In order to increase the fractionation efficiency of the wheat straw, a deep eutectic solvent (DES) system consisting of chlorine/lactic acid was used in this study for wheat straw pretreatment. The outcomes exhibited that DES pretreatment significantly enhanced the capability to extract lignin, retain cellulose, and remove hemicellulose. The best condition for the pretreatment of wheat straw was 150 °C for 6 h. The process retained most cellulose in the pretreated biomass (49.94–73.60%), and the enzymatic digestibility of the pretreatment residue reached 89.98%. Further characterization of lignin showed that the high yield (81.54%) and the high purity (91.33%) resulted from the ether bond cleavage in lignin and the connection between hemicellulose and lignin. As for application, the enzymatic hydrolysis of the best condition reached 89.98%, and the lignin also had suitable stability. The investigation exhibited that DES pretreatment has the potential to realize an efficient fractionation of lignocellulosic biomass into high-applicability cellulose and lignin of high-quality.

Suitable fermentation substrates and fermentation modes can effectively improve the fermentation ethanol yield. In this study, we optimised the hydrothermal pretreatment conditions by orthogonal optimisation using waste tissue paper as substrate. These conditions consisted of 50 min duration in a high-pressure reactor with pure water as solvent at a temperature of 160 °C. The biomass to water ratio was maintained at a constant level. The cellulose content of the pretreated TP was 81.19 ± 4.06%, which was an increase of 21.59% compared to the blank control. The 72 h reducing sugar yield of pretreated TP was 0.61 g sugar/g paper, which was 38.64% higher than that of untreated TP. Subsequently, the pretreated TP was fermented under optimal conditions. The mixed group of Saccharomyces cerevisiae and Candida shehatae (SC) showed a distributed saccharification fermentation pattern, with an ethanol yield of 28.11 g/L in 72 h. On the other hand, the single Saccharomyces cerevisiae (S) exhibited a homobloc saccharification fermentation pattern, with an ethanol yield of 35.15 g/L in 72 h.