Impact of disk milling on corn stover pretreated at commercial scale

•Dilute acid pretreated corn stover was obtained from a commercial plant.•Disk milling enhanced sugar yields of dilute acid pretreated samples.•Cutting and internal and external fibrillation were achieved by milling.•Enzymes were more effective than milling in increasing xylose yields.•Dilute acid pretreatment condition affected final sugar yields.

In cellulosic biofuel production, chemical pretreatment performed at laboratory or pilot scale, followed by mechanical refining, has been demonstrated to be effective to increase feedstock enzyme digestibility. To take the combined pretreatment process one step closer to commercialization, disk milling was performed with commercially pretreated corn stover. Dilute acid pretreated samples with combined severity factors (cSF) of 0.09 (DA09) and 0.43 (DA43) were obtained from a commercial plant. Effects of pretreatment conditions (DA09 and DA43), milling cycles (0, 3, 9, and 15) and enzyme dosages (7.8, 15.6 and 31.2 mg cellulase/g dry biomass) were evaluated. Milling improved glucose yields by 0.7 to 1.2-fold. Higher enzyme dosages enhanced sugar yields. Milling was more effective to improve glucose yields, while enzyme dosage was more effective to improve xylose yields. However, dilute acid pretreatment condition was the most important factor to increase final sugar yields compared to milling cycles and enzyme dosages.