ENZYMATIC HYDROLYSIS OF CORN STOVER PROCESS DEVELOPMENT AND EVALUATION

The hydrolysis of acid treated corn stover with cellulase from T.reesei Rut-C-30 was evaluated.Experiments were conducted with substrate concentrations of 5-25% by weight, enzyme activities of0.5-7IU/ml and residence times of 24-48 hours.Maximum conversion was 55% for specific cellulase activity of 25-30 IU/g.Optimum cellobiase activity for minimum cellobiose production was found approximately 1.8 cellobiase units to 1 FPA unit.to be Hydrolysis experiments with steam exploded corn stover led to a maximum conversion of 80%, significantly higher than the results obtained for acid treated substrate.Steam exploded corn stover was demonstrated as a suitable carbon source for growth of T. reesei in submerged cultures.Computer aided process evaluations were conducted for several processing alternatives.Among the alternatives considered were steam explosion or dilute acid pretreatment, equilibrium solid-liquid contacting or ultrafiltration for enzyme recovery, and batch, continuous or continuous with cell recycle enzyme production.Using dilute acid pretreated materials, glucose may be produced for 12-22 cents per pound for corn stover cost ranging from 0-30 $/ton.This constitutes a 33% reduction over previous processing schemes employing cellulase from T. reesei QM9414.Enzyme production is the single most expensive processing step, accounting for 40% bf processing costs.Preliminary evalua-iii tion of processing with steam exploded corn stover leads to a glucose cost of 10-15 cents/pound for corn stover costing 0-30 $/ton; with further improvement possible. .At the current level of development, ethanol may not be manufactured profitably from.cornstover; furthermore, the dominance of raw material cost tends to dampen the effect of process improvements on the cost of manufacturing ethanol.TABLE OF CONTENTS l.Production of ethanol from cellulosic materials takes place in two discreet steps.First, cellulose is hydrolyzed to produce glucose~ Subsequently, glucose is fermented by .yeasts to produce ethyl alcohol.Thus, if ethanol is to be manufactured from cellulose at competitive price, an economical means of carrying out the hydrolysis step is essential.Cellulose may be hydrolyzed to produce glucose by ' V1 ( 3 3) • Von Stocka r, Yang and Wilke ( 34) developed a two stage continuous process employing cell recycle to boost productivities to 19 IU/1/hr using strain QM9414.