Abstract: A self-contained, recirculating flush liquid, type of water closet for passenger aircraft; wherein, the means for periodically draining the contents of the waste holding tank, comprises an inverted U-shaped tube which is separated at the bend of the U-shape or elbow thereof, into approximately two half-parts. These half-parts are joined by a movable or flexible connection in order that one of the half-parts can be moved relative to the other half-part. One end of the U-shaped tube is rigidly fixed to and projects out from the bottom of the tank; and the other movable half-part has an intake nozzle opening which when it is positioned at the bottom surface of the tank, it is at an operative waste removal position, and when it is moved to a raised position where the intake nozzle opening is at the top of the tank, the removal of waste from the tank is prevented.

Abstract: A vacuum flush waste disposal system for aircraft; wherein, the required vacuum is acquired at altitude through the differential pressure between the aircraft cabin pressure and the ambient pressure above approximately 15,000 feet. When the aircraft is below this altitude or on the ground, the vacuum is provided by a blower. For flushing the toilet bowl, a timing device is initially actuated and functions: to introduce a recirculated flush fluid into a flush ring in the upper portion of the toilet bowl; and to open a drain in the lower portion of the toilet bowl, leading to the vacuum waste line; whereby, the waste and flush water are rapidly propelled through the waste line towards a centrally located holding tank, by the differential pressure acting upon it. Once in the holding tank, the waste fluid is filtered out for further use as the recirculated flush fluid.