Sediment collecting pipe of biogas slurry, water and fertilizer integrated field returning device

The utility model discloses a sediment collecting pipe of a biogas slurry, water and fertilizer integrated field returning device, which is arranged at a preset position behind a 90-degree turning position of a main pipeline of the biogas slurry, water and fertilizer integrated field returning device from the vertical direction to the horizontal direction, and comprises a vertical collecting pipe extending downwards, the gradual change connecting part is used for connecting the vertical collecting pipe and the horizontal main pipeline; the lateral cross section of the gradual change connecting part is a T-shaped three-way pipe with a lower corner in a fillet transition shape; the transverse section of the gradual change connecting part in the flow direction is in a shape of an ellipse with a semicircular upper part and a gradually elongated longitudinal axis until the gradual change connecting part is communicated with the vertical collecting pipe and then is in smooth transition with the vertical pipe wall o