JPS6456191A - Denitrification structure for septic tank - Google Patents

Abstract

PURPOSE:To maintain a stable denitrification effect by providing an air lift pipe into an aerobic treatment chember, opening the bottom end of the pipe to the position above the air diffusion pipe of an aerator and returning part of the sewage under the aerobic treatment into an anaerobic treatment chamber. CONSTITUTION:The sewage flowing from an inflow port 4 into a 1st chamber 1a receives anaerobic decomposition during the passage through a downward current anaerobic filter bed 5. This sewage transferred to the lower side of an upward current anaerobic filter bed 9 and is again subjected to the anaerobic decomposition during the upward passage. The sewage is then transferred into the aerobic treatment chamber a3 and is aerobically decomposed by the air from the air diffusion pipe 13b of the aerator 13 until finally the cleaning of the sewage is executed. Part of the sewage under the aerobic decomposition treatment is lifted to an upper collecting inlet 14a by the air from the diffusion pipe 13b blown from below into the air lift pipe 14 and is thereby subjected to an air-water sepn. at this time. This sewage is continuously returned to the 1st chamber a1. The sewage in the 1st chamber 1a is, therefore, neutralized by the acidic sewage from the aerobic treatment chamber a3 and the propagation of the anaerobic bacteria in the 1st chamber a1 is not suppressed.