Environmental Footprint of Twisted Polyester Yarn: Carbon Emissions, Water Resources and Microplastics

What is polyester twisted yarn? Application scenarios and basic principles

Polyester twisted yarn is a yarn formed by rotating and heating polyester filaments through a twisting machine to entangle multiple fibers. Twisting improves the strength, elasticity and feel of the yarn, making it widely used in:

• Clothing fabrics: knitting, woven, sportswear, elegant and durable
• Home textile fabrics: curtains, sofa fabrics, carpets, etc. to maintain color fastness and structural stability
• Industrial webbing: safety belts and conveyor belts need to bear high tension

The production process mainly includes: raw material polymerization → fusion drawing → multi-head doubling → twisting and shaping → winding inspection. Each step is accompanied by the input of energy, water and chemicals, which has a potential impact on the environment.

Carbon emission analysis in polyester twisted yarn production

The upstream of polyester production is to produce terephthalic acid (PTA) and ethylene glycol from petroleum cracking to synthesize polyester, and the midstream is drawing and twisting. The overall carbon footprint is concentrated in:

• Raw material synthesis: petroleum extraction and preparation, generally produces about 4.5-6.4 kg CO₂e/kg polyester fiber.
• Spinning and twisting: melt spinning and twisting and shaping require high temperature (200-280℃), and energy consumption is significant; if the heat source depends on coal/gas, additional emissions are about 1.5 kg CO₂e/kg.
• Logistics and post-processing: transportation and downstream finishing (setting, dyeing and finishing) additional emissions are about 0.8 kg CO₂e/kg.

Overall, the average carbon emissions of polyester twisted yarn production are 6.8-8.7 kg CO₂e/kg. In the entire life cycle of textiles, this stage accounts for about 25-30% of the total carbon emissions, so it is most efficient to focus on upstream and production links to reduce emissions.

Water consumption and pollution risks of polyester twisted yarn and downstream processing

Although polyester fibers do not require planting and irrigation of natural fibers, but:

• Finishing and dyeing: Twisted yarns are mostly used for dyeing and finishing after weaving, and the upstream drainage volume is large. The global textile and garment industry uses about 79 billion cubic meters of water annually.
• Chemical additives: Softeners, antistatic agents, flame retardants and other additives will remain in wastewater, and if improperly handled, they will cause heavy metal and organic pollution.
• Regional concentration: 92% of polyester production capacity is distributed in Asian regions with relatively tight water resources or limited sewage treatment capacity, such as the Yangtze River Delta and the Pearl River Delta, further exacerbating the local water load.

Recommendation: Factories should adopt closed-loop water treatment technology and zero-emission dyeing and finishing systems to increase the wastewater reuse rate to more than 80%, and regularly monitor indicators such as COD and heavy metals.

The current status of microplastic release in the use of polyester twisted yarn and washing

The release of microplastics from synthetic fiber clothing is becoming a new hot spot for marine pollution:

• Release amount: Each wash of 1 kg polyester fabric can release about 0.7–1.5 g of microplastic fibers, equivalent to 60,000–150,000 fibers.
• Destination: The interception rate of sewage treatment is only 20–40%, and the rest enters rivers and oceans with the effluent, and the concentration of microplastics continues to rise.
• Ecological and health risks: Microplastics can absorb harmful substances, and after entering the food chain, they may cause reproductive and immune damage to organisms such as fish and shellfish, and ultimately affect human health.

Tips:

• Using Guppyfriend laundry bags or washing machine filters at home can intercept about 80% of the fibers.
• Purchase three-dimensional woven or high-twist yarns to reduce the source of fiber shedding.
• Recycling technology and recycling of discarded polyester twisted yarn
• Mechanical recycling: crush, loosen and respin the waste fabrics. Advantages: mature process, low energy consumption; Disadvantages: reduced fiber strength, often used for roving or filling. Carbon emissions are about 1.2 kg CO₂e/kg, which is only 15–20% of the original material.
• Chemical recycling: PET polyester chains are broken into monomers PTA and EG through pyrolysis or enzymatic hydrolysis, and then polymerized to prepare new materials. The recovery rate can reach >95%, but the cost of chemical reagents and energy consumption is high.
• Thermal energy recovery: Incineration of waste textiles at high temperatures to generate electricity. Advantages: Reduce landfill; Disadvantages: CO₂ and dioxin emissions, requiring supporting high-efficiency flue gas purification.

Actionable solutions for enterprises and individuals to reduce the environmental impact of polyester twisted yarn

Implement life cycle assessment (LCA)

• Recommended tools: OpenLCA, SimaPro, customize models for polyester twisted yarn, and find high emission/high water use links.

Prioritize the purchase of recycled polyester twisted yarn

• Choosing products containing ≥50% rPET can reduce CO₂e emissions by 60–70% on average.

Upgrade energy-saving and emission-reduction equipment

• Replace old heating furnaces with electric steam furnaces; add variable frequency energy-saving motors.

Closed-loop water treatment and zero-emission dyeing and finishing

• Install MVR evaporation and concentration systems to recycle wastewater; use biofilm or nanofiltration technology to improve treatment efficiency.

Introduce environmental certification and standards

• OEKO‑TEX®️ Standard 100, GOTS, Bluesign®️, etc. to improve market recognition.

Establish a closed-loop recycling system

• Cooperate with recycling platforms (such as fiber recycling networks) to trace and reuse raw materials.

Conclusion and future prospects

Polyester twisted yarn has excellent performance and a wide range of uses, but its carbon emissions, water consumption and microplastic pollution cannot be ignored. Through LCA, we can accurately identify key links, give priority to the use of recycled materials, upgrade process equipment, and strengthen recycling and utilization. We can:

• Enterprise perspective: achieve cost reduction and efficiency improvement, meet ESG disclosure and market differentiation advantages.
• Consumer perspective: Purchase environmentally friendly yarns and clothing, participate in recycling programs, and reduce microplastic emissions.

In the future, with the deepening of policy guidance, technological innovation and circular economy concepts, the green transformation of the polyester twisted yarn industry will usher in more opportunities, and jointly help the textile industry move towards the 1.5℃ carbon neutrality goal!