Sewage treatment device and sewage treatment system

The invention relates to a sewage treatment device and a sewage treatment system. The sewage treatment device comprises an anaerobic tank, an anoxic tank, an aerobic tank and a sedimentation tank which are communicated in sequence. The sedimentation tank is further communicated with the anaerobic tank, a first aeration device is arranged in the aerobic tank, and an aeration port of the first aeration device is arranged close to the middle line of the depth of the aerobic tank. The aeration direction of the aeration port deviates from the bottom of the aerobic tank, so that an aerobic zone is at least formed above the first aeration device, and an anoxic zone is formed below the first aeration device, so that sludge in the aerobic tank is accumulated in the anoxic zone for forming a carbon source. The space occupied by the aerobic zone in the aerobic tank is larger than that of the anoxic zone in the aerobic tank, so that the sewage treatment device provided by the invention can automatically generate a carbon