Abstract: The invention relates to a device for the treatment of a material, in particular a web or material or pulp, which is made to pass between at least two endless, permeable belts, for instance screen belts or the like conveying means, in particular for the displacement washing of a filter cake or for washing fibrous matter, the material being made to pass between the belts along containers serving for the introduction or discharge of a treatment medium, for instance a wash liquid. The main object is to save energy and surface space requirement in the washing of filter cakes or the like, to reduce the production expenditure for such treatment devices and to increase the washing effect.