Returned sludge elutriation process of biological sewage treatment system

Abstract

The invention provides a returned sludge elutriation process of a biological sewage treatment system. A sludge return pump conveys a sludge mixture in a secondary sedimentation tank to a hydraulic cyclone separator; under the dynamic action of the sludge return pump, the hydraulic cyclone separator separates impurities such as large-density particles in returned sludge, and the separated low-density sludge mixture enters into a filtration screen through an overflow port in the upper end of the hydraulic cyclone separator; the filtration screen separates out substances such as large granular paper scraps, plant fibers and fur in the sludge mixture, and the screened returned sludge enters into a sludge activation tank so as to be subjected aeration activation treatment; the activated returned sludge enters into an aeration tank, active microbial populations in the returned sludge are increased, so that the sludge load in the aeration tank is improved, and thus the sewage treatment efficiency is improved; during the whole elutriation process, the sludge return pump is needed to lift only one time, facility required for the process can be simplified, the energy consumption can be reduced and the operating expense is reduced.

Description

technical field [0001] The invention relates to an urban sewage treatment system, in particular to an elutriation and activation process for return sludge in an urban sewage activated sludge treatment system. Background technique [0002] In the urban sewage treatment system, the sewage is generally treated by the pre-set grit chamber and primary sedimentation tank, then enters hydrolytic acidification or anaerobic treatment, and then enters the aeration tank for aerobic biological treatment. Aerobic biological treatment mainly includes activated sludge Method and biofilm method, the sewage enters the secondary sedimentation tank after aerobic biological treatment in the aeration tank, and realizes the solid-liquid separation of mud and water. After the solid-liquid separation, the sewage meets the standard discharge or undergoes advanced treatment, and the sludge enters the corresponding subsequent treatment process . [0003] The activated sludge in the activated sludge m...

AI Technical Summary

Problems solved by technology

The existing sludge return method is to use a sludge return pump to directly pump a certain amount of sludge in the secondary settling tank into the aeration tank. Since the sludge mixture in the secondary settling tank contains inorganic substances, including the grit chamber and the primary The sedimentation tank cannot remove the denser fine particle sediment, the lower density paper scraps, plant fibers and hair, etc., and the sludge containing these inorganic substances will be directly returned to the aeration tank, which will aggravate the inorganic components in the aeration tank. The accumulation and increase of organic matter will lead to a further reduction in the content of active microbial populations with metabolic functions, thereby affecting the treatment effect of sewage in the aeration tank

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