Polymer-Specific Mechanical Recycling of Pre-Sorted Post-Consumer Municipal Plastics for Enhanced Environmental Sustainability

Summary: Can plastic recycling preserve material quality? A study found sorting PET, HDPE and LDPE supported high recovery and retained properties. #Recycling #Sustainability

Shankar D ; Nouri J ; Ho S ; Hitesh B ; Sankaramuthukumar M
Source: Global Journal of Environmental Science and Management Published:2027

Abstract

BACKGROUND AND OBJECTIVES: Mechanical recycling of municipal plastic waste can reduce landfill burden, energy demand, and environmental impacts while recovering reusable polymers. The study objectives were to assess the performance of polyethylene terephthalate, high-density polyethylene, and low-density polyethylene using polymer-specific pre-processing methods, shredding, thermal consolidation, and compression moulding. The assessment focused on waste minimization, material recovery, energy requirements, estimated carbon dioxide emission reductions, sustainability, and mechanical and thermal performance. METHODS: A total of 37 kilograms of pre-sorted post-consumer polyethylene terephthalate, high-density polyethylene, and low-density polyethylene was separately processed using polymer-specific treatment and compression moulding. Environmental performance was evaluated within a cradle-to-gate framework using secondary emission factors, and the Sustainability Index was derived from predefined parameters. Recycled materials were evaluated for mechanical and thermal properties. Exploratory one-way analysis of variance assessed polymer differences, with probability values adjusted using the Benjamini-Hochberg false discovery rate procedure. FINDINGS: Waste reduction and material recovery rates exceeded 95 percent for all polymers, with low-density polyethylene achieving the highest recovery of 99 percent. Low-density polyethylene also showed the lowest energy consumption of 0.95 kilowatt-hours per kilogram and the observed sustainability index of 82.6 ± 2.1, although polymer-specific differences in the Sustainability Index were not statistically significant. Polyethylene terephthalate showed the highest tensile strength (55.2 megapascals), compressive strength (83.4 megapascals), density (1.36 grams per cubic centimetre), and carbon dioxide emission reduction (2.10 kilograms of carbon dioxide per kilogram). High-density polyethylene showed intermediate performance. Analysis of variance indicated polymer-specific differences, with F-statistic values of 1.72–412.3 and probability values of <0.001–0.27. After Benjamini-Hochberg adjustment, most physical and mechanical properties, energy consumption, and carbon dioxide emission reduction showed significant differences, whereas landfill diversion and the Sustainability Index did not differ significantly. CONCLUSION: Polymer-specific mechanical recycling of pre-sorted post-consumer polyethylene terephthalate, high-density polyethylene, and low-density polyethylene achieved high material recovery while maintaining mechanical and thermal properties. The polymers showed differences in material recovery, energy consumption, carbon dioxide emission reduction, and evaluated material properties. Further evaluation using heterogeneous municipal plastic waste and larger-scale processing is required. © 2027 The author(s). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).