Cupro or Cuprammonium Rayon is a complicated fabric from a sustainability standpoint. It’s made using cotton linter but don’t get that confused with cotton lint. Many call this a by-product of the cotton industry, which is not wrong, but not necessarily accurate either. It’s still cotton. Like all rayon, cupro is 100% biodegradable!
According to Asahi Kasei, the leading producer of cupro, 99.8% of the waste created during the production of their cupro is recyclable. That waste is used to power their factory through incineration. I should note, about 40% of the energy needed to power Asahi’s plants comes from renewable resources, while the remaining comes from mostly coal and natural gas... which is a great start.
Now, here’s the confusing stuff. While the process might be nearly 100% zero waste, it’s not closed looped. I don’t see this as a negative but instead, an important distinction for what follows. Since the chemical solution cannot be reused, it’s either incinerated or deemed a waste. I am not sure if a closed loop process is possible for cupro but Asahi Kasei does not claim such.
Now for that small amount (0.2%) of waste. While the environmental impact of cupro’s waste is a contentious topic, my understanding is that when treated correctly, the waste is considered to have a low environmental impact. However, the treatment of this waste (again a contentious topic), has been considered by some to not be economically feasible. In 1996, the United States government stopped the production of cupro due to the “cost of cleaning waste water to meet clean water standards”. The European Union and Japan (where Asahi Kasei is located) do not have such bans and treat cupro wastewater.
With so little waste coming from Asahi’s process, I don’t see any major environmental concerns with Asahi's process. I do not hold the same opinion with other companies cupro production processes. Lastly, I would love to see more research into the environmental profile and water footprint of cupro!