JPS5551496A - Device for deep layer aeration treatment of sewage - Google Patents

Abstract

PURPOSE:To increase the efficiency of sewage treatment with less axial power, axial impellers are provided in each of downward and upward routes in the sewage circulating route. CONSTITUTION:Down-flow axial impeller 2 is installed in the downward route 1a in the tank 1 and up-flow axial impeller 4 in the upward route 1b. When sewage in the tank circulates, the heads of the impellers 2, 4 cause the water level of the route 1a to fall and the water level of the route 1b to rise. The difference between the water levels allows the sewage falling into the route 1a to trap bubbles. The bubbles are crushed by the impeller 2 into finer bubbles and fall down through the route 1a. At high pressure zone of the bottom 1c, DO in the sewage is caused to increase, and at the fixed bed 3 microbe treatment is conducted. The water is then raised by the impeller 4 and discharged from the discharge pipe 6. At this time, the pressure in the route 1b reduces causing bubbles, and agitation of the impeller 4 separates SS attached to the bubbles. Thus, the device facilitates SS precipitation and collection from sewage charged in the tank 7.