The invention relates to a module, which allows a user to individually adapt its use to a respective task with regard to the treatment of fluids, taking advantage of the housings and connections of existing filtration devices without making any modifications. The module has one or more stacked cells, each having at least one opening, said cell opening or cell openings of the same type together forming at least one channel for the supply or discharge of the fluid to be treated. Each cell has two porous, flat components, which delimit an inner chamber and are traversed by the fluid, the inner chamber(s) being connected to the channel. The inner chamber of the cell or cells at least partially contains a treatment substance for the fluid. According to the method for producing a module of this type, a treatment material is introduced into the cells with a carrier fluid through the channel provided for supplying the fluid.