DEWATERING CHARACTERISTICS OF AEROBICALLY DIGESTED SLUDGE

of several days during which time a large percentage of the solids are de stroyed by endogenous respiration. Also, during this period, materials re sistant to biod?gradation accumulate. To maintain satisfactory operation of the plant, sludge must be removed from the digester at regular intervals for ultimate disposal. The most com mon method of disposal for small in stallations involves dewatering and drying of the sludge on open-air sand beds. In a typical design of a waste treatment plant of this type, the di gestion compartment constitutes ap proximately 40 percent of the total plant volume and the sludge drying beds require about as much area as