Energy efficient of ethanol recovery in pervaporation membrane bioreactor with mechanical vapor compression eliminating the cold traps

An energy efficient pervaporation membrane bioreactor with mechanical vapor compression was developed for ethanol recovery during the process of fermentation coupled with pervaporation. Part of the permeate vapor at the membrane downstream under the vacuum condition was condensed by running water at the first condenser and the non-condensed vapor enriched with ethanol was compressed to the atmospheric pressure and pumped into the second condenser, where the vapor was easily condensed into a liquid by air. Three runs of fermentation-pervaporation experiment have been carried out lasting for 192 h, 264 h and 360 h respectively. Complete vapor recovery validated the novel pervaporation membrane bioreactor. The total flux of the polydimethylsiloxane (PDMS) membrane was in the range of 350 g m−2 h−1 and 600 g m−2 h−1. Compared with the traditional cold traps condensation, mechanical vapor compression behaved a dominant energy saving feature.