PROCESS FOR THE DIRECT PRODUCTION OF FERMENTATION PRODUCTS FROM BIOMASSES IN A BIOFILM REACTOR

摘要

A dense but oxygen permeable membrane (28) separates the oxygen supply compartment (30) from the fermentation compartment (31), which contains all microorganisms, a nutrient medium and the pretreated lignocellulose. The oxygen, necessary for the growth and the activity of the aerobic cellulolytic enzymes producing microorganisms is solely transported from the oxygen supply compartment (30) through the membrane (28), which leads to an oxygen gradient within the biofilm growing on the membrane (28). The oxygen rich zone of the biofilm lies on the membrane (28) whereas the biofilm further away from the membrane as well as the surrounding nutrient medium are oxygen depleted. In the aerobic biofilm the extra-cellular enzymes are produced in situ and are released into the nutrient medium where they hydrolyse the cellulose and hemicellulose into soluble monosugars, which are then converted to the desired fermentation product by suitable microorganisms in the anaerobic zones of the reactor (21). The process can be run in batch mode as well as in a continuous mode.