Jun 15 2021
A research team from Kaunas University of Technology (KTU) and the Lithuanian Energy Institute has suggested a new technique to transform lint-microfibers found in cloth dryers into energy.
Dr. Samy Yousef, senior researcher at KTU Faculty of Mechanical Engineering and Design. Image Credit: Kaunas University of Technology.
The researchers not only built a pilot pyrolysis plant but also designed a mathematical model to determine the potential environmental and economic outcomes of the technology. The team believes that lint microfibers produced by one million people could be converted into almost 10 tons of char, nearly 14 tons of oil and 21.5 tons of gas.
The global population uses around 80 billion pieces of clothing annually, and roughly €140 billion ends up in the landfill. This results in higher amounts of emissions, leading to serious health and environmental problems. As a matter of fact, about 300 mg of microfiber is produced from 1 kg of textile during a machine-washing process. Limiting the laundry impact is one of the ways to reduce the footprint of consuming clothes.
Lint-microfibers are classified as microplastics. Whereas large plastic items can be sorted out and recycled relatively easily, this is not the case with microplastic — tiny plastic pieces, less than 5 mm in diameter. Large quantities of microplastic are being washed down our drains and enter our seas threatening the environment.
Dr Samy Yousef, Senior Researcher, Kaunas University of Technology, Faculty of Mechanical Engineering and Design
Around 70% Conversion Rate
Dr. Yousef heads the inter-institutional team, which designed an eco-friendly technology to derive energy products from textile waste. For the experiment, the team collected lint-microfibers extracted from the filters of the drying machines used in KTU’s dormitories. The collected samples were highly diverse since the dormitory residents belong to different cultures in Africa, Asia, America, and Europe.
Then, using a pilot pyrolysis plant, constructed at the laboratories of Lithuanian Energy Institute, the researchers extracted three energy products; char, oil and gas, from the collected lint-microfiber batches. When put under thermal treatment, the lint-microfibers decomposed into energy products with a conversion rate of around 70%.
When we think about textile waste, we usually imagine long fabric with high crystallinity, which is contaminated with dye and dirt. Much energy is needed to turn the solid waste into liquid. However, lint-microfiber is a somewhat ‘broken fiber’ textile waste; it has a uniform size and shape, contains a lot of flammable compounds (resulted cotton and polyester elements), its transformation is easier.
Dr Samy Yousef, Senior Researcher, Kaunas University of Technology, Faculty of Mechanical Engineering and Design
The researchers also designed a mathematical model to assess the environmental and economic performance of the proposed strategy, based on the lint-microfibers produced by one million people.
The study demonstrated that if this strategy was to be applied on an industrial scale, it would be both eco-friendly and profitable: the energy generated from the lint-microfiber produced by one million people has estimated profitability of about €100 thousand and a reduced carbon footprint of 42,039,000 kg CO2-equivalent of lint-microfibers.
Would Accelerate the Transition to Circular Economy
I believe that the collection system, similar to deposit-return for drink containers, could be developed based on our research. A household would bring the lint-microfiber from their drying machine filters to a collection point and receive some kind of compensation for it. We have proposed the technology and made calculations, which may be developed further.
Dr Samy Yousef, Senior Researcher, Kaunas University of Technology, Faculty of Mechanical Engineering and Design
The study also showed that lint-microfibers can be regarded as a renewable energy source that ensures sustainability and significantly contributes to the general transition of the textile industry into a circular economy.
Apart from the study explained above, Dr. Yousef and his research team have also designed other green and eco-friendly technologies to extract glucose, cotton and energy products from end-of-life banknotes and textile waste using thermal, chemical, biological and mechanical treatments.
The study was published in the journal Science of The Total Environment. It was funded by the Research Council of Lithuania (LMTLT), agreement No. S-MIP-20-27.
Journal Reference:
Yousef, S., et al. (2021) A new strategy for using lint-microfibers generated from clothes dryers as a sustainable source of renewable energy. Science of The Total Environment. doi.org/10.1016/j.scitotenv.2020.143107.