Abstract: A permanently hydrophilic membrane on an aromatic polysulphone basis and a method for its production. Due to their chemical and thermal resistivity and also because they are unobjectionable with respect to their contacting foodstuffs, membranes on an aromatic polysulphone basis represent a preferred filtration material. But since they are hydrophobic, they would have to be hydrophilated before they are used. Known hydrophilation methods were insufficient to maintain the hydrophilic properties of the membranes, especially after repeated sterilization. The new method aims at making the membranes permanently hydrophilic under sterilization conditions. In an aftertreatment step, the membranes on an aromatic polysulphone basis are conducted, before or after drying, through an impregnating bath of polyvinylpyrrolidone, a copolymer of vinylpyrrolidone and one or more hydrophobic monomers and peroxodisulphate, then heated to 70 to 150.degree. C. and cooled down again.

Abstract: A regenerable deep bed filter element and method for making it, the element being provided as a closed system, in the case of which a deep bed filter (21), disposed inside at least one hollow-cylindrical chamber (17), is formed by a bulk material filling of regenerable, filtration-active substances of a particulate and/or fibrous structure. The hollow-cylindrical chamber accommodates radial flow by means of porous inner and outer peripheral walls (18, 19). The deep bed filter can be either washed, or regenerated by flushing back with water, steam or chemical cleansing agents, during which the filtration-active substances remain inside the chamber (17).

Abstract: A filter cartridge with a filter element inserted in a receiving space formed by a central cylindrical flow pipe 32 and a peripheral wall 34 is in terms of its possibilities of use and possibilities of adaptation to filtration problems substantially improved in that the filter element consists of fleece-like filter material and in that in its radial direction it comprises mutually enclosing zones of different filtering properties. For practical purposes, these zones can follow one another without any transition or they may be constructed with filtering properties which are varied in stepwise fashion. The filter element can be formed by the combination of a pleated filter fleece with a rolled-up filter fleece, the pleated part of the filter element being optionally on the inside or the outside.

Abstract: A regenerable deep bed filter element provided as a closed system, in the case of which a deep bed filter (21), disposed inside at least one hollow-cylindrical chamber (17), if formed by a bulk material filling of regenerable, filtration-active substances of a particulate and/or fibrous structure. The hollow-cylindrical chamber can be flowed through radially by means of porous inner and outer peripheral walls (18, 19). The deep bed filter can be regenerated by flushing back with water, steam or chemical cleansing agents, during which the filtration-active substances remain inside the chamber (17).