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

BACKGROUND The 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). RESULTS Multilayer 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. CONCLUSIONS The 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