TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Conditions: The secondary heat is administered individually to each pervaporation membrane of the pervaporation unit. The mixture is fed into a vaporizer and vaporized. A stream of vaporized mixture of ethanol and water from the vaporizer is fed to a heat exchanger unit (HEX1) for condensing. The mixture is cooled to condense in the heat exchanger unit arranged cooperative with unit (HEX7). A stream of liquid phase mixture (5) of ethanol and water is fed to each membrane of the membrane unit (MU) of the pervaporation process. The stream of mixture (5) of ethanol and water in the membrane unit in the pervaporation unit is divided into stream (I) of mixture of ethanol and water and the stream of vaporized mixture of ethanol and water from the membrane unit is fed, and into stream (II) of dewatered mixture of ethanol and water and fed. At a process location (6,HEX7,HEX10), the entering stream (5) of mixture of ethanol and water is heated to the pervaporation process temperature by the secondary energy restored from at least one of stream (I) and stream (II) directed through a heat exchanger (HEX1,HEX6) which is arranged to transfer thermal energy from at least one of stream (8) and stream (7) to at least one process location (6,HEX7,HEX10) downstream the vaporizer but upstream the membrane of the membrane unit of the pervaporation process. A semipermeable membrane, a porous membrane, a ceramic membrane, a membrane comprising a molecular sieve, and/or a membrane comprising a zeolite material is used in the membrane unit of the pervaporation process. The stream of mixture of ethanol and water in the membrane unit of the pervaporation unit in a pervaporation step is divided into a vaporized permeate stream of vaporized mixture of ethanol and water, which is fed, and into a retentate stream of dewatered mixture of ethanol and water, which is fed. The vaporized permeate stream of vaporized mixture of ethanol and water from the membrane unit is fed to a cooling unit which is implemented by at least one heat exchanger in heat exchangers, to direct at least a potion of the heat gained by cooling to the process location (6,HEX7) downstream from the vaporizer to heat the stream upstream the pervaporation unit. The vaporized permeate stream of vaporized mixture of ethanol and water is condensed in the cooling unit to a liquid permeate vaporized mixture of ethanol and water, and a liquid permeate stream of vaporized mixture of ethanol and water is fed to a distilling unit. The liquid permeate stream of vaporized mixture (8) of ethanol and water in the distilling unit in a distillation step is divided into a stream of vaporized mixture of ethanol and water and a stream of water. The process location to be heated comprises at least one membrane unit with one or several membranes in series in a pervaporation unit to be heated. The process location to be heated is heated indirectly by units (HEX10,HEX1,HEX9) and/or directly by unit (HEX7) arranged to heat the stream. A stream of the column bottom product water to be disposed is fed to heat exchanger (HEX10) to be used as a source of heat energy for secondary energy for utilization in a process location (6,HEX7) for pervaporation. A stream of high-concentration ethanol is fed into heat exchanger (HEX1) for utilization as a source of heat energy for secondary energy. Preferred Arrangement: A pervaporation unit is provided for splitting a stream of mixture of ethanol and water into a water-rich permeate stream (8) as flow (I) and an ethanol-rich retentate stream (7) as flow (II). A distillation unit is provided for vaporizing the water-rich permeate stream and for splitting the water-rich permeate stream into a water-rich bottom discharge stream and an ethanol-rich top discharge stream. At least one heat exchanger (HEX1,HEX10) is arranged so that at least one of streams (7,8) is directed through heat exchanger (HEXI,HEX10) for transferring thermal energy as secondary energy from streams (7,8) to at least one process location (6,HEX7) downstream the vaporizer but upstream the membrane unit of the pervaporation process. Conduit (I) is provided for feeding a stream of vaporized mixture of ethanol and water from the vaporizer to heat exchanger unit (HEX1) for condensing the vaporized mixture to liquid phase. Conduit (II) is provided for feeding a stream of the mixture of ethanol and water from heat exchanger unit (HEX1) to a pervaporation unit for dividing the stream of mixture (5) of ethanol and water into a stream (8) of vapor-phase ethanol and water and into a stream (7) of dewatered mixture of ethanol and water. At least one heat exchanger is arranged to be operable as a two-phase device so that it comprises unit (I) for phase (I) arranged to condense the mixture from vapor phase to liquid phase, and unit (II) for phase (II) to cool the fluid either at a process location where the vapor phase is dominantly present or the liquid phase is dominantly present. The pervaporation unit is configured to divide the stream of liquid phase mixture of ethanol and water in a pervaporation step into a vaporized permeate stream of the mixture (8) of ethanol and water and into a retentate stream of dewatered mixture (7) of ethanol and water. Conduit (IV) is provided for feeding the vaporized permeate stream of vaporized mixture (8) of ethanol and water from the membrane unit to cooling unit for condensing and/or cooling the vaporized permeate stream of vaporized mixture (8) of ethanol and water to a liquid permeate mixture of ethanol and water. Conduit (V) is provided for feeding a liquid permeate stream of vaporized mixture of ethanol and water from cooling unit into a distilling unit for dividing the liquid permeate stream of vaporized mixture of ethanol and water in a distillation step into a stream of vaporized mixture of ethanol and water and into a stream of water. The process location comprises at least one membrane unit at the process location. The apparatus comprises a reflux line arranged for a reflux flow from heat exchanger (HEX1) location of the process to the vaporizer. The apparatus consists of heat exchanger (HEX9) arranged to be cooperable with another heat exchanger (HEX7) to control the heating of the membrane unit.