Biochemical reactor

The utility model discloses a biochemical reactor which comprises a biochemical reaction structure, a three-phase separation structure and a drainage structure, a part or all of the anaerobic reaction zone of the biochemical reaction structure and/or a part or all of the anoxic reaction zone are/is distributed below the aerobic reaction zone; the three-phase separation structure comprises a baffle assembly, the baffle assembly is installed above the aerobic reaction area and forms a settling area located above the three-phase separation structure, and the baffle assembly is provided with a non-vertical flowing gap communicating the aerobic reaction area with the settling area; the drainage structure comprises an overflow assembly, the overflow assembly is provided with overflow grooves arranged at intervals, and supernate in the settling area flows into the overflow grooves from overflow ports in the overflow grooves and then is discharged out of the biochemical reactor. In the biochemical reactor, the three-