Researchers at Delft University of Technology (TU Delft) and Dutch fashion label Hul le Kes have developed garments coloured with a pigment recovered from wastewater treatment sludge. The project demonstrates how waste streams can become valuable resources for the fashion industry.

The innovative pigment comes from a melanin-like biopolymer extracted from sewage sludge. It offers a potential alternative to both animal-derived and synthetic textile dyes. Although the material is still in the research phase, the first garments show promising opportunities for more circular textile production.

Recovering Pigments From Wastewater

TU Delft Associate Professor Yuemei Lin led the research. She developed a process that recovers a melanin-like biopolymer from sewage sludge generated during wastewater treatment. The team then used the pigment to dye wool fibres.

Melanin is a natural pigment known for its UV-protective and antioxidant properties. Today, manufacturers often obtain commercial melanin from cuttlefish ink. This raises ethical concerns and limits supply because catches vary throughout the year. Synthetic alternatives are available, but researchers have found that they do not fully match the structure and performance of natural melanin.

By recovering a similar material from wastewater sludge, the researchers create a more sustainable source of pigment while giving value to a waste product.

From Laboratory To Garment

The project moved beyond the laboratory when Lin successfully dyed wool with the recovered pigment. The material proved suitable for textile applications when it was used to create a knitted jumper.

Lin then approached Dutch fashion label Hul le Kes, which is known for its circular approach to fashion. The brand embraced the experiment and incorporated the pigment into a collection of garments. The collaboration shows how scientific research and fashion design can work together to develop new sustainable materials.

A Circular Alternative To Conventional Dyes

Founded by Sjaak Hullekes and Sebastiaan Kramer, Hul le Kes focuses on craftsmanship, repair, upcycling and natural materials. The brand regularly collaborates with organisations that aim to create alternatives to the current fashion system.

The wastewater-derived pigment fits this vision. In addition to replacing animal-based and synthetic dyes, the material offers functional benefits such as UV protection and antioxidant activity. Researchers also found that it can speed up the textile dyeing process.

Although further testing and regulatory approval are still required, the project highlights the potential of wastewater as a source of high-value biobased materials. By transforming sewage sludge into a functional textile dye, the researchers demonstrate how circular thinking can inspire new material solutions for the fashion industry.

Source: Delft University of Technology
Photos: Delft University of Technology / Hul le Kes