NOVELTY - The cage assembly comprises a main body provided with a first vertical baffle plate and a second horizontal baffle plate to form an inverted T-shaped baffle plate component, where the main body is divided into an anoxic zone, an aerobic zone and a settling zone. A clapboard is located at a bottom portion of the plate component, so that the waste water flows into the aerobic zone from the anoxic zone, where an upper part of the anoxic zone is provided with a water inlet. The aerobic zone is provided with a return channel. The settling zone is provided with a water outlet with an overflow pipe.    USE - Used as an integrated denitrification biological rotating cage assembly.    ADVANTAGE - The cage assembly has compact structure, occupies small floor area, does not need air circulation fan, and can be operated at low cost.    DETAILED DESCRIPTION - The cage assembly comprises a main body provided with a first vertical baffle plate and a second horizontal baffle plate to form an inverted T-shaped baffle plate component, where the main body is divided into an anoxic zone, an aerobic zone and a settling zone. A clapboard is located at a bottom portion of the plate component, so that the waste water flows into the aerobic zone from the anoxic zone, where an upper part of the anoxic zone is provided with a water inlet. The aerobic zone is provided with a return channel. The settling zone is provided with a water outlet with an overflow pipe. The cage assembly further comprises a transmission shaft, and a speed reducing box body that is connected with a motor. A first bearing and a second bearing are installed in the main body. A biological filler is installed in a lower part of the aerobic zone. The transmission shaft is located far away from the reduction box. A lifting device is located in the main body. The return channel is provided with a return pipe. The rotating cage is made of porous material having a particle size of 5-50 mm. The biological filler is provided with a biological film, where the shape of the filler is circular, oval or square. The anoxic zone is provided with a sludge discharge port. A sludge discharge port is located at a bottom portion of the settling zone. The first clapboard is provided with an opening. The main body is provided with a sealing device. The water inlet is provided with a fine grid. An INDEPENDENT CLAIM is included for a method for operating an integrated denitrification biological rotating cage assembly.