Abstract: The support material (27) in the reactor is uniformly subjected, over the height of the reactor bed, to a gas flow ensuring supply and evacuation. The biological film reactor (22) can be fed with oxygen, hydrogen and/or carbon dioxide. The reactor (22) is in the form of a fluidized bed and has an inlet (42) near the floor of the reactor and an outlet (33) near the top. Located in the fluidized bed (32) between a distribution network (4) for the inlet water and the outlet (33) is a material exchanger (15) consisting of a support frame (20) on which is fitted a thin-walled pipe (26) of roughly helicoidal shape, made of non-porous plastic and having its turns (34) spaced at intervals. The pipe is connected to a gas supply device (35). An absorber (12) can be connected to the gas supply line (36).

Abstract: A method of improving the backwashing of fixed beds formed of granular materials and used during waste water purification or water treatment, wherein the fixed bed, during the course of the backwashing thereof, is maintained during a predetermined time duration filled with a quiescent liquid. This liquid contains at least one substance which is distributed as uniformly as possible therein. In the presence of a spontaneous, catalytically triggered decomposition reaction, this substance releases a gaseous component. Then, the fixed bed is backwashed with water.

Abstract: A method of improving the operation of backwashable fixed beds formed of granular materials and used during purification of waste water of sewage or during water treatment, wherein the fixed bed is conditioned during a last step of the backwashing operation by filling the fixed bed with a liquid for a predetermined time duration. The liquid contains distributed as uniformly as possible therein at least one substance which in the presence of a catalytically triggered decomposition reaction gives off a gaseous component and thereafter the liquid to be treated is filtered.