Viscose could close the textile loop: there is a chance for this fiber of the future, as long as it becomes fully biodegradable

the word viscose reminds us of negative and unsustainable practices but new options are coming in the near future – such as fibers obtained by extruding procedures, according to four industry players

Viscose is understood to be an environmentally negative fiber; yet companies such as Södra, Lenzing, Renewcell and Infinited Fiber are working towards creating more sustainable alternatives that have the potential to combat the issue of it not being one hundred percent biodegradable. By using traditional techniques, combined with the concepts of a circular economy, all companies have been able to produce a fiber that provides a new kind of viscose with a lesser environmental footprint. Instead of relying on viscose production from environmentally unsustainable sources, these companies have been working towards minimizing chemical usage and maximizing the use of waste materials, so as to close the textile loop. While production of these fibers remains small-scale, within a short amount of time, they expect to be able to scale production in a way that would allow these innovative cellulose fibers to become the new norm.

It is estimated that 120 million trees are cut down each year for viscose production, often from forests that are ancient and endangered. This logging can impact ecosystems, as they are degraded and destroyed, and non-indigenous trees are used to replace those that are cut. During cultivation of forests, chemicals used in pest control and in fertilization, soil erosion, degradation of water quality and deforestation all have the potential to impact the local hydrological patterns. Viscose is a cellulose-based fiber; sourced from hardwood forests and plantations, as well as plants such as bamboo, soy and sugar cane. It has applications from clothing textiles to industrial uses. Although it is derived from natural fibers, chemicals are used in its production. This makes viscose a semi-synthetic textile that is not necessarily better for the environment.

In production, trees from forests or plantations are harvested, peeled and cut into logs which are transported to a mill to be debarked. The logs are then processed to break them down into wood pulp and transformed into viscose filament yarns or staple fibers. Wood logs are reduced to chips so that they can go through chemical pulping: a process that involves the purification and separation of the wood fibers. The brown pulp produced is then washed and cleaned through caustic extraction to increase its purity. Caustic extraction used to be polluting as its run off would be released into water sources; now it is more likely to be recovered for energy production, where it is evaporated and burned to generate steam. After being cleaned and washed, the pulp is bleached with chemicals that cannot be recovered. In viscose production, the pulp is treated with carbon disulphide and dissolved by adding a sodium hydroxide solution. The solution is then turned into fiber strings by forcing liquid through a spinneret and into an acid bath, where the acid coagulates and solidifies the filaments ready to be spun into yarn. These fibers require bleaching before they are dyed. Each of these production steps requires high levels of energy and chemical inputs, contributing to significant air and water emissions. Fast-fashion companies are putting pressure on production plants to increase their yields at faster speeds and lower costs. In order to accommodate for this, increasingly unsustainable practices are used: ones that do not end with a biodegradable material. However, there are ways to overcome these environmental issues at production level, by altering the chemicals used at each step (or making them a closed loop), and through sustainable logging practices.

Cellulose is one of the most abundant organic molecules in the world. Previously, its presence in waste textiles has not been harnessed. With the increasing demand for textiles and regular technological innovations, viscose was conceived as a biodegradable, ‘eco-friendly’ textile sourced from hardwood. Innovation in the textile industry shows that waste textiles have potential uses in creating cellulose fibers; an alternative to conventional viscose.

Södra, a large forestry group based in Sweden, works in the field of cellulose-based fibers as an alternative to viscose. They combine recycled poly-cottons, one of the most widely used textile blends, and their dissolving pulp fiber to create a viable cellulose pulp: named OnceMore. Their initial focus was on sustainable forestry, utilizing every part of the tree, and, as a result, Södra’s net climate change is positive, as the potential CO2 uptake of their forests is higher than that released in Sweden. The concept of recycling textiles arose from the knowledge that paper recycling was accessible, yet there was nothing in place for textiles: «Half of the paper that has been used in the world comes from recycled fibers». Annica Larsson Ahlstedt, OnceMore’s project manager describes how «we were surprised that there wasn’t a similar initiative in place for the large quantities of textile waste». Utilizing their existing Mörrun mill, where dissolving pulp production

takes place, Södra have been able to manufacture their recycled product alongside dissolving pulp.

Södra’s innovation in OnceMore cellulose-based pulp aims to enable recycled textiles to become a part of the circular economy. The production process involves combining wood cellulose with textile waste to create a pure, high-quality dissolving pulp that can be used to produce new clothing and other textile products. The raw material itself is both recycled and renewable so that «when we reuse textiles, we can replace fossil fuel-based materials». The recycled pulp produced is a high alpha cellulose pulp, which can be used for textile applications, is easy to process with a high brightness and emulates the quality, purity and properties of dissolving pulp used for viscose and lyocell production. Whilst a fully-closed global textile loop might not be possible, Södra have shown that it can make many fractions of production and the chemicals involved circular, and ultimately overcome the issues of biodegradability. «We have a closed system using a recovery loop for our main chemical, that we use to separate the wood components in our digesters. We’ve designed our processes with this in mind, to ensure little wastage». To secure a closed loop, the polyester ‘waste’ is used for energy production in the mill.

Peter Bartsch, the sustainability director at Lenzing explains how the journey to creating environmentally sustainable fibers began in the Seventies, «when people didn’t seem to care about the environment». Despite Lenzing already producing viscose in a traditional manner, the company began to realize that environmental problems were becoming severe. In altering its technologies, Lenzing has managed to change its mind-set and become more focused on trying to combat the issues of biodegradability. Nearly fifty years later, it has nearly been able to close its loop, managing to use just under one hundred percent of its wood input through bio-refinery, and re-use the solvents used in processing. This closing of the loop, and high recovery rate, not only allows for environmental benefits, but helps to reduce costs throughout each production stage. Lenzing has adapted its production methods to allow for the majority of the input material to be used (and reduce waste products). «About forty percent of the wood which is used in our fiber production is cellulose. The other sixty percent can be used to extract valuable by-products that we sell into other industries; processes that we can do on site».

This concept of bio-refinery, extracting all valuable products from the raw material, is a «building block to achieving our target of fifty percent recycled content by 2024, acting as a link between using all our raw material and recycling textile waste to make new fibers. We use bio-refinery to create a blended product with thirty percent recycled content». Using waste wood products and recycled materials helps Lenzing to meet its carbon neutrality goals, as it does not have to rely on fossil fuels for powering its production, or creating new textiles. The concept for Renewcell was born from a realization that fashion houses were producing large quantities of waste, without receiving any benefits from these cellulose-rich waste materials. Harald Cavalli-Björkman, Chief Marketing Officer & Head of Investor Relations, highlights that now is a time for change «fashion houses are aware of the climate crisis and are thinking of ways to make sustainable change a part of their brand history».

The Royal Institute of Technology in Stockholm, a global research institution for cellulose pulp technology, has been innovating the use of waste cotton to create a usable fuel. The team saw parallels in the breakdown processes, with those that could be utilized in make dissolving pulp out of waste cotton. Within two years, Renewcell produced its first prototype; a yellow dress that proved that it was possible to innovate fibers that could be used in textile production. Cavalli-Björkman explains that their recycled pulp product is «still easy to adopt within the value chain; it’s more practical to work with a fiber, similar to viscose, that is known and utilized already». The aims has been to ensure that the recycling system is more sustainable than manufacturing textiles from raw materials. It uses less water and chemicals and emits less CO2, which helps to preserve the world’s resources.

Renewcell has focused on lowering environmental impact, on the path to creating a biodegradable material, by utilizing pre-existing production processes and sites, using Swedish based paper-pulp mills, and adapting them to allow for the production of its raw pulp. It is recycling local infrastructure; from water plants to roads, electricity to renewable energy. Renewcell is also harnessing worker knowledge from the paper mills to create Circulose from the cotton in clothes. In doing this it is able to recycle knowledge. The process itself is less polluting than making new clothing from cotton, as there is no need for pesticide or land use to grow the crops and ninety-nine percent less water is needed. The production process is less intensive than that of traditional cellulose fibers, such as viscose, as, it does not have to carry out debarking or chipping of the hardwood. Renewcell focuses on utilizing textiles that have reached the end of their lives and it aims to be a pioneer for the future, paving the way for other pulp-producing companies to make a shift towards sustainability. «Our aim is to take better care of materials that require intensive human and natural resources to extract from the Earth. We must make better use of these materials and ensure that they last longer». By ensuring the longevity of materials, with constant innovation to achieve this, Renewcell has positioned itself as a pioneer for «human progress and the ability to handle the challenges that humanity faces».

With the concept of recycling at the fore, Infinited Fiber aims to provide a solution to the large quantities of clothing that are sent to landfill, or burnt, and to reimagine the fashion industry by cultivating an ecosystem where natural resources are no longer abused. To respond to the industry’s concerns over the unsustainable demand for cotton, it has created a man-made cellulose fiber; an alternative to viscose, using chemical recycling. With similar characteristics to cotton, it looks and feels soft and natural. As a regenerated alternative to virgin cotton, textile fiber production reduces demand on freshwater supplies.

Infinited Fiber’s textile fiber regeneration process is different to other man-made cellulose fibers, in its ability to use any cellulose-rich material as raw material. Discarded clothes, used cardboard, wood, rice or wheat straw can be used as an input. The opportunity to have multiple input streams means that its production can be commercially viable. Kirsi Terho, Infinited Fiber’s key Account Manager explains that, «if a material has cellulose, we can use it». Whilst the output is high (approximately ninety-nine percent from one hundred percent cotton), Infinited Fiber is aware that it is still producing waste products.«When we remove the polyester from the textile waste, we also take out all the other waste products, which form a sludge. We can then burn this and use it as energy in our production process». Whilst this process is not yet streamlined, they have been «looking at finding a partner who can work out how to remove the polyester from the sludge and break it down to reduce the waste at this step». Infinited Fiber’s awareness of not being ‘perfect’, with respect to circularity, means that it is taking steps to «make sure that every single stream is circulated and that all products, from those streams, are collected to make the process as closed as possible».

With these innovations in cellulose fiber production, we hope to target the global textile industry, focusing its efforts at the source of the environmental problem. To make efficient use of what has already been produced, and would otherwise go to waste, to subsume these textiles back into the clothing production system. This creates opportunity for agricultural land to be used to feed the growing global population, as no new land would be required to produce textile fibers.