce how much organic waste you send to the landfill. And it doesn’t hurt that it’s awesome for your houseplants, either.  

Biodegradable and Compostable Items: What’s the Difference?

In your zero waste journey, you’ve probably become more conscious of terms like biodegradable and compostable.

What’s the difference?

First, you have to take note that ALL matter will eventually biodegrade. And this includes even traditional plastic, because it’s made of fossil fuel and its derivatives.

From the word itself, “bio” meaning life and “degrade” meaning to break down, it means that bacteria, fungi, and some other biological process will physically and chemically break down all matter.

But not all the biodegradable things are created equal.

The thing is, without further description on time and preferred setting, the term biodegradable does not distinguish the rate of biodegradation.

Something that decays for a thousand years versus something that decays in a compost pile in 180 days? Both can be labeled biodegradable!

That’s why as a consumer, you may want to find out how long something will biodegrade. A plastic material labeled biodegradable will not necessarily compost.

What about compostable?

Compostable products are biodegradable. Their advantage is that they are specifically made to break down without damaging plant growth. It will generate water, CO2, and biomass once it’s degraded into the soil.

As we’ve mentioned, composting is good for soil, and it lessens the waste otherwise dumped into landfills.

And it can be done at any scale: in an industrial-scale facility, in smaller-scale community composting systems, in anaerobic digesters, and even right at your own home.

But there’s also a caveat here.

Compostable products require certain conditions and settings in order to degrade into the soil.

This means compostable products biodegrade faster than other “biodegradable” materials, but only with the right set of conditions.

Compostable Products: What to Look For

Compostable products are getting more popular as we become more mindful of waste. And from what we’ve learned, it’s definitely better than disposable single-use plastic.  

But before you grab that compostable bag, straw, or applaud the latest compostable packaging, check out these key considerations for compostables:

Be aware of what “commercially compostable” means

In the Greenpeace report, Throwing Away the Future, there’s a strong caution about bioplastic and compostable plastic. In fact, they deem these innovations as another form of greenwashing.

Some might disagree, but the organization explains that these labels mislead consumers into thinking that the material will easily and naturally decompose.

If you see a product labeled industrially or commercially compostable, these materials require specially formulated microbial conditions and high temperatures in order to compost.

Materials like PLA (polyactic acids) fall under this category. Made from cornstarch or sugarcane, they look and feel like traditional plastic but can be composted in a facility. Composted in the proper industrial facility, these materials can break down as fast as 180 days.

Unfortunately, very rarely will these be useful in home compost. And most likely your area doesn’t have the commercial composting facility needed (the U.S. only has 185 facilities at the moment).

If your area doesn’t provide drop-off or pickup services for commercially compostable products, these will most likely be en route to a landfill or incinerator.

Not much different than traditional plastic.

If you do have access to an industrial facility, make sure that it’s certified by the Biodegradable Products Institute (BPI). BPI is the nonprofit that created the industrial composting standards based on ASTM methods.

Choose home compostable instead

If you’re on the lookout for compostable products, choose home compostable over commercially compostable.

Home compostable materials are made entirely from uncoated paper or plant fibers. These do not need the specialized heat and microbial requirements of industrial facilities.

Home compostable products will degrade under moderate temperatures and natural microbial activity – your own backyard compost pile will do!

PHA is the only bioplastic material that can degrade in a home compost.

Currently, the U.S. standards for home compostable materials are still being set.

ASTM International and BPI have not yet included home compostables in their testing and certification processes. They’ve only determined biodegradability in composting facility and marine environments.

It’s the same in Canada as well. There is no certification yet regarding backyard compostability. In the white paper published by the National Zero Waste Council, they stated that there are too many uncontrolled factors in home composting.

From low temperatures, longer cycle time, and variable aeration, these will lengthen the time it takes to degrade a compostable product. Researchers are still figuring out how to standardize such variables.

So how do you know if a product is home compostable?

Look for the OK Compost Home label. Right now this is the only third-party standard for home compostables. The European certification requires at least 90% degradation in 12 months at moderate temperature. 

There’s no equivalent standard in North America so this is the best possible certification to look for at the moment.

Beware of any variations of “degradable”

These include, “biodegradable” and “oxo-degradable”, “oxo-fragmentable” and “made from recycled materials” to name a few.

Why?

Because they’re usually put on a product to make you think that it’s good for the environment (the ol’ greenwashing tactic).

Oxo-degradable plastic is especially harmful. This type of plastic is touted as highly recyclable, adding chemicals to speed up the biodegradation process.

But instead of breaking down the material naturally back into the earth, the process just breaks the plastic into tiny fragments (microplastics) that won’t biodegrade.

Again, don’t be easily swayed by these vague and often misleading labels. Check first if there are any valid certifications on the product’s compostable features.

The Takeaway

Composting is one of the key practices in zero-waste lifestyle. You can do it right at home, or support your community-wide system.

Compostable products check two R’s in zero waste practice: Rot and Recycle. It’s a great way to naturally recycle organic matter, keep trash out of landfills, and cut emissions.

The key is to be aware of the life cycle of compostable materials. Some can degrade in your own compost pile, while some would need industrial-level specifications. Choose what works for you.