Biodegradable and compostable plastics — challenges and ...

What are the challenges?

Plastics are a key material in modern life. They are versatile, light and can be produced at relatively low cost. Currently, only about 1 % of plastics and plastic products on the global market are considered bio-based, compostable and/or biodegradable (European Bioplastics e.V., b).

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Most plastics continue to be made from fossil fuels in a process that contributes to increased greenhouse gas emissions along their value chain. Indeed, plastics pollute throughout their life cycle from production, to use and finally through their disposal.

Recycling rates of plastic are low and plastics leak into the environment through, for example, littering, improper waste management and wear and tear of products. They can stay in nature for many years and potentially enter the food chain. Contamination with plastic particles is a particular challenge in terms of keeping compost made from separately collected bio-waste clean (EEA, ).

Biodegradable, compostable and bio-based plastics are increasingly promoted as a solution to some of these challenges. More and more consumer products, such as plastic bags, packaging and single-use cups, are labelled as &#;compostable&#;, &#;biodegradable&#; or &#;bio-based&#;. But what exactly do these terms mean? To what extent can biodegradable, compostable and bio-based plastics help solve the sustainability challenges posed by plastics? And do they create new ones?

Biodegradable, compostable, bio-based &#; what does it all mean?

Biodegradable and compostable materials can be broken down by microorganisms into water, carbon dioxide, mineral salts and new biomass within a defined period of time. Whether a biodegradable or compostable plastic item biodegrades and how quickly that happens, strongly depends on the conditions it is exposed to during disposal. These include temperature, duration, the presence of microorganisms, nutrients, oxygen and moisture (De Wilde et al., ; van den Oever et al., ).

Different types of biodegradable and compostable plastics are designed to biodegrade under specified conditions (Box 1). In other conditions, they might biodegrade slowly or not at all  or fragment into microplastics.

Box 1. Overview of types of plastic

Biodegradable plastics are designed to biodegrade in a specific medium (water, soil, compost) under certain conditions and in varying periods of time.

Industrially compostable plastics are designed to biodegrade in the conditions of an industrial composting plant or an industrial anaerobic digestion plant with a subsequent composting step.

Home compostable plastics are designed to biodegrade in the conditions of a well-managed home composter at lower temperatures than in industrial composting plants. Most of them also biodegrade in industrial composting plants.

Bio-based plastics are fully or partly made from biological raw materials as opposed to the fossil raw material (oil) used in conventional plastics.

Non-biodegradable plastics last for long periods of time. They can disintegrate into smaller pieces, forming microplastics, and accumulate in the environment.

Oxo-degradable plastics include additives that, through oxidation, lead to their fragmentation into microplastics or chemical decomposition.

Biodegradable or compostable plastics can be produced from either bio-based or fossil raw material (feedstock) (Figure 1). They can be produced to have similar functionality to or the same functionality as conventional plastics (WRAP, ). The sustainability of bio-based materials, just as of fossil-based plastics, depends on production practices, the products&#; lifetime and end-of-life treatment (EEA, ). The term bioplastics is sometimes used for plastics that are either bio-based or biodegradable, or both (European Bioplastics e.V., c). Given that these have very different properties, consumers could misunderstand the rather vague term &#;bioplastics&#;.

Figure 1. Bio-based, bio-degradable and compostable plastics

Source: ETC/WMGE and EEA.

Standards, labels and logos

European standards exist for assessing the compostability of plastics in industrial composting plants and the biodegradability of mulch films in soil for use in agriculture. Plastic materials or products fulfilling these standards may be certified and labelled accordingly (Table 1). To date, there is no European standard for assessing biodegradability in water. This is because the very variable conditions in freshwater and marine environments make standardisation difficult. However, the International Organization for Standardization is developing standards for testing biodegradability in specific marine environments.

Table 1. European standards for compostability and biodegradability of plastics in different environments and selected logos and certification schemes

Sources: TÜV AUSTRIA (a, b, c, , ), DIN CERTCO (, , ), Hilton et al. (), European Bioplastics e.V. (, a, b), CIC (). Logos reproduced with permission from TÜV Austria Belgium NV, European Bioplastics e.V., DIN CERTCO and CIC &#; Consorzio Italiano Compostatori.

Any claim of compostability or biodegradability should be precise and clearly related to the conditions under which the properties apply. Certifications guarantee that a product complies with an established standard or a set of conditions defined by the certifier. Nevertheless, real-life conditions can differ from these conditions and hamper biodegradation. This is especially of concern for home composting and for biodegradability in soil and water (Hilton et al., ).

Industrially compostable plastic products are designed to biodegrade under specific, controlled conditions in industrial composting plants. They do not necessarily (fully) compost in semi-controlled home composters or in the uncontrolled conditions of the natural environment. Although labels for industrial compostability usually refer to the standard used for certification, bad practice exists in the consumer market (Hilton et al., ). Providing additional information beyond the label itself would enhance understanding of how to dispose of the product.

Consumer behaviour

The differences between &#;compostable in industrial composting plants&#;, &#;home compostable&#;, &#;biodegradable in soil/freshwater/marine water&#; and &#;bio-based&#; are not easy to understand. For example, in a survey in Germany, 58 % of respondents thought that all &#;bioplastics&#; were compostable (Blesin et al., ). Many consumers struggle to understand environmental claims and labels and do not differentiate between certified labels and self-declared labels (EC et al., ).

Experience from bio-waste (food and garden waste) collection shows that measures that depend on consumer behaviour are only adopted by a certain share of the population. To increase participation, the measures need to be accompanied by customised awareness-raising and information campaigns (EEA, ). Teaching children about labels and correct waste sorting can also play an important role. How to correctly dispose of products made of industrially compostable plastics also depends on the local waste management system and treatment infrastructure.

Therefore, repeated, targeted and clear communication with consumers is needed to explain the differences between compostability and biodegradability in different environments. Additional measures, such as standardised colouring for industrially compostable bags or QR codes providing further information, could improve clarity.

There are fears that consumers might misunderstand biodegradability or compostability claims as a &#;licence to litter&#;, but evidence supporting or refuting these fears is scarce (Hilton et al., ).

Waste management of biodegradable and compostable plastics

A circular economy retains the value of products and materials in the economy as much as possible. Although biodegradable and compostable plastics are technically recyclable, they are currently not recycled back into plastic material. Rather, they are treated as an impurity in the recycling of conventional plastics when collected together. Increasing market shares in future could aggravate the situation but could also make recycling of certain biodegradable or compostable plastics economically viable (Crippa et al., ). Nevertheless, further research, innovation and investment into recycling plastics is required.

Anaerobic digestion treats bio-waste without the presence of oxygen. It generates a digestate and biogas, which is a renewable energy source.

Although compostable plastics do not add nutrient value to compost (Burgstaller et al., ), they have a role in supporting sustainable bio-waste management. Bio-waste from households and other sources is increasingly collected separately from other waste across Europe. Digesting or composting bio-waste in industrial digestion or composting plants results in compost or digestate that can be used as soil improver and fertiliser, as long as they comply with national quality requirements. Separate collection or home-composting of bio-waste will be mandatory in all EU Member States from the end of onwards (EU, ).

Contamination with conventional plastics is an increasing challenge for compost quality (EEA, ). Replacing conventional plastics with certified compostable plastics for items that are often mixed with or attached to food waste, e.g. fruit stickers or tea bags, can help reduce contamination with conventional plastics (Crippa et al., ; Hilton et al., ).

Experience shows that using compostable plastic bags increases the capture rate of food waste because consumers find them convenient (Burgstaller et al., ). Some municipalities and waste collectors therefore recommend or require the use of certified compostable plastic bags for collecting bio-waste. Others will not accept compostable plastic bags. The strategy also depends on the existing bio-waste treatment infrastructure (e.g. typical composting period, treatment capacity, anaerobic digestion technology, strategy for removing impurities, including plastics) (Burgstaller et al., ; Hilton et al., ).

Implications for Europe&#;s policy actions

The circular economy action plan envisages creating a clear policy framework for plastics with biodegradable properties (EC, ). This may entail:

• harmonised rules for defining and labelling compostable and biodegradable plastics
• finding out in which applications using such plastics has environmental benefits.

For example, compostable plastics have a potential environmental benefit in specific applications such as bio-waste collection bags and items attached to bio-waste (Hilton et al., ). This is provided that the technical set-up of the local bio-waste management infrastructure guarantees effective collection and biodegradation of such plastics. Agricultural mulch film is another example. Using biodegradable mulch film instead of conventional mulch film can potentially avoid long-term plastic accumulation in soil. This is because mulch films made of conventional plastics are difficult to completely remove from farmland (Crippa et al., ).

A labelling system needs to avoid confusing consumers. Awareness-raising campaigns and clear communication with consumers will improve their understanding of the labels used on plastics and ensure their correct disposal. Applications that increase the risk of littering or contamination of compost with plastics (including those that are compostable or biodegradable) might have to be restricted. They may need to be prevented from being marketed as biodegradable or compostable.

Biodegradable and compostable plastics can offer environmental benefits if developed for specific situations and applications. Further improvements are urgently needed. The market for such products is likely to grow in the coming years. However, compostable and biodegradable plastics are far from providing a general, stand-alone solution to the challenges Europe faces with plastics today.

Posted on Jul 26th

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Ever picked up a product labeled "biodegradable" or &#;compostable&#; and wondered what it means? You're not alone! 

The terms biodegradable and compostable are often used interchangeably. While there is some overlap, they do not mean the same thing!

All compostable products are biodegradable, but not all biodegradable products are compostable.

While it is great that sustainable products are becoming more popular, some of the terms used to describe them aren&#;t always clear. Understanding the definitions of terms such as compostable and biodegradable empowers everyone with the knowledge to make sustainable choices.

It's important that both brands and consumers know the difference. Customers want to know they're making the best choice when purchasing from you. Your customers need to know how to properly dispose of your packaging. Being clear that your packaging is compostable creates confidence in your sustainable brand and allows consumers to make smarter purchasing decisions. 

Compostable Definition: What Does Compostable Mean?

Compostable materials break down completely into their basic parts (water, carbon dioxide, and biomass). They will break down in a timely manner at a rate consistent with similar organic materials and will not release harmful residue or toxins.

Products labeled as compostable must be tested to meet US industrial composting standards ASTM D and ASTM D. These standards require that compostable products biodegrade and disintegrate within 90 days and leave no harmful residue. Testing includes a seed germination trial, which ensures the compost produced is not harmful to plant life.

Compostable products add value to the planet's ecosystem by decomposing into nutrient-rich compost. Packaging that is labeled as compostable should be disposed of in a compost bin.

More Information on Elevate Packaging&#;s Composting Standards

Biodegradable Definition: What Does Biodegradable Mean?

If something is biodegradable it can be broken down by naturally occurring microorganisms such as bacteria and fungi. Every material will biodegrade, given enough time (even centuries!).

Unlike compostable, the term biodegradable is not regulated. There is no time limit for biodegradation, and no testing is done to ensure that the product is free from dangerous toxins. Ideally biodegradable material will break down quickly and safely, however not every product advertised as biodegradable meets these criteria. 

A product labeled as biodegradable without any further context is vague and misleading to consumers. Because this term is so vague, biodegradable products may contaminate compost and should be disposed of in trash collection destined for landfill.

Read More: What is Compost Contamination?

Which is Better, Compostable or Biodegradable?

Both terms describe a natural process for recycling organic waste. All compostable products are biodegradable, but biodegradable products are not always compostable.

The main difference is that compostable products have undergone strict testing to ensure that they break down within a specific time frame and do not release anything harmful into the environment. Biodegradable products have no such requirements, meaning that they may not be as beneficial as they first appear.

Compostable packaging will:

• Break down within the time needed by the composting environment
• Not release harmful toxins as it decomposes
• Create healthy compost that enriches the soil

Compostable packaging must adhere to strict standards and has been rigorously tested. Packaging labeled only as biodegradable cannot be composted and must therefore be sent to a landfill.

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Other Terms

Degradable

The term degradable defines a broad category of things that are capable of breaking down and disintegrating. There is no standard for how it breaks down, how long it will take, or what it will break down into. It could be safe, but it is most likely not.

Oxo-Degradable

The term Oxo-Degradable is simple greenwashing. Oxo-degradable products are conventional plastic mixed with an additive that helps them disintegrate faster. If you&#;re familiar with the problems caused by microplastics you can see that this is not only a poor solution to plastic waste, but actually incredibly harmful!

Once disposed of, the plastic becomes brittle and quickly fragments into smaller and smaller pieces. Oxo-degradable products produce harmful microplastics by design!

Both degradable and oxo-degradable products are not compostable and are not suitable for recycling. They should be disposed of in a landfill.

How to Choose the Most Sustainable Packaging

Understanding the nuances between "biodegradable" and "compostable" might feel overwhelming initially, but once you're armed with this knowledge, your sustainable packaging decisions become clearer!

Every phase, from sourcing raw materials to the disposal of the product, has an environmental stake. This is where a product life cycle assessment may be helpful &#; it provides a view of a product's full environmental journey, revealing areas for possible sustainable improvements. Curious about how to do this? Dive deeper with our guide on how to conduct a product life cycle assessment.

A circular economy aims to eliminate waste and pollution, circulate materials, and regenerate nature. What Does the Life Cycle of Your Compostable Packaging Look Like? Choosing compostable packaging means you're helping to reduce waste and keep our soil healthy. We're here to help you make the most environmentally friendly choices. Together, we can keep moving towards a world with less waste and more respect for our environment.

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*Originally posted Mar 21st , updated July 26

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