Studies were carried out to improve the effectiveness and cost-effectiveness of a semi-continuous ethanol fermentation of lactose mash combined with a pervaporation module. During a 20-day fermentation/pervaporation with an immobilized biocatalyst, the fermentation of the lactose mash (12%) averaged 4.56% m/v EtOH. In the circulation pervaporation module, ethanol from about 2000 g portions of the fermented mash was removed to below 0.7% m/v in 10-12 h. The effectiveness of ethanol separation (Dr) ranged between 88 and 95% and was determined by the ethanol concentration in the fermented mash. The productivity of 15.6% m/v ethanol obtained in such a system was about 530 g/day. The PDMS-PAN-PV membrane applied in the pervaporation system proved to be highly selective towards ethanol (a > 8) and exhibited very advantageous permeation properties (J = 2600-3500 g/m(2) x h). (c) 2006 Elsevier Ltd. All rights reserved.