Single-group B-BAF filter tank device and sewage denitrification treatment method

The invention provides a single-group B-BAF filter tank device and a sewage denitrification treatment method, and belongs to the technical field of sewage treatment. The single-group B-BAF filter tank device comprises a water inlet and backwashing air inlet pipe 1, a water distribution chamber 2, a supporting layer 3, a filter material layer 4, a water outlet chamber 5 and a water outlet pipe 6 which are connected in sequence; a return pipe 7, abottom aeration pipe 8 and a middle perforated aeration pipe 9. The return pipe 7 is connected with the water inlet and backwashing air inlet pipe 1 and the water outlet pipe 6; the bottom aeration pipe 8 is arranged in the supporting layer 3; the middle perforated aeration pipe 9 is arranged in the filter material layer 4; and the filter material layer 4 contains bacillus. According to the single-group B-BAF filter tank device provided by the invention, bacillus is introduced, so that a bacillus dominant flora can be formed, anoxic and aerobic heterotrophic denitrific