Continuous Alkali-Cellulase Processing of Corn Stover to Glucose for Bioethanol

Abstract

Preprocessing of biomass at or near the growing site has considerable advantages over transporting to distant fermentation refineries equipped to process cellulosic material. The alkali-cellulase (Alkcell) process converts biomass to glucose using materials and methods that can be implemented at or near a growing site. This study has shown that the Alkcell process can be configured to run continuously. The use of carriers to contain the biomass allows continuous movement along a treatment train starting with alkali pretreatment and ending with glucose release. Conditions for pretreatment with NaOH, washing, and pH adjustment have been determined. Immersion of the carriers in a cellulase bath at optimal temperature and duration follows. The carriers are then submerged in a large volume of buffer at pH and temperature that allows release of glucose. Finally, the residual solids are returned to the start of the process to be mixed with fresh biomass and the treatment cycle is repeated. The glucose solution can be concentrated locally to reduce volume and enhance transportation savings. The local operation can be done at farms or near regional centers prior to being transported to distant existing conventional fermentation facilities.