SEMICONTINUOUS ENZYMATIC-HYDROLYSIS OF LIGNOCELLULOSES

Lignocelluloses (steamed hardwood and hardwood kraft pulp) were semicontinously hydrolyzed on a large scale [2-2.5 kg of substrate vs. 20,000 IU filter paperase (FPase)] using a 10-L hydrolysis reactor with an ultrafiltration unit for the recovery and reuse of cellulases. The substrate was added to the reactor at appropriate intervals to keep a concentration of approximately 5% (w/v). All of the enzyme was added at the beginning and no further addition was done. The ultrafiltration unit was operated intermittently rather than continuously due to its enough capacity (dilution rate of 2.5 h-1) and making the enzyme durable. The enzyme required to produce one gram of reducing sugar in this reactor was 27.3 FPase IU/g RS for steamed hardwood and 7.4 FPase IU/g RS for hardwood kraft pulp. The sugar composition of hydrolyzate was unaltered virtually from beginning to end of the hydrolysis in spite of the progressive loss of enzyme activities. The analysis of the enzyme composition in the hydrolyzate during hydrolysis revealed that an exo-beta-D-glucanase component was adsorbed selectively at the stages of advanced hydrolysis extent.