Which plastic is biodegradable


Can you dispose of bioplastic products in the bio bin? Or throw it on the compost? Can you just leave the cutlery made of bioplastics in the forest after the picnic? No! No way! The term “bioplastic” can not only mislead consumers. Neither the raw materials, nor the production, nor the disposal of bioplastics is definitely more environmentally and climate-friendly than that of fossil plastic. Keywords: land use, incorrect disposal, unclear definitions. The WWF sorts the chaos in the bioplastic mountain:

Bioplastics are not uniformly defined. The supposedly environmentally friendly “organic” can refer to production from renewable raw materials or their possible biodegradability or both. The term is used for a variety of different types of polymers. In the specialist literature, bioplastics are considered to be those that

  • are biodegradable and / or
  • consist of renewable raw materials (i.e. are bio-based).

This results in three different types of bioplastic:

  • petroleum based + biodegradable
  • bio-based + biodegradable or compostable
  • bio-based + not biodegradable

Materials that are produced organically but are not biodegradable are also referred to as bioplastics. Materials that are biodegradable but made from petroleum are also considered bioplastics.

What does "biodegradable" mean?

"Biodegradability comprises the property of a substance to be decomposed by microorganisms in the presence of atmospheric oxygen to form carbon dioxide, water, biomass and minerals and in the absence of air to form carbon dioxide, methane, biomass and minerals, whereby no period is defined." German Institute for Standardization (DIN) in 16208.

“Biodegradable” should not be confused with “degradable”. The former describes a breakdown into components that occur in nature, in particular carbon dioxide and water. The latter refers to the weathering or disintegration of large pieces of plastic into microplastics. Although it is barely visible in this form, it is no less harmful to the environment.

“Composting” refers to the same process in fast motion under optimized conditions - that is, man-made circumstances that normally do not occur in nature. All compostable plastics are also biodegradable, but not all biodegradable plastics are compostable. Bioplastics marked as “compostable” are not designed for compost in the home garden, but at best for industrial composting.

The time frame in which a biodegradable plastic decomposes depends on many factors. In addition to the respective type of bioplastic, temperature, oxygen supply, moisture, salt content, UV radiation and the presence of microorganisms all play a role. Accordingly, no general statements can be made on the duration of decomposition. The duration always depends on the material as well as the situation and environment. Most of the bioplastics currently labeled as "biodegradable" are only degraded under very specific conditions that are not necessarily present in the environment. This situation harbors the risk of greenwashing. In the oceans, for example, many “biodegradable” materials simply cannot be broken down. This is another reason why bioplastics should not end up in nature. Bioplastics are neither suitable to decimate the plastic vortex in the sea, nor to solve the microplastic problem.

Waste recovery systems not designed for bioplastics

The biodegradability or compostability of bioplastics is currently still a theoretical option. In practice, in Germany - as in most parts of the world - there is still no bioplastic composting on an industrial scale.

Biodegradable plastics need a longer residence time in the rotting plants than, for example, kitchen waste. So that no plastic residues remain in the compost, biodegradable plastics are sorted out in the waste recycling plant and incinerated. Currently, the proportion of bioplastics is only around one percent of the plastic used worldwide.

Without a specific recycling process (material flow), bioplastics cannot be recycled (materially recovered).

What does "bio-based" mean?

Materials that are made from biomass, i.e. organic substances, are called “bio-based”. In the case of bioplastics, the biomass comes from renewable raw materials such as corn, sugar cane or cellulose. In the case of bioplastics, although products are labeled as “bio-based”, they only consist partly of biomass and partly of fossil raw materials (polymers). There is no clear definition or regulation here.

Renewable raw materials for bioplastics can be classified according to generations. The first generation of raw materials refers to traditional crops such as corn or sugar cane. The second generation includes cellulose cultures, residues and agricultural waste. The third generation includes algae, for example. The generation of raw materials does not say anything in general about the environmental compatibility or climate impact of the resulting plastic, because this depends on various factors. On the one hand, this is determined by the environmental impact of raw material extraction. These must be reassessed on a case-by-case basis. On the other hand, this also depends heavily on whether plastic is composted, recycled or incinerated.

Bioplastics made from renewable raw materials are not necessarily more environmentally or climate-friendly than fossil-based plastics. While conventional (fossil-based) plastics usually cause more greenhouse gases, the renewable raw materials of bioplastics are in most cases grown on agricultural land. This means that cultivation can compete with food supplies or contribute to the deforestation of forest areas. Depending on the cultivation method, this can lead to acidification of the soil or an oversupply of nutrients (eutrophication).

Certifications offer orientation

There is no whitelist of raw materials that can definitely be used for bioplastic production with good environmental conscience. It always depends on the cultivation situation. In any case, the materials should be certified according to Bonsucro, Roundtable on Sustainable (RSB) Biomaterials or International Sustainability and Carbon Certification (ISCC PLUS) with the addition "GMO-free". See the WWF's Certification Assessment Tool (CAT).

WWF demands: closed cycles for bioplastics

Basically, plastic - including bioplastics - must never end up in the environment. Therefore: The less material used, the better for nature and people. Avoiding and reducing plastics should come first in all industries and households.

Bioplastics are only (more) environmentally friendly than petroleum-based if their renewable raw material base is sustainably obtained and they are consistently circulated.

The material cycle closes when bio-based and biodegradable plastic is collected, processed and recycled in a system adapted to the material. Clear labeling - bio-based, biodegradable or both - is essential.

Outlook: EU legislation

The European Commission has set itself the goal of bringing clarity to the bioplastics debate. As part of the implementation of the European Circular Economy Action Plan, it should be clearly regulated which plastics can be classified as “compostable” or “biodegradable” and how they should be disposed of. Furthermore, the commission wants to precisely define terms such as “bio-based”, “biodegradable” and work out a life cycle analysis to determine which types of bioplastics are advantageous and when. The WWF welcomes the initiative of the Commission and sees an urgent need for more transparency, education and technical progress in the bioplastics sector.

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