Biodegradable and compostable. What is the difference?

Year by year, more and more municipal waste in Poland is recycled. However, this number is still not staggering compared to all the garbage. In 2020, 26.7% of waste was processed . For comparison, almost 40% of garbage ended up in landfills ¹ . The remaining waste was either incinerated (21.5%) or composted and fermented (12%) .

Let's look at this last group. Bio-waste and plastics marked as compostable are sent here . During disposal, they do not need additional raw materials, as is the case, for example, during the glass recycling process (read about it here ) or plastic processing. What about biodegradable plastics ? This is a completely different group. They are neither compostable nor recyclable. We already explain why.

What does biodegradable mean?

The term “biodegradable” can be misleading for people who care about caring for the environment. Biodegradation is the process of material decomposition under the influence of microorganisms - bacteria, fungi, algae. There is no specific time limit for this disintegration to occur ² . It only means that the packaging will decompose. Yes, this entire process will take less time than in the case of ordinary plastic. However, such material may release chemicals into the environment , including: microplastics or metal particles. Legal standards do not specify the composition of biodegradable plastics. There is no requirement that they be of natural or plant origin. According to the law, the biodegradable marking does not mean that the material will disintegrate completely ³ . The manufacturer only has to guarantee that after 45 days, 70% of the material's weight will be degraded ⁴ . Decomposition often requires quite high temperatures (e.g. 60 ° C), specific humidity and air access . If these conditions are not met, there is no guarantee that the plastic will decompose.

What does compostable mean?

This is a narrower concept . It means that the material decomposes under the influence of naturally occurring microorganisms in the conditions of a composter . This process takes place over a specific period of time, no longer than 6 months. During degradation, carbon dioxide, water, inorganic substances and biomass are released. These substances do not leave behind significant pollutants or toxic residues ⁵ . Compostable plastics usually have one of two types of certificates – “ home compostable ” or “ industrial compostable ”. They can also have both. As the name suggests, the first of these certificates means that the packaging will easily decompose in a home composter. The second type concerns plastics intended for composting in industrial conditions, where the entire process is accelerated. In both cases, the compostable plastic will decompose in a relatively short time. It won't leave any "chemistry" behind.

Biodegradable and compostable – what's the difference?

These 2 terms are very similar and many people confuse them. Every compostable material is biodegradable. However, not every biodegradable plastic is compostable. Biodegradable materials may leave behind particles of artificial origin , e.g. metals or microplastics. In this way, they pollute the environment. Compostable – no. Biodegradable plastics can take decades to decompose. In the case of compostable products, this time is much shorter - usually up to 6 months. If they are composted, they also create added value . As a result of their decomposition, the so-called Hummus. Of course, it's not about a chickpea snack, but about a mineral fertilizer. It contains valuable ingredients for the soil and supports plant growth.

Why is it important to distinguish between biodegradable and compostable packaging?

By throwing biodegradable packaging into a composter, we can disrupt the decomposition process of natural materials and pollute them with toxic residues. We will waste all the compost . Plastics marked as biodegradable cannot be recycled together with other plastics. If we throw them into the yellow metal and plastic bin, it may make their processing difficult or even impossible .

Therefore, packaging marked “biodegradable” should be thrown into the mixed waste container . The brown waste segregation container with the inscription BIO is intended for packaging with a compostability certificate and natural waste . Vegetable and fruit peelings, coffee or tea grounds, remains of food products of plant origin, egg shells, leaves, grass and wilted plants should go here.

Biodegradation is not "eco".

As you can see, biodegradation only sounds "eco". In practice, such plastics simply increase the amount of waste in landfills . On the one hand, they are not suitable for processing. On the other hand, we don't know when they will fall apart . Some plastic bags marked as biodegradable contain additives that help break them down into microplastics ⁶ . However, smaller plastic particles can be even more dangerous. They are carried by the wind across the planet. They are eaten by animals and humans. Microplastics settle in our bodies. And its effects on health are not well studied by scientists, especially in the long term. Therefore, it is not worth relying on the word "biodegradable" when choosing the packaging of the product we buy.

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