Textiles are a HUGE component of material culture. The textile industry is concerned with the production, manufacturing, and distribution of cloth. Both production and consumption of textile produce waste. Therefore, waste recycling becomes crucial to conserve matter and energy. Fibre production has been continuously increasing for the last two to three decades. In 2000, the global fibre production was 59MT while it has doubled with a figure of 109MT in 2020. Management of textile waste has become necessary as the number of production will increase in the future also. This article will analyze the recycling techniques that have been employed in the fashion industry. The textile/fashion waste is difficult to manage because of the varieties of fabric. These include silk, denim, leather, satin, and linen, just to name a few. Since the complexity of the material that composes the fabric varies, it has become challenging to come up with a single reliable solution for recycling fashion waste. Continuous shifts in fashion distinctively increase the number of disposed of items. So, proper handling of end-of-life textile has become necessary. Recycling is the recovery of material to reprocess them into valuable products. However, energy recovery is not possible through recycling. The best practice is to prevent the production of waste or reuse it for valuable products.
The best practice is to prevent the production of waste or reuse it for valuable products.
Categories of waste: Waste can be categorized as pre-consumer recycling waste and post-consumer recycling waste. Pre-consumer textile waste can be used for surgical pads, bedding, and also for mushroom maturation. In contrast, post-consumer waste is treated chemically and biologically to obtain valuable products.
Types of Recycling Technologies: Usually, the fabric is sorted colour-wise to eliminate the need for dying. This process is done manually, which reduces recycling efficiency since the chances of contamination are high. NIR spectroscopy can help to distinguish cotton, wool, and nylon. Types of recycling technologies are as follows:
- Mechanical recycling
- Chemical recycling technology
- Biological recycling
- Textile for paper-making
- Composite technology
- Thermal recycling technology
1 – Mechanical recyclingMechanical recycling is the process of recycling fabric without chemical treatment. Mechanical recycling includes shredding cloth to extract the fabric, which is then spun to make yarn for woven or knitted fabric. Mechanical recycling is suitable for mono-fibre. The process starts from shredding fibre into small pieces sent to the garnet machine to extract the desired fibre. It is then mixed with virgin fibre to get fine yarn. Recycling of knitted fibre is efficient up to 75 percent. However, the recycling of woven fibre becomes more complicated, and the shodden yarn is produced.
2 – Chemical recycling:Chemical recycling involves a series of chemical processes to dissolve the fibre from fabric to solvent to make a new fibre or extract a valuable material out of it. Chemical recycling processes are more superior to physical recycling as the recovered product is similar to virgin material. An example of chemical processing is glycolysis. Glycolysis is the process of breaking down the ester linkage in fibre at a temperature of 200 degrees. The chemical processing of cotton converts it into viscos. The process is quite simple. Pure cotton fabric is depolymerized into a cellulosic pulp and then converted into viscos. A small amount of raw viscos is added to the final product to ensure the strength of the fabric. Although it is a promising technology to recycle a piece of fabric into another, strict conditions must be met to make the process successful. There should be no contamination – the material should be hundred percent cotton – and the only solid fabric is acceptable for this process.
3 – Biological recycling:Enzymatic recycling of textiles is a promising technique to recover the material. Enzymes are bio-catalysts made of protein and are very selective for specific chemical reactions. Although enzymes have been widely used in the textile industry for washing denim and surface treatment, their use for recycling is increasing extensively. Cellulase enzyme is used to process the cellulose-based fabric such as cotton and viscose. Enzymes hydrolyze the fibre, which can be reused or can be converted into biofuel.
4 – Composite technology:This technology involves the melting of thermoplastic fibre such as polyester and polyamide into recyclable fibre. Recyclable fibre is used in automobile interior, agro-textile, food packaging material, and insulation also.
5 – Textile for paper-making purposes:An ancient process of processing cotton rages and plant fibre is practiced to make handmade papers. A study conducted in Ghana tested different fabric waste with mulberry to make high-quality art paper. The results found that natural fabric waste is suitable for the production of papers compared to processed fabric. It is the most eco-friendly solution to make paper, tea bags, envelopes, and carry bags from textile waste. The quality of paper produced is up to 70 percent that shows that it’s a highly efficient method to reduce the deforestation and utilization of waste.
6 – Composting:Increasing awareness of the ill effects of non-biodegradable fibre has made the world think again about their habits. Shifting to natural and biodegradable textile could be better as it can be recycled back to nature. Composting is way better to manage textile waste.
6 –Thermal recycling:Thermal recycling aims at recovering the heat energy from the incineration of wasted textiles. Pyrolysis with the mixture of different textile materials can be processed in waste-to-energy plants. The product of pyrolysis is oil and gas, which the industry itself can employ.
Conclusion:The textile industry is flourishing day by day, so does the waste production linked with it. Unsustainable fashion habits making this industry the second most polluting industry after the oil and petrochemical industry. Recycling of textile waste has also been increasing to cope up with the issue. Pre-consumer waste recycling usually produces surgical pads and paper. However, the post-consumer fabric is processed physically, chemically, and biologically to produce fine fibre. Moreover, composting is a better solution to bring the waste back to nature. No doubt, prevention of waste production and reuse of material are the best solutions.
References:Textile recycling processes, state of the art and current developments: A mini-review