Biodegradable vs Compostable: Breaking Down The Differences Of Breaking Down Waste
It’s a sustainability smackdown!
In one corner of the ring, we’ve got the reigning champion of the people: biodegradability. He’s old school, a little dirty, but hey, he’s familiar, and the people love him.
In the other corner, we have compostability, the new kid on the block, but rapidly rising his way through the ranks of eco conscious consumers.
Let’s throw down the gauntlet and let the battle begin: biodegradable vs. compostable!
Before the battle, let’s back it up and set the stage. One piece of our sustainable product criteria is thoughtful packaging. Or in the case of our zero waste lists, zero waste packaging. As we always note, this means either that it is naked, reusable, or compostable.
But what does compostable mean? How does compostable differ from biodegradable? These are the questions we haven’t really taken the time to answer, and we feel it’s high time we do.
While both terms represent the breakdown of matter, the misunderstandings bred by their similarities tend to cause a lot of problems when it comes to proper disposal. While “compostable” and “biodegradable” are often used incorrectly and interchangeably, they are quite different and it’s time we, as conscious consumers and zero waste advocates, learned the difference.
QUICK LINKS FOR BIODEGRADABLE VS COMPOSTABLE
- What does biodegradable mean?
- What does compostable mean?
- Verifying compostability, scientifically and legally
- Biodegradable and compostable certifications
WHAT DOES BIODEGRADABLE MEAN?
Let’s start with the broader (and thus somewhat more confusing) of the two terms. But first….
Don’t confuse biodegradable with just plain degradable.
Somewhere along your sustainability journey, you may have heard the phrase, “Technically, everything is biodegradable!” What they really mean is that everything is degradable.
Degradation also refers to the breaking down of materials, but it stops short of biodegradability’s natural end.
Traditional petroleum-based plastics and other heavy metal and chemical based materials fall into this category of degradable but not biodegradable. They never break down fully into their natural elements to be repurposed by the earth; merely into smaller pieces. And even that takes a very very long time (we’re talking thousands of years here).
Plastics are the biggest offender, because these are either photo-degradable (break down in sunlight) or oxo-degradable (now heavily restricted in the EU) into smaller pieces called microplastics. While much of society has adopted an “out of sight, out of mind” mentality when it comes to microplastics, these insidious buggers are poisoning every corner of the planet. They’re even making their way into the food chain through plankton, fish, birds, and, eventually, humans.
Ever heard the rumor that every piece of plastic ever made still exists? According to GreenPeace, it’s 100% true and 200% terrifying.
Then what is biodegradable?
At its most basic, for something to biodegrade is simply for it to break down into its natural elements, namely water, carbon dioxide, and biomass. This is the same for either solid waste or liquid waste entering water systems (like natural cleaning products).
This decomposition is accomplished by microorganisms such as bacteria and fungi in an environment of suitable temperature, moisture, and oxygenation. Things get tricky, however, when we factor in the time it takes to accomplish this.
The rate at which a material biodegrades depends on the conditions its given to do that in. Landfills, for instance, not only contaminate the process of biodegradation with toxic chemicals, but act as terrible environments for it. That and the sheer variety in the composition of different materials yield biodegradation rates that fall across a huge span of time, from several months to indefinitely.
Not everything that’s biodegradable breaks down in a reasonable amount of time.
From a consumer standpoint, this is why there is no certification or universal legal definition of what constitutes a biodegradable product. “Biodegradable” is quite often utterly meaningless in product labeling.
“Biodegradable” in legal terms.
Recently, the Federal Trade Commission has attempted to establish standards regarding biodegradability. Current FTC guidelines regarding biodegradability claims mandates that the entire product or package must “completely break down and return to nature within a reasonably short period of time after customary disposal”, as indicated by reliable scientific evidence.
There’s a lot going on with that phrase so let’s dissect it:
- “completely break down and return to nature”: This means it can’t simply break up into microplastics or similar smaller pieces of the original. However, this guideline makes no mention of toxic leachings from the breakdown process, which is a pretty big loophole.
- “reasonably short period of time”: This was formerly the most vague area of the guidelines which led to a lot of problems, as we mentioned above. However, the FTC recently extended this timeline to one year. They also mandate that the label must clearly qualify the rate of degradation.
- “after customary disposal”: This essentially means that marketers may not claim an item is biodegradable if it is normally disposed of in the solid waste stream where it will not properly biodegrade within one year. For example, if an item is almost certainly bound for either the landfill, recycling plant, or incinerator, it cannot be labeled as biodegradable. You may immediately notice the problem with this vague qualifier: how do we police where consumers will dispose of something? An irresponsible consumer could realistically dispose of anything improperly so is nothing truly biodegradable?
Why proper disposal of biodegradable items is so important.
Let’s expand briefly on the last point. Why does the FTC place such importance on how something will actually be disposed of?
Well, it’s no secret that lots of biodegradable products often find their way to the landfill. How many people use biodegradable bags for their trash?
Landfills are not only a horrible environment for biodegradation, but a downright dangerous one. Due to the amount of trash in landfills that makes for an extremely low oxygen content, any biodegradation that does happen will happen anaerobically, a process that released methane gas. Which, according to the EPA, is 25 times more potent than CO2.
What’s all the buzz about biodegradable plastics?
Biodegradable plastic became somewhat of a buzzword in the 1980s and like many 80s trends (we’re looking at you parachute pants), it would have been best to stay there. Especially considering there was no way to scientifically prove biodegradability until 2002. That’s two decades of unqualified claims leading people to falsely think they’re being environmentally responsible.
Thankfully, we now have test methods that can scientifically test whether something can fully biodegrade without leaving any residue, and can more properly certify products. We’ll get to the certifications shortly.
Technology has also progressed so far that it is IS possible to adapt organic materials to function exactly the same as plastic packaging. The most common plant-based plastics include:
- Cellophane: wood (one of the first forms of plastic ever made, actually!)
- Polylactic Acid (PLA): vegetable starch
- Plastarch (PSM): plant starch and polypropylene
- Mater-Bi: plant starch
And while we’ve truly made strides toward more sustainable product packaging, biodegradable plastic is still somewhat deceptive and we should treat it warily for two reasons:
- As noted above, FTC regulations technically only mandate that something must fully break down, not that it must leave no toxic residue. Many “biodegradable plastics” might fully break down, but they might also be laden with lots of chemicals.
- Many companies blend biodegradable plastic with regular plastic then place the clever caveat of “made WITH biodegradable plastic” on the label. Since they’re not technically actually calling the packaging biodegradable, the FTC can’t do much about it.
These deceptions are why some places, like the state of California, have made it illegal to label any plastic as biodegradable.
WHAT DOES COMPOSTABLE MEAN?
Now for the term that’s puts the “c” in “eco friendly”. If a material is compostable, it’s also biodegradable (though the reverse isn’t necessarily true). Think of compostability as the gold (or green) standard of biodegradation.
Essentially, composting merely enhances biodegradation by controlling moisture, temperature, and oxygenation to optimize microbial action. So rather than the biodegradation process taking anywhere from 6 months (at best) to 10,000 years (at worst), it takes place in a mere 12 weeks.
This entire process takes place in compost piles, compost bins, or other compost specific devices. It CANNOT occur in landfills, natural waterways, or oceans.
Unlike general standards of biodegradability, compostable products must also break down into completely non-toxic components. Even natural materials can be non-compostable due to alterations and additives during processing and manufacturing. Lumber is a prime example. While wood as a material class is 100% organic and thus compostable,building lumber is typically treated with toxic chemicals that negate its ability to be safely composted.
The whole process must not only not harm the environment, but benefit it by yielding “usable compost” created in “a safe and timely manner,” according to FTC guidelines.
The timeline for safe compostability is defined as about the same as whatever materials are being composted with it. For example, a piece of plant-based plastic that hits all other compostability criteria could not be considered compostable if it’s meant to be home composted with food scraps that biodegrade in half the amount of time as the plastic. This is why home compostability criteria are MUCH stricter than industrial ones.
FTC guidelines also mandate that all claims of compostability in marketing and packaging must qualify where the item is designed to be composted. Specifically, it must be explicitly stated if it can’t be home composted.
Home composters are often not sufficient for materials outside paper, food waste, and yard trimmings because they do not reach high enough temperatures.
Is there a difference between actual compostable and biodegradable products?
So what exactly is the difference between, say, biodegradable vs compostable containers? Both must entirely break down into natural elements and leave no toxic residue, but compostable containers must just do it faster.
Let’s take disposable coffee cups as an example. The difference between biodegradable vs compostable coffee cups lies not in the paperboard cup itself, but in whatever coating gives it is water resistant quality. A biodegradable cup might have a plastic coating which breaks down within a year, but still doesn’t entirely decompose in a composter in three months.
Let’s talk a bit more about these plastics.
Comparing biodegradable vs compostable plastics.
When comparing compostable vs biodegradable plastic, we must first bear in mind the biggest problem with biodegradable plastics.
The very term “biodegradable” is so misunderstood that it leads people to assume it still biodegrades regardless of how it’s disposed of. This “blind embrace” of the notion of biodegradable is why we see so much biodegradable plastic doing more harm in landfills.
In truth, we should just call any plastic capable of safely biodegrading compostable. Compostable plastics, aka bioplastics, are better than biodegradable plastic if for no other reason than the very phrase is less misleading.
To be considered a bioplastic, it must still break down quickly, support plant life in its broken down state, contain no toxic material, and be consumable by worms.
The persistent problem with even compostable plastics is that they are rarely home compostable because they require far hotter temperatures fostered by industrial composting facilities.
That said, packaging made of things like cornstarch, rice husks, and soy protein has truly revolutionized the world of eco friendly packaging. Considering many FDA and other product regulatory agencies now require certain products to be sold in sealed bags, it’s crucial we have a totally compostable option.
However, seeing “compostable plastic” on the label isn’t a license for us to get lazy. We must still be conscious of how we dispose of them. When buying items either made from or packaged in bioplastics, make sure to double check whether it is home compostable or whether you must take it somewhere else.
BioCycle’s Find A Composter is a good resource for finding composting facilities near you.
VERIFYING COMPOSTABILITY USING SCIENTIFIC TESTING AND LEGAL STANDARDS
American Compostable Standard:
The most important globally recognized name in compostable certification is ASTM International. Formerly known as The American Society of Testing and Materials, ASTM International provides 12,000 safety standards and product certifications.
In terms of compostability, the ASTM provide 3 go-to tests to determine a material’s compostability.
- ASTM D6400: The baseline test for compostability for plastics designed to be composted in municipal or industrial aerobic composting facilities. To pass, the material must biodegrade “at a rate comparable to known compostable materials” and produce usable compost undiminished in quality.
- ASTM D6868: Identical to above but for paper materials coated with a biodegradable plastic film (i.e. paper coffee cups with a water resistant PLA laminate). This certification ensures ALL parts will compost in municipal facilities.
- ASTM D6866: A radiocarbon analysis to determine a material’s bio-base carbon to its “fossil carbon” (derived from fossil fuels). Lots of dense science in this one, but essentially, the presence of carbon 14 indicates a material will break into biomass rather than fossil fuels.
European Compostable Standard:
Europe has two strict standard measures of compostability.
- EN 13432: Standards for compostable plastic packaging alone, in order to completely degrade in an industrial composting plant.
- EN 14995: An expansion of the former for compostable plastics used outside product packaging.
Both standards specify microbial action rate (must achieve 90% biodegradation in 6 months), end fragment size, ecotoxicity, and chemical analysis (must have additives no more than 1% and they must be environmentally harmless).
Australian Compostable Standard:
Australia also has two different standards of compostability, both regarding compostable plastics only.
- AS 4736-2006: The general standard of a plastic being “suitable for composting and other microbial treatment”. To err on the side of caution, this generally means in an industrial facility.
- AS 5810-2010: Verification for plastics that are home compostable.
LOOK FOR BIODEGRADABLE AND COMPOSTABLE CERTIFICATIONS
Biodegradability especially sees a lot of greenwashing due largely to its past of non-qualified standards and lack of definition.
Yet even composting gets a lot of false claims these days. Especially considering most of the above standards pertain to compostability in industrial facilities rather than home composters.
The best way to avoid greenwashing is to look for trustworthy labels and certifications that verify compostability.
- Scientific Certification Systems (SCS) Certified Biodegradable: Verification that cleaning and sanitation products disposed of in the liquid waste stream will not lead to chemical buildup in the environment.
- Biodegradable Products Institute (BPI) Compostable Logo: Since creation in 1999, the BPI Compostable Logo has used the ASTM D6400 and D6868 standards to certify and archive over 4,600 products (so far!)
- Australasian Bioplastics Association (ABA): Certifier for Australian and New Zealand products based on compliance with AS 4736-2006 and AS 5810-2010.
- The Coalition of Northeastern Governors (CONEG): Specifically ensures the absence of toxic heavy metals like lead, mercury, cadmium and chromium in packaging and labeling.
- Cradle to Cradle (C2C): a measure of safer, more sustainable products made for the circular economy.
- US Department of Agriculture (USDA): The USDA acts as a regulatory agency for nearly 80 independent authorized certifiers as part of the National Organic Program (NOP). Each individual certifying agent can be found in the Organic INTEGRITY Database.
- TÜV OK Compost: An Austrian-based certification based on the EN 13432 standard. This certification has two versions: one for industrial compostability and one for home compostability.
- DIN CERTCO Seedling: German-based certifications given based on either EN 13432 or AS 4736-2006.
And because natural compostable materials like wood can still be made non-compostable through chemical treatments during manufacturing, here are some certifications to look for specifically regarding wood-based products:
- Sustainable Forestry Initiative (SFI): Internationally recognized certifier for lumber and wood fiber products derived from responsible forestry and natural manufacturing.
- Forest Stewardship Council (FSC): An organization aimed at encouraging responsible forest management, the FSC certification verified ethical standards from forest origin all the way through organic production and manufacturing.
- DEBIO: A Norwegian certifier for wood and lumber products grown using organic forestry.
If you’re still not sure about a product, try searching for it in the Biodegradable Products Institute’s Product Catalogue of certified compostable products.
FINAL THOUGHTS ON BIODEGRADABLE VS COMPOSTABLE
For consumer purposes, both in product and packaging, we will ideally seek out compostable products. That way, we know they’ll biodegrade in a short amount of time without leaving any toxic imprint.
Plus the phrase is far more clear! Compostable = should be composted. It’s up to us as consumers to make sure that happens.
Composting’s main problem is its lack of infrastructure. According to a 2017 BioCycle study, the U.S. has a total of 4,713 municipal or industrial composting facilities, and not all of them are equipped to accept all types of organic waste. Considering how huge America is, this number is appallingly low.
No wonder the EPA’s 2015 Municipal Solid Waste report found that Americans only compost 8.9% of their waste.
We highly recommend you consider getting into composting, whether in your apartment or in your yard. It’s actually much easier than you think! We personally use a traditional compost bin and a vermi-composter (with worms) to compost and have grown quite fond of our wiggly waste wonders (they eat just about everything!). If you find these creepy crawlers a little, well, creepy, there are lots of other indoor compost bin options.
Again, for all your non-home compostable bioplastics, check out BioCycle’s Find A Composter to find your nearest municipal composting facility. Also check out the ShareWaste App which connects you with people in your area that want your organic waste!
Hopefully this cleared up some of the cloudiness around compostability and biodegradability. However, if you have any questions, please feel free to reach out to us! In the meantime, read those labels with a healthy dose of skepticism, look for the certifications, and compost as much as you can!