Abstract: A filter for cleaning large quantities of contaminated gas, wherein the gas to be cleaned is passed through a filter medium which is spanned onto a drum. The retained contaminants are removed by a device which wipingly passes over the filter medium. The drum is fixedly connected with a conduit or line through which there is conducted the contaminated gas. The removal device comprises a compressed gas-blast device equipped with at least one jet nozzle and movable over at least part of the outer surface of the drum surrounds the periphery of such drum. The jet nozzle is directed towards the surface of the filter medium. Means serve for the withdrawal of the separated contaminants from the internal hollow space or compartment of the drum.