Green Machine: Post-consumer Blended Textile Separation and Recycling by Hydrothermal Treatment

This project aims to conduct the feasibility studies of polyester and cellulose recycling by hydrothermal treatment and dissolution treatment on cotton and polyester blends. The parameter will then be optimized to improve the recycling yield and recycling efficiency. In addition, the feasibility of re-spin the polyester residue will also be conducted.

Nowadays, polyester and cotton are the most two demanding fibre types. By 2015, 54.5% of textile is polyester while 28.4% is cotton, textiles waste increase greatly due to high demand on textile products. By 2013, an estimated of 12.4 million tons of textile waste was generated according to the U.S. Environmental Protection Agency. Over 55% of it had been ended up in either landfill or low equality products.


The whole process uses only heat, water and less than 15% of green chemical with a recovery rate of over 97% for polyester fibres in 2 hours.

Industry Benefit

Green Machine offers a lower-energy consumption textile recycling solution. It uses only 19 GJ to produce the same amount of separated polyester fibres. When compared to the 67 GJ needed for producing every ton of PET, it saves 70% of total production energy used.

Technological Breakthrough
  • The separated fibres with no depolymerisation are ready for spinning and manufacturing of new fabric, while the cellulose powders, decomposed from the cotton, can be applied to functional products such as super-absorbency materials and regenerated cellulose fibres.
  • A pre-industrial scale hydrothermal system is now set up in a Tai Po factory to evaluate the parameters for scale-up, such as the treatment conditions in a scale of 500L, energy consumption, and optimisation of operation. The system is now under phase II development for further industrialisation. 
46th International Exhibition of Inventions of Geneva (2018) - Gold Medal
2017 Hong Kong Green Innovations Awards - Silver Award
2019 Asia International Innovative Invention Award - Gold Award
Project Name (ITF)

Hydrothermal Treatment and Dissolution Treatment to Recycle PET and Cellulose from the Cotton and PET Blends

Project Number (ITF)