Life Cycle Assessment of Synergistic Technologies for Pollution and Carbon Reduction in Cotton Knitted Fabric Dyeing and Finishing: A Case Study of Zhejiang Province, China

The textile dyeing and printing (TDP) industry in Zhejiang Province faces significant pressure to reduce conventional pollutants and carbon emissions. Dyeing and finishing (DF) are key links in energy consumption and pollutant emissions in the TDP industry. However, the trade-offs between pollution reduction and carbon mitigation remain poorly understood. This study evaluated five synergistic technology pathways using a hybrid life cycle assessment (LCA) approach. The pathways included low-carbon energy substitution, waste heat recovery, advanced wastewater treatment, intelligent process control, and integrated application. The IMPACT 2002+ method was used to quantify 7 environmental impact categories. The results showed that no single technology pathway achieved optimal performance across all categories. Scenario 3 (advanced wastewater treatment) reduced eutrophication potential by 54.97% but increased global warming potential by 18.00%. Scenario 5 (integrated application) achieved the best overall performance. It reduced non-renewable energy consumption by 30.90%, global warming potential by 32.69%, acidification potential by 26.08%, and eutrophication potential by 40.00%. The synergy coefficient of Scenario 5 was 1.08, indicating strong pollution-reduction synergy. Extrapolation to the provincial level showed reductions of 40% for COD, 39.76% for ammonia nitrogen, 40.78% for SO2, 10.67% for NOx, and 14% for VOCs. These findings demonstrate that systematic technology integration can resolve the trade-offs inherent in individual pollution control measures under the conditions evaluated in this Zhejiang-based case study. This study provides scientific guidance for technology selection and policy formulation in the DF industry.