Ethanol Fermentation Coupled with Pervaporation by Energy Efficient Mechanical vapor Compression

Abstract

Abstract Ethanol production could be enhanced with ethanol removal in situ from the broth, during the experiments of ethanol fermentation coupled with pervaporation by mechanical vapor compression. The yeast cell could continuously grow for long time with cell density of 38 g/L obtained. The byproducts accumulation in the broth led to the culture deterioration of the fermentation and became the main inhibitor against the cell growth. The total flux of the polydimethylsiloxane (PDMS) membrane was in the range of 350 g/m 2 /h and 600 g/m 2 /h. At the downstream of the membrane, part of the permeate vapor under the vacuum condition before the inlet of the vacuum pump was condensed at the first condenser by the running water at the room temperature and the non-condensed vapor enriched with ethanol was compressed to the atmospheric pressure and pumped into the second condenser by the vacuum pump. The vapor in the second condenser was easily condensed into a liquid by air at room temperature since the pressure was increased. Ethanol concentration of over 50wt% could be obtained in the second condenser, which could greatly reduce the amount of the waste water treatment. Recovery of the permeate vapor heat would be achieved by the use of mechanical vapor compression heat pump, which could evidently save energy.