The State of Circular Innovations in the Indian Fashion and Textile Industries
During the processing stage, the fibres, yarns, fabrics or garments go through multiple steps to achieve the performance and aesthetic properties desired by the brand and its consumers. These steps can be broadly categorised into pretreatment, dyeing, printing and finishing treatments.
Pretreatment is done to prepare for dyeing or printing and can involve removing dirt, bleaching or transforming the materials from a hydrophobic to a hydrophilic state. Hydrophobic is when something repels water whilst hydrophilic is when something can be dissolved in water. Pretreatments account for the highest toxic effluent within wet processing15.
Modern synthetic dyeing is very effective but highly polluting, regardless of dye type and process: all end with washing out excess colour, which ends up contaminating wastewater. As modern dyes are designed to resist biodegradation, they also accumulate in the environment, especially when wastewater treatment is not done effectively. Dyeing is also a water and energy-intensive process16.
Finishing treatments give a textile a specific desired effect such as being water repellant or stain resistant. Finishes contain a high amount of hazardous chemicals that have been difficult to replace with lower impact alternatives, as these often face difficulties meeting the same high performance requirements.
The effluent discharge, often hazardous toxic waste, can be full of colour and organic chemicals from dyeing and finishing treatments. To combat the negative health and environmental impact of high effluent discharge, there is increasing traction for safer dyes, pigments and auxiliaries that are biobased and, in some cases, biodegradable, often referred to as “green chemistry”.
Overall, wet processing consumes around 5% of the chemicals that are used in apparel manufacturing17. Beyond environmental concerns, there are also growing concerns on the impact of these chemicals on human health. Only some of the 80,000 chemicals registered for use have undergone basic human health screening and many of the petrochemical-based products in use today are known to be toxic18.
KEY FINDINGS FROM THE REGION
- Given its cultural and environmental context, there is a strong focus in India’s innovation landscape on reducing or eliminating the need for water in wet processing, and this space has seen a number of incremental innovations both at R&D as well as commercial application phases.
- The abundance of lush flora and fauna as well as its characterisation as mainly an agrarian economy means India shows maturity in innovations using natural dyes and pigments; however, their use at scale is still limited.
- Digital printing is a significant area of action in India’s dyeing landscape, representing a more sustainable alternative to traditional water-heavy dyeing processes.
To address challenges of wet processing, a growing number of innovative, environmentally friendly technologies are emerging in the market, with some of the most promising innovation areas outlined below
Plasma, the fourth state of matter, is formed when gas is ionised and becomes more reactive. When this ionised form of gas is applied to a substrate aka surface or material, it is able to alter its properties i.e. activating its surface, removing impurities, depositing a coating. It is a more sustainable alternative to current pretreatment and finishing process as it uses no water, is effluent free and uses significantly less energy and chemicals.
ULTRASONIC & FOAM DYEING
Ultrasonic treatment is a process that utilises acoustic waves to create microscopic bubbles which, when burst, release large amounts of energy that can be used to clean the surface or dye or finish a textile. Using ultrasonic treatment reduces the amount of water, energy, dye and other chemicals required. Besides this, processing time is decreased and the preparatory process in spinning, fabric preparation, dyeing, printing and finishing can be improved. Foam dyeing is another technology applying the pressure of bursting (larger) bubbles, resulting in similar environmental savings.
Another interesting waterless dyeing method is dyeing using supercritical CO2. This technology involves filling a tank with pressurised gas (instead of water), in which dye can be dissolved. When the fluid gas with the dissolved dye comes into contact with fabric, the dye is deposited onto the fabric. When depressurised, the supercritical gas reverts to its gaseous state, separating from any remaining dye. As a result, this technique leads to a significant reduction in chemicals normally used in the dyeing process and completely eliminates wastewater19.
Sasmira’s Institute of Man-made Textiles (SMMT) has developed a patented technology for waterless dyeing and has built two systems that use supercritical CO2 technology with a capacity of 3 and 20 litres.
With spray dyeing and finishing, nozzles spray the exact amount of dyestuff or finishing chemistry required directly onto the fabric. The process is digitally controlled and therefore highly efficient. As a result, large quantities of water, energy and additional chemistry are saved.
CATIONIC AND ENZYMATIC PRE-TREATMENT AND FINISHES
Changing the current pre-treatment methods could significantly decrease water and chemical requirements of further processing steps. Existing innovations include cationic and enzymatic processes.
An example of cationic treatment is when cotton is modified so that it has a permanent cationic, or positive charge, this makes cotton “friendlier” to dye and increases the dye uptake20. Cationic treatments have the opportunity to enhance the dyeability of cotton but require advanced effluent treatment as they can cause eutrophication21. Eutrophication is when there are too many nutrients in a body of water which can then disrupt the ecosystem22.
Enzymes can be used to modify the fabric to be more receptive to dyes through processes such as bio scouring, they can be used in both pretreatment and finishing. An enzyme is a substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction23. By using these treatments, water and chemical usage in these supply chain steps can be reduced.
Nano Dye is a salt free cationic treatment that changes the charge of the cotton molecule to the opposite charge of the dye to enhance the absorption of the dye into the fibre. Resulting in a significant reduction of waste dye, other auxiliaries and water (75%) and energy (90%) usage.
Digital printing is an almost waterless process. Colour fastness depends on different factors such as the colours, layers of printing and fabric type. The current most promising innovation in digital printing is the use of pigments, which has the potential to be suitable for all substrates and improve performance. The fabric however has to be ready-for-dye (RFD) and heat press is required as post-treatment for curing. The growth of digital textile printing technologies is another significant step towards more sustainable textile colourisation. This almost waterless technique can replace traditional dyeing’s intensive water, chemical and energy consuming process. Besides this, it enables near-shoring, on-demand production and customisation. Digital printing can be done both on rolls of fabric as well as garments such as shawls, saris, etc. (known as the “direct to garment” mode24). While this technique is also time and colour efficient, our research in India shows that it is currently two or three times more expensive than traditional dyeing, which is a barrier to its full scale implementation.
NTX – Cooltrans – Cooltrans provides a digitally enabled gravure printing method for both artworks and solids. They distinguish themselves from other printing technologies through their superior fastness, precision and proprietary inks that are manufactured in-house. The technology is applicable to natural, man-made and synthetic fibres.
PLANT BASED DYES AND PIGMENTS
Plant-based dyes and pigments have existed for centuries but have been largely discarded by the fashion industry due to its inferior performance, limited colour palette and higher price than synthetic dyes. However, new cultivation, extraction and application processes have the potential to overcome these barriers and enable the (re)implementation of plant based dyes at scale. As plant based dyes and pigments come from bio-based renewable resources such as wood and algae, they have the potential to significantly decrease the use of chemicals in the dyeing process.
Microbial pigments are produced in natural or genetically modified organisms (GMO), after which they are extracted to be used in traditional dyeing processes.The use of engineered bacteria can scale microbial pigment production, improve dyeing methods as well as performance. The biggest challenges lie in scaling, making mills and dye houses legally compliant to work with genetically modified bacteria.
KB cols use naturally occuring coloured microbes, which are a waste and inexhaustible source, to extract different natural colours, that can be applied in textiles and other applications. They aim to change the landscape of dyeing in the fashion industry by focusing on harnessing the true potential of Biotechnology.
● Continued research is needed on identifying new sustainable products and processes such as new dyes which are, for instance, biodegradable, free of halogens and heavy metals in new chemical structures with very high exhaust and fixation values.
● Rapid industrial uptake by private sector players is a major gap that needs to be filled to bridge the gap between research and adoption. India’s evolving policy landscape sometimes acts as a deterrent, putting researchers in a race to procure private sector investment for continued research.
● A significant part of the industry is unorganised25, with several small dye houses that are unable or unwilling to invest in sustainable solutions. Larger players’ adoption would hopefully bring in economies of scale and trickle down this effect to India’s unorganised sector.
● Sludge treatment and water purification needs to go hand in hand with replacing chemical-based dyes, ensuring that where the industry does not change its input, its output is reduced in toxicity. Policy intervention alongside innovation would enable this.
Sustainable innovation in wet processing areas of textile manufacturing can make significant impact in reducing water, dyes and chemical consumption and energy requirements. At the same time it can also bring in new performance attributes to the end products in terms comfort, easy care and health and wellness. I urge industry colleagues to support innovators in this space so that as an industry, we move away from the `largest polluter’ name tag."Umasankar Mahapatra, Vice President and Group Head – Innovation (Welspun India Ltd.); Business Head – Welspun Health