Life cycle assessment of recycling options for polylactic acid

This paper presents an attributional life cycle assessment for different recycling technologies for post-industrial and post-consumer polylactic acid (PLA) waste in Germany. The study investigates mechanical recycling of post-industrial and post-consumer PLA waste as well as solvent based recycling and chemical recycling of post consumer PLA waste. Recycling of PLA waste is exclusively 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. The life cycle impact results show environmental benefits of all recycling technologies. Environmental benefits are achieved by replacing virgin PLA with PLA recyclates. The substitution of virgin PLA by recyclates leads to higher savings of greenhouse gas emissions compared to incineration. Depending on the recycling technology, savings are 0.3-1.2 times higher. The lower global warming impact goes along with higher savings in primary energy demand and less fossil resource depletion. Apart from benefits related to global warming impact and energy, the comparison between thermal treatment and the recycling shows benefits in the category agricultural land occupation since biomass cultivation is avoided. Further environmental benefits are achieved in the impact categories photochemical ozone formation, terrestrial and aquatic eutrophication, acidification, and particulate matter due to avoided biomass cultivation, harvesting, and transportation. The latter three impacts are mainly influenced by agricultural activities and transportation, whereas eutrophication is driven by fertilization. The results demonstrate that recycling of PLA products can contribute to a better environmental performance of PLA products in their life cycle.