Aerobic sludge digestion is a biological process that takes place in the presence of oxygen. With oxygen, bacteria present in the sludge (activated sludge) consumes organic matter and converts it into carbon dioxide. Prior to dewatering, solids that are produced in treatment undergo a digestion process. Solids from the primary clarifiers, as well as waste activated sludge, are directed to the aerobic digesters via a splitter box. Normally one basin is filling, while the other is in the digestion process, and its contents are being directed to the centrifuges for dewatering. Air provided by positive displacement blowers is added in high volumes to the two digesters to create aerobic conditions. Under these conditions, bacteria rapidly consume organic matter in the solids and convert it into carbon dioxide. Once the organic matter becomes limited, the bacteria die, become food for other bacteria, and the volume of sludge is reduced through this process of endogenous respiration.