Life cycle assessment of mechanical plastic recycling processes

Abstract

Since the advent of plastics in industry and in our daily lives, plastic pollution has caused significant damage to ecosystems and human health. As a result of economic and population growth, the use of plastics and the generation of plastic waste could almost triple worldwide in the 30 coming years. In addition, greenhouse gas emissions from the life cycle of plastics are expected to more than double, as are several related effects (ozone formation, acidification, human toxicity, etc.). To counter these effects and to try to shift the projections of these grim predictions towards a healthier future for the environment and humans, it becomes essential to study the life cycle of the most widely used plastics today and more specifically their recycling processes. At present, 99% of recycled thermoplastic waste is recycled through a so-called "mechanical" recycling process. This recycling consists of several stages: collection, sorting, washing, grinding, extrusion and transformation. Among the most used plastics in the world, we choose to study polypropylene, polyethylene terephthalate and high-density polyethylene. We will carry out an analysis of the environmental impacts of the mechanical recycling processes of these three plastics using the free software OpenLCA, in a Life Cycle Assessment approach. By comparing the results obtained in our study, we hope to provide additional data and help other ongoing or future studies on these sensitive and important topics.