Anaerobic co-digestion of textile waste with food waste could convert two hard-to-manage waste streams into renewable methane while reducing reliance on landfilling and incineration, according to a study published in Waste Disposal & Sustainable Energy. The research, accepted on 3 July 2026, was conducted by scientists at the University of Auckland in New Zealand and James Cook University in Australia.
The findings carry weight because textile waste is generated at enormous scale, with roughly 92 million tonnes disposed of annually. Landfilling, incineration and recycling each remain costly or environmentally problematic. Anaerobic digestion can transform organic-rich waste into biogas, but digesting textiles alone is hampered by imbalanced carbon-to-nitrogen ratios, the recalcitrant keratin in wool, and non-biodegradable polyester in blended fabrics. Those materials can slow hydrolysis, trigger acidification or ammonia inhibition, and depress methane output. Food waste, by contrast, is readily biodegradable and nutrient-rich, making it an attractive co-substrate.
The team evaluated mono- and co-digestion of cotton, polycotton and wool with food waste in mesophilic batch reactors, testing substrate-to-inoculum (S/I) ratios of 0.5 and 1 along with multiple textile-to-food-waste and textile-to-textile blends. They combined methane measurements, kinetic modeling with a modified Gompertz model, chemical and physical analyses of digestate, and calculation of co-digestion performance index (C1) values to identify synergistic or antagonistic effects. The full study is available via its published (DOI: 10.1007/s42768-026-00316-y) record.
Methane yields rose as the S/I ratio decreased. Cotton performed best in mono-digestion, producing 103 mL/g volatile solids and reaching 25.87% biodegradability at an S/I ratio of 0.5. Co-digestion with food waste generally increased production, and the highest yield, 129.7 mL/g VS, came from a cotton-to-wool ratio of 6:1, which carried a balanced C/N ratio of 20.63. Synergy was strongest when food waste made up more than 80% of the blend, particularly with cotton, where C1 exceeded 1.
Kinetic analysis showed that more food waste shortened lag phases and accelerated biogas production. A 1:4 cotton-to-food-waste blend reached 111 mL/g VS with about 29% methane content, while a 1:1 wool-to-food-waste blend produced almost no methane because of ammonia inhibition. Polycotton and wool displayed antagonistic effects, with C1 below 1, as polyester resisted degradation and wool's keratin structure limited microbial access. Post-digestion analyses tied poor performance to residual volatile fatty acids, soluble chemical oxygen demand and free ammonia nitrogen above inhibitory thresholds.
The authors described a clear operating principle: co-digestion works best when food waste dominates the blend and the C/N ratio stays in the optimal window. Cotton-rich mixtures were especially promising, while polycotton and wool would need pretreatment or fiber separation. For textile manufacturers, waste managers and biogas operators, the study suggests co-digestion can improve yields, stabilize digesters and divert waste from landfill. Most treatments produced free ammonia nitrogen within safe biofertilizer limits, though polycotton and wool blends exceeded inhibitory thresholds. The work was supported by Open Access funding organized by CAUL and its member institutions, with additional information available through http://chuanlink-innovations.com.
