Experiment of Continuous Ethanol Fermentation with a Pervaporation Membrane Bioreactor and TH-AADY

摘要

A free cell yeast bioreactor and a module with the novel composite silicone rubber membrane for continuously removing and concentrating the product ethanol from the broth by pervaporation were used to develop a continuous ethanol fermentation-pervaporation technology. The combined system consisted, of two integrated units: one was fermentation unit including free cell fermentor, membrane module and circulating path; the other was for condensation and recovery of the permeating ethanol vapor with condensers and vacuum pump. The effective membrane area was 0.024m~2. The membrane has a flux of over 1500g/(m~2.h) and a selectivity of about 9.5 (5% aqueous ethanol at 40℃). The affect of different temperatures on the fermentation was tested. The results show that the lower temperature is more suitable for TH-AADY to grow and produce ethanol. At the present time, due to impact of the centrifugal pump for circulating the broth through the bioreactor and membrane module on the yeast cell, continuous fermentation-pervaporation for long period in this system have not been achieved. New system should be design to avoid the disadvantageous impact. In experiments, PDMS membrane has shown high and stable separation performance.