Anaerobic co-digestion of textile waste with food waste could transform two problematic waste streams into renewable methane while reducing reliance on landfilling and incineration, according to a study published in Waste Disposal & Sustainable Energy. The research, conducted by scientists at the University of Auckland and James Cook University, examined how different textile types and mixing ratios affect methane yields under mesophilic conditions.
The findings are significant because textile waste is generated at enormous scale—about 92 million tonnes disposed of annually—yet current disposal methods remain costly or environmentally harmful. Anaerobic digestion can convert organic-rich waste into biogas, but textiles alone are difficult to digest due to imbalanced carbon-to-nitrogen ratios, recalcitrant keratin in wool, and non-biodegradable polyester in blended fabrics. Food waste, being highly biodegradable and nutrient-rich, serves as an effective co-substrate.
The study tested mono- and co-digestion of cotton, polycotton, and wool with food waste at substrate-to-inoculum ratios of 0.5 and 1. Results showed that lower ratios and higher food waste shares generally improved methane production, but performance depended strongly on textile type and carbon-to-nitrogen balance. Cotton performed best in mono-digestion, producing 103 mL/g volatile solids and reaching 25.87% biodegradability. Co-digestion with food waste raised methane production further, with the highest yield of 129.7 mL/g VS achieved from a cotton-to-wool ratio of 6:1, which had a balanced C/N ratio of 20.63.
Synergy was strongest when food waste made up more than 80% of the blend, especially with cotton, where the co-digestion performance index exceeded 1. Kinetic analysis showed that more food waste shortened lag phases and accelerated biogas production. For instance, a 1:4 cotton-to-food waste blend reached 111 mL/g VS and about 29% methane content, while a 1:1 wool-to-food waste blend produced almost no methane due to ammonia inhibition. Polycotton and wool exhibited antagonistic effects, with polyester resisting degradation and wool's keratin structure limiting microbial access.
The authors noted that co-digestion is most effective when food waste dominates the blend and the C/N ratio stays within the optimal window. Cotton-rich mixtures were especially promising, while polycotton and wool require pretreatment or fiber separation. They added that kinetic modeling helped explain why food waste shortens lag phases and speeds up biogas production, and that the co-digestion performance index provides a simple way to screen feedstock combinations before scaling up.
For textile manufacturers, waste managers, and biogas operators, the study suggests that co-digesting textile waste with food waste can improve methane yields, stabilize digesters, and divert waste from landfill. The full study is available via published (DOI: 10.1007/s42768-026-00316-y), and additional information about the research and its applications can be found at http://chuanlink-innovations.com.
