(780a) Continuous Enzymatic Hydrolysis of Biomass in a Membrane-Assisted Reactor

Although enzymatic hydrolysis of lignocellulosic biomass is usually conducted in batch mode, continuous operation is desirable for a number of reasons. Higher overall investment costs due to larger reactor volumes, higher running costs due to frequent startup/shut down, one-time use of enzymes as well as enzyme separation costs are disadvantages of batch operation. Recovery and reuse of the enzymes during enzymatic hydrolysis of biomass is attractive as the enzyme cost is a major economic constraint. In addition, high sugar concentrations are desirable for subsequent fermentation steps, but obtaining high sugar concentrations directly from batch enzymatic hydrolysis is limited by product inhibition of the enzymes and material handling of slurries at high-solids concentrations. Development of a continuous saccharification process with integrated membrane separations overcomes the limitations of batch operation. Membrane separation steps integrated with the enzymatic hydrolysis reaction could enable recovery and reuse of enzymes, as well as concentration of product sugars.  Further capital cost will be lower due to smaller process stream volumes as a result of higher concentrations.

In this study we have designed and tested an integrated continuous membrane reactor. The integrated membrane reactor includes a microfiltration/ultrafiltration membrane for recovery and recycle of the enzyme as well as a nanofiltration membrane for concentration of the sugars.  Here, we present results for our continuous integrated membrane reactor.  These results are compared to a batch reactor.  We show that glucose production rates and product sugar concentrations are higher for the integrated continuous membrane reactor.