SEPTIC TANK

PURPOSE:To uniformize the flow of sewage to the 1st chamber of a cleaning tank provided with an anaerobic treatment chamber consisting of the 1st chamber and 2nd chamber and an aerobic treatment chamber by disposing plural flow transfer pipes in the positions equidistant from a sewage inflow pipe to the partition wall which partitions the 1st chamber and the 2nd chamber. CONSTITUTION:The sewage flowing from the inflow port 4 into the 1st chamber a1 receives anaerobic decomposition during the passage through a downward current anaerobic filter bed 5 and the solid matter in the sewage sticks to the filter media and receives the anaerobic decomposition. After the coarse solid matter of this sewage is settled in the bottom of the 1st chamber a1, the sewage is passed through the 1st and 2nd flow transfer pipes 10, 11 and is transferred to the lower part of the upward current anaerobic filter bed 9 of the 2nd chamber a2 where the sewage passes from below to above and again receives the anaerobic decomposition. This sewage is further sent into the aerobic treatment chamber a3 and is finally cleaned. The 1st and 2nd flow transfer pipes 10, 11 provided to the partition wall 1 are disposed in the positions equidistant from the sewage inflow port 4 and, therefore, the flow of the sewage in the 1st chamber a1 is uniformized in all parts and the generation of channeling is prevented.