A Revolve Green guide to sustainable materials

Next time you find yourself perusing the aisles of your local grocery store, take a moment to read the fine print on the packages. Chances are, you’ll find one of three terms proudly displayed on the packaging: biodegradable, compostable, or bio-based. Companies use terms such as biodegradable and compostable to signal that the product is making a good choice for the environment. Environmentally conscious shoppers are likely to gravitate towards products that carry these terms, since they’re a convenient indicator that the product is better for the environment.

The problem is that the terms may have specific meanings in scientific or industry jargon, but are often mixed-up by well-meaning consumers, leading to the products in question finding their way into the wrong disposal systems, and failing to do what their manufacturers claim. At Revolve Green, we field questions from customers nearly every day asking something along the lines of “isn’t that the same thing?” We’re going to explain the fundamental differences between the three terms and what they really mean, so you can understand how they relate to one another

Why there is this misunderstanding surrounding the terms?

Let’s start by breaking down why the confusion occurs in the first place. “Biodegradable” refers to a property of certain materials. “Compostable” refers to a specific type of biodegradation process with additional requirements that transform the material into compost. “Bioplastic” refers to the source of the material. All three terms relate to the lifecycle of packaging materials, but each term examines a different aspect of the lifecycle.

“Biodegradable” refers to materials that can naturally decompose or break-down over time as a result of natural biological processes such as the actions of bacteria or fungi, into water, carbon dioxide, and biomass. The rate at which this process occurs and the conditions required for it to occur aren’t specified or regulated. You can see why “biodegradable” might be misleading, as technically, all materials can eventually breakdown given enough time. A plastic fork isn’t going to suddenly start turning into organic matter the moment you throw it in the trash, but given thousands of years, it could. “Biodegradable” is a very vague and broad term that isn’t very useful in isolation. A product that’s labeled “biodegradable” might not actually biodegrade in a reasonable amount of time if it doesn’t have the right conditions for biodegradation such as high amounts of heat, water, and microorganisms. In the best case scenario, you’re dealing with a product that might take centuries to naturally decompose in the right conditions. Worse case scenario, you’re throwing away something that was misleadingly labeled “biodegradable” thinking it would do something it isn’t physically capable of doing.

Biodegradable materials can be broken down naturally by organisms such as bacteria or fungi. A product labeled “biodegradable” may or may not break down in a reasonable amount of time depending on the conditions.

“Compostable” refers to materials that can be broken down into compost, or organic matter that can be used as fertilizer. Something that is genuinely compostable will naturally decompose into nutrient-rich soil within a certain amount of time (usually several months), without leaving behind any harmful toxins. In short, compostable materials can be turned into compost, or organic matter that can be used as fertilizer. “Compostable” is a much more specific claim than “biodegradable,” and it’s generally much harder to falsely assert. The exact requirements for a material to be compostable aren’t standardized around the world, but most countries and regions agree on the fact that the material must be able to breakdown into compost within a certain amount of time under certain conditions

Industrial compostable vs. home compostable

This can get a bit confusing, as there are basically two categories of compostable materials, and the difference between the two might not be readily apparent at first

• Industrail compostable materials require the controlled conditions such as heat and humidity that are only available in large-scale composting facilities.

• Home compostable materials can be broken down into compost within roughly six months in the average home compost.

So while industrial compostable materials can technically be broken down by homeowners, they’re much more suitable for large-scale composting facilities. Materials such as PLA (polylactic acid) which is commonly used in compostable bags and food packaging can be composted in large-scale facilities that have the equipment to accommodate such materials. They can also technically be composted at home, but the process will take much longer and won’t yield the same results. The problem arises when compostable materials that are only suitable for industrial composting facilities and commercial composting services get tossed into either the regular recycling bin or the home compost. In either case, they’re not going to get the conditions they need to be effectively composted, and in the case of the recycling bin, they might even compromise the entire batch of recyclable materials if the sorting facility isn’t equipped to separate compostable materials from plastic ones.

What is a bioplastic?

The term that confuses people the most, since it sounds like it should have something to do with biodegradability or compostability, but ultimately serves a completely different purpose. This one is rather simple, actually. A bioplastic is a type of plastic made from renewable biological sources such as plants, algae, or vegetable oils, rather than petrochemical sources such as crude oil and natural gas. So while the term ‘bioplastic’ does have to do with the lifecycle of the material, it refers to the source materials rather than the end result. In essence, the term ‘bioplastic’ refers to the inputs that went into the production of the plastic, while the terms ‘biodegradable’ and ‘compostable’ refer to the outputs. So a bioplastic can be biodegradable, compostable, or neither, depending on its manufacturing process and disposal conditions. To illustrate the difference, let’s briefly outline the three possible scenarios:

Bio-based, non-biodegradable

Bio-based plastics such as Bio-PE and Bio-PET are essentially identical to their fossil fuel counterparts, with the sole difference being the source materials. When discarded, they must be recycled in the same way as petroleum-based plastics and will not biodegrade or compost.

Bio-based and biodegradable

PLA (polylactic acid) is a bioplastic made from starch that is biodegradable under the right conditions.

Fossil fuel-based and biodegradable

PBAT (Polybutylene adipate terephthalate) is a biodegradable polymer that is not bio-based.

So in summary, “bioplastic” refers to the source materials that went into the production of the plastic, while “biodegradable” and “compostable” refer to the end result and what happens to the plastic once it’s discarded.

How do the three terms intersect?

Let’s briefly go over the different ways in which the three terms intersect. As mentioned above, compostable materials are always biodegradable in a specific and regulated manner. Not all biodegradable are compostable, as something that takes significantly longer to biodegrade wouldn’t qualify as compostable. Not all bioplastics are biodegradable or compostable, as illustrated by the example with Bio-PE and Bio-PET. Similarly, not all compostable materials are bioplastics, as some can be made from starch, paper, or other biological materials. In theory, a bioplastic can be either compostable or biodegradable, or neither, depending on the materials and manufacturing process.

A bioplastic can be compostable, biodegradable, or neither, depending on its manufacturing process and disposal conditions.

Where do the terms overlap?

All compostable materials are biodegradable in a specific and regulated manner.

Summary

Think of the terms as three overlapping circles with some intersecting parts

A compostable material is always biodegradable in a regulated manner, but not all biodegradable materials are compostable. A bioplastic can be either compostable, biodegradable, or neither, depending on its manufacturing process.

What to look out for

As mentioned above, each term serves a different function and pertains to a different aspect of the lifespan of the material. However, the lack of universal regulations means that terms such as “biodegradable” and “compostable” can be misleading if you don’t know what to look out for. A good rule of thumb is to be wary of vague language and ask for specific details. Products that are genuinely compostable will usually have specific instructions and will state how long it takes to compost under what conditions.

Products that are genuinely biodegradable will specify the conditions under which they can biodegrade, if they can biodegrade in a reasonable amount of time, and if they can biodegrade in the environment they’re going to be disposed of in (landfill, home compost, etc). In reality, many products that are marketed as compostable or biodegradable won’t necessarily specify any details, and will rely on the vague, misleading term alone to convey information. In most cases, a product that has been genuinely compostable or biodegradable will have a certification mark stating this, as there are industry standards that manufacturers can adhere to in order to prove that a product is genuinely compostable.

What certification marks should I look out for?

There are several industry certifications that can serve as third-party verification that a product is genuinely compostable

BPI Certified

The Biodegradable Products Institute certification indicates that industrial compost facilities across North America have been able to successfully compost the product.

TÜV “OK Compost”

A European compostability certification that has two variations: “OK Compost Industrial,” which is similar to BPI, and the more difficult to attain “OK Compost Home.”

EN 13432

The compostability standard that covers compostable packaging and materials in Europe.

ASTM D6400/D6868

The compostability standards that apply to plastics and plastic packaging in the United States that hold the same requirements as EN 13432. Most products that carry the BPI certification comply with the standards set by these documents.

So a product that carries one of these certifications has been verified as compostable by an independent third party, which means it can be relied upon to actually be compostable as stated

How to use these terms in practice

Now that you understand the differences between the three terms, their relationship with one another, and why they often get confused with one another, let’s go over the practical implications of the information.

1. Always check if a compostable product is home compostable, or if it needs to be sent to an industrial composting facility in order to be disposed of properly.

2. Don’t recycle compostable plastics. Even if you put a PLA plastic bag in the recycling bin, it won’t be recycled alongside other plastics, since it’s chemically different from petroleum-based plastics. Having a small amount of PLA mixed in with a larger amount of PET can render an entire batch of recyclable plastic unusable.

3. Treat “bioplastic” as a raw material, rather than a disposal instruction. If you see a product that’s labeled as bioplastic, make sure to research what you should do with it once you’re done using it.

4. Check what composting facilities are available in your area, as products that are industrially compostable often still have to wait for a composting facility to accept them, rather than being disposed of in the nearest landfill.

5. Whenever possible, reduce and reuse rather than recycle or compost. The best option in any situation is to get rid of the need for unnecessary packaging materials by reusing what you already have.

Why does it matter?

It’s always disappointing to see an otherwise environmentally friendly company fail to live up to expectations, or to see well-meaning consumers get misled and end up doing more harm than good by accident. The misleading information and vague language around the topic of biodegradable, compostable, and bioplastic materials ultimately serve to undermine the goal of creating an environmentally conscious society and a sustainable cycle of production and consumption.

Environmentally conscious consumers that are aware of the misleading practices can ensure that the companies that claim to be better for the environment actually do what they claim to do, and that the products that do what they claim to do can reach the consumers that genuinely want to support eco-friendly manufacturing practices. At Revolve Green, we believe that choosing the right materials based on actual properties and environmentally friendly practices is a much more productive way to focus our efforts on making the world a better place.

Conclusion:

Vague environmental language not only fails to communicate effectively, but it can also adversely affect behavioural change at scale. The fact that a product will 'just' biodegrade and instead ends up in a landfill or compostable packaging wrongly disposed of in the trash, contaminating otherwise viable industrial compost, is counterproductive to the desired goal. If you've remembered anything from this article, it should be what each word is actually answering:

Biodegradable answers the question 'will this break down, eventually?', and given enough time, the answer is yes for almost anything, which is why the descriptor has little value on its own without additional context about the timeframe and environment in which it will do so.

Compostable answers the question 'will this break down into usable soil, quickly and safely, under specific conditions?' and is the only term out of the three that actually goes through a standardized certification process.

Bioplastic answers the question 'what is this made out of?', not 'what will it turn into'. A product made out of plant-based PLA doesn't automatically become biodegradable, and not all biodegradable packaging is necessarily made out of plant-based materials.

With these distinctions in mind, hopefully, the next time you see packaging with any of these terms on it, it will serve to educate you or make it clear what actions you need to take to have the intended effect. More transparency, education, and specificity are always valuable tools towards achieving real change and building sustainable product systems that work within the confines of nature.

At Revolve Green, this is why we advocate for designing with consideration for the output materials and their end use. Wherever possible, we encourage the use of truly compostable materials in environments where they can be composted, and if they require a specific process, we believe it's important to be clear about that. And finally, we remain committed to being clear about what limitations or special considerations, if any, apply to a given material, whether it's plant-based or not, compostable or not, biodegradable or not. After all, nature isn't likely to care what your product was, where it came from, or what special instructions it required to get there – only what it'll become.

How we use this information at Revolve Green

We focus on materials that have proven benefits to the environment and a realistic potential for contributing to a sustainable cycle of material use. We make sure to clearly communicate the limitations and specifications for the materials we carry, and we make informed decisions based on what we know rather than relying on vague terms that can be misleading. We believe that the best way to promote sustainability is to ensure that the materials we recommend are suitable for the recycling or composting infrastructure that will eventually process them, rather than pretending those infrastructural limitations don’t exist.