Abstract: A process and apparatus is disclosed for treating waste water. After treatment, essentially no sludge remains for disposal. The treatment includes mixing the waste water with activated sludge solids in an aeration tank (15). The mixed liquor from the tank is then moved to a clarifier settling tank (17). About 5-25% of the activated sludge separated in the settling tank is returned to an aerobic digester (23) and treated for about 16-24 hours. The aerobic digester can be a batch unit or a continuous process unit. After treatment in the aerobic digester, the activated sludge solids are returned to the aeration tank (15).