Environmental Impact of Conventional Textile Dyeing
For professionals and consumers alike it is well-known that the fashion industry has a complex supply chain, with each of the stages offering many challenges, huge environmental and social impacts, as well as opportunities for transformation.
And while the effect of some of the industry's areas is widely discussed, for example that of the raw materials extraction and product's end-of-use, other stages, like dyeing and finishing of yarns and textiles, are still less talked about.
Today, we are taking a good look at the impacts of conventional synthetic and fossil fuel based dyes and dyeing on the environment.
A note on human impact
It is important to mention right away that conventional dyeing has a huge impact on the people, both in the fashion supply chain as well as the local communities and fashion consumers. We believe it is worth dedicating a separate article to those, so stay tuned for that!
Water Contamination
The contamination of freshwater with synthetic chemicals is one of the main damages the dyeing industry causes to the environment. During the textile washing process, which is one of the final stages of conventional dyeing, 10-50% (about 200,000 tonnes a year) of dyes used end up in the wastewater.
These hazardous chemicals escape conventional wastewater treatment and persist in the environment (due to high stability to water, temperature, light), thus contaminating the water bodies. Given the effluent volume and composition, dye wastewater is one of the most severe sources of pollution globally.
Reduction of photosynthesis
These compounds that end up in the water bodies have strong colour and low biodegradability. Apart from the aesthetic pollution, they hinder the passage of sunlight through the water, thus reducing the photosynthesis and oxygenation processes in the affected water bodies.
Soil and plant damage
Some of the widely used dyes in the textile industry are azo dyes. 15-50% of those don't bind to the fabric and end up in wastewater which in turn is commonly used for soil irrigation in agriculture. Therefore, azo compounds negatively affect microbial communities in soil, as well as plant growth. Oxidative stress from chromium in dyes also inhibits the development of plants.
Energy emissions
When it comes to conventional processing, aside from water and chemicals, dyeing baths also use significant amounts of energy (coal & thermal) to keep water at a constant high temperature. As a result, this stage of the supply chain generates 75-90% of its energy emissions. It is important to note that dyeing baths are not only used in synthetic dyeing, but also in some of the natural methods.
Biomagnification and diseases
By persisting in the environment, effluents of textile dyeing result in biomagnification - increasing buildup of toxic substances in organisms at each stage of the food chain. They act as highly toxic, mutagenic and potentially carcinogenic agents and are related to degradation and diseases in animals. The aforementioned azo dyes have been found to have such an effect (thus, their usage is restricted in the EU for example), as well as the nitro type.
Conclusion
A detail such as colour has huge consequences, which we often fail to notice. We usually hear it is the amount of water used that is the biggest pitfall of the dyeing industry, while in fact it is the water pollution and consequently the loss of biodiversity that present the biggest challenges.
In the biological world, colours are connected to survival strategies. Working with nature is the only solution we can apply in order to sustain and restore biodiversity on the planet in order for the human species to survive.
Sources
Beat J. Brüschweiler, C. Merlot,
Azo dyes in clothing textiles can be cleaved into a series of mutagenic aromatic amines which are not regulated yet, In: Regulatory Toxicology and Pharmacology, Volume 88, 2017,Pages 214-226, Available at: https://www.sciencedirect.com/science/article/pii/S0273230017301812
Textile Processing Guide: Pre-treatment, colouration and finishing, edited by, J. Van der Berger, G. Parker, available at: https://reports.fashionforgood.com/report/textile-processing-guide-pre-treatment-colouration-and-finishing/
Chequer, F. M. D. , de Oliveira, G. A. R. , Ferraz, E. R. A. , Cardoso, J. C. , Zanoni, M. V. B. , de Oliveira, D. P. . Textile Dyes: Dyeing Process and Environmental Impact. In: Günay, M. , editor. Eco-Friendly Textile Dyeing and Finishing [Internet]. London: IntechOpen; 2013, Available from: https://www.intechopen.com/chapters/41411
B. Lellis, C.Zani Fávaro-Polonio, J.Alencar Pamphile, J.C. Polonio,
Effects of textile dyes on health and the environment and bioremediation potential of living organisms, In: Biotechnology Research and Innovation,Volume 3, Issue 2, 2019, Pages 275-290, available at: https://www.sciencedirect.com/science/article/pii/S2452072119300413