Enhanced anaerobic digestibility of waste activated sludge by plant-derived biosurfactant

- Anaerobic digestibility of waste activated sludge (WAS) was enhanced by saponin (SB).
- SB showed positive effects on WAS hydrolysis and acidogenesis.
- Methanogenesis was enhanced at lower dosage and inhibited at higher dosage.
- Hydrolytic enzymes activity was improved.
- SB could decompose the LB-EPS layer, and further detach the TB-EPS layer of WAS.