Abstract: A system for reducing emission of nitrous oxide during sewage treatment, including: a regulating pool, a first aerobic constructed wetland, an anoxic pool, and a second aerobic constructed wetland. The water outlet of the regulating pool is connected to the water inlet of the top of the first aerobic constructed wetland via a pipe and a first control valve. The first aerobic constructed wetland includes sequencing batch constructed wetlands arranged in parallel. A branch pipe and a second control valve are disposed on the pipe between the regulating pool and the first aerobic constructed wetland. The outlet of the branch pipe and the water outlet of the first aerobic constructed wetland are combined together and connected to the water inlet of the bottom part of the anoxic pool. The anoxic pool is an upward flow biological filter.

Abstract: A reactor for sewage treatment including: an inner layer including a water distribution zone; a middle layer including a biological aerated filter, the biological aerated filer including a wall and a bottom including a water outlet; and an outer layer including an artificial wetland, the artificial wetland including a bottom including a water inlet. The water distribution zone, the biological aerated filter, and the artificial wetland are in the shape of a circle. The sewage is introduced into the water distribution zone via a water inlet pipe. The water distribution zone communicates with the biological aerated filter via a first overflow. The water outlet arranged on the bottom of the biological aerated filer is connected to the water inlet arranged on the bottom of the artificial wetland to allow the biological aerated filter to communicate with the artificial wetland.