Bioplastic Waste in the Waste Streams – SustRecPLA (2014)

Since years the amount and diversity of products made from bio-based plastics is continuously increasing, especially in the packaging segment. Actually polylactide (PLA) is the most important bio-based polymer on the packaging market and because many  concepts use PLA as composite material or in blends, the recycling of PLA-containing waste streams is very difficult with conventional processes (e.g. re-granulation), if not impossible.

The information of German consumer associations describes the dilemma very explicitly:”Because bioplastics can actually not be recycled and hinder the recycling of other plastics, they should not be placed into the “yellow bag” (for packaging plastics waste) or the recycling bin. The German Environmental Agency actually recommends the disposal via the residual waste, because then bioplastics can at least be incinerated with energy recovery"3). And even though the term “bio” generally has a positive connotation, the disposal industry over and over again expressed concern, that PLA can disturb the established plastic recycling.

Therefore the objective of the research project “SustRecPLA” was the recovery of clean and high-quality PLA recyclates from post-consumer waste. The project was funded by the German Agency for Renewable Resources (FNR) and the German Federal Ministry of Food and Agriculture (BMEL) and started in November 2014.

2017 SustRecPLA Partner ENEight project partners including Fraunhofer IVV worked within the scope of this project. On one hand the physical solvent-based CreaSolv® Process was optimized for selected PLA waste streams1) and on the other hand compared with mechanical recycling (recompounding) in regard to the quality of the recyclates and the economic viability.

The examined PLA originated from industrial and post-consumer waste and the CreaSolv® Technology allowed the production of PLA recyclates2)

  • from heterogeneous waste mixtures with impurities of approx. 30%.
  • Injection molding tests show no significant differences compared to virgin material.
  • significant advantage over mechanical recycling: approx. 50% higher yields (mechanical tolerates impurities up to 5%).

Mechanical and solvent-based recycling are based on physical processes, whereby the polymer structure is retained and the polymer material can be reused. Both processes are therefore classified as Material Recycling (synonym: Physical Recycling). While mechanical recycling requires mono-polymer streams, the CreaSolv® process can also handle composites (e.g. multilayer packaging) and remove trapped additives and toxic contaminants.

Based on their comprehensive work the project partners were able to demonstrate that there exist different options for PLA recycling. The findings provide a good basis for the inclusion of PLA waste into established recycling streams and therefore come just at the right time, because the new regulations of the Packaging Law will come into effect on 1st January 2019.

 

Life Cycle Assessment

SustRecPLA project partner Fraunhofer Umsicht developed an environmental assessment of mechanical, solvent-based (CreaSolv® Process) and chemical recycling of PLA and published in 2019 – Life cycle assessment of recycling options for polylactic acid9).

2019 SustRecPLA LCA 1Recycling of PLA waste is compared to thermal treatment since a comparison of the different recycling options is not possible due to different qualities of the waste streams and of the products. Environmental benefits are achieved by replacing virgin PLA with PLA recyclates.

In this study, the complete path of PLA waste was considered starting from its waste source covering also its collection, sorting and transportation to its recycling or energetic recovery.
Mechanical recycling is investigated for post-industrial and post-consumer PLA waste.
Solvent-based purification (CreaSolv® Process) and chemical recycling are investigated for PLA from post-consumer waste only.

2019 SustRecPLA LCA 2The CreaSolv® Process (scenario 4) is especially suitable to produce PLA-recyclate from contaminated PLA waste.
In case of solvent-based recycling (scenario 4), a total amount of 521 kg CO2-eq./FU are emitted. 50% of those GHG emissions (green house gas) are associated with the separation and drying of PLA. About 30% result from primary treatment, preceding collection and sorting of PCW. The remaining 20% arise from the extrusion process. However, through substitution of virgin PLA, a credit of 2040 kg CO2-eq. is calculated, leading to potentially saved GHG emissions of 1519 kg CO2-eq./FU.

Comparing all 3 recycling options the LCA showed lower CO2 emissions of 60% for mechanical recycling, 49% for solvent-based purification (CreaSolv® Process) and 36% for chemical Recycling of post-consumer PLA waste compared to waste incineration.

 

Which main advantages do bioplastics really offer?

In our current language the prefix “bio” stands for two properties: “biobased” and2018 ZAKB Bergstraße Bioabfall mit Störstoffen 1 “biodegradable”. Biobased products are manufactured partially or completely from renewable raw materials. These products can be biodegradable or not biodegradable.

According to DIN EN 13432 biodegradable means, that a material is capable of being decomposed by more than 90% to water, carbon dioxide (CO2) and biomass within a defined period of time at defined temperature, oxygen and humidity conditions in the presence of micro-organisms or fungi4).

2018.12 Bioplastic Loss of ForrestFor biobased plastics we need of course cultivation areas, which are becoming increasingly scarce with a growing world population and its increasing food requirements and biodegradable bioplastics decompose to water and the greenhouse gas CO2, that contributes to global warming. So the same is generated as during an incineration. Even the German Environmental Protection Agency therefore describes it as a “bluff package” and recommends – together with Environmental Action Germany (DUH) – the incineration of bioplastic waste, because this allows at least an energetic recovery5,6). Due to problems during the composting German municipalities refuse as a general rule the disposal of bioplastics with the biowaste7). A recent study of the University in Bonn suggests that shifting to bioplastics will lead to loss of forest and increased greenhouse gas emissions8).

 

Conclusion

Bioplastics sounds „sustainable“, but competent authorities and environmental organizations consider them as a problem. However, one can and should recycle such plastics with the CreaSolv® Process just as other thermoplastic polymers, so that they can be fully reused again and will not get lost as a resource with a high energy content in a Circular Economy.

 

 

Literatur

  1. Kunststoffe 7/2013 – Tanja Siebert, Martin Schlummer, Andreas Mäurer „Bioverpackungen wiederverwerten“ in Kunststoffe 7/2013 Seite 79 – 82 - Link
  2. Project Results Summary "PLA in the Waste Stream“ - German Agency for Renewable Resources (FNR) and the German Federal Ministry of Food and Agriculture (BMEL) published on October 2017 - Link
  3. Verbraucher Service Bayern „Biokunststoffe nicht automatisch gut“ vom 23.06.2016 – Link
  4. Umweltbundesamt  im August 2009 „Biologisch abbaubare Kunststoff“ – Link
  5. Umweltbundesamt am 8.Juni 2017 „Tüten aus Bioplastik sind keine Alternative“ Homepage letzter Check 31 Oktober 2018 – Link
  6. Environmental Action Germany (DUH) „Bioplastics – Myths und Facts“ updated 20.02.2018 – Link
  7. BVSE - Fachverband Kunststoffrecycling "Bioplastik bereitet in Kompostwerken große Probleme" vom 21. September 2018 - Link
  8. University of Bonn. "More bioplastics do not necessarily contribute to climate change mitigation: Potential implications of transitioning to plant-based plastics." ScienceDaily. ScienceDaily, 7 December 2018. - Link
  9. “Life cycle assessment of recycling options for polylactic acid”, D. Maga, M. Hiebel, N. Thonemann in Resources, Conservation and Recycling, Volume 149, October 2019, Pages 86-96 – Link
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