SEWAGE TREATMENT SEPTIC TANK

摘要

PROBLEM TO BE SOLVED: To always keep the filtering capacity of sewage well by enhancing the washing effect of a carrier (filter material) in a sewage treatment septic tank. SOLUTION: A biological filter tank D is provided so as to communicate with a carrier fluidizing tank C on the upper side thereof and a treated water tank E on the bottom side thereof and constituted of a filter tank portion 24 packed with a carrier (n) and the sheath pipe portion 25 provided to the side wall of the filter tank portion 24. The sheath pipe portion 25 is formed in a bottomed tubular state at a position where sewage flows in from the filter tank portion 24 when a water level becomes constant so as to be provided with a backwashing water transfer port 35. A suction pipe 30 having a water suction port 30a at its lower end is vertically inserted in the sheath pipe portion 25 and an air lift pomp is connected to the upper end of the suction pipe. When the carrier is washed, sewage is sucked up from the water suction port 30a by the air lift pump to generate water level difference between the biological filter tank D and the treated water tank E and clean treated water is introduced into the filter tank portion 24 by the water level difference to form an ascending flow to wash the carrier (n).