Tween-80 is effective for enhancing steam-exploded biomass enzymatic saccharification and ethanol production by specifically lessening cellulase absorption with lignin in common reed

•Steam explosion much reduces cellulose DP and largely extracts polymers in reed.•Tween-80 is effective for high biomass saccharification in steam-exploded residues.•Additional CaO pretreatment leads to the highest ethanol yield at 19% of dry matter.•Tween specifically blocks lignin absorbing with cellulase for high biomass digestion.•It provides an optimal biomass process approach for high ethanol yield in reed. In this study, eight physical and chemical pretreatments were compared in terms of their enhancements on biomass enzymatic saccharification in reed. Despite 8% NaOH pretreatment could result in 100% biomass enzymatic digestion while co-supplied with 1% Tween-80, it only produced bioethanol at 10% (% dry matter). By comparison, 10% CaO pretreatment with Tween-80 is a relatively low-cost biomass conversion with ethanol yield at 12%. Notably, the steam-explosion pretreatment with 1% Tween-80 could cause a complete biomass enzymatic hydrolysis with bioethanol yield at 17%. The sequential 5% CaO pretreatment with the steam-exploded residues could lead to the highest ethanol yield at 19% with an almost complete sugar–ethanol conversion rate. Due to much low-DP cellulose and less noncellulosic polymers (lignin, hemicelluloses) that increase biomass surfaces, the steam-exploded residues were specifically effective for Tween-80 either to block lignin absorbing with cellulases or to disassociate hemicelluloses, leading to an efficient lignocellulose enzymatic digestion. Compared with previously reported pretreatments in other C4-grasses (Miscanthus, corn, sweet sorghum, switchgrass), to our knowledge, this study has therefore provided three more applicable approaches for high ethanol production with relatively low cost, less contaminate release and efficient biomass conversion rates in reed.