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Torrefaction is known to reduce the logistical costs of biomass. Torrefied biomass' prospects as feedstock for fermentation to liquid biofuel are largely unknown. This study investigated the interactions of torrefaction and alkaline pretreatment of wheat straw on glucose yields from enzymatic hydrolysis, including treatment order and the potential for pH to play a role in the process. Across a range of torrefaction severities with temperatures of 200 °C, 220 °C, and 240 °C and durations of 20, 40, and 60 min, torrefaction had a negative impact on glucose yield of wheat straw with or without alkaline pretreatment and regardless of the order of alkaline pretreatment. Alkaline pretreatment after torrefaction results in higher glucose yield than alkaline pretreatment before torrefaction, or by torrefaction alone. Hence, there is the prospect for adding logistical benefits of torrefaction to the bioethanol system if alkaline pretreatment is coupled with torrefaction. Decreasing trend in pH with increase in torrefaction severities was observed for trials without buffer, indicating chemical changes causing the decrease in pH might be associated with the reduction in yield. [ABSTRACT FROM AUTHOR]

The sequential combination of torrefaction and alkaline treatment is one possible design strategy for a circular economy in which torrefied cellulosic paper with enhanced wet strength is repeatedly used as a packaging material, then hydrolyzed downstream for bioethanol production after alkaline treatment. The wet-tensile strength of cellulose filter paper increased by 1533%, 2233%, 1567%, and 557% after torrefaction for 40 mins at 200 °C, 220 °C, 240 °C and 260 °C, respectively. Glucose yield decreased with increase in torrefaction severity but after treating torrefied filter samples with alkaline (NaOH) solution, glucose yield increased. For instance, the glucose yield of raw filter paper was 955 mg/g of substrate whereas it was 690 mg/g of substrate for the same filter paper sample torrefied at 200 °C. The glucose yield increased to 808 and 933 mg/g of substrate with 1% and 10% alkaline treatment, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]