Experimental assessment of the integration of in situ removal of ethanol by pervaporation with a simultaneous saccharification–fermentation process

Abstract

ABSTRACTBACKGROUNDThe effect of process integration in bioethanol productivity was experimentally evaluated by coupling an ethanol‐selective pervaporation module to a simultaneous saccharification–fermentation process (SSF). Ethanol concentration in the permeate stream and ethanol productivity were evaluated. Polydimethylsiloxane (PDMS) and silicalite, pure and composite multilayer membranes, supported on porous stainless steel disks, were synthesized and used. Selectivity tests were conducted using ethanol–water mixtures and fermentation broths (5–12 wt% ethanol).RESULTSMultilayer composite membranes showed the best performance among the membranes studied; separation factor, permeance and ethanol concentration in the permeate stream were 31.4, 5.39 kg m−2 h−1 bar−1 (959 gas permeation units (gpu)) and 81.77 wt%, and 26.5, 5.02 kg m−2 h−1 bar−1 (894 gpu) and 77.41 wt%, with model solutions (12.76 wt% ethanol) and actual fermentation broths (11.69 wt% ethanol), respectively. The coupled pervaporator–SSF system, using silicalite‐PDMS multilayer composite membranes, achieved ethanol concentrations in the permeate up to 71.53 wt% and an increase of 3% in productivity with respect to the SSF process without in situ removal of ethanol; permeance and separation factor in the coupled system were 3.25 kg m−2 h−1 bar−1 (578.4 gpu) and 24.8, respectively.CONCLUSIONSThe integrated process improves bioreactor productivity and could reduce the energy penalty in the distillation process conventionally used in bioethanol production. © 2016 Society of Chemical Industry