Abstract: A process and a stationary dredging apparatus for periodically removing marine or river sediment of relatively high density from the bottom of an arm of the sea, a channel or a harbor basin by means of a stationary dredging means consisting of a substantially horizontal intake duct, which may be positioned at the bottom of a mud trap, an individual riser pipe operating either on the principle of an air-lift pump, or by aspiration of a mechanical pump, optionally according to a preestablished programme by regulating the air-arrival or the opening of the valves of the riser pipes, and a delivery pipe.