Abstract: A method and apparatus for treatment of waste on ships and the like, in the form of solid waste and black water collected in a tank from reduced flush toilets. The solid waste is mixed with black water from the tank in a drum. Rotating knives in the drum effect the disintegration of the solid waste, and also the picking up of the waste in the drum from the bottom thereof to permit it to drop repeatedly by gravity from the upper regions of the drum. A flow of hot air is passed through the drum and hence through the dropping mixed black water and disintegrated solid waste. The axis of the drum is substantially horizontal, and may be slightly inclined with bottom ridges to inhibit the flow of liquids therealong.