Does anaerobic digestion improve environmental and economic benefits of sludge incineration in China? Insight from life-cycle perspective

•The INC outperforms traditional ADI due to low AD efficiency and VS content of sludge.•The ADI route exhibits greater sustainability potential with higher AD efficiency.•The energy gap between ADI and INC is expected to be eliminated with 7% TS in AD.•Higher AD efficiency can decrease energy consumption and I&O in thermal drying.•A demonstration LCA model on sludge ADI and INC was constructed.