<p>Recycling plastics through mechanical and chemical processes is crucial for tackling plastic pollution, but it is essential to evaluate their environmental impacts. A Life Cycle Assessment (LCA) using GaBi (now LCA for Experts) software was performed to assess the environmental impacts across all operations and processes within recycling plants, focusing on a gate-to-gate scope. This study analysed ten environmental impact categories to identify the contributions of various units involved in both recycling processes. For chemical recycling, the cooling tower and condenser exhibited lower environmental burden on certain environmental categories, while in mechanical recycling, the flake washing unit emerged as the top contributor to environmental impact indicators. The findings suggest that targeting specific unit processes could reduce the overall environmental footprint for both recycling methods. Furthermore, a sensitivity analysis was conducted using Entropy and the CRITIC method to determine the weightings of different unit processes with respect to the environmental indicators. Multi-Criteria Decision Making (MCDM) was then employed to rank these processes based on their environmental impacts, emphasising that improving the efficiency of specific units can significantly lessen the overall environmental impact. This integrated LCA-MCDM framework highlights the transparency and robustness in environmental decision-making for the development of sustainable plastic waste management.</p>