NOVELTY - The device comprises a pre-processor (1), an anaerobic digestion reactor (2), a short-cut nitrification reactor (3), an anaerobic ammoxidation reactor (4) and a heat pump device comprising a refrigerant circulating system formed by connecting a compressor, a condenser, an expanding valve or a capillary tube and an evaporator in series using a bearing tube. The pre-processor is connected with a water inlet tube and the anaerobic digestion reactor. The anaerobic digestion reactor is connected with the short-cut nitrification reactor.    USE - The device is useful in sewage treatment process including denitrification and decarbonization for generating electricity.    ADVANTAGE - The sewage treatment device is capable of simply generating the electricity with less energy consumption.    DETAILED DESCRIPTION - The device comprises a pre-processor (1), an anaerobic digestion reactor (2), a short-cut nitrification reactor (3), an anaerobic ammoxidation reactor (4), and a heat pump device comprising a refrigerant circulating system formed by connecting a compressor, a condenser, an expanding valve or a capillary tube and an evaporator by a bearing tube. The pre-processor is connected with a water inlet tube and the anaerobic digestion reactor. The anaerobic digestion reactor is connected with the short-cut nitrification reactor. The short-cut nitrification reactor is connected with the anaerobic ammoxidation reactor. The anaerobic ammoxidation reactor is connected with a drainage tube. One channel of a first set of tubular heat exchanger (6) is used as the condenser, and the other channel of the first set of tubular heat exchanger is connected on a communicating tube of the preprocessor and the anaerobic digestion reactor. One channel of a second set of tubular heat exchanger is used as the evaporator of the heat pump device, and the other channel of the second set of tubular heat exchanger is connected on the drainage tube. A methane recovering device is connected to the anaerobic digestion reactor for recovering the methane. The methane recovering device is linked to a gas generator by a pressure pump tube, where the gas generator is electrically connected to the compressor of a heat pump system. An INDEPENDENT CLAIM is included for a sewage treatment process.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a sewage treatment device.    Pre-processor (1)    Anaerobic digestion reactor (2)    Short-cut nitrification reactor (3)    Anaerobic ammoxidation reactor (4)    First set of tubular heat exchanger. (6)