in order to provide a filter press which operates especially reliably and free of wear , a membrane for a membrane plate has a membrane surface enclosed by a membrane margin which is free of perforations . furthermore , a membrane plate has such a membrane . moreover , a chamber plate has a number of sludge inflows , each with an inflow orifice spaced apart from the chamber plate margin . finally , a plate stack has a number of membrane plates and / or a number of chamber plates and also a corresponding filter press .