The shift from natural to synthetic
Textile dyeing has been around for thousands of years. People have been extracting dyes from different plants, minerals, and other natural resources.
But, in 1856 things started to change. It’s when British chemist Sir William Henry Perkins discovered the use of synthetic dyes and we got a much wider range of colors that were brighter and more resistant to washing and sunlight.
This itself is not a bad thing, but synthetic dyes consist of many chemicals and compounds (sulfur, naphthol, vat dyes, nitrates, acetic acid, soaps, enzymes chromium compounds), heavy metals (copper, arsenic, lead, cadmium, mercury, nickel, cobalt), and auxiliary chemicals which, unfortunately, often end up in the environment.
It is estimated that the dyeing industry uses approximately 10 000 different dyes and pigments. Up to 200 000 tons of these dyes are lost to effluents every year during the dyeing and finishing operations.

Excessive water usage
Like the yarn and textile manufacturing process, textile dyeing is heavily dependent on water. It takes about 20-50 liters of water for 1 kilogram of cloth and about 60 liters of water for 1 kilogram of yarn to get their color. About 20% of the dyes used are not fixed to the textile and thus go down the drain.
The wastewater produced by textile dyeing consists of numerous different pollutants (partly named above) and many of them cannot be removed after treatment. A lot of the textile industry is also located in countries (Bangladesh, Cambodia, Ethiopia, India) where wastewater treatment is not well regulated if at all.
When chemicals end up in different water bodies, they do not only give the water a bad appearance and smell but stop the sunlight to get through the water and so affect photosynthesis. Photosynthesis is necessary for oxygen production and the lack of oxygen greatly affects the marine life and water self-purification process.
This heavily polluted water often flows to the fields where people grow their crops. Over the years it reduces soil productivity and affects negatively the harvest.
The water from different water bodies (e.g.rivers) is also being used by many for washing clothes and dishes and is, therefore, a big threat to the communities who live near textile dyeing factories. You can watch a great documentary about this problem here.

Health effects for consumers
As consumers, we tend to think much more about eating clean and organic food and using natural cosmetics than wearing for example clothes that would not consist of toxic compounds.
The compounds that are used to improve our clothes quality (e.g making them softer and stain, flame, and wrinkle-resistant, odor-free) can at the same time cause allergies, dermatitis, cancer, organ failure, hormone disruption, infertility, etc. To name a few of these toxic compounds: PFCs, formaldehyde, solvents, phthalates, chromium, mercury, and metals (if not correctly traced throughout the supply chain).
Now think about the health of the people working in the textile industry who do not only wear clothes containing these compounds but are daily exposed to them as well. The only compensation they get for putting their health at stake is a poor salary.

Is sustainable textile dyeing industry possible?
Effluents from the textile industry are extremely complex. They contain a large variety of dyes, additives, and derivatives that change seasonally, increasing the challenge to find effective, feasible treatments. Due to the high demands for textile durability by the consumer market, the dye compounds are made to be resistant to biodegradation and therefore remain in the environment for a long time.
Small steps though are being taken to make the textile industry as a whole greener and less harmful (a combination of different effluent removal methods to improve efficiency, adsorption of textile dye effluent with activated carbon, reducing and recycling water, Air Dyeing Technology; beeswax, aloe vera, vitamin A to soften and finish the fabric, potato starch for sizing, etc), but it is far from enough.
There have to be better laws and regulations in place (both locally and internationally) and new technologies invented and applied to make the textile industry less chemically intensive and not so heavily dependent on water.
A small step we can take as consumers is making better choices when purchasing new clothes and as mentioned in another article about different textiles, buying fewer clothes is always a good idea.