A rotary drum filter is a mechanical filtration device used in industrial and municipal wastewater treatment applications. It consists of an inclined cylindrical drum that is partially submerged in a tank of wastewater. Inside the drum is a series of filter screens and a rotating brush. As the drum rotates, the wastewater passes through the screens and the brush cleans the screens, removing any solids that are trapped. The solids are then removed from the wastewater and disposed of. The filtered wastewater is then collected in a separate tank for further treatment.