A study from researchers at the University of Auckland in New Zealand and James Cook University in Australia has found that anaerobic co-digestion of textile waste with food waste can convert two difficult waste streams into renewable methane while reducing landfilling and incineration. The work, accepted on 3 July 2026 and published (DOI: 10.1007/s42768-026-00316-y) in Waste Disposal & Sustainable Energy, examined mono- and co-digestion of cotton, polycotton and wool with food waste under mesophilic conditions, testing substrate-to-inoculum ratios of 0.5 and 1 and multiple feedstock mixing ratios.
The findings matter because textile waste is generated at enormous scale, with about 92 million tonnes disposed of annually, yet landfilling, incineration and recycling remain costly or environmentally problematic. Anaerobic digestion can convert organic-rich waste into biogas, but textiles resist digestion alone due to imbalanced carbon-to-nitrogen ratios, recalcitrant keratin in wool and non-biodegradable polyester in blended fabrics. Food waste is highly biodegradable and nutrient-rich, making it a promising co-substrate.
Methane yields increased as the substrate-to-inoculum ratio decreased. Among textiles, cotton performed best in mono-digestion, producing 103 mL/g volatile solids and reaching 25.87% biodegradability at a ratio of 0.5. Co-digestion with food waste generally raised methane production, and the highest yield, 129.7 mL/g volatile solids, came from a cotton-to-wool ratio of 6:1, which had a balanced carbon-to-nitrogen 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, with the modified Gompertz model fitting the data well. A 1:4 cotton-to-food-waste blend reached 111 mL/g volatile solids and about 29% methane content, while a 1:1 wool-to-food-waste blend produced almost no methane because of ammonia inhibition. Polycotton and wool showed antagonistic effects: polyester resisted degradation, and wool's keratin structure limited microbial access. Post-digestion analyses linked poor performance to residual volatile fatty acids, soluble chemical oxygen demand and free ammonia nitrogen above inhibitory thresholds.
The authors said the findings offer a clear operating principle: co-digestion is most effective when food waste dominates the blend and the carbon-to-nitrogen ratio stays within the optimal window. Cotton-rich mixtures were especially promising, while polycotton and wool need pretreatment or fiber separation because polyester and keratin resist microbial breakdown. 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. Pretreatment strategies such as thermal hydrolysis for cotton and wool, and environmentally friendly solvents to separate polyester from blended fabrics, could further improve digestibility. Most co-digestion treatments produced free ammonia nitrogen within safe biofertilizer limits, although polycotton and wool blends exceeded inhibitory thresholds. Additional information about related innovation efforts is available through Chuanlink Innovations.
