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Finland Study Shows Fiber Dyeing Methods Can Promote Circular Economy

Starting in 2025, it will be mandatory to have separate collection processes for textile waste in the European Union, and Finland aims to be a pioneer of this development.

Taking textile waste to landfills has already been banned and the next step is to find new ways to reuse textiles instead of incinerating them. Research by Finland’s VTT textile research and development institute and Aalto University reveals that dyeing methods and decolorization affect the reuse of textiles.

VTT already has a long-standing foundation of research into the chemical recycling of cotton textiles and their decolorization as part of this process. VTT and Aalto University have now joined forces to examine the compatibility of different dyeing methods and color removal. The study involves using different methods to dye cotton materials and then decolorizing the textiles.

The dye and the dyeing method proved to be decisive for color removal, meaning it is only possible to effectively reuse waste textile if information is available on the dyeing methods used. Textiles with different types of dye would have to be sorted apart if the aim is to remove the color completely for the purpose of dyeing the textile again, the study showed.

A paper on the study, titled “Color Management in Circular Economy: Decolorization of cotton waste” has been granted the Paper Award in the 2020 Emerald Literati Awards. The paper notes that on an industrial scale, dyeing and decolorizing textile fibers have a high environmental impact. The process consumes chemicals, energy and water, and generates wastewater.

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“Decolorization turns a textile light-colored again,” VTT principal scientist Marjo Määttänen said. “It produces textile fiber that is easy to dye and print. During this process, the fibers can also be purified from other harmful chemicals, avoiding their transfer to recycled fiber products. All this opens up new opportunities for reuse. Clothing made from recycled textiles doesn’t have to look recycled.”

On the other hand, a recycled look is a desirable feature for some products made from waste textile. In this case, there is no need to separate textiles dyed with different methods and try to remove the dye, the paper noted. Textiles dyed with a particular method could also be identified and collected separately, allowing the colors to remain as is.

“For us to be able to use textile waste, we need information on what kind of fibers it contains, what kinds of dyes and methods it has been dyed with, and what kinds of chemicals have been used in the process,” professor Kirsi Niinimäki from Aalto University said. “This information should be collected at the manufacturing stage and stored alongside the textile fiber until it reaches the end product.”