Life cycle assessment of mechanical recycling of post-consumer polyethylene flexible films based on a real case in Spain

Mechanical recycling of plastic waste is a common practice in industry and is an environmental solution to the problem of plastics disposal. In this article, a case study of mechanical recycling of post-consumer polyethylene flexible films in Granada (Spain) was analyzed from an environmental point of view by the Life-Cycle Assessment methodology. The industrial process is divided into four large areas of operation: sorting, washing, extrusion and wastewater treatment. The results show that the washing area has the largest environmental impacts, mostly due to the electricity consumption, followed by sorting. Also, the overall mechanical recycling process causes damage, mainly, on human health, which dominates over ecosystems and resources with 93.4% of the total impact of the process. Two different scenarios have also been considered for the generated waste, and they critically affect the overall environmental performance of the entire process. The first scenario considers the impacts of the landfill disposal of the humid organic matter generated and the losses of PE. In this scenario, all the CH4 resulting from the anaerobic degradation of organic matter was emitted into the atmosphere. In this case, human health impact was high. In the second end-of-life scenario, all the CH4 generated would be captured and burned in a gas turbine for energy generation. Lower impacts were found in human health and ecosystems categories, as well as the total value, in the second scenario.