Abstract: Low aliphatic alcohols or organic solvents, especially ethanol are continuously produced by fermentation from sugar containing nutrient substrates. The process includes two fermentation steps or stages in which the substrate is subjected to the effects of microorganisms such as yeast. The first fermentation stage has a volume of 10 to 20% of that of the second fermentation stage. By adjusting the environmental conditions in each stage a large cell growth with a small portion of the total supplied substrate quantities takes place in the first activation stage and a high product formation rate is achieved with a considerably larger portion of the entire supplied substrate quantity in the second production stage. A partial outflow stream from the first stage is microfiltered and the permeate as well as the unfiltered outlet flow of the first stage, is directed into the second stage.

Abstract: For the separation of suspensions in the form of liquid solid component mixtures with the aid of porous filter membranes or for the separation of suspensions free of solid components into the liquid components with the aid of solution diffusion membranes, a reduced pressure is produced on the permeate side of the membrane. For this purpose the permeate is sucked off by a jet pump and is transferred into a closed circuit flow in which it serves as a drive medium for the jet pump. The apparatus for performing the method includes a membrane filter arrangement (6) with a closed circuit conduit (11) connected to the permeate discharge conduit. A conveying pump (13) and a jet pump (10) as well as a collecting container (12) is arranged in the closed circuit conduit. The permeate discharge conduit is connected with the jet pump.

Abstract: A method for separating a liquid/liquid suspension with the aid of a solution diffusion membrane provides for producing such a reduced pressure on the permeate side that the permeate evaporates and that the permeate is then again condensated back into the liquid state. In order to require a small energy input and to provide advantageous conditions for a sterile operation, it is provided that the permeate passing through the membrane is subjected to the suction effect of a jet pump and that the evaporated permeate is condensed in the drive jet of the jet pump. The permeate is supplied into a closed circuit flow in which it functions as the drive medium for the jet pump.

Abstract: This invention relates to a method for separating organic compounds, particularly lower aliphatic alcohols from fermentation fluids. This is accomplished by the use of a two-step extraction process whereby said lower aliphatic alcohols are selectively extracted from said fermentation fluids by a first solvent. The fermentation fluids from which the lower aliphatic alcohols have been extracted contain some of this first solvent. Therefore, a second solvent, which substantially differs from the first solvent in polarity is employed to extract the residual amounts of first solvent from said fermentation fluids. Then, the fermentation fluids, thus purified, can be returned to the fermentation process without the danger of toxic influences on the fermentation by the presence of said first solvent.