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RECYCLING EFFORTS OF COTTON MATERIAL WASTE IN THE TEXTILE INDUSTRY (Part I)

BULETIN TEKSTIL.COM/ Jakarta – To fulfill the increased demand for textile items, worldwide cotton output surpassed 26 million metric tons in 2018. Cotton accounts for one-third of the global textile market, according to statistics from The World and United States Cotton Outlook (2018), and output climbed 6.5% in 2019. As demand grows, so do the negative effects on the environment, particularly in terms of chemicals and water. Cotton production used more than 2.6% of world water usage in 2004. Cotton cultivation also makes extensive use of chemicals in the form of pesticides, which are harmful to the environment. Cotton production is estimated to have contributed 11% of global pesticide usage in 2013.

According to the US Environmental Protection Agency (US EPA), 9.5 million metric tons of clothes and textiles end up in landfills in the United States each year. Only around 1% of all clothing manufactured is recycled into new garments. Indeed, more than 80% of cotton waste is thought to be eligible for mechanical recycling into new textiles. Cotton waste recycling can help reduce the use of water, electricity, pesticides, dye chemicals, and textile waste.

PRE-CONSUMER & POST-CONSUMER COTTON TEXTILE WASTE

Cotton textile waste, in reality, refers to more than only discarded post-use apparel textile items. However, cotton material waste is generated at every stage of the cotton textile production process in the business. Pre-consumer cotton textile waste is trash generated during the manufacturing process in industry. There is a significant amount of pre-consumer cotton textile waste, the majority of which may still be recycled.

Cotton material waste (pre-consumer cotton textile waste) produced by garment manufacturing from August 2018 to July 2019 (as stated in The World and United States Cotton Outlook)

Post-consumer cotton is just as abundant as pre-consumer cotton. Various research and statistics indicate that only around 15% of post-consumer textile waste is recycled/recyclable. According to a 2004 research in England, around 2.35 million tons of varied post-consumer textile and garment waste were discarded. Only 13% of the 2.35 million tonnes is recycled or recyclable, another 13% is disposed of in incineration facilities, and the other 74% is disposed of in landfill. The Department of Environmental Protection (US EPA) revealed similar statistics in 2019, specifically that only around 15% of post-consumer items were recycled/recyclable, another 19% were burnt in incinerators, and the other 66% were disposed of in landfills.

Flow of post-consumer cotton garments in the United States per year

LOTS OF WASTE? WHY CAN’T COTTON WASTE JUST BE RECYCLED?

Even though it sounds simple, recycling cotton waste is more difficult than it appears. Many research have been conducted to date in order to gain technology, construct an efficient and environmentally friendly recycling supply chain system, and strategies to generate high quality recycled products (with both product and economic value).

According to the source of the trash, pre-consumer cotton waste is easier to recycle since it is still relatively pure and has not been blended with other materials. This becomes much more problematic when we consider mixed fiber waste, which is made up of two fibers (for example, polyester-cotton textile material waste). Given this, unmixed pre-consumer cotton fiber material is more attractive for recycling. Unmixed cotton waste from spinning factories in the form of cotton lint created during the carding process, for example, is an example of pre-consumer cotton waste material with high recycling potential.

Based on the inherent qualities of the material, the process of recovering cotton waste material is more difficult than, say, recycling polyester fiber. Polyester fiber waste may be recycled into recyclable fiber by a very simple process of melt extrusion and re-formation via a melt spinning process. However, due to changes in the inherent characteristics of the cellulose molecules (the component material of cotton), the melt-spinning process cannot be performed on cotton fibers. As a result, certain techniques/technology are required to convert cotton waste into valuable items.

RECYCLING PROCESS: MECHANICAL RECYCLING & CHEMICAL RECYCLING

According to present technological research, pre-consumer cotton waste material (100%) may be recycled mechanically or chemically.

Depending on the demands and condition of the cotton waste material to be handled, each of these procedures offers advantages and disadvantages.

CHEMICAL RECYCLING

In general, the pre-consumer chemical recycling cotton waste fiber recycling technique includes a fiber processing process that incorporates a chemical reaction process that uses certain reagents to dissolve and reform the cotton fiber into fiber form. The chemical recycling method employs the technology used to produce regenerated cellulose fibers (for example, rayon), which includes solvent reagents and coagulants. Pre-consumer cotton waste fiber may be molded and reshaped into virgin fiber using this procedure. Despite being recycled, the fiber resulting from this procedure can have physical and chemical qualities similar to virgin rayon fiber (if treated using the suitable settings and techniques).

Another advantage is that this chemical recycling process can be applied to pre-consumer cotton waste material (cotton lint) that is difficult or impossible to process mechanically (for example, cotton fiber waste with a fiber length/effective length that is too short). When cotton fiber waste is spun using a mechanical recycling technique, it produces low quality yarn. The chemical recycling process’s downside is that it generates a large amount of liquid chemical waste, which is less ecologically favorable. Nonetheless, researchers continue to hunt for possible chemical recycling techniques that generate less chemical waste and are ecologically beneficial.

As of this writing, 14 different types of chemical recycling techniques have been developed and are claimed to be capable of processing cotton fiber waste with varying output outcomes. The goods produced by these 14 techniques are not restricted to regenerated cellulose fiber products; they can also yield additional derivative products with economic value or that can be used for other purposes (rather than being thrown away). Of course, innovation does not stop here; these methods are continually being enhanced to provide more efficient and ecologically friendly manufacturing costs.

Types of chemical processes for recycling cotton waste materials in the chemical recycling category

Cupraamonium Rayon Extrusion Process which is made from cotton material which can actually also be made from cotton waste material

Diagram of the recycling process for cellulose fiber from textile waste material which has the potential to be applied

MECHANICAL RECYCLING

Because it does not involve a polymer regeneration process that requires particular chemical solutions, mechanical recycling is considered a more ecologically responsible choice in the process of recovering discarded cotton fiber material. This is an important benefit of the mechanical recycling process. This procedure employs mechanical processing techniques such as fiber opening, fiber alignment, trapping, and fiber production using specific spinning technology (to be utilized as raw material for lower grade yarn products). The experts agree that this method can only be carried out if the cotton fiber waste is still spinnable. However, since it is very short and has a poor fiber strength value, cotton noil generated from combing waste is too short and difficult to reprocess via mechanical recycling. This intricacy is one of the mechanical recycling process’s major flaws.

At the end of this article, despite the fact that cotton waste has the potential for recycling and that there are many recycled materials on the market, the price of these recycled materials is sometimes “much relatively more expensive” than the price of virgin materials. This diminishes recycled cotton material’s economic competitiveness, making most industries less interested in working in this sector. This is still task for researchers and all textile workers to be able to produce more efficient technologies that can boost the competitiveness of this recycled fiber.

(Red B-Teks/Andrian W)

Magister Rekayasa Tekstil & Apparel, Politeknik STTT Bandung

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