Concentration of ethanol from the fermentation broth is an energy-intensive process. Very high gravity (VHG) process with modified polyvinyl alcohol-immobilized Zymomonas mobilis cells integrated with in situ bioethanol removal via vacuum membrane distillation (VMD) was proposed to mitigate product inhibition effects in VHG fermentation. The proposed VHG + VMD system, at 300 g/L glucose loading, produced 127.4 g/L (16.1% v/v) ethanol, at 63.7 g/L-h productivity and 84.9% glucose conversion rate, which is the highest in reported literature. (C) 2017 Elsevier Ltd. All rights reserved.