TO DYE FOR
Biotechnology firms invest in bio-based alternatives to petroleum-based dyes. when it comes to crimes
against the environment, the apparel sector has become industry non-grata. Among the highest-impact categories is denim, which historically relies on water-polluting dyestuffs and chemicals to achieve the washes and characteristics that jeans buyers love. → In recent years, denim innovators have been attempting to turn the tide, bringing forth new, bio-based solutions to help the industry slash its sludgy output. → Copenhagen, Denmark-based biotechnology firm Octarine Bio is among the pioneers carving out this new frontier.
“Our dyes are produced from natural pigments produced in minute scale by exotic bacteria found in the natural world,” said Nethaji Gallage, Octarine Bio cofounder and CEO. “But instead of isolating and extracting these colors directly from the natural world, we instead have elucidated the genetic instructions these bacteria use to produce the pigments and transferred this ability into common baker’s yeast.”
The process—similar to beerbrewing—allows Octarine to produce an array of vibrant dyes. Only renewable resources are employed to make the products, releasing much less CO2 and requiring far fewer resources than conventional dyes. “Fermentation’s allure also lies in its long-standing familiarity, making it an adaptable and globally accessible process that can be seamlessly integrated into commercial partners’ supply chains,” Gallage said.
Today, most textile dyes are synthetic, petroleum-derived and “highly unsustainable,” she added. “There is also evidence indicating that many synthetic textile days are toxic, carcinogenic and mutagenic,” making them unsafe for wearers as well as the environment.
Additionally, they’re also less efficient to use, Gallage asserted. “Synthetic dyes also typically need a lot of ‘help’ attaching to fibers,” she said. In the form of mordants and chemical additives, they require high temperatures, pressures and extreme pH’s to do their job. The textile dyeing process contributes to more than 2.4 percent of all greenhouse gas emissions, 20 percent of global wastewater, and 35 percent of all chemicals released into the environment.
“Octarine’s microbially fermented colors provide sustainable alternatives to both the production of textile dyes, as well as the dyeing process,” Gallage said. The firm’s color program is focused primarily on purple, pink, blue and green spectra—hues which are both highly sought-after and hard to source. The proprietary dyeing process allows colors to adhere directly to natural and synthetic fibers under ambient conditions without the use of other chemicals or mordants.
The group’s lifecycle analysis shows that the OB-CLR production process has the potential to reduce CO2e emissions by 91 percent, human toxicity potential by 47 percent, energy usage by 94 percent, and eco-toxicity by 92 percent compared to making conventional dyes. When it comes to the actual fabric-dyeing process, OB-CLR has the potential to slash CO2e emissions by 96 percent, human toxicity potential by 99 percent, energy usage by 97 percent and eco-toxicity by 99 percent compared to traditional methods.
So why hasn’t everyone adopted the bio-technology? “There are some key commercial and technical risks to scaling our solution,” Gallage said. While the dyestuff doesn’t require new infrastructure, it does come with a learning curve. Dyehouses must reduce their chemical, mordant, heat and water usage, and there are some technological improvements both upstream and downstream that must occur for the solution to achieve target productivity.
“There will be first movers, but if the conservative industry as a whole moves slowly, our solution will not scale rapidly,” she added. The group has worked to present a model that integrates seamlessly with existing operations to mitigate the cost of switching.
French biotechnology firm Synovance also employs a fermentation process to create its bio-produced pigments. “The dyes are developed by introducing into a chassis microorganism gene of a different species,” said Efthimia Lioliou, Synovance co-founder. “Expression of these ‘ foreign’ genes is then tightly controlled so it does not create a burden into the host microorganism, while at the same time, the output of the final product is optimized.”
Microorganisms are grown in high volumes using inputs like sugar, salt and water, and the end product is harvested and purified using a biophysical process.
The resulting pigments replace synthetic-based dyes used in textiles and cosmetics.
“We are fighting against pollution caused by the use of chemicals in these industries,” Lioliou said. Indigo—the bedrock of denim production—uses aniline and hydrogen cyanide in its chemical synthesis, and those two toxic chemicals end up in waterways, destroying ecosystems and community drinking water while also posing dangers to workers and consumers.
Synovance’s bio-based dyes don’t just cut out the aniline and hydrogen cyanide used in indigo synthesis, they emit 10 times less CO2 than the conventional synthesizing process.
The co-founder believes the biotechnology sector is bound to see an acceleration in the wake of new legislation. “In the EU there is a regulatory framework in place for the production of sustainable textiles; there are regulations in place or envisaged to be implemented soon as well as worldwide voluntary standards that will force brands into sustainable solutions,” she said. “Traceability and eco-labels will not allow brands to use components,” like dyes, “that are
“WE ARE FIGHTING AGAINST POLLUTION CAUSED BY THE USE OF CHEMICALS IN THESE INDUSTRIES.”
not environmentally friendly and have consequences for the people working in the industry and the final consumers.”
For supply chain partners, the application of Synovance’s solution should be simple, as it directly replaces synthetic dye in their existing processes. “The efficiency in dyeing is currently under industrial testing with different types of fiber with very promising results,” Lioliou said.
The group is also very focused on cost, with the goal of making its solution competitive with synthetic indigo by 2028. Synovance is currently working to scale its operations, having moved from lab scale to 100 liters to 1,000 liters. Soon, it will reach 10,000 liters or demo scale.
It’s also working on new hues. “Today we are developing at pilot scale a second color alongside indigo,” according to Lioliou. The group has engineered strains for follow-up colors that will be brought to production within two years. “The power and versatility of our Synthetic Biology platform allows us to develop other colors according to customer demand,” she added. “We are open to joint development projects in search of other colors.”
France’s Pili Bio has developed its own bio-based solution powered by industrial fermentation. According to CEO Jérémie Blache, reducing waste, energy consumption and chemical use is “the basis of our innovation process.”
“Combining chemistry and biology can develop the most relevant pathway to produce an ecological and high-performance dyestuff,” he said. Through the firm’s patented hybrid process, industrial fermentation is used to produce a bio-based dye. At the end of fermentation, “Pili extracts the dyestuff precursor through purification steps that remove microorganisms and co-products applying proven technologies commonly used for decades in the food or pharmaceutical industries,” Blache added.
The precursors are chemically transformed into a dye or pigment. “By implementing the principles of green chemistry, our processes reduce heat, energy, chemicals, waste and CO2 emissions compared to the petrochemical process,” he said.
Today, most colors are produced using fossil fuels. “Bringing circularity to color production means switching from petroleum to biomass,” he asserted. “Because biomass captures atmospheric carbon to grow, this resource is the most relevant to use as a starting material.”
“As a carbon conscious color company, we are aware that we cannot totally get rid of CO2 emissions but we are committed to reducing as much as possible our impact on the environment,” Blache said.
The firm will soon release the results of a peer-reviewed Life Cycle Assessment that illuminates the solution’s reductions in energy use, CO2 emissions, fossil resources and chemical waste. Blache said the dyes don’t lose any of their efficacy, and provide similar shades, depth and color-fastness, as well as equivalent meters dyed per kilogram of dyestuff, to conventional dyes. Operation times are also identical, and processing can take place using existing equipment.
“The only drawback would be the higher price per kilo of Pili’s innovative products during the first years of scale-up compared with conventional dyes that have been produced for more than a century,” he said. However, Pili’s bio-based indigo is compatible with premium applications, and the firm has sold tons of the product, with contracts worth over one million euros, he said. A production unit compatible with premium denim is currently under construction.
“Thanks to the continuous optimization of our process and the economies of scale of a larger manufacturing unit, we’ll be able in the medium term to offer prices compatible with mid-range and later on mass market prices,” Blache said. “This next stage will be reached thanks to the first Pili biomanufacturing plant now being designed.”
Meanwhile, Pakistan-based denim mill Soorty has teamed with chemical company Bozzetto Group to develop a textile dyeing process that replaces traditional methods that employ toxic chemicals.
“From the environmental point of view, particularly the textile dyeing process constitutes a major pollution problem due to the variety and complexity of chemicals employed,” said Noman Nadir Khan, Soorty’s VP of denim research and product development. “Typically, sodium dithionite is employed to reduce dyes, particularly in industrial vat and indigo dyeing processes, resulting in the generation of hazardous byproducts.”
To tackle these ecological concerns, the firm replaced sodium dithionite with an organic reducing agent that significantly reduces the environmental footprint associated with textile dyeing. “By utilizing a natural reducing agent, we achieve sulfate-free dyeing, leading to a substantial reduction in effluent load,” Khan said.
The solution was developed using green chemistry that does not impact a mill’s water treatment systems or leave residue on the fabric itself. What’s more, it’s safe for workers who come into contact with it regularly. It is fully biodegradable during the water treatment process and can be easily removed from treated fabrics without a trace left over, the researcher and product development lead said.
Currently, production capacity and scalability remain the same as conventional solutions, “with the only limitation which is noted up till now that it has a slightly lower color yield, especially for deep, dark color,” he added.
“By adopting this method, we contribute to significant waste reduction, promoting a more sustainable textile dyeing process, which is a good and strong movement towards our sustainability program and goal.”