Deep bed denitrification filter tank

The utility model discloses a deep bed denitrification filter tank. The device comprises a tank body, an air disc and a sealing door, wherein a water inlet pipe is mounted at the upper end of the tankbody; a transverse plate is mounted at the upper end of the interior of the tank body; a hard siliceous sand filter material box is arranged below the transverse plate; a circular hard siliceous sandbox is arranged below the hard siliceous sand filter material box; a biological membrane is mounted below the round hard silica sand box; the transverse plate, the hard siliceous sand filter materialbox, the circular hard siliceous sand box and the biological membrane are connected with the tank body through mounting blocks; an air disc is located at the bottom of the pool body, an air outlet hole is formed in the upper end of the air disc, a fixing pipe is fixedly installed at the lower end of the air disc and connected with an air conveying pipe through a connecting pipe, a sealing door isinstalled at the left end o