+1 vote

Hello, I am modelling the life cycle of a small plastic component (A micro-plastic filter housing). This component is made up of one material (Recycled polypropylene) and is then transported from Italy to the United Kingdom, and then driven from the airport to my final assembly location (The micro-plastic filter housing integrates into a larger product). I am using the Environmental Footprints database. I have created the following processes with the following inputs and outputs:

  • Polypropylene Recycling (I: Plastic (unspecified) & O:Recycled polypropylene)
  • Housing Production (I:Recycled Polypropylene, Plastic part (Stretch blow moulded) & O: Microplastic Filter Housing)
  • Housing Transportation: (I: Microplastic Filter Housing, Transport, Transport & O:Microplastic Filter Housing, Transported)

Please note that "Recycled polypropylene", "Microplastic Filter Housing" and "Microplastic Filter Housing, Transported" are flows I have created myself. When I combine these together into my product system my 'Model Graph' does not make sense to me. I think the issues lies with how I am modelling my 'Recycled Polypropylene'. I have put an image of how I modelled my 'Polypropylene Recycling' process and the resulting model graph below. Is there a different way I should be modelling recycled material as an input to my system?

  • Polypropylene Recycling Process: When I leave the 'Plastic (unspecified)' in 'Category' 'End of-life treatment' as just (with no allocated 'Provider', my model graph makes sense but I lose all the analysis to do with recycling:

  • Polypropylene Recycling Process: By ticking the 'Avoided Waste' box the program allows me to select the Provider for my 'Plastic (unspecified) as 'Plastic granulate secondary (low metal contamination), production mix, at plant, from post-consumer plastic waste, via grinding, metal separation, washing, pelletization, plastic waste with low metal fraction - EU-28'. However this changes me Plastic to be an output instead of an input. Why is that?

If there is any documentation on how to include my own recycled material, I would be really appreciative if anybody could point me in its direction. Thank you for any help

Kind regards.


in openLCA by (190 points)

1 Answer

+1 vote
by (87.2k points)
Hi Andrew,

first, thank you for your detailed explanation, that helps it to understand the issue. Basically, I think PP recycling in your system is a multi-functional process: for one, it picks up unspecified plastics; second, it produces recycled PP. And for the undefined plastics, there is a first life cycle. In PEF (since you are using the PEF database) this first life cycle is addressed in the famous and often debated and not often well-explained CFF (circular footprint formula). If you want to consider this recycling and the new plastic production in your system, you can apply an allocation or the CFF. "Avoided waste" would also be possible but you should include some effort for the transportation and processing of waste plastic.

Hth, Andreas

- the side of the avoided waste is a bit confusing in the model graph, I agree