THE DESIGN OF A MEMBRANE-BASED INTEGRATED ETHANOL-PRODUCTION PROCESS

By applying pervaporation and microfiltration to an ethanol fermentation, the substrate consumption was greater by a factor of two and the productivity by a factor of 15 than that in a conventional continuous culture. The fermentation data can be described adequately by a kinetic model. The membrane techniques are relatively easy to operate, and fouling occurs in microfiltration modules, but not in pervaporation modules. Simulations show that the fermentation performance can further be improved and that the process configuration can be optimized to reduce the membrane area. On a large scale a membrane area as high as 2000-3000 m2 may be needed, which may give rise to logistic problems. With the presently available equipment, commercial ethanol production with membrane-based integrated systems is not economically feasible. The flux of existing pervaporation membranes may be acceptable; however, the selectivity is still too low to make pervaporation competitive with other separation techniques. © 1991 Humana Press Inc.