Effects of ultrasonic vibration-assisted pelleting of cellulosic biomass on sugar yield for biofuel manufacturing

Ultrasonic vibration-assisted (UV-A) pelleting can increase the bulk density of cellulosic biomass, thus reduce the feedstock transportation cost in cellulosic biofuel manufacturing. UV-A pelleting can also increase the biomass sugar yield in enzymatic hydrolysis. There are two major processes in the sugar conversion of cellulosic biomass: pretreatment and enzymatic hydrolysis. Sugar yield definition used in reported UV-A pelleting studies is enzymatic hydrolysis sugar yield. This definition is based on enzymatic hydrolysis this single process without considering the pretreatment process. In fact, converting cellulosic biomass into fermentable sugar (glucose) is the combined effort of pretreatment and enzymatic hydrolysis. There are no papers in the literature investigating whether UV-A pelleting could increase the total sugar yield when both pretreatment and enzymatic hydrolysis are considered. This paper reports the first study using total sugar yield to investigate the effects UV-A pelleting on biomass sugar yield. Experimental results show that, for all the four types of cellulosic biomass (wheat straw, corn stover, switchgrass, and sorghum stalk) used in this study, total sugar yield of biomass processed with UV-A pelleting was 30 to 43 % higher than that of biomass not processed with UV-A pelleting.