Life cycle assessment of melange yarns from the manufacturer perspective

Different proportions of colored fibers are able to spin into melange yarns with different colors and textures. With the advantages of energy saving, water saving, and emissions reduction in their production, melange yarns become more and more popular in manufacturers. However, the environmental performance of melange yarns with different colors has not been well investigated, which makes fashion designers unable to consider environmental performance when determining the color scheme of their design works. This study focuses on evaluating the environmental impacts of melange yarns spun from different colored fibers and identifying the environmental hotspots, in order to seek opportunities for improvement from the manufacturer’s perspective.

A cradle-to-gate life cycle assessment (LCA) of melange yarns was performed, where the investigated phases include raw material acquisition, transportation, dyeing, mixing, and spinning. The functional unit is 1 ton of the finished melange yarns. The primary data of nine melange yarns spun from monochrome fibers, i.e., white, brown, blue, purple, green, yellow, red, black, and gray, were collected by on-site investigation in a large manufacturer in China. The environmental impacts of the nine melange yarns were evaluated using the ReCiPe method. The environmental impacts were indicated by 15 impact categories including climate change, terrestrial acidification, freshwater eutrophication, marine eutrophication, ozone depletion, water depletion, metal depletion, fossil depletion, freshwater ecotoxicity, marine ecotoxicity, terrestrial ecotoxicity, human ecotoxicity, ionizing radiation, particulate matter formation, and photochemical oxidant formation.

The results obtained from the LCA demonstrated that spinning phase and dyeing phase in the production of melange yarns are main contributors to environmental impacts. The electricity and tap water consumptions are found to be the dominant contributors to most of impact categories, except terrestrial ecotoxicity, metal depletion, and ionizing radiation, whereas these environmental impacts are related to the wastewater treatment process. The recycled water is beneficial to reduce environmental burdens and can bring over 30% environmental benefits to the category of freshwater ecotoxicity.

Melange yarns spun from white fibers have the least impact on the environment because of the lower electricity and water consumptions. The potential hotspots identified are tap water use, reactive dyestuffs and auxiliaries use in the dyeing phase, and the electricity consumption in spinning phase. This work points out the future direction for the textile industry to improve the environmental performance.