4-23: Cellulases recovery from biomass enzymatic hydrolysis experiments using microfiltration and ultrafiltration membranes

The need to decrease the use of fossil fuels is pushing towards the use of ethanol as a renewable, “zero-emission” fuel. For the production of biomass ethanol the lignocellulosic materials need to be pretreated before its enzymatic saccharification to release fermentable sugar. However, factors such as the high cost of enzymes, low productivity of the hydrolysis process and the current difficulties in reaching the expected yields are scientific and technical challenges for the commercial success of biomass ethanol.

This work studied enzymes recovery from the biomass hydrolysate using a system for recycling the enzymes used in biomass hydrolysis experiments using microfiltration and ultrafiltration membranes. After 14 hours of batch hydrolysis the coarse biomass particles were removed by conventional filtration. The resulting hydrolysate suspension was recirculated through a microfiltration membrane (pore diameter of 0.22 microns) for the removal of suspended solids. The resulting permeate was recirculated through an ultrafiltration membrane (molecular weight cut-off membrane of 30 kDa) to separate soluble sugars and concentrate the cellulases for a subsequent use in a new batch or in a fed batch process.

Hydrolysis experiments were carried out using 1.0 FPU/mL and 4.06 BGU/mL. After 14h of hydrolysis enzyme concentration dropped to 0.320 FPU/mL and 3.76 BGU/mL. The four fold ultrafiltration concentration increased the residual enzyme activities to 0.79 FPU/mL for FPase and 9.07 BGU/mL for β-glucosidase, indicating an enzyme residual activity recovery of 62% for FPU and 60% for BGU.

Acknowledgements: This work received financial support from FINEP and CNPq.