TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Method: In the step (i), the perforated aeration tube in the anoxic zone stirs the raw material, so that the raw mater achieves the denitrification under the anoxic condition. In the step (ii), the concentration of dissolved oxygen in the aerobic zone is 1.8-2.5 mg/l, the level in the aerobic zone is increased by the aerator to form the level difference with the level in the anoxic zone. The nitration solution re-flows in the aerobic zone by the reflux pipe in the top of the aerobic zone to form the reflux solution. In the step (iii), the large particle condensate in the discharged water of the aerobic zone is naturally settled to the sludge zone, the other small particle condensate is settled to the sludge zone under the action of the efficient bevel board, so that the liquid and the condensate are separated. The separated clean water is discharged by a water discharge pipe. The residual sludge is discharged by a sludge discharge pipe arranged at the bottom of the aerobic zone and extending in the sludge zone. The sludge discharge pipe is used for emptying sludge in the aerobic zone.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The bevel board is arranged in the middle of the bevel board settlement zone. One end of the distribution energy dissipation tube is connected with the aerobic zone. The anoxic zone and aerobic zone are provided with a perforation aeration tube and an aerator, which are respectively connected with the blower. A sludge discharge pipe is arranged at the bottom of the anoxic zone. The outer end of sludge discharge tube penetrates through the outer wall of the anoxic zone. The inner end of sludge discharge tube penetrates through the aerobic zone and extends in the sludge zone. A biological filling is arranged in the aerobic zone and a reflux pipe is arranged at the top, where one end of the reflux pipe is arranged below the level in the aerobic zone, and the other end of the reflux pipe extends in the anoxic zone.