METHOD AND APPARATUS FOR STABILIZATION OF RETURN SLUDGE CONCENTRATION

摘要

PURPOSE:To perform a series of activated sludge treatment stably and advantageously, by returning the return sludge of which concentration is stabilized to the aeration tank without causing bridge phenomenon in the lower part of the sludge precipitation tank. CONSTITUTION:When an air pump 2 is operated and a valve V4 is gradually closed, the sludge layer in a communicating tube 3 is forced out to the side of a sludge precipitation tank 5. This operation is continued until the level of the sludge layer 12 in the communicating tube 3 reaches level L. Simultaneously with this operation, the settling sludge layer 12 in the sludge precipitation tank 5 is pushed up by the extent corresponding to the shift of the sludge in the communicating tube 3, thus moving until the original level l' reaches level L'. Afterwards, when the valve V4 is opened and the vapor phase part in the communicating tube 3 is returned to the atmospheric pressure, the level L' in the settling sludge layer 12 returns to l', while the level of the sludge layer in the communicating tube 3 also returns from L to l. By repeating this operation, the sludge bridge phenomenon in the lower part of sludge precipitation tank 5 is broken, so that the return sludge may be returned to the aeration tank always stably through a sludge return pipe 9.