How does biodegradable plastic help the environment?

Bioplastic Real ALTERNATIVE or new PROBLEM?

From: Heike Westram

Status: 07.12.2020

Bioplastics are becoming more popular and used more often. But often the bio-plastic is not "bio" at all - neither sustainable nor environmentally friendly. Bio-based and / or biodegradable - where bioplastics can be a real alternative.

Bioplastic: What is that, actually?

Bioplastics are both plastics that biodegradable are, as well as plastics that from renewable raw materials were produced (biopolymers). These do not necessarily have to be biodegradable - for example natural fiber-resin mixtures for coffee mugs made from bioplastics. Bioplastics is not a protected term!

good idea: Mulch film made of bioplastic

In agriculture, a lot of plastic is used that remains in the fields - for example in depot fertilizers or mulch films

Again and again in agriculture, aids are used in which plastic is introduced into the soil and sometimes remains simple there - for example, plastic covers with depot fertilizer, which gradually break down into microplastics in the field and are to be banned. Mulch films, on the other hand, are already made from "plastic that is biodegradable in the soil" - with a seal. In the end there is really nothing left that is not allowed in the ground.

Bamboo cups & Co: More in there than hoped

You know: There is this mostly cute colored, super-light and tasteful crockery in the shop, bowls, plates and mugs - and then it's made of bamboo! You can immediately see the koala in front of you, oh no, it was the panda. And the panda, it stands for environmental protection, doesn't it?

Bamboo cups - a sham?

But: by no means! For the great natural material bamboo, the end as a coffee mug is probably the most inglorious. The bamboo cup is not biodegradable. Melamine resins are included as an adhesive so that it is so beautifully colorful and dishwasher-safe. And - as the Stiftung Warentest found out in summer 2019 - often enough pollutants that about every second bamboo cup releases into the drink.

In addition, the bamboo does not grow abundantly here, but has to be imported in large quantities from China.

Quote: Less sustainable than normal plastic

"A bamboo plastic cup is usually not as sustainable as a pure plastic cup. In the end, I can recycle this plastic because it is single-origin. This is not possible with mixtures of bamboo, corn starch and melamine. They can only be incinerated. "

Uwe Lauber, Chemical and Veterinary Investigation Office in Stuttgart

Shown: Classification of bio-plastics

Bio-based or biodegradable?


  • consists (in part) of biomass (sugar, starch or plant fibers) or bio-polymers, e.g. produced by algae or bacteria
  • can be mixed with petroleum-based plastic ("blends")
  • may contain resins and other substances
  • can be biodegradable
  • only 23.2% of bio-based plastics are biodegradable (as of 2016)
  • not always recyclable, except in incinerators


  • decomposes in the soil or when composting to at least 90% in water, oxygen, CO2 and humus
  • but sometimes only under industrial conditions such as composting plants
  • sometimes too slow for composting plants
  • can, but does not have to be, bio-based
  • Petroleum-based plastic may also be biodegradable

What is important for the degradability of a plastic is not its raw material, but the chemical structure of the substance: Bio-based plastics such as bio-PET or bio-PVC behave like synthetically produced plastic.
Novel biopolymers such as PLA (polylactides made from sugar), which are used for packaging films or plastic bottles, are, on the other hand, biodegradable as long as they are not mixed with other plastics.

good idea: Nylon stockings made from leftover chicory

At the University of Hohenheim, bioplastics are produced from chicory roots - for plastic bottles or nylon stockings.

Ok, plastic bottles could be avoided completely if you drag a little more instead. But do without nylon stockings? Could be a major loss for some and some.

At the University of Hohenheim, a bio-based plastic is made from agricultural residues: After the chicory has been harvested, around 800,000 tonnes of the roots are left over as waste across Europe. Inulin, a multiple sugar, can be obtained from beets. And from this, the scientists produce the biopolymer hydroxymethylfurfural (HMF) - a basic chemical for plastics. At the German Institute for Textile and Fiber Research (DITF), PEF is produced from beet HMF - 100 percent bio-based.

This plastic is produced in a resource-friendly manner: neither crude oil flows into the biopolymer, nor is additional land used for cultivation. Depending on the processing, the end product could also be biodegradable. But at the University of Hohenheim, the aim is to ensure that the plastic is ultimately recyclable.

Source: University of Hohenheim

Quote: Recyclable instead of degradable

"We do NOT make biodegradable plastics, but recyclable plastics. It is much more environmentally friendly to reuse plastics than to compost them. And plastics that can be composted cannot be recycled.
But you can, if you want, make PEF biodegradable. If you really want to. However, you then have to store your clothes (in this case a jacket or coat) very dry and use them up quickly. And please don't sweat too much either! :-) "

Prof. Dr. Andrea Kruse, Institute for Agricultural Engineering, University of Hohenheim, opposite Bayerischer Rundfunk, October 2020

youtube Bioplastic bowl DIY

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Make your very own bioplastic bowl!

Recipe: Cook your own bioplastic!

1 tbsp starch
1 teaspoon vinegar
4 tbsp water
1 teaspoon glycerine (from a pharmacy or drugstore, preferably from vegetable fats)

Source: Science Luxembourg

Mix the ingredients thoroughly with the whisk and heat in a saucepan over medium heat. Keep stirring until the porridge thickens significantly.
Pour the mixture into molds or roll out on a baking sheet and allow to dry. Finished!

AND: not only bio-based, but completely biodegradable.

Expert: Piles of plastic rubbish

"We have a much bigger problem with the fact that a good fifty percent of the amount of plastic ever produced is stored in landfills somewhere in the world that slowly spread out into the world - as microplastics or other plastic fragments that continuously fill our world. That is why it is so important that we produce and use plastics which at least consist of renewable raw materials, but which must be biodegradable. "

Professor Cordt Zollfrank, TUM Campus Straubing

good idea: Delicious plates made from wheat bran

100% biodegradable - and edible: plates made from wheat bran

Wheat bran plate: Wheat bran falls as a by-product of flour extraction and is more of a waste product. The Polish miller Jerzy Wysocki presses the bran into plates that can replace disposable plastic plates. Not only are they biodegradable, but they are also edible. And they smell, so Wysocki in an interview with rbb: "After the first pressing I knew: That's it! How the plate smelled, how beautiful it was!" Strictly speaking, however, the plates are not made of bioplastics. Nevertheless, or perhaps because of that, a real alternative to plastic disposable tableware.

Bio-plastic garbage: Bio bin or yellow sack?

  • Currently, unfortunately, mostly: neither nor!

Bioplastic in the bio bin?

Not in the organic waste bin or compost
Most bio-based plastics are not biodegradable at all and therefore do not belong in the compost or in the bio bin. Biodegradable plastics often only decompose at high temperatures, such as those offered by industrial composting plants, but not domestic compost. However, the biodegradable plastic often takes too long for industrial composting plants.

Bio-based plastic is currently mostly not recycled

Not for recycling
Even in the yellow sack or the yellow bin, bioplastics are currently not in good hands. It is true that bio-based plastics can be recycled - also into new granulate and not just new park benches. To do this, however, the plastic must be of one type, not a mixture. And the bioplastic would then have to be recognized by the infrared sorting machines. As long as the proportion of bioplastics is still so low, recycling and the necessary retrofitting for waste management does not pay off, a waste disposal company in Moosburg an der Isar told Bayerischer Rundfunk in July 2020.

Bioplastic ends up being incinerated as residual waste and belongs in the residual waste bin. Incidentally, this is also often referred to as recycling, because energy is generated through incineration. Well

Inquired: Does bioplastics save CO2?

In fact, one could consider bio-based plastics as a CO2 sink, i.e. something that absorbs and stores carbon dioxide and thus relieves the atmosphere and the climate. Example Green PE: This is a polyethylene film that is not based on petroleum, but is made from sugar cane. In sugar cane - as in every tree and every plant - CO2 is bound. According to the manufacturer, there are three kilograms of carbon dioxide in every kilogram of Green PE film.

Of course, only until the film has either decomposed or burned in the garbage dump - then all the CO2 is released again.

Look closely: This is how I recognize the different bio-plastics

Industrially compostable plastic Requirements: In industrial composting plants, ninety percent of the plastic must have disintegrated into particles smaller than two millimeters in about three months. After six months, the material must be at least ninety percent degraded. The resulting compost is tested for normal plant growth. All ingredients must be safe for composting. Petroleum-based plastic can also meet the requirements.

Pro Contra: Less plastic waste in the sea thanks to bioplastics?

"The way we are going here is: to produce plastics from biological materials that degrade in a few weeks and therefore do not even end up in the sea." Thomas Brück, TU Munich, Chair for Industrial Biocatalysis

"Even if I find a substance that is actually completely metabolized by the microorganisms into water and CO2 afterwards, that doesn't mean that microplastics or tiny fragments cannot develop on the way there." Hanna Behnsen, Institute for Bio-Plastics, University of Hanover

Greenwashing: The good "organic" image

In the past few years, the amount of bio-plastics produced has increased continuously. In 2018, 3.4 million tons of bio-based plastics were produced worldwide. The amount of biodegradable plastic, on the other hand, has remained almost the same. But the prefix "bio" can deceive the consumer, for example when a layer of aluminum lies between two layers of bioplastic on bio-PE film and the packaging still says: "80 percent made from biomass". Sounds good, but above all it helps the image of the provider.

Plastic made from oil is ugh, plastic made from plants is good

In September 2020, the nova Institute published a consumer study based on depth psychology on bio-plastics. It turned out that the term plastic has a negative connotation: plastics are perceived as "bad" and kill the animals in the sea. But when the raw material changes, the image also changes: bamboo is great, so is the bamboo cup. "In this way, the properties of the raw materials are transferred directly to the end products in the minds of the consumer. Plant properties are also expected for the end products," the study says.

Quote: Feel good

"Bioplastic gives people a good feeling: Many would reject the disposable cutlery, but do not do so because of the supposed biodegradability. In the end, it may lead to people paying more for such single-use products. [Bioplastic] is a lot lucrative for the plastics industry and packaging manufacturers, but leads to even more plastic ending up in the environment. "

Thomas Fischer, German Environmental Aid e.V.

good idea: Bio-based and no plastic at all

Disposable cutlery made of wood: even better than made of bio-based plastic

Programs on the topic:

  • Aluminum, paper, plastic - we have to get away from packaging waste. Planet Wissen, November 21, 2020, 3 p.m., ARD-alpha
  • Bioplastic. IQ - From science and research. October 26, 2020, 6:05 p.m., Bavaria 2
  • Finally more sustainable. October 12, 2020, 8.15 p.m.,, ARD-alpha
  • Bioplastic. Good to know, April 27, 2019, 7 p.m., BR television

question Curious? Should we report more often on this topic?