also possible to use a single condenser operating with temperature gradients in fermentation vessel 2 the low concentration condensate 31 is mixed by means of a pump 15 and while taking up heat 16 with the mash 1 flowing toward pervaporator 5 condensate 32 which has been enriched to more than 60 etoh is conducted from condenser 12 to a buffer vessel 17 from which it can be processed further to make the alcohol absolute the ethanol is conducted into a second pervaporation system 21 for this purpose the ethanol is pumped by means of a pump 19 and conducted through heat exchangers 20 to the second pervaporator 21 through which it flows the water is removed from the flowing ethanol water mixture by the installation of a suitable semipermeable membrane a membrane of type b as described below is used the concentrated retentate 22 or 34 in fig1 leaves the system as absolute alcohol product while giving heat to the intake here again heat must be supplied to pervaporator 21 by means of a heating stream 23 applying a vacuum by means of a vacuum pump 24 produces a permeate vapor which depending on the type of semipermeable membrane employed has an ethanol content of from about 20 to about 50 by volume the permeate vapor may be conducted by way of a pipeline 29 or 36 in fig1 to.