Abstract: A dialysis membrane is made of a regenerated cellulose polymer in the form of a hollow fiber with a continuous internal cavity filled essentially with a gas. The hollow fiber has a porous inner and an outer surface. The outer surface of the hollow fiber is formed by a thin skin which has fine lengthwise grooves. The inner surface of the hollow fiber is positively modified by physical and/or chemical means.The invention also includes a method for manufacturing such a dialysis membrane.

Abstract: A cross-counter-stream module for material and/or heat exchange done with a hollow filament bundle cast into a housing at its ends and a mechanism for conducting the material flow to the outside of the hollow filaments. The hollow filaments are cast at their ends as a stack into a housing, the stack being composed of one or more layers which consist of strata of hollow filaments fixed in a plane through cross-pieces transverse to their lumen directions, the cross-pieces being arranged tightly superimposed at all locations inside one layer, disposed at predetermined constant intervals, with the intermediate spaces between the hollow filaments filled by the cross-pieces at the places of crossing, and with the cross-pieces composed of a polymer with a melting point from 80.degree. to 190.degree. C. and a residual adhesion at room temperature. Preferably, the polymer is a polyamide, a polyethylene, a copolymer of polyethylene and vinyl acetate, or a copolyether-ester.

Abstract: Fermented beverages of a reduced alcohol contents are made by causing the fermented beverage having a normal alcohol contents as produced in the fermentation to flow along one face of a dialysis membrane at a pressure differential below 5.0 bar while simultaneously a dialysate liquid which is substantially alcohol-free is passed along the other face of the dialysate membrane. An apparatus for carrying out the process comprises a housing in which two separate chambers are provided. Each chamber has separate inlet and outlet ducts. The inlet ducts are connected to separate feeding devices for liquids. Separate regulating devices are arranged for regulating the flow through each of said two chambers and means are provided for regulating the pressure differential between the two chambers.