Continuous enzymatic cellulose hydrolysis in a tubular membrane bioreactor

Cellulose hydrolysis by Celluclast 1.5L (Novozymes A/S, Denmark) enzyme preparation was studied in a special tubular membrane reactor, where a porous stainless steel filter was covered by a non-woven technical textile layer providing a fine, hairy surface for simultaneous adsorption of both the cellulose particles and the biocatalyst. Solka Floc BW 200 powder and Mavicell pellets were used as substrates in the process. Beyond the adsorption studies, the composite membrane was characterized, having 30 l/m2 bar h hydraulic permeability and an ability to retain both cellulose and enzyme, while glucose (product) permeated easily across the membrane. Using Solka Floc substrate experiments were carried out in both the hairy tubular and a “normal” flat sheet membrane bioreactor. It was found that 10% higher average conversion was possible to achieve in the special layered tubular unit compared to the “traditional” ultrafiltration membrane reactors. Finally, milled and sieved Mavicell pellets were applied as substrates, and 70% conversion was reached with the pretreated fraction.