Advances in ethanol production from hardwood spent sulphite liquors

► Hardwood spent sulphite liquor as resource for 2nd generation bioethanol production. ► The composition of SSLs was compared and related with wooden origin stressing specificity of microbial inhibitors from HSSL and their antimicrobial effect. ► The different fermentative processes, the microorganisms used and the strategies to improve yield and productivity were also reviewed. ► Optimization of detoxification processes, fermentation strategies and selection of suitable microbial strains need to be developed. ► Process integration for HSSLs conversion, contributing for sustainability of pulping mills is proposed.