ENZYMATIC-HYDROLYSIS OF LIGNOCELLULOSICS IN PACKED-COLUMN AND BALL MILL REACTORS

Reactor design and operation were explored for increased utilization of cellulase as well as for enhanced conversion and rate of saccharification of cellulose. The highest possible concentrations of cedar, pine and oak wood particles were hydrolyzed by a relatively low concentration of cellulase. The time courses in a batch stirred cell were well simulated with an apparent Michaelis-Menten rate equation. The results obtained in a single packed-column reactor showed that cellulase diffused into and adsorbed at the inner surface of substrate particles was susceptible to deactivation and that the denatured enzyme was reactivated on its desorption. A ball mill reactor and a dual packed-column in which buffer solution alone was fed alternately into the column for saccharification and the column for enzyme recovery were employed in order to hydrolyze cellulose particles with simultaneous renewal of particle surface and thus reactivation of denatured enzyme at the inner surface. The saccharification in the ball mill reactor proceeded in two stages, the kinetic parameters for which were almost identical. The ball mill reactor was superior to the dual packed-column reactor with respect to cellulase utilization, productivity, reducing sugar concentration and ease of operation.