TS-SSF and GS-SSF for bioethanol production from sweet sorghum stalk (SSS) at different particle thicknesses. (A) Fermentation kinetic profile of TS-SSF for bioethanol production at different SSS particle thicknesses. (B) Ethanol yield for TS-SSF and GS-SSF at different SSS particle thicknesses. (C) Relations between the remaining ethanol in the solid substrate residue and gas stripping ethanol in the gas phase during GS-SSF. TS-SSF conditions: 70% moisture content, pH 5.0, 35°C, and 0.5 g yeast/100 g SSS (DM); fermentation time 28 h. GS-SSF conditions: 70% moisture content, pH 5.0, 35°C, and 0.5 g yeast/100 g SSS (DM); initial gas stripping time 10 h and fermentation time 28 h. DM, dry matter; GS-SSF, gas stripping solid state fermentation; SSS, sweet sorghum stalk; TS-SSF, traditional static solid state fermentation.