Ionic liquid pretreatment to enhance the anaerobic digestion of lignocellulosic biomass

- Lignin of 23.7-64.8% was removed from pretreated biomasses.
- Crystallinity of 21.0-15.2% was reduced by the pretreatment.
- The biogas production of pretreated water hyacinth was increased by 64-140%.
- Recovered ILs showed stable effect on the anaerobic digestion.
- Biogas production enhancement was WH > SP > RS > ML.