Who is behind it?
Re:newcell is the company behind Circulose. They are a swedish company which was formed as a spin-out venture from The Royal Institute of Technology (KTH) in Stockholm. They opened their first plant in Kristinehamn, Sweden in 2017 which works as a demo plant with the capacity to produce 7,000 tons of Circulose pulp every year.

What is it?

Circulose® is made from discarded textiles, using a breakthrough process powered by 100% renewable energy, old clothes are transformed into a pristine natural material that needs no cotton fields, no oil, and no trees.  Circulose is an alternative cellulose pulp that is used for making rayon fibres, such as viscose.

How is it made?

Circulose is made by taking cotton waste and purifying it with a water-based chemical process to remove dyes and other contaminants. The properties of cellulose are also altered enough that it is suitable as a feedstock for the production of these rayon fibres. One important property is the molecular weight – the average length of the cellulose molecules, which typically needs to be reduced before viscose fibres are made.

Renewcell takes in worn-out garments that can’t be resold and they prefer cotton clothes as they contain a lot of cellulose. The clothes are shredded, de-buttoned, de-zipped, de-colored and turned into a slurry. Contaminants like plastic polyester are taken out. What remains is cellulose - the biodegradable organic polymer that cotton, trees and all green plants on earth are made out of. The slurry is dried to produce sheets of pure Circulose®.

Environmental impact.
It saves resources compared to making a shirt from cotton; no land has to be used to grow plants, and the process uses as much as 99% less water. Cotton is also a heavy user of pesticides. Brands are aware that the resources required to produce cotton make it increasingly less viable for the future.
Currently, the only real option for recycling cotton waste is to chop it up and twist it into a new yarn, which results in a low-quality yarn which often requires blending with other fibres or virgin cotton. This is known as mechanical recycling of cotton.

Which brands use it? 
H&M was the first brand that partnered up with re:newcell to become the first brand to begin using their proprietary sustainable fibre Circulose. Later this year three of the brands from the danish fashion retailer Bestseller started to produce garments using Circulose.