A study on enzymatic hydrolysis of cellulose in an attrition bioreactor

In the biological conversion of cellulose, a physical or chemical pretrealment proceeds the hydrolysis by an enzyme. The hydrolysis rate however, is slowed down as the active sites in the pretreated substrates are reduced. In this study, attempts were made to use an attrition bioreactor in which the pretreatment and the hydrolysis were carried out at the same time, where higher hydrolysis rales were achieved. Glass beads of 0.3-cm-diameter and sand were used as the milling media in a batch reactor where pure cellulose, Solka Floc BW200 was hydrolyzed by cellulase secreted from a fungus mutant,Trichoderma reesei. The higher rates observed are believed due to the synergistic effects of the size reduction and the conversion of the crystalline to the amorphous form of cellulose which was observed by comparing the X-ray diffractorgrams of the cellulose hydrolyzed in the reactors with and without milling medium. A simple kinetic model was found satisfactory in depicting the hydrolysis mechanism, and the kinetic parameters were estimated. Higher power consumption as compared to a reqular stirred reactor was observed and a quantitative expression was derived for its estimation.